Home Physical Sciences Mechanical and microscopic properties of fiber-reinforced coal gangue-based geopolymer concrete
Article Open Access

Mechanical and microscopic properties of fiber-reinforced coal gangue-based geopolymer concrete

  • Zhong Xu EMAIL logo , JiaNing Wu , Min Zhao , ZhiJie Bai , KunYun Wang , JieWei Miao and ZhuoYue Tan
Published/Copyright: January 19, 2022
Become an author with De Gruyter Brill

Abstract

In order to explore the engineering application potential of coal gangue-based geopolymer concrete (CGGPC), this article formulated the fiber-reinforced coal gangue-based geopolymer concrete (FRCGGPC). The mechanical properties of the specimens were tested to analyze the effects of different types and dosing amounts of fibers on the mechanical properties of CGGPC. The microscopic morphology of the specimens was observed by scanning electron microscopy (SEM) to analyze the strengthening mechanism of fibers on the mechanical properties of the CGGPC. The experimental results show that the splitting tensile strength of FRCGGPC can be improved obviously, but the improvement of compressive strength is not obvious. The control groups containing steel fiber (SF) and polyester fiber (PF) had peaks in their compressive strength. Under the same dosage, the effect of SF and PF on the splitting tensile strength of FRCGGPC is better than basalt fiber. The results of SEM analysis show that within a certain range of dosage, the fiber is closely combined with the matrix, which has a good force transmission effect and strengthens the matrix material. When the fiber dosage is too much, it is easy to agglomerate, which leads to the decrease in the mechanical properties of the specimens.

1 Introduction

Geopolymer is a new type of green engineering material developed in recent years, first discovered and named by French scientist Prof. Joseph Davidovits in 1970s [1,2,3], which is formed by inorganic aluminosilicate natural minerals or solid wastes as raw materials under alkaline exciter conditions by appropriate process. Since the concept of geopolymer was proposed, scholars have been greatly interested. A large number of studies have shown that geopolymer materials have excellent mechanical properties and durability [4,5,6], a wide range of raw materials, simple processes, low production energy consumption, and low pollution. It is an environmentally friendly green building material, which can be widely used in construction engineering [7], traffic engineering [8], etc. At present, research on geopolymer concrete (GPC) is still relatively scattered, and the engineering application is also limited due to the lack of systematic theoretical support and sufficient experimental data [9,10,11,12,13,14,15]. Therefore, the targeted comprehensive performance test and mechanism analysis of GPC are the key works and research points that need to be carried out urgently at this stage.

At present, among the many experimental explorations of GPC, scholars more often use fly ash (FA) [16,17], slag [18,19,20], and metakaolin [21,22] as cementitious material to prepare new GPC in order to improve the mechanical properties and durability of GPC. However, for coal gangue (CG) as an important geopolymer raw material, relatively few researchers carry out mechanical properties test, and carry out inadequate mechanistic analysis [23,24,25]. As one of the industrial wastes with the largest emissions all over the world, CG is mainly composed of aluminosilicate minerals and carbon, rich in silica and alumina and abundant in reserves. It can also be used to prepare GPC by mixing with other silica-alumina raw materials to optimize strongly. The mechanical properties of GPC can be complemented by the characteristics of different materials. Geng et al. used low-calcium red mud and physically excited kaolinite CG as raw materials to prepare dual-doped geopolymers. The experimental results proved that the strength of the geopolymer synthesized by mechanical grinding and pre-activation was relatively higher [26]. Huang et al. mixed calcined CG, granulated slag, and lime to prepare geopolymer [27]. The experiment proved that the low dosage of active calcium in CG was the reason for the low strength of geopolymer. The increase in the granulated slag and lime would increase the dosage of active calcium and the strength. Zhang et al. proved through experiments that destroying the stable kaolinite structure and improving the activity of CG is one of the effective methods to change the reactivity of CG. By this way, CGGPC can improve its comprehensive mechanical properties [24]. The above studies show that it is feasible to prepare CGGPC meeting the performance requirements by mixing CG with other silica-alumina raw materials under the premise of ensuring the activity of CG. Further exploration of engineering performance is the basis for the popularization and application of CGGPC.

In the exploration of the engineering performance of GPC, low strength and brittle failure characteristics are the biggest problems faced currently. Many scholars have carried out tentative explorations to solve the problem [2832]. Saranya et al. found that steel fiber (SF) enhances the engineering and durability properties of ground granulated blast-furnace slag-Dolomite GPC and explained how to improve the bond strength and impact resistance by adding SF [33]. Sahin et al. analyzed the influence of different proportions of basalt fiber (BF) on metakaolin-based GPC mortar produced with different aggregate types. The results show that BF had a positive effect, especially with the best performance when 0.8–1.2% is used [34]. Research by Gao et al. showed that polyester fiber (PF)-reinforced polymer composites as lateral confining materials can improve the strength and ductility of the recycled aggregate concrete significantly [35]. The above studies show that it is of great value to explore the mechanical properties of the CGGPC by adding fibers. The fiber-reinforced CGGPC (FRCGGPC) reflects the idea of composite design, which not only retains the original characteristics of high compressive strength of concrete, but also greatly increases its crack resistance, toughness, and impermeability, making it more in line with the requirements of new construction materials. The magnitude of the effect of fiber concrete on concrete modification depends on the interaction between the fiber and concrete boundary as well as the type, size, density, and direction of fiber distribution in the concrete, which are all related to the microstructure of FRCGGPC. By comparing the mechanical property strengthening effects of incorporating different fibers on CGGPC and exploring their differences in microstructure, we can provide a reference for further selective or composite applications of engineering fiber materials.

Based on the above, this article uses calcined CG as the base raw material and BF, SF, and PF as the reinforcing materials to prepare FRCGGPC. The mechanical properties test and microstructure analysis were carried out, and the effects of different types and dosages of fibers on the mechanical properties of the GPC specimens were compared, and combined with scanning electron microscopy (SEM) its mechanical strengthening mechanism was analyzed. The purpose is to explore the engineering performance and application potential of the CGGPC, and to provide research cases and data support for the development and promotion of the CGGPC.

2 Materials and methods

2.1 Experimental materials

Cementitious materials: calcined CG, low-calcium FA, and blast-furnace slag were all produced by Chuanxing Mineral Powder Factory, Lingshou County, Hebei Province. The physical photographs are shown in Figure 1; the chemical composition analyses are shown in Table 1.

Figure 1 
                  Cementitious materials. (a) CG, (b) FA, and (c) slag.
Figure 1

Cementitious materials. (a) CG, (b) FA, and (c) slag.

Table 1

Chemical composition of cementitious materials

Materials Unit CG FA Slag
SiO2 wt% 53 65.6 39.2
Al2O3 42 8.7 17.6
Fe2O3 ≤0.5 3.9
H2O ≤0.3 0.01
S 0.24
CaO 3.5 36.55
MgO 4.6
MnO 1.7

Fiber: BF, SF, and PF were from Changzhou Bochao Engineering Materials Co., Ltd. The physical photographs are shown in Figure 2; the chemical composition analyses of BF, SF, and PF are shown in Tables 24, respectively.

Figure 2 
                  Fibers. (a) BF, (b) SF, and (c) PF.
Figure 2

Fibers. (a) BF, (b) SF, and (c) PF.

Table 2

Performance parameters of BF

Performance Diameter (μm) Density (g/cm3) Breaking tenacity (MPa) Modulus of elasticity (MPa)
Parameter 15.0 1.6 1.29 × 103 6.52 × 104
Table 3

Performance parameters of SF

Performance Length (mm) Diameter (μm) Density (g/cm³) Tensile property (MPa)
Parameter 12 28 5.34 577
Table 4

Performance parameters of PF

Performance Length (mm) Diameter (μm) Density (g/cm³) Breaking tenacity (MPa) Initial modulus (MPa)
Parameter 32 28 1.15 864 3.2 × 103

Double solution alkali exciter: water glass and sodium hydroxide (NaOH) solution composition.

Fine aggregate: natural river sand, fineness modulus of 2.6–3.0 and apparent density of 2,635 kg/m3.

Coarse aggregate: continuous graded pebbles, with a particle size of 5–16 mm, an apparent density of 2,745 kg/m3, a bulk density of 1,460 kg/m3, and a mud dosage of 0.1%.

Water: ordinary tap water in Chengdu, which meets the relevant technical requirements of “Water Standard for Concrete Mixing” (JGJ63-89).

2.2 Experiment apparatus

The main experiment apparatus used in this test are shown in Table 5.

Table 5

Laboratory apparatus

Name Model
Classifier Inside diameter: 5–20 mm
Electronic scale YP3002N
Concrete mixer
Specimen mold box 100 mm × 100 mm × 100 mm
Concrete vibration table ZD/LX-PTP
Electric drying oven 841Y-0
Microcomputer-controlled stress testing machine WHY-2000
Fixture for splitting tensile test PLJJ
SEM S-3000N

2.3 Casting of specimens

2.3.1 Mix proportion design

The preliminary mix proportion design of materials in this test were based on “Specification for mix design of ordinary concrete” (JGJ 55-2011), “Technical code for the application of mineral admixture” (GB/T 51003-2014), and the existing studies [36].

The mass proportion of calcined CG, low-calcium FA, and blast-furnace slag were determined to be 2:1:1. The mass proportion of water glass to NaOH solution in alkali activator solution was 7:3. The sol proportion was set to 0.5. The mass proportion of solid to water in NaOH solution was about 1:1. After many trials, the optimum proportion of CGGPC material in this test was obtained. In each square meter of CGGPC, the amount of each component of the geopolymer cementitious material was about 247.71 kg calcined CG, 123.85 kg low-calcium FA, 123.85 kg blast-furnace slag, 74.34 kg NaOH solution, 173.47 kg water glass solution, and 13.36 kg sodium hydroxide solid was needed to reduce the modulus of water glass.

The fiber dosage as a variable in this experiment was determined mainly through previous studies [3739] and trial matching. Among the three selected fibers, BF dosage was 0.1, 0.3, and 0.5% of the total volume of FRCGGPC; SF dosage was 0.3, 0.5, and 0.75% of the total volume of FRCGGPC; PF dosage was 0.5, 1.0, and 1.5% of the total volume of FRCGGPC.

The specific mix proportion is shown in Table 6.

Table 6

Mixed proportion of FRCGGPC (kg/m3)

Test group CG FA NaOH Water glass Water Sand Coarse aggregate Fiber dosage (vol%)
Preparation of solution Reduced modulus Water dosage of sodium silicate NaOH External water mode
CGGPC-0 247.71 123.85 37.17 13.36 173.47 112.76 37.17 57.72 559.67 1039.39 0
BFCGGPC-0.1 247.71 123.85 37.17 13.36 173.47 112.76 37.17 57.72 559.67 1039.39 0.1
BFCGGPC-0.3 0.3
BFCGGPC-0.5 0.5
SFCGGPC-0.3 247.71 123.85 37.17 13.36 173.47 112.76 37.17 57.72 559.67 1039.39 0.3
SFCGGPC-0.5 0.5
SFCGGPC-0.75 0.75
PFCGGPC-0.5 247.71 123.85 37.17 13.36 173.47 112.76 37.17 57.72 559.67 1039.39 0.5
PFCGGPC-1.0 1.0
PFCGGPC-1.5 1.5

Note: CGGPC – coal gangue-based geopolymer concrete; BFCGGPC – basalt fiber-reinforced coal gangue-based geopolymer concrete; SFCGGPC – steel fiber-reinforced coal gangue-based geopolymer concrete; PFCGGPC – polyester fiber-reinforced coal gangue-based geopolymer concrete. The number in the specimen name column indicates the volume of fiber admixture accounted for the proportion of the total volume of FRCGGPC, for example in BFCGGPC-0.1, said BF admixture is 0.1% of the experimental group.

2.3.2 Mixing and curing of specimens

Prepare the alkali stimulant 12 h in advance, and let it stand at room temperature for later use. First, the silica-alumina powder material and coarse and fine aggregates were put into the agitator for drying, stirring for 3 min until mixed evenly. Meantime, according to the mix proportion standard, the required fiber was weighed and evenly separated under dry conditions, stirring at low speed for about 3–5 min. Then, the fibers were pulled out from the soaking container and put evenly into the slurry after absorbing the excess water on the surface. Finally, after mixing for 1 min, the concrete mixture was put into the corresponding mold of 100 mm × 100 mm × 100 mm and vibrated to dense.

After the specimens were formed, the surface was covered with impermeable film immediately and placed in an environment with a temperature of 20 ± 5°C for 24 h and then demolded. Subsequently, the specimen was densely wrapped with film membrane, and maintained in an oven at 105°C for 12 h. After removal from the oven, it was transferred to a drying room with a temperature of about 20°C for maintenance to a specified age (3, 7, or 28 days), as shown in Figure 3.

Figure 3 
                     Concrete specimens placed in oven for curing.
Figure 3

Concrete specimens placed in oven for curing.

According to the design mix proportion, 150 effective cube specimens were finally poured for mechanical performance test and microscopic morphology analysis.

2.4 Strength test

According to “Standard Test Method for Physical and Mechanical Properties of Concrete” (GBT50081-2019), the precast concrete cured to the specified age was taken out and subjected to cubic compressive strength test by using the microcomputer-controlled pressure test machine (WHY-2000) with the measurement accuracy of ±1%, as shown in Figure 4(a). Then, the cubic splitting tensile test was conducted with the assistance of splitting tensile jig and pressure transfer tool to ensure the stability of the specimen during testing, as shown in Figure 4(b). Three specimens were tested in each group, and the average value was taken as the final value. Since the concrete specimens in this test are 100 mm × 100 mm × 100 mm non-standard specimens, the compressive strength and the splitting tensile strength are calculated according to the following formulas (1) and (2), respectively.

(1) f cu = 0.95 × F A ,

where F is the compressive failure load, and A is the bearing area of the specimen.

(2) f ts = 0.85 × 2 F Π A = 0.85 × 0.637 × F A ,

where F is the splitting failure load, and A is the splitting bearing area of the specimen.

Figure 4 
                  Strength test laboratory apparatus. (a) Microcomputer-controlled stress testing machine and (b) splitting tensile jig.
Figure 4

Strength test laboratory apparatus. (a) Microcomputer-controlled stress testing machine and (b) splitting tensile jig.

2.5 Micromorphology analysis

After the compressive test and splitting tensile test, the residual bulk specimens containing fibers were selected as test specimens, which were divided into 10–20 mm diameter chips. Then, the group with the most obvious strength change in the control group of different mixed CGGPC under the mechanical performance test was selected, and observed by SEM (Thermo Fisher Scientific’s Prisma-E), as shown in Figure 5. The microscopic morphology of the matrix after failure was restored to the maximum extent, and the mechanism of the mechanical property test results was analyzed.

Figure 5 
                  SEM. (a) Instrument appearance. (b) Carrier table.
Figure 5

SEM. (a) Instrument appearance. (b) Carrier table.

3 Research results and discussion

3.1 The influence of different fiber types and dosages on the compressive strength of FRCGGPC

3.1.1 Failure morphology

Figures 6 and 7 show the failure morphology of the specimens in the cube compressive test.

Figure 6 
                     Benchmark group. (a) During fracturing and (b) complete fracturing.
Figure 6

Benchmark group. (a) During fracturing and (b) complete fracturing.

Figure 7 
                     Control groups. (a) BFCGGPC, (b) SFCGGPC, and (c) PFCGGPC.
Figure 7

Control groups. (a) BFCGGPC, (b) SFCGGPC, and (c) PFCGGPC.

Among them, Figure 6 reflects the failure morphology of the benchmark group of specimens after the compressive test. During the test process, this group of specimens has continued to develop cracks, which were large in number and width. Figure 6(a) reflects the situation in the loading process. Subject to the increased compression, the cracks in the middle of the specimens were quickly penetrated, and the surface of the FRCGGPC was gradually spalling off; Figure 6(b) reflects the situation after the end of loading. The skin around the specimen was peeling off seriously, the residual matrix was curved, and the internal aggregate and cement paste were completely exposed. Figure 7 reflects the failure morphology of the control group mixed with different fibers after loading. Although the difference between the failure morphology of CGGPC with different fibers was not obvious, the specimens all showed a certain degree of lateral expansion, and a small number of long cracks occurred on the four side surfaces, accompanied by a small amount of debris falling. The integrity was stronger than the benchmark group, and there was no large-area peeling of the case.

3.1.2 Experimental data and results analysis

As shown in Table 7, the cube compressive strength of the specimens with three different fibers and dosages under standard curing for 3, 7, and 28 day are obtained. Figure 8 shows the law of compressive strength with different fibers and dosages.

Table 7

Test results of cube compressive strength

Fiber type Fiber dosage (vol%) Serial number Compressive strength
3 days 7 days 28 days
0 CGGPC 21.95 22.61 28.41
BF 0.1 BFCGGPC-0.1 22.52 23.85 29.07
0.3 BFCGGPC-0.3 23.66 24.80 29.83
0.5 BFCGGPC-0.5 23.56 25.18 30.22
SF 0.3 SFCGGPC-0.3 23.75 24.04 30.21
0.5 SFCGGPC-0.5 22.14 23.47 28.79
0.75 SFCGGPC-0.75 19.19 20.71 26.70
PF 0.5 PFCGGPC-0.5 23.94 24.89 29.93
1.0 PFCGGPC-1.0 21.76 22.04 27.36
1.5 PFCGGPC-1.5 19.48 19.86 25.56
Figure 8 
                     Compressive strength of FRCGGPC.
Figure 8

Compressive strength of FRCGGPC.

It can be seen from Figure 8 that the compressive strength of CGGPC was slightly improved when the dosage of three different types of fiber exceeds a certain volume, but it is not significant. When the BF dosage was 0.1, 0.3 and 0.5%, the compressive strength of FRCGGPC reached the maximum of 23.66 MPa (3 days), 25.18 MPa (7 days), and 30.22 MPa (28 days), respectively, which were 7.79, 11.34, and 5.69% higher than those of the benchmark group. When the SF dosage was 0.3%, the compressive strength of FRCGGPC reached the maximum of 23.75 MPa (3 days), 24.04 MPa (7 days), and 30.21 MPa (28 days), respectively, which were 8.22, 6.3, and 6.35% higher than those of the benchmark group. When the PF dosage was 0.5%, the compressive strength of FRCGGPC reached the maximum of 23.94 MPa (3 days), 24.89 MPa (7 days), and 29.93 MPa (28 days), respectively, which were 9.09, 10.08, and 5.35% higher than those of the benchmark group.

It is worth noting that when adding the control group containing SF and PF, the compressive strength of FRCGGPC showed a peak value. Finally, its compressive strength was lower than that of the benchmark group, and the maximum reduction was 12.55%. As shown in Figure 8(b), the compressive strength of the control group reached the peak value when the SF dosage was 0.3%, and then gradually decreased with the increase in the SF dosage. When the SF dosage reached 0.75%, the compressive strength of the control group at 3, 7, and 28 days were all lower than that of the benchmark group. As shown in Figure 8(c), the change trend of compressive strength of the control group containing PF was similar to that of the SF control group. It can be seen that each fiber has a suitable range of admixtures, and within this range, the compressive strength of FRCGGPC can be slightly improved. However, exceeding its scope will have a certain negative impact on it.

Researchers have confirmed through numerous tests that too much fibers are detrimental to the compressive properties of geopolymer composites [4045]. One of the reasons is that when the fiber dosage reaches the most suitable proportion, excessive incorporation of fiber will destroy the best structure of the GPC that has been formed. The fiber cannot be wrapped by sufficient slurry, and the specific surface area increases greatly, resulting in the decrease in the density of GPC, the increase in internal defects, and the occurrence of microcracks and pores. The other reason is that the physical form of fibers also affects the compressive strength of FRCGGPC to some extent. The results show that PF and SF are more prone to agglomeration than BF. The agglomerations are aggravated by increasing the amount of dosage, which results in more pores in the mix and less internal continuity, and thus lowering compressive load capacity.

3.1.3 Micromorphology analysis

Figure 9, respectively, shows the 28 days microscopic morphology of benchmark group, the control group BFCGGPC-0.5 group, SFCGGPC-0.5 group, and PFCGGPC-1.0 group under the compressive test.

Figure 9 
                     Micromorphology of the matrix after curing for 28 days. (a) CGGPC, (b) BFCGGPC-0.5, (c) SFCGGPC-0.5, and (d) PFCGGPC-1.0.
Figure 9

Micromorphology of the matrix after curing for 28 days. (a) CGGPC, (b) BFCGGPC-0.5, (c) SFCGGPC-0.5, and (d) PFCGGPC-1.0.

It can be seen from Figure 9 that the amount of polymerized gel on the surface of the matrix was not affected after the fiber was incorporated, and a few cracks, holes, and unreacted FA particles can be observed on the surface of the matrix. The cracks may be generated by the expansion of high temperature curing, and the holes may be caused by the residual air during mixing and evaporation of mixing water in the matrix after hardening. The incorporation of fibers did not change the properties of the cementitious materials and aggregates subjected to compressive load in the matrix. Therefore, the effect of fiber incorporation on the compressive strength of CGGPC is not obvious.

Based on the analysis from the perspective of microstructure, as shown in Figure 9(b), there was no obvious hole or loose matrix around the BF, and the exposed fiber ends were tightly connected with the geopolymer matrix. There was no significant difference between the overall morphology and the benchmark group. It can be seen that the incorporation of BF has no adverse effect on the matrix. Based on the analysis from chemical composition level, BF as an inorganic fiber, the chemical composition is very similar to that of silica-alumina raw materials. Under the action of alkali activator, Si and Al provided by BF were released and reacted with Na+ and Ca2+ in the environment to generate C–S–H and N/C–A–S–H silicate aluminates, and the polymer gels in the matrix further increased. It can be used as a kind of micro-aggregate in the geopolymer matrix, which helps to improve the compactness and homogeneity of the matrix. Therefore, the compressive strength of the control group containing BF is generally improved [46].

Compared with the other two fibers with smaller diameters, the gap between the SF and the matrix was wider, and the looseness near the matrix was also higher, as shown in Figure 9(c). It is confirmed that the abovementioned SF dosage is too high, causing the porosity in the matrix and the number of interfacial weak areas to increase. Obviously, as shown in Figure 9(d), the PFs agglomerate in this area. There were multiple PFs interwoven in a small field of vision, which were bound to increase the formation of small holes and reduce the coherence between the cementitious materials in the matrix, causing the compressive strength of FRCGGPC to decrease.

3.2 The influence of different fiber types and dosages on the splitting tensile strength of FRCGGPC

3.2.1 Failure morphology

Figures 10 and 11 show the failure morphology of the specimens in the cube splitting tensile test.

Figure 10 
                     Benchmark group. (a) During fracturing and (b) complete fracturing.
Figure 10

Benchmark group. (a) During fracturing and (b) complete fracturing.

Figure 11 
                     Control groups. (a) BFCGGPC, (b) SFCGGPC, and (c) PFCGGPC.
Figure 11

Control groups. (a) BFCGGPC, (b) SFCGGPC, and (c) PFCGGPC.

Among them, Figure 10 reflects the failure morphology of the benchmark group of specimens after the splitting tensile test. The specimen of this group was not only split in the vertical direction, but also has transverse fracture at the waist. Figure 11 shows the failure morphology of the control group. A small amount of cracks gradually developed from the compression part and finally penetrated, but there was no transverse splitting. The cracked part also appeared in the situation of fiber bridging matrix, which effectively prevented the expansion of cracks. Compared with the benchmark group, the specimens obviously changed from brittle failure to ductile failure. Meanwhile, there were obvious differences in the failure interface of CGGPC with different fibers. The broken interface of BF was difficult to identify the residual fiber, and the interface debris was less, and there was no scattered granular debris distribution. The broken interface of SF has no excessive debris remaining. The broken interface of PF has more debris and a lot of adhesion.

3.2.2 Experimental data and results analysis

As shown in Table 8, the cube splitting tensile strength of the specimens with three different fibers and dosages under standard curing for 7 and 28 days are obtained. Figure 12 shows the law of splitting tensile strength with different fibers and dosages.

Table 8

Test results of cube splitting tensile strength

Fiber type Fiber dosage (vol%) Serial number Compressive strength
7 days 28 days
0 CGGPC 1.43 1.57
BF 0.1 BFCGGPC-0.1 1.74 2.06
0.3 BFCGGPC-0.3 1.66 1.95
0.5 BFCGGPC-0.5 2.16 2.30
SF 0.3 SFCGGPC-0.3 2.22 2.30
0.5 SFCGGPC-0.5 2.42 2.62
0.75 SFCGGPC-0.75 2.18 2.54
PF 0.5 PFCGGPC-0.5 2.10 2.58
1.0 PFCGGPC-1.0 2.46 2.73
1.5 PFCGGPC-1.5 1.88 2.35
Figure 12 
                     Splitting tensile strength of FRCGGPC.
Figure 12

Splitting tensile strength of FRCGGPC.

It can be seen from Figure 12 that the incorporation of three different fibers has a significant effect on the splitting tensile strength of FRCGGPC. When the BF dosage was 0.5%, the splitting tensile strength of FRCGGPC reached the maximum of 2.16 MPa (7 days) and 2.3 MPa (28 days), which were 51.33 and 46.15% higher than those of the benchmark group, respectively. When the SF dosage was 0.5%, the splitting tensile strength of FRCGGPC reached the maximum of 2.42 MPa (7 days) and 2.62 MPa (28 days), which were 69.64 and 66.80% higher than those of the benchmark group, respectively. When the PF dosage was 1.0%, the splitting tensile strength of FRCGGPC reached the maximum 2.46 MPa (7 days) and 2.73 MPa (28 days), which were 72.32 and 73.68% higher than those of the benchmark group, respectively.

Fiber has a relatively large influence on the splitting tensile strength of FRCGGPC, mainly due to two reasons. First, the fibers act as a restraint to effectively mitigate the lateral deformation of the GPC matrix in the process of being pulled. When the load is further increased resulting in the formation of cracks in the matrix, the crack development in the fiber is restricted, and the crack path is forced to be blocked or transferred. Second, the fiber enhances the bite force between the aggregate and slurry phase materials. The materials of each phase will form a hole when the force is applied, effectively inhibiting the extension of cracks. Although all three fibers can enhance the compressive strength of CGGPC to varying degrees, the fibers can only share a small portion of the transverse tensile stress in the matrix. The strength of FRCGGPC depends on the strength of the aggregate, as well as the interaction between the aggregate and the cementitious material.

At the same time, under the same fiber dosage, the improvement effect of BF on the splitting tensile strength of FRCGGPC is less than that of PF and SF. Comparing Figure 11, it can be seen that the 7 days splitting tensile strength of BFCGGPC was generally lower than that of PF and SF. After curing for 28 days, although the splitting tensile strength of control groups containing BF increased significantly, it was still inferior to PF and SF. The reasons are as follows: First, BF is mainly composed of SiO2, Al2O3, CaO, and other compounds, which can react with strong alkaline solution and generate new aluminosilicate. Although the compressive strength of the matrix is improved, a part of BF will be dissolved in the process. When the dosage is not high, the number of fibers in the matrix that can bear the stress is less, and the limiting effect on crack generation and expansion is also weakened. Second, Some research results show that on the basis of this experiment, slightly increasing the dosage of BF can achieve better results. For example, the fiber-reinforced and toughened slag-coal FA-steel slag-based polymer cementitious material prepared by Xu et al. [47]. When the amount of basalt doping is increased to 0.6%, the mechanical properties of the specimens obtained are good, including the flexural strength reaching 10.8 MPa. Saloni et al. showed that BF exhibited positive effects on the fiber-matrix transition zone when the initial setting time, final setting time, bulk density, and compressive and flexural strengths were increased with the increased BF contents [48]. It can be seen that the optimal dosage range of BF in FRCGGPC can be further explored to optimize its mechanical properties.

3.2.3 Micromorphology analysis

Figures 13 and 15, respectively, show the 28 days microscopic morphology of the control groups BFCGGPC-0.5 group, SFCGGPC-0.5 group, and PFCGGPC-1.0 group under the splitting tensile test.

Figure 13 
                     BFCGGPC-0.5. (a) mag2500× BF contact interface (b) mag2000× regular holes (c) mag2000× lens and needle hydration products (d) mag6500× lens and needle hydration products.
Figure 13

BFCGGPC-0.5. (a) mag2500× BF contact interface (b) mag2000× regular holes (c) mag2000× lens and needle hydration products (d) mag6500× lens and needle hydration products.

Figure 14 
                     PFCGGPC-1.0. (a) mag1000× PET fibers (b) mag5000× PET fibers (c) mag6500× groups and grooves and indentations (d) mag1200× fractured fiber ends.
Figure 14

PFCGGPC-1.0. (a) mag1000× PET fibers (b) mag5000× PET fibers (c) mag6500× groups and grooves and indentations (d) mag1200× fractured fiber ends.

Figure 15 
                     SFCGGPC-0.5. (a) mag1000× SF and matrix contact interface (b) mag2000× SF and matrix contact interface.
Figure 15

SFCGGPC-0.5. (a) mag1000× SF and matrix contact interface (b) mag2000× SF and matrix contact interface.

It can be seen from Figures 1315 that there were no excessive dispersion between the phases of FRCGGPC, and the integrity was good. Each fiber was wrapped in the slurry. The interaction between the matrix and the fiber was obvious, and some fibers were pulled out. The above situation shows that the fibers share part of the external load and thus fracture, which shows that the fibers significantly increase the tensile strength of CGGPC.

According to the results of the splitting tensile test in this study, the three kinds of fibers had inconsistent improvement in the splitting tensile performance of CGGPC. Among them, SF has the best effect, followed by PF, and BF has the lowest enhancement. The reasons are analyzed from the micromorphology level as follows. As shown in Figure 13, first, BF was not wrapped in the matrix part of the smooth surface, with less adherent matrix and no obvious scratches, revealing a small gap between the root of the fiber and the contact part of the matrix. The fracture section of the fiber end was smooth, without tearing characteristics, which was brittle fracture. Second, it was clear that a large number of crystals and needle-shaped hydration products were attached around the BF, and some fibers’ structure were incomplete. Therefore, this study believes that fibers are corroded in alkaline environment, and there is a phenomenon of reorganization after dissolution. This directly leads to a significant reduction in the number of fibers that can share the external load, and further weakens the limitation effect on the generation and expansion of cracks. In addition, the part of BF that can withstand the stress when subjected to damage does not have ductile characteristics. The surface was smooth, and the friction force between the BF and the matrix was relatively small.

However, the microscopic characteristics of PF and SF in the matrix were very different from those of BF. First of all, as shown in Figure 14, part of the surface of PF not wrapped in the matrix was not as smooth as BF. Some fiber surfaces not only had a small amount of adhesion matrix, but also had depressions and scratches, indicating that there was a certain friction between the fiber and the matrix. Ranjbar described the effect of fiber roughness on the local stress of the matrix [49]. The stress generated by the rough fiber at the contact interface is more complex, and the relative motion constraint on the fiber-matrix is stronger. The effect also radiates to the circular area at a certain distance from the contact interface. In addition, the smooth fiber will produce relative slip at the contact interface and the relative force is weaker. Second, PF is a kind of hydrophobic fiber, whose surface roughness is low. It can be improved by some surface treatment (such as fibrosis, indentation, and placement in alkaline environment) to strengthen the contact stress with the concrete matrix. The PFs in this experiment were roughened due to the dry alkaline environment. The adhesion matrix in Figure 14(c) was the activated polar group generated in the alkaline environment. In the process of mixing, the agglomeration phenomenon is obvious, and the dispersed fiber cannot give full play to the overall constraint effect on the matrix. At the same time, the agglomeration also leads to the formation of some holes in the matrix and the formation of weak links around it. Third, from Figure 14(d), it can be clearly seen that the end of a PF that was pulled off showed obvious tearing characteristics when it broke, and has a certain degree of deformation. This was the performance of its ductile characteristics, indicating that the PF was bridging the substrate while offsetting some of the energy from external loading. Eventually, it was pulled off when it reached its own ultimate bearing capacity.

The most significant effect of SFs on the splitting tensile performance of CGGPC is analyzed from the following two reasons. In the first place, as shown in Figure 15, the surface of SF is very rough, and it is wrapped with a large number of adhesion matrix. There is a strong contact stress (adhesion and friction) between the fiber and the matrix, which effectively restricts the relative motion of the fiber and the matrix and inhibits the generation of cracks. In the next place, the wavy structure of the SF itself substantially strengthens the mechanical bite between it and the matrix. In addition, the material characteristics that are not easy to break under the tensile condition of the SF make it fully play the bridging role in the whole loading process.

4 Conclusion

In this article, mechanical tests and micromorphology analysis of CGGPC with different fibers and dosages are carried out. The objectivity of mechanical properties test results is verified by micromorphology analysis. The main conclusions are as follows:

  1. A certain dosage of BF, SF, and PF can slightly increase the compressive strength of CGGPC. The compressive strength of the control group containing BF continues to increase with the increase in the dosage, and its optimal dosage value can be further explored; The control group containing SF and PF has peak dosage. When the dosage is too high, the compressive strength will be lower than that of the benchmark group, showing a certain negative effect.

  2. BF, SF, and PF have a significant effect on improving the splitting tensile strength of CGGPC. The improvement rate of 7 days splitting tensile strength of different control groups is about 16–72%, and the improvement rate of 28 days splitting tensile strength is about 44–73%. At the same dosage, the splitting tensile strength of SF- and PF- reinforced CGGPC is better than that of BF.

  3. Within a certain dosage range, the three kinds of fibers are tightly wrapped in the matrix, and play a role in bearing part of the stress of the matrix. Under the compressive test, there is no obvious hole or loose matrix around the BF. The connection between the exposed fiber ends and the matrix is relatively tight, so the doping does not have adverse effects on the benchmark group’s matrix; The gap between the SF and the matrix is wider, and the looseness near the matrix is also higher; PFs are interwoven with each other, causing agglomeration.

  4. Under the splitting tensile test, the surface of BF is smooth, and there are voids at the root of contact with the matrix and dissolution occurring at some positions. The interaction force between this fiber and the matrix is weaker, and the number of fibers that can bear the tensile stress is small; While the surface of SF and PF is relatively rough, both have scratches and adherent matrix, and the adhesion performance of the interface between the fiber and matrix is good. The end of PF shows a tearing state with certain ductility characteristics. The unique wavy structure and performance characteristics of SF play a bridging role in the whole process of matrix cracking, which can effectively inhibit crack expansion and improve the macro mechanical properties of FRCGGPC.

This article compares the effect of three different FRCGGPCs on the mechanical properties and analyzes the microscopic mechanism, which provides a reference value for its research and application in the concrete industry. However, it can be seen from the test results and conclusions that there are still many problems restricting the application and promotion of the material, such as small increase in strength at the later stage of curing and insufficient optimization of fiber types and additives. Subsequent studies hope to try compound addition of nanomaterials to explore the improvement and enhancement of the mechanical properties and durability performance of FRCGGPC, and further explore the internal mechanism and law of strength growth.

Acknowledgments

The writing of this article has been supported by many projects, which can be seen in funding information. At the same time, the project team members and all authors have supported this article. A note of thanks to them.

  1. Funding information: This study was supported by Sichuan Mingyang Construction Engineering Management Co., Ltd. Specialized Project (MY2021-001), the Philosophy and Social Science Research Fund Project of Chengdu University of Technology (YJ2021-ZD002), Special Project of Marxist Theory Research of Chengdu University of Technology (20800-2021MLL005), Project of Western Ecological Civilization Research Center (XBST2021-YB002), Chengdu University of Technology Development Funding Program for Young and Middle-aged Key Teachers (10912-JXGG2021-01003), and College Students’ Innovation and Entrepreneurship Training Program (202010616009, S202110616011, S2021106160114, S202110616013, and S202110616099).

  2. Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.

  3. Conflict of interest: The authors state no conflict of interest.

References

[1] Davidovits J. The ancient egyptian pyramids-concrete or rock. Concr Int. 1987;9(12):28–39.Search in Google Scholar

[2] Davidovits J. Geopolymers and geopolymeric new materials. J Therm Anal Calorim. 1989;35(2):429–41.10.1007/BF01904446Search in Google Scholar

[3] Davidovits J. Geopolymers: inorganic polymeric new materials. J Therm Anal Calorim. 1991;37(8):1633–56.10.1007/BF01912193Search in Google Scholar

[4] Kurtoglu AE, Alzeebaree R, Aljumaili O, Nis A, Gulsan ME, Humur G, et al. Mechanical and durability properties of fly ash and slag based geopolymer concrete. Adv Concr Constr. 2018;6(4):345–62.Search in Google Scholar

[5] Luhar S, Chaudhary S, Luhar I. Development of rubberized geopolymer concrete: strength and durability studies. Constr Build Mater. 2019;204:740–53.10.1016/j.conbuildmat.2019.01.185Search in Google Scholar

[6] Xu Z, Huang ZP, Liu CJ, Deng XW, Hui D, Deng SJ, et al. Research progress on mechanical properties of geopolymer recycled aggregate concrete. Rev Adv Mater Sci. 2021;60(1):158–72.10.1515/rams-2021-0021Search in Google Scholar

[7] Ribeiro RAS, Ribeiro MGS, Sankar K, Kriven WM. Geopolymer-bamboo composite – a novel sustainable construction material. Constr Build Mater. 2016;123:501–7.10.1016/j.conbuildmat.2016.07.037Search in Google Scholar

[8] Noushini A, Castel A. The effect of heat-curing on transport properties of low-calcium fly ash-based geopolymer concrete. Constr Build Mater. 2016;112:464–77.10.1016/j.conbuildmat.2016.02.210Search in Google Scholar

[9] Liu CJ, Huang XC, Wu YY, Deng XW, Liu J, Zheng ZL, et al. Review on the research progress of cement-based and geopolymer materials modified by graphene and graphene oxide. Nanotechnol Rev. 2020;9(1):155–69.10.1515/ntrev-2020-0014Search in Google Scholar

[10] Amran YHM, Alyousef R, Alabduljabbar H, El-zeadani M. Clean production and properties of geopolymer concrete: a review. J Clean Prod. 2020;251:119679.10.1016/j.jclepro.2019.119679Search in Google Scholar

[11] Jiang X, Xiao R, Zhang MM, Hu W, Bai Y, Huang BS. A laboratory investigation of steel to fly ash-based geopolymer paste bonding behavior after exposure to elevated temperatures. Constr Build Mater. 2020;254:119267.10.1016/j.conbuildmat.2020.119267Search in Google Scholar

[12] Aguirre-guerrero AM, Robayo-salazar RA, de Gutierrez RM. A novel geopolymer application: coatings to protect reinforced concrete against corrosion. Appl Clay Sci. 2017;135:437–46.10.1016/j.clay.2016.10.029Search in Google Scholar

[13] Xu Z, Huang ZP, Liu CJ, Deng XW, Hui D, Deng YT, et al. Experimental study on mechanical properties and microstructures of steel fiber-reinforced fly ash metakaolin geopolymer-recycled concrete. Rev Adv Mater Sci. 2021;60(1):578–90.10.1515/rams-2021-0050Search in Google Scholar

[14] Xu Z, Huang ZP, Liu CJ, Deng H, Deng XW, Hui D, et al. Research progress on key problems of nanomaterials-modified geopolymer concrete. Nanotechnol Rev. 2021;10(1):779–92.10.1515/ntrev-2021-0056Search in Google Scholar

[15] Zhang HY, Kodur V, Wu B, Yan J, Yuan ZS. Effect of temperature on bond characteristics of geopolymer concrete. Constr Build Mater. 2018;163:277–85.10.1016/j.conbuildmat.2017.12.043Search in Google Scholar

[16] Gunasekara C, Setunge S, Law DW, Willis N, Burt T. Engineering properties of geopolymer aggregate concrete. J Mater Civ Eng. 2018;30(11):04018299.10.1061/(ASCE)MT.1943-5533.0002501Search in Google Scholar

[17] Biondi L, Perry M, Vlachakis C, Wu Z, Hamilton A, McAlorum J. Ambient-cured fly ash geopolymer coatings for concrete. Materials. 2019;12(6):923.10.3390/ma12060923Search in Google Scholar PubMed PubMed Central

[18] Mendes SES, Oliveira RLN, Cremonez C, Pereira E, Trentin PO, Medeiros RA, et al. Estimation of electrical resistivity of concrete with blast-furnace slag. Aci Mater J. 2021;118(4):27–37.10.14359/51732597Search in Google Scholar

[19] Mayhoub OA, Nasr EAR, Ali Y, Kohail M. Properties of slag based geopolymer reactive powder concrete. Ain Shams Eng J. 2021;12(1):99–105.10.1016/j.asej.2020.08.013Search in Google Scholar

[20] Laskar SM, Talukdar S. Preparation and tests for workability, compressive and bond strength of ultra-fine slag based geopolymer as concrete repairing agent. Constr Build Mater. 2017;154:176–90.10.1016/j.conbuildmat.2017.07.187Search in Google Scholar

[21] Alanazi H, Yang MJ, Zhang DL, Gao ZL. Bond strength of PCC pavement repairs using metakaolin-based geopolymer mortar. Cem Concr Comp. 2016;65:75–82.10.1016/j.cemconcomp.2015.10.009Search in Google Scholar

[22] Alanazi H, Zhang DL, Yang MJ, Gao ZL. Early strength and durability of metakaolin-based geopolymer concrete. Mag Concr Res. 2017;69(1):46–54.10.1680/jmacr.16.00118Search in Google Scholar

[23] Zhang DM, Ren FY. Study on coal gangue based geopolymer characteristics with dry powder activator. Non-Metallic Mines. 2016;39(6):35–7.Search in Google Scholar

[24] Zhang WQ, Dong CW, Huang P, Sun Q, Li M, Chai J. Experimental study on the characteristics of activated coal gangue and coal gangue-based geopolymer. Energies. 2020;13(10):2504.10.3390/en13102504Search in Google Scholar

[25] Liu CJ, Deng XW, Liu J, Hui D. Mechanical properties and microstructures of hypergolic and calcined coal gangue based geopolymer recycled concrete. Constr Build Mater. 2019;221:691–708.10.1016/j.conbuildmat.2019.06.048Search in Google Scholar

[26] Geng JJ, Zhou M, Li YX, Chen YC, Han Y, Wan S, et al. Comparison of red mud and coal gangue blended geopolymers synthesized through thermal activation and mechanical grinding preactivation. Constr Build Mater. 2017;153:185–92.10.1016/j.conbuildmat.2017.07.045Search in Google Scholar

[27] Huang GD, Ji YS, Li J, Hou ZH, Dong ZC. Improving strength of calcinated coal gangue geopolymer mortars via increasing calcium content. Constr Build Mater. 2018;166:760–8.10.1016/j.conbuildmat.2018.02.005Search in Google Scholar

[28] Liu CJ, Su X, Wu YY, Zheng ZL, Yang B, Luo YB, et al. Effect of nano-silica as cementitious materials-reducing admixtures on the workability, mechanical properties and durability of concrete. Nanotechnol Rev. 2021;10(1):1395–409.10.1515/ntrev-2021-0097Search in Google Scholar

[29] Liu CJ, Chen FL, Wu YY, Zheng ZL, Yang JW, Yang B, et al. Research progress on individual effect of graphene oxide in cement-based materials and its synergistic effect with other nanomaterials. Nanotechnol Rev. 2021;10(1):1208–35.10.1515/ntrev-2021-0080Search in Google Scholar

[30] Liu CJ, Huang XC, Wu YY, Deng XW, Zheng ZL. The effect of graphene oxide on the mechanical properties, impermeability and corrosion resistance of cement mortar containing mineral admixtures. Constr Build Mater. 2021;288:123059.10.1016/j.conbuildmat.2021.123059Search in Google Scholar

[31] Liu CJ, Huang XC, Wu YY, Deng XW, Zheng ZL, Xu Z, et al. Advance on the dispersion treatment of graphene oxide and the graphene oxide modified cement-based materials. Nanotechnol Rev. 2021;10(1):34–49.10.1515/ntrev-2021-0003Search in Google Scholar

[32] Liu CJ, He X, Deng XW, Wu YY, Zheng ZL, Liu J, et al. Application of nanomaterials in ultra-high performance concrete: a review. Nanotechnol Rev. 2020;9(1):1427–44.10.1515/ntrev-2020-0107Search in Google Scholar

[33] Saranya P, Nagarajan P, Shashikala AP. Performance studies on steel fiber- reinforced GGBS-dolomite geopolymer concrete. J Mater Civ Eng. 2021;33(2):04020447.10.1061/(ASCE)MT.1943-5533.0003530Search in Google Scholar

[34] Sahin F, Uysal M, Canpolat O, Aygormez Y, Cosgun T, Dehghanpour H. Effect of basalt fiber on metakaolin-based geopolymer mortars containing rilem, basalt and recycled waste concrete aggregates. Constr Build Mater. 2021;301:124113.10.1016/j.conbuildmat.2021.124113Search in Google Scholar

[35] Gao C, Huang L, Yan LB, Jin RY, Kasal B. Strength and ductility improvement of recycled aggregate concrete by polyester FRP-PVC tube confinement. Compos Part B-Eng. 2019;162:178–97.10.1016/j.compositesb.2018.10.102Search in Google Scholar

[36] Zhou M, Xu M, Li ZW, Sun QW. Preparation and basic properties of spontaneous combustion gangue-slag-fly ash gepolyer. Bull Chin Ceram Soc. 2013;32(9):1826–31.Search in Google Scholar

[37] Wang YC, Zhao JP, Tong YY, Ding JX. Different fiber toughened slag/fly ash based geopolymer. Bull Chin Ceram Soc. 2016;35(12):4173–9.Search in Google Scholar

[38] Bhutta A, Borges PHR, Zanotti C, Farooq M, Banthia N. Flexural behavior of geopolymer composites reinforced with steel and polypropylene macro fibers. Cem Concr Comp. 2017;80:31–40.10.1016/j.cemconcomp.2016.11.014Search in Google Scholar

[39] Shaikh FUA. Tensile and flexural behaviour of recycled polyethylene terephthalate (PET) fibre reinforced geopolymer composites. Constr Build Mater. 2020;245:118438.10.1016/j.conbuildmat.2020.118438Search in Google Scholar

[40] Bashar II, Alengaram UJ, Jumaat MZ, Islam A, Santhi H, Sharmin A. Engineering properties and fracture behaviour of high volume palm oil fuel ash based fibre reinforced geopolymer concrete. Constr Build Mater. 2016;111:286–97.10.1016/j.conbuildmat.2016.02.022Search in Google Scholar

[41] Moradikhou AB, Esparham A, Avanaki MJ. Physical & mechanical properties of fiber reinforced metakaolin-based geopolymer concrete. Constr Build Mater. 2020;251:118965.10.1016/j.conbuildmat.2020.118965Search in Google Scholar

[42] Liu YW, Shi CJ, Zhang ZH, Li N, Shi D. Mechanical and fracture properties of ultra-high performance geopolymer concrete: effects of steel fiber and silica fume. Cem Concr Comp. 2020;112:103665.10.1016/j.cemconcomp.2020.103665Search in Google Scholar

[43] Liu YW, Zhang ZH, Shi CJ, Zhu DJ, Li N, Deng YL. Development of ultra-high performance geopolymer concrete (UHPGC): influence of steel fiber on mechanical properties. Cem Concr Comp. 2020;112:103670.10.1016/j.cemconcomp.2020.103670Search in Google Scholar

[44] Yang MQ, Li WG, He Y, Zhang XY, Li Y, Zhao ZY, et al. Modeling the temperature dependent ultimate tensile strength of fiber/polymer composites considering fiber agglomeration. Compos Sci Technol. 2021;213:108905.10.1016/j.compscitech.2021.108905Search in Google Scholar

[45] Tang C, Li X, Tang YJ, Zeng J, Xie JY, Xiong BF. Agglomeration mechanism and restraint measures of SiO2 nanoparticles in meta-aramid fibers doping modification via molecular dynamics simulations. Nanotechnology. 2020;31(16):165702.10.1088/1361-6528/ab662cSearch in Google Scholar PubMed

[46] Punurai W, Kroehong W, Saptamongkol A, Chindaprasirt P. Mechanical properties, microstructure and drying shrinkage of hybrid fly ash-basalt fiber geopolymer paste. Constr Build Mater. 2018;186:62–70.10.1016/j.conbuildmat.2018.07.115Search in Google Scholar

[47] Xu Y, Zhang YJ, Wang YC, Xu DL. Preparation of ternary geopolymer toughened by basalt fiber. N Chem Mater. 2011;39(11):128–31.Search in Google Scholar

[48] Saloni, Parveen, Pham TM. Enhanced properties of high-silica rice husk ash-based geopolymer paste by incorporating basalt fibers. Constr Build Mater. 2020;245:118422.10.1016/j.conbuildmat.2020.118422Search in Google Scholar

[49] Ranjbar N, Zhang MZ. Fiber-reinforced geopolymer composites: a review. Cem Concr Comp. 2020;107:103498.10.1016/j.cemconcomp.2019.103498Search in Google Scholar

Received: 2021-12-10
Revised: 2021-12-27
Accepted: 2022-01-03
Published Online: 2022-01-19

© 2022 Zhong Xu et al., published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 International License.

Articles in the same Issue

  1. Research Articles
  2. Theoretical and experimental investigation of MWCNT dispersion effect on the elastic modulus of flexible PDMS/MWCNT nanocomposites
  3. Mechanical, morphological, and fracture-deformation behavior of MWCNTs-reinforced (Al–Cu–Mg–T351) alloy cast nanocomposites fabricated by optimized mechanical milling and powder metallurgy techniques
  4. Flammability and physical stability of sugar palm crystalline nanocellulose reinforced thermoplastic sugar palm starch/poly(lactic acid) blend bionanocomposites
  5. Glutathione-loaded non-ionic surfactant niosomes: A new approach to improve oral bioavailability and hepatoprotective efficacy of glutathione
  6. Relationship between mechano-bactericidal activity and nanoblades density on chemically strengthened glass
  7. In situ regulation of microstructure and microwave-absorbing properties of FeSiAl through HNO3 oxidation
  8. Research on a mechanical model of magnetorheological fluid different diameter particles
  9. Nanomechanical and dynamic mechanical properties of rubber–wood–plastic composites
  10. Investigative properties of CeO2 doped with niobium: A combined characterization and DFT studies
  11. Miniaturized peptidomimetics and nano-vesiculation in endothelin types through probable nano-disk formation and structure property relationships of endothelins’ fragments
  12. N/S co-doped CoSe/C nanocubes as anode materials for Li-ion batteries
  13. Synergistic effects of halloysite nanotubes with metal and phosphorus additives on the optimal design of eco-friendly sandwich panels with maximum flame resistance and minimum weight
  14. Octreotide-conjugated silver nanoparticles for active targeting of somatostatin receptors and their application in a nebulized rat model
  15. Controllable morphology of Bi2S3 nanostructures formed via hydrothermal vulcanization of Bi2O3 thin-film layer and their photoelectrocatalytic performances
  16. Development of (−)-epigallocatechin-3-gallate-loaded folate receptor-targeted nanoparticles for prostate cancer treatment
  17. Enhancement of the mechanical properties of HDPE mineral nanocomposites by filler particles modulation of the matrix plastic/elastic behavior
  18. Effect of plasticizers on the properties of sugar palm nanocellulose/cinnamon essential oil reinforced starch bionanocomposite films
  19. Optimization of nano coating to reduce the thermal deformation of ball screws
  20. Preparation of efficient piezoelectric PVDF–HFP/Ni composite films by high electric field poling
  21. MHD dissipative Casson nanofluid liquid film flow due to an unsteady stretching sheet with radiation influence and slip velocity phenomenon
  22. Effects of nano-SiO2 modification on rubberised mortar and concrete with recycled coarse aggregates
  23. Mechanical and microscopic properties of fiber-reinforced coal gangue-based geopolymer concrete
  24. Effect of morphology and size on the thermodynamic stability of cerium oxide nanoparticles: Experiment and molecular dynamics calculation
  25. Mechanical performance of a CFRP composite reinforced via gelatin-CNTs: A study on fiber interfacial enhancement and matrix enhancement
  26. A practical review over surface modification, nanopatterns, emerging materials, drug delivery systems, and their biophysiochemical properties for dental implants: Recent progresses and advances
  27. HTR: An ultra-high speed algorithm for cage recognition of clathrate hydrates
  28. Effects of microalloying elements added by in situ synthesis on the microstructure of WCu composites
  29. A highly sensitive nanobiosensor based on aptamer-conjugated graphene-decorated rhodium nanoparticles for detection of HER2-positive circulating tumor cells
  30. Progressive collapse performance of shear strengthened RC frames by nano CFRP
  31. Core–shell heterostructured composites of carbon nanotubes and imine-linked hyperbranched polymers as metal-free Li-ion anodes
  32. A Galerkin strategy for tri-hybridized mixture in ethylene glycol comprising variable diffusion and thermal conductivity using non-Fourier’s theory
  33. Simple models for tensile modulus of shape memory polymer nanocomposites at ambient temperature
  34. Preparation and morphological studies of tin sulfide nanoparticles and use as efficient photocatalysts for the degradation of rhodamine B and phenol
  35. Polyethyleneimine-impregnated activated carbon nanofiber composited graphene-derived rice husk char for efficient post-combustion CO2 capture
  36. Electrospun nanofibers of Co3O4 nanocrystals encapsulated in cyclized-polyacrylonitrile for lithium storage
  37. Pitting corrosion induced on high-strength high carbon steel wire in high alkaline deaerated chloride electrolyte
  38. Formulation of polymeric nanoparticles loaded sorafenib; evaluation of cytotoxicity, molecular evaluation, and gene expression studies in lung and breast cancer cell lines
  39. Engineered nanocomposites in asphalt binders
  40. Influence of loading voltage, domain ratio, and additional load on the actuation of dielectric elastomer
  41. Thermally induced hex-graphene transitions in 2D carbon crystals
  42. The surface modification effect on the interfacial properties of glass fiber-reinforced epoxy: A molecular dynamics study
  43. Molecular dynamics study of deformation mechanism of interfacial microzone of Cu/Al2Cu/Al composites under tension
  44. Nanocolloid simulators of luminescent solar concentrator photovoltaic windows
  45. Compressive strength and anti-chloride ion penetration assessment of geopolymer mortar merging PVA fiber and nano-SiO2 using RBF–BP composite neural network
  46. Effect of 3-mercapto-1-propane sulfonate sulfonic acid and polyvinylpyrrolidone on the growth of cobalt pillar by electrodeposition
  47. Dynamics of convective slippery constraints on hybrid radiative Sutterby nanofluid flow by Galerkin finite element simulation
  48. Preparation of vanadium by the magnesiothermic self-propagating reduction and process control
  49. Microstructure-dependent photoelectrocatalytic activity of heterogeneous ZnO–ZnS nanosheets
  50. Cytotoxic and pro-inflammatory effects of molybdenum and tungsten disulphide on human bronchial cells
  51. Improving recycled aggregate concrete by compression casting and nano-silica
  52. Chemically reactive Maxwell nanoliquid flow by a stretching surface in the frames of Newtonian heating, nonlinear convection and radiative flux: Nanopolymer flow processing simulation
  53. Nonlinear dynamic and crack behaviors of carbon nanotubes-reinforced composites with various geometries
  54. Biosynthesis of copper oxide nanoparticles and its therapeutic efficacy against colon cancer
  55. Synthesis and characterization of smart stimuli-responsive herbal drug-encapsulated nanoniosome particles for efficient treatment of breast cancer
  56. Homotopic simulation for heat transport phenomenon of the Burgers nanofluids flow over a stretching cylinder with thermal convective and zero mass flux conditions
  57. Incorporation of copper and strontium ions in TiO2 nanotubes via dopamine to enhance hemocompatibility and cytocompatibility
  58. Mechanical, thermal, and barrier properties of starch films incorporated with chitosan nanoparticles
  59. Mechanical properties and microstructure of nano-strengthened recycled aggregate concrete
  60. Glucose-responsive nanogels efficiently maintain the stability and activity of therapeutic enzymes
  61. Tunning matrix rheology and mechanical performance of ultra-high performance concrete using cellulose nanofibers
  62. Flexible MXene/copper/cellulose nanofiber heat spreader films with enhanced thermal conductivity
  63. Promoted charge separation and specific surface area via interlacing of N-doped titanium dioxide nanotubes on carbon nitride nanosheets for photocatalytic degradation of Rhodamine B
  64. Elucidating the role of silicon dioxide and titanium dioxide nanoparticles in mitigating the disease of the eggplant caused by Phomopsis vexans, Ralstonia solanacearum, and root-knot nematode Meloidogyne incognita
  65. An implication of magnetic dipole in Carreau Yasuda liquid influenced by engine oil using ternary hybrid nanomaterial
  66. Robust synthesis of a composite phase of copper vanadium oxide with enhanced performance for durable aqueous Zn-ion batteries
  67. Tunning self-assembled phases of bovine serum albumin via hydrothermal process to synthesize novel functional hydrogel for skin protection against UVB
  68. A comparative experimental study on damping properties of epoxy nanocomposite beams reinforced with carbon nanotubes and graphene nanoplatelets
  69. Lightweight and hydrophobic Ni/GO/PVA composite aerogels for ultrahigh performance electromagnetic interference shielding
  70. Research on the auxetic behavior and mechanical properties of periodically rotating graphene nanostructures
  71. Repairing performances of novel cement mortar modified with graphene oxide and polyacrylate polymer
  72. Closed-loop recycling and fabrication of hydrophilic CNT films with high performance
  73. Design of thin-film configuration of SnO2–Ag2O composites for NO2 gas-sensing applications
  74. Study on stress distribution of SiC/Al composites based on microstructure models with microns and nanoparticles
  75. PVDF green nanofibers as potential carriers for improving self-healing and mechanical properties of carbon fiber/epoxy prepregs
  76. Osteogenesis capability of three-dimensionally printed poly(lactic acid)-halloysite nanotube scaffolds containing strontium ranelate
  77. Silver nanoparticles induce mitochondria-dependent apoptosis and late non-canonical autophagy in HT-29 colon cancer cells
  78. Preparation and bonding mechanisms of polymer/metal hybrid composite by nano molding technology
  79. Damage self-sensing and strain monitoring of glass-reinforced epoxy composite impregnated with graphene nanoplatelet and multiwalled carbon nanotubes
  80. Thermal analysis characterisation of solar-powered ship using Oldroyd hybrid nanofluids in parabolic trough solar collector: An optimal thermal application
  81. Pyrene-functionalized halloysite nanotubes for simultaneously detecting and separating Hg(ii) in aqueous media: A comprehensive comparison on interparticle and intraparticle excimers
  82. Fabrication of self-assembly CNT flexible film and its piezoresistive sensing behaviors
  83. Thermal valuation and entropy inspection of second-grade nanoscale fluid flow over a stretching surface by applying Koo–Kleinstreuer–Li relation
  84. Mechanical properties and microstructure of nano-SiO2 and basalt-fiber-reinforced recycled aggregate concrete
  85. Characterization and tribology performance of polyaniline-coated nanodiamond lubricant additives
  86. Combined impact of Marangoni convection and thermophoretic particle deposition on chemically reactive transport of nanofluid flow over a stretching surface
  87. Spark plasma extrusion of binder free hydroxyapatite powder
  88. An investigation on thermo-mechanical performance of graphene-oxide-reinforced shape memory polymer
  89. Effect of nanoadditives on the novel leather fiber/recycled poly(ethylene-vinyl-acetate) polymer composites for multifunctional applications: Fabrication, characterizations, and multiobjective optimization using central composite design
  90. Design selection for a hemispherical dimple core sandwich panel using hybrid multi-criteria decision-making methods
  91. Improving tensile strength and impact toughness of plasticized poly(lactic acid) biocomposites by incorporating nanofibrillated cellulose
  92. Green synthesis of spinel copper ferrite (CuFe2O4) nanoparticles and their toxicity
  93. The effect of TaC and NbC hybrid and mono-nanoparticles on AA2024 nanocomposites: Microstructure, strengthening, and artificial aging
  94. Excited-state geometry relaxation of pyrene-modified cellulose nanocrystals under UV-light excitation for detecting Fe3+
  95. Effect of CNTs and MEA on the creep of face-slab concrete at an early age
  96. Effect of deformation conditions on compression phase transformation of AZ31
  97. Application of MXene as a new generation of highly conductive coating materials for electromembrane-surrounded solid-phase microextraction
  98. A comparative study of the elasto-plastic properties for ceramic nanocomposites filled by graphene or graphene oxide nanoplates
  99. Encapsulation strategies for improving the biological behavior of CdS@ZIF-8 nanocomposites
  100. Biosynthesis of ZnO NPs from pumpkin seeds’ extract and elucidation of its anticancer potential against breast cancer
  101. Preliminary trials of the gold nanoparticles conjugated chrysin: An assessment of anti-oxidant, anti-microbial, and in vitro cytotoxic activities of a nanoformulated flavonoid
  102. Effect of micron-scale pores increased by nano-SiO2 sol modification on the strength of cement mortar
  103. Fractional simulations for thermal flow of hybrid nanofluid with aluminum oxide and titanium oxide nanoparticles with water and blood base fluids
  104. The effect of graphene nano-powder on the viscosity of water: An experimental study and artificial neural network modeling
  105. Development of a novel heat- and shear-resistant nano-silica gelling agent
  106. Characterization, biocompatibility and in vivo of nominal MnO2-containing wollastonite glass-ceramic
  107. Entropy production simulation of second-grade magnetic nanomaterials flowing across an expanding surface with viscidness dissipative flux
  108. Enhancement in structural, morphological, and optical properties of copper oxide for optoelectronic device applications
  109. Aptamer-functionalized chitosan-coated gold nanoparticle complex as a suitable targeted drug carrier for improved breast cancer treatment
  110. Performance and overall evaluation of nano-alumina-modified asphalt mixture
  111. Analysis of pure nanofluid (GO/engine oil) and hybrid nanofluid (GO–Fe3O4/engine oil): Novel thermal and magnetic features
  112. Synthesis of Ag@AgCl modified anatase/rutile/brookite mixed phase TiO2 and their photocatalytic property
  113. Mechanisms and influential variables on the abrasion resistance hydraulic concrete
  114. Synergistic reinforcement mechanism of basalt fiber/cellulose nanocrystals/polypropylene composites
  115. Achieving excellent oxidation resistance and mechanical properties of TiB2–B4C/carbon aerogel composites by quick-gelation and mechanical mixing
  116. Microwave-assisted sol–gel template-free synthesis and characterization of silica nanoparticles obtained from South African coal fly ash
  117. Pulsed laser-assisted synthesis of nano nickel(ii) oxide-anchored graphitic carbon nitride: Characterizations and their potential antibacterial/anti-biofilm applications
  118. Effects of nano-ZrSi2 on thermal stability of phenolic resin and thermal reusability of quartz–phenolic composites
  119. Benzaldehyde derivatives on tin electroplating as corrosion resistance for fabricating copper circuit
  120. Mechanical and heat transfer properties of 4D-printed shape memory graphene oxide/epoxy acrylate composites
  121. Coupling the vanadium-induced amorphous/crystalline NiFe2O4 with phosphide heterojunction toward active oxygen evolution reaction catalysts
  122. Graphene-oxide-reinforced cement composites mechanical and microstructural characteristics at elevated temperatures
  123. Gray correlation analysis of factors influencing compressive strength and durability of nano-SiO2 and PVA fiber reinforced geopolymer mortar
  124. Preparation of layered gradient Cu–Cr–Ti alloy with excellent mechanical properties, thermal stability, and electrical conductivity
  125. Recovery of Cr from chrome-containing leather wastes to develop aluminum-based composite material along with Al2O3 ceramic particles: An ingenious approach
  126. Mechanisms of the improved stiffness of flexible polymers under impact loading
  127. Anticancer potential of gold nanoparticles (AuNPs) using a battery of in vitro tests
  128. Review Articles
  129. Proposed approaches for coronaviruses elimination from wastewater: Membrane techniques and nanotechnology solutions
  130. Application of Pickering emulsion in oil drilling and production
  131. The contribution of microfluidics to the fight against tuberculosis
  132. Graphene-based biosensors for disease theranostics: Development, applications, and recent advancements
  133. Synthesis and encapsulation of iron oxide nanorods for application in magnetic hyperthermia and photothermal therapy
  134. Contemporary nano-architectured drugs and leads for ανβ3 integrin-based chemotherapy: Rationale and retrospect
  135. State-of-the-art review of fabrication, application, and mechanical properties of functionally graded porous nanocomposite materials
  136. Insights on magnetic spinel ferrites for targeted drug delivery and hyperthermia applications
  137. A review on heterogeneous oxidation of acetaminophen based on micro and nanoparticles catalyzed by different activators
  138. Early diagnosis of lung cancer using magnetic nanoparticles-integrated systems
  139. Advances in ZnO: Manipulation of defects for enhancing their technological potentials
  140. Efficacious nanomedicine track toward combating COVID-19
  141. A review of the design, processes, and properties of Mg-based composites
  142. Green synthesis of nanoparticles for varied applications: Green renewable resources and energy-efficient synthetic routes
  143. Two-dimensional nanomaterial-based polymer composites: Fundamentals and applications
  144. Recent progress and challenges in plasmonic nanomaterials
  145. Apoptotic cell-derived micro/nanosized extracellular vesicles in tissue regeneration
  146. Electronic noses based on metal oxide nanowires: A review
  147. Framework materials for supercapacitors
  148. An overview on the reproductive toxicity of graphene derivatives: Highlighting the importance
  149. Antibacterial nanomaterials: Upcoming hope to overcome antibiotic resistance crisis
  150. Research progress of carbon materials in the field of three-dimensional printing polymer nanocomposites
  151. A review of atomic layer deposition modelling and simulation methodologies: Density functional theory and molecular dynamics
  152. Recent advances in the preparation of PVDF-based piezoelectric materials
  153. Recent developments in tensile properties of friction welding of carbon fiber-reinforced composite: A review
  154. Comprehensive review of the properties of fly ash-based geopolymer with additive of nano-SiO2
  155. Perspectives in biopolymer/graphene-based composite application: Advances, challenges, and recommendations
  156. Graphene-based nanocomposite using new modeling molecular dynamic simulations for proposed neutralizing mechanism and real-time sensing of COVID-19
  157. Nanotechnology application on bamboo materials: A review
  158. Recent developments and future perspectives of biorenewable nanocomposites for advanced applications
  159. Nanostructured lipid carrier system: A compendium of their formulation development approaches, optimization strategies by quality by design, and recent applications in drug delivery
  160. 3D printing customized design of human bone tissue implant and its application
  161. Design, preparation, and functionalization of nanobiomaterials for enhanced efficacy in current and future biomedical applications
  162. A brief review of nanoparticles-doped PEDOT:PSS nanocomposite for OLED and OPV
  163. Nanotechnology interventions as a putative tool for the treatment of dental afflictions
  164. Recent advancements in metal–organic frameworks integrating quantum dots (QDs@MOF) and their potential applications
  165. A focused review of short electrospun nanofiber preparation techniques for composite reinforcement
  166. Microstructural characteristics and nano-modification of interfacial transition zone in concrete: A review
  167. Latest developments in the upconversion nanotechnology for the rapid detection of food safety: A review
  168. Strategic applications of nano-fertilizers for sustainable agriculture: Benefits and bottlenecks
  169. Molecular dynamics application of cocrystal energetic materials: A review
  170. Synthesis and application of nanometer hydroxyapatite in biomedicine
  171. Cutting-edge development in waste-recycled nanomaterials for energy storage and conversion applications
  172. Biological applications of ternary quantum dots: A review
  173. Nanotherapeutics for hydrogen sulfide-involved treatment: An emerging approach for cancer therapy
  174. Application of antibacterial nanoparticles in orthodontic materials
  175. Effect of natural-based biological hydrogels combined with growth factors on skin wound healing
  176. Nanozymes – A route to overcome microbial resistance: A viewpoint
  177. Recent developments and applications of smart nanoparticles in biomedicine
  178. Contemporary review on carbon nanotube (CNT) composites and their impact on multifarious applications
  179. Interfacial interactions and reinforcing mechanisms of cellulose and chitin nanomaterials and starch derivatives for cement and concrete strength and durability enhancement: A review
  180. Diamond-like carbon films for tribological modification of rubber
  181. Layered double hydroxides (LDHs) modified cement-based materials: A systematic review
  182. Recent research progress and advanced applications of silica/polymer nanocomposites
  183. Modeling of supramolecular biopolymers: Leading the in silico revolution of tissue engineering and nanomedicine
  184. Recent advances in perovskites-based optoelectronics
  185. Biogenic synthesis of palladium nanoparticles: New production methods and applications
  186. A comprehensive review of nanofluids with fractional derivatives: Modeling and application
  187. Electrospinning of marine polysaccharides: Processing and chemical aspects, challenges, and future prospects
  188. Electrohydrodynamic printing for demanding devices: A review of processing and applications
  189. Rapid Communications
  190. Structural material with designed thermal twist for a simple actuation
  191. Recent advances in photothermal materials for solar-driven crude oil adsorption
Downloaded on 3.2.2026 from https://www.degruyterbrill.com/document/doi/10.1515/ntrev-2022-0033/html
Scroll to top button