Use of polyvinyl chloride (PVC) powder and granules as aggregate replacement in concrete mixtures

1 Introduction

To help reduce environmental pollution, and increase the performance and economy of concrete, much research has been conducted with different types of polymer waste, primarily crushed and fiber-shaped polyethylene terephthalate (PET), polyester, polypropylene, and rubber polymer types. Fiber polymers are often used to increase the flexural strength and energy absorption capacity of concrete; however, there is far less published research dealing with concrete that contains crushed irregularly sized polymers. Accordingly, the ready-mixed concrete industry has not widely adopted the use of crushed irregularly sized polymers.

In the last 50 years, polyvinyl chloride (PVC) has become a major building material. Global vinyl production now totals over 35 million tons per year, and is estimated to reach 49 million tons by 2017, the majority of which is directed to building applications, furnishings, and electronics [1, 2].

Ismail et al. [3] used waste plastic (Figure 1A) of Fabriform shapes as a partial replacement for sand by 10%, 15%, and 20% of concrete mixtures. Accordingly, they determined plastic waste rate increases slump, and decreases density and compressive strength. They noted this might be attributed to the decrease in the adhesive strength between the surface of the waste plastic and cement paste. In addition, they noted that waste plastic is a hydrophobic material that may restrict the hydration of cement.

Figure 1

Plastic wastes: (A and F) plastic waste, (B and C) polyvinyl chloride waste, (D and E) polyethylene terephthalate waste.

In a study by Kou et al. [4], a number of laboratory prepared concrete mixes were tested, in which river sand was partially replaced by PVC pipe waste granules (Figure 1B and C) in percentages of 5%, 15%, 30%, and 45% by volume. They determined two major findings. The positive side indicates that the concrete prepared with a partial replacement by PVC was lighter (lower density), was more ductile (greater Poisson’s ratios and reduced modulus of elasticity), and had lower drying shrinkage and higher resistance to chloride ion penetration. The negative side revealed that the workability, compressive strength, and tensile splitting strength of the concretes were reduced. The results provided useful information for recycling PVC plastic waste in lightweight concrete mixes

Ferreira et al. [5] studied the influence of curing conditions on the mechanical performance of concrete containing waste plastic aggregate (Figure 1D) with replacement ratios of 0%, 7.5%, and 15% of natural aggregates by three types of plastic aggregate. The mechanical performance was evaluated under three curing environments (outdoor environment, laboratory environment, and wet chamber) to represent different conditions that concrete may be subjected to. Increasing the ratio of plastic incorporated and its size leads to a reduction in compressive and splitting tensile strength and modulus of elasticity. However, plastic did improve abrasion wear resistance.

Hannawi et al. [6] used various volume fractions of sand 3%, 10%, 20%, and 50% replaced by the same volume of two types of plastic, polycarbonate (PC) and PET (Figure 1E and F) to investigate the influence on physical and mechanical properties. Their study showed the feasibility of PC and PET waste materials for use as partial volume substitutes for natural aggregates in cementitious materials. Despite some drawbacks, such as a decrease in compressive strength, the use of PC and PET waste aggregates presents various advantages, specifically the reduction of the specific weight of the cementitious materials and a significant improvement in the post-peak flexural behavior.

Fraternali et al. [7] prepared prismatic mortar specimens with recycled polyethylene terephthalate (R-PET) fibers for bending tests. Three fiber lengths were used, 1.13, 2.26, and 3.50 mm, and all at 1% volume content. They determined that all the R-PET fiber configurations were beneficial in terms of material toughness.

Jang-Ho et al. [8] used fibers constructed with three different geometries, embossed, straight, and crimped, from waste PET bottles and used them to control plastic shrinkage cracking in cement-based composites. They determined increased fractions of recycled PET fiber resulted in improved control of plastic shrinkage cracking.

Silva et al. [9] investigated the effect of curing conditions (outdoor environment, laboratory environment, and wet chamber) on the durability of concrete mixes containing selected PET wastes. They tested for shrinkage, water absorption by immersion, water absorption by capillarity action, carbonation, and chloride penetration. The test results showed a decline in the properties of concrete made with plastic aggregates, in terms of durability, compared with conventional concrete.

This paper examines the influence of PVC size and substitution on the performance of concrete. In order to produce normal and high-strength concretes, 10%, 20%, and 30% replacement ratios by volume of PVC granules and powder are used. Slump, fresh and hardened densities, compressive strength, capillary water absorption, and abrasion were tested on all concrete types. The effects of using PVC aggregates on physical properties, water absorption by capillary action, abrasion resistance, and compressive strength on concrete were investigated.

2 Materials and methods

2.1 Materials

The materials used in this study were as follows: cement: type CEM II/A-M (P-LL) 42,5 R (EN 197-1) was used in all types of concrete mixtures. The chemical and physical properties of the cement are presented in Table 1. Aggregate: both fine and coarse aggregates were natural crushed limestone and supplied from the Gumushane city in Turkey. Aggregate was graded according to TS 802 [10], and the natural aggregate gradation is presented in Figure 2. The bulk chemical composition of the natural aggregate is given in Table 2. PVC additives: two type of PVC additives were used, they were powder (P) and granules (G) (Figure 3). Granule PVC size is between 2 and 4 mm and powder PVC size is between 0 and 0.25 mm. The PVC properties are summarized in Table 3. The 10%, 20%, and 30% PVC replacement levels in concrete were achieved by a corresponding reduction in the natural fine aggregate content.

Table 1

Cement properties.

Chemical composition		Physical properties
SiO2	18.59	Fineness (45 μ sieve %)	8.58
Al2O3	4.69	Specific gravity (g/cm3)	3.05
Fe2O3	3.04	Blaine (cm2/g)	4145
CaO	60.34	Initial setting time (min)	123
MgO	1.92	Final setting time (min)	198
SO3	2.89	Soundness (mm)	0.7
Cl	0.0189	Water need (%)	29.9
Na2O	0.11
K2O	0.64	Compressive strength (MPa)
Additives (%)	17.87	2 days	23.9
Loss of ignition (%)	7.19	28 days	51.1
Total	100

Table 2

Aggregates chemical composition.

Limestone
SiO2 (%)	Al2O (%)	Fe2O (%)	MgO (%)	CaO (%)	CaCO3 (%)	MgCO3 (%)	Total (%)
2.95	0.43	0.46	–	–	73.93	22.22	99.99

MgO and CaO were below the limit of detection.

Table 3

Polyvinyl chloride additives properties.

Properties	Unit	Standard values	In this study
Specific gravity	kg/dm3	1.4	1.4
Heat conductivity	kcal/kg/°C	0.110–0.135	0.122
Water absorption	%	0.4–1.0	0.7
Modulus of elasticity (tension)	kg/cm2	30–197	113
Tensile strength	kg/cm2	70.3–2450	1225
Elongation	in 5 cm %	185–430	270
Bending cold temperature	°C	(-57)–(-18)	(-40)–(-20)
Volume resistivity	Ω-cm	1–700×1012	1–700×1012
Dielectric factor	60 Hz	0.05–0.15	0.09

Figure 2

Aggregates gradation.

Figure 3

Granule and powder polyvinyl chloride.

2.2 Mixture proportioning

Two type concrete were produced (dimensions: 10 cm diameter and 20 cm height) as normal (N) (C25/30) and high (H) (C35/45) strength classes according to TS 802 (Table 4). Concrete types (Figure 4) were abbreviated as follows:

• RN (normal strength reference concrete);

• RH (high strength reference concrete);

• PPN10 (normal strength concrete including 10% PVC powder);

• PPN20 (normal strength concrete including 20% PVC powder);

• PPN30 (normal strength concrete including 30% PVC powder);

• PPH10 (high strength concrete including 10% PVC powder);

• PPH20 (high strength concrete including 20% PVC powder);

• PPH30 (high strength concrete including 30% PVC powder);

• GPN10 (normal strength concrete including 10% PVC granule);

• GPN20 (normal strength concrete including 20% PVC granule);

• GPN30 (normal strength concrete including 30% PVC granule);

• GPH10 (high strength concrete including 10% PVC granule);

• GPH20 (high strength concrete including 20% PVC granule);

• GPH30 (high strength concrete including 30% PVC granule).

Table 4

Concrete mixtures of 1 m³.

Concrete components	Normal (dm3)				High (dm3)
	RN	PN10	PN20	PNB30	RH	PH10	PH20	PH30
Water	218	218	218	218	218	218	218	218
Cement	133	133	133	133	180	180	180	180
Water-to-cement	0.53	0.53	0.53	0.53	0.39	0.39	0.39	0.39
Air	19	19	19	19	19	19	19	19
Polyvinyl chloride	–	63	126	189	–	58.3	116.6	174.9
0–4 mm aggregates	302.4	239.4	176.4	113.4	280	221.7	163.4	105.1
4–11.2 mm aggregates	151.2	151.2	151.2	151.2	140	140	140	140
11.2–22.4 mm aggregates	176.4	176.4	176.4	176.4	163	163	163	163
Total	1000	1000	1000	1000	1000	1000	1000	1000

Figure 4

Appearance of concrete in cross-section.

3 Results and discussion

3.1 Slump test

The results of the slump tests with PVC additives concrete mixtures are presented in Figure 5. Generally, concrete produced with PVC experienced a loss of slump. These results indicate a sharp reduction in slump at the 10% replacement level, but less reduction at the 20% and 30% replacement level. The lowest slump was reported for mixture GPH10, containing PVC granules, and was 17% less than the reference concretes (RN-RH).

Figure 5

Slump of polyvinyl chloride-containing concretes.

3.2 Fresh density test

The results of the fresh density tests with PVC are presented in Figure 6. Generally, fresh density test results indicate that as PVC ratio increases, the density decreases. The PVC granule containing mixtures, GPH30 and GPN30, had higher fresh densities than the equivalent PVC powder containing mixtures, PPH30 and PPN30. Mixture GPH30, containing PVC granules, showed the least reduction in fresh density. The PVC powder mixtures, PN and PH, had fresh density values 14.5% lower than the reference mixtures, RN and RH. The PVC granule mixtures, GN and GH, had fresh density values 9.4% lower than RN and RH.

Figure 6

Fresh density tests of polyvinyl chloride-containing concretes.

3.3 Physical properties of hardened concretes

The results of the dry density (DD) and saturated unit density (SUD) tests with PVC additives concrete mixtures are presented in Figures 7 and 8.

Figure 7

Dry density tests of polyvinyl chloride-containing concretes.

Figure 8

Saturated density tests of polyvinyl chloride-containing concretes.

Generally, DD and SUD tests results indicate that while PVC ratio increases, the density of hardened concretes decreases. The lowest SUD was determined for PPN30. The lowest DD was determined for PPN30.

Water absorption tests indicate that while PVC ratio increases, the water absorption decreases (Figure 9). The lowest water absorption is determined PPN30, the highest is in RN and RH. High-strength concretes have less water absorption than normal strength concretes about 6.6% as compared to RN and RH.

Figure 9

Water absorption tests of polyvinyl chloride-containing concretes.

Permeable pore space test results indicate that while PVC ratio increases, the permeable pore space decreases (Figure 10). This may attributed to the fact that PVC does not absorb water. The lowest permeable pore space is determined in GPN30 and the highest is in RN.

Figure 10

Permeable pore space of polyvinyl chloride-containing concretes.

3.4 Compressive strength

The results of the 7- and 28-day compressive strength tests for the PVC-containing concrete mixtures are shown in Figures 11 and 12. By increasing the PVC ratio, the results show a tendency for compressive strength values of PVC-containing concretes to decrease. This result can be attributed to the decrease in adhesive strength between the surface of the PVC and the cement paste. Additionally, PVC is considered to be a hydrophobic material, so this property may restrict the water necessary for cement hydration from entering through the structure of the concrete specimens during the curing period. The results are in agreement with the findings of studies of Ismail et al. [3], Marzouk et al. [17], and Pezzi et al. [18].

Figure 11

Seventh day compressive strength.

Figure 12

Twenty-eighth day compressive strength.

The compressive strength is decreased as the PVC ratio increased. For PPN10, PPN20, PPN30, PPH10, PPH20, PPH30, GPN10, GPN20, and GPN30, the compressive strength was 10%, 33.1%, 39.8%, 17.3% 25.6%, and 33.6%, respectively, lower than that of RN. For PPH10, PPH20, PPH30, GPN10, GPN20, GPN30, GPH10, GPH20, and GPN30, the compressive strength was 2.2%, 13.8%, 37.5%, 9.6%, 13.2%, and 27.5%, respectively, lower than that of RH. The trends for the 28-day compressive strength results are similar for the 7-day results. The largest strength reductions were determined for the normal and high-strength PVC granule containing concretes.

3.5 Capillary water absorption (CWA)

Figures 13–16 show the CWA results for all of the concrete types in 8 days. For all of the PVC-containing concretes, CWA is lower than the reference mixtures. CWA results indicate that while PVC ratio increases, the CWA decreases, especially for PVC powder containing concretes. The contrast in performance between the PVC powder and PVC granule concretes may be due a combination of its hydrophobic nature and the filling (plugging) of the capillary gaps.

Figure 13

Capillary water absorption of polyvinyl chloride powder containing normal strength concretes.

Figure 14

Capillary water absorption of polyvinyl chloride granule containing normal strength concretes.

Figure 15

Capillary water absorption of polyvinyl chloride powder containing high strength concretes.

Figure 16

Capillary water absorption of polyvinyl chloride granule containing high strength concretes.

3.6 Abrasion resistance

Figure 17 shows the abrasion resistance results for all of the concrete types. All of the PVC-containing concretes are lower than the references. The results indicate that as PVC ratio increases, the abrasion resistance increases. The lowest abrasion resistance is determined for RN, the highest is in 30% PVC granule containing concretes. It is likely that the elastic behavior of PVC helps to prevent ruptures due to friction.

Figure 17

Abrasion differences compared to reference mixtures.

4 Conclusions

Plastic wastes mix design, which have dangerous effects to the environment as with many other wastes, should be multifaceted planned in concrete researches. Because of using two different strength concretes and two regular size PVC wastes, it is thought that these study results are objective. PVC wastes hydrophobic effects are understood so that the produced concrete samples are dry slump.

This study demonstrates that it is possible to use waste plastics in situations where resistance to capillary water absorption and abrasion is desired, provided there are no significant reductions in compressive strength. Possible applications include the production of concrete for curb and gutter, pavements, parks, gardens, and coverings for water-containing structures. Furthermore, waste plastic may be used in lightweight concrete applications. Based on the results, the following conclusions can be drawn. The compressive strength values of all PVC-containing concrete mixtures tend to decrease below the values of the references concrete mixtures. This may be ascribed to the decrease in the adhesive strength between the surface of the PVC and cement paste. In addition, PVC is a hydrophobic material that may restrict the hydration of cement.

All of the PVC-containing concretes capillary water absorption values are lower than that of the reference mixtures. As PVC substitution ratio increases, the CWA decreases, especially for PVC powder containing concretes. The PVC powder, when dispersed in the cement paste, helps to interrupt the continuity of capillary pores and is hydrophobic.

All of the PVC-containing concretes abrasion resistance values are lower than that of the references mixtures. As the PVC substitution ratio increases, the abrasion resistance increases. The best abrasion resistance was found for the PVC granule containing concretes. The elastic properties of PVC help prevent the pulverization that normally occurs with natural aggregate.

Due to the physical properties of PVC, as PVC ratio increases, the fresh and hardened concrete densities decrease. Furthermore, as a result of the permeable pore space values, as PVC ratio increases, the permeable pore space decreases.

Generally, using PVC powder and granule as aggregate replacement had the positive effects of increased abrasion resistance and decreased water absorption. Using PVC powder and granule also reduced the density of the concrete but at the same time reduced compressive strength.