Evaluation of concrete pavers using plastic as fine aggregate

Stéphanie Rocha | Jesse Lima | Pedro Quintino | Daniel Machado | Lino Maia
CONSTRUCT, Faculdade de Engenharia, Universidade do Porto | FASA-MOC - Faculdade Santo Agostinho

It was attributed the drop in strength after analyzing the adhesion of plastic in the binder, because it was noted the easy
tearing of the fragments after rupture (figure 4), a fact that implies in the viability of these pavers – there is no exception in
the standard for a value less than 35 MPa. However, Fioriti (2007) when studying pavers using tire waste, concluded that
values above 15 MPa are acceptable, as long as these blocks are used if only if in places where the predominance use is the
Dimensional Evaluation pedestrian traffic.
The increase in solid waste, through the consumption of disposable products such as paper, plastic and glass, caused a
decrease in the useful life of landfills, consequently impacting the environment (SANTOS E ROVARIS, 2017). In 2012, Brazil After 28 days, dimensional evaluation test was performed. The values of the dimensions of the samples presented a difference in
relation to the size of the formwork, but the variations between the samples of each mix were not greater than ± 3 mm, which is Abrasion strength
produced around 200 000 tons per day of solid waste, with 13.5% of this amount being composed of plastic (CEMPRE, The percentage of mark lost for the reference mix, mix with 10% and mix with 20% plastic aggregate, was 0.36%, 0.84% and
2015). The low cost of production and good durability makes its consumption increasing day after day. The incorrect the value required by the standard.
1.96% respectively, according to Table 1.
disposal has consequence impacts on the environment due to the materials characteristics – decomposition is not in a
short time. Water absorption of pavers
Figure 2 presents the average values ​of the blocks of each mix in percentage. Table 1: Average abrasion result
Piatti and Rodrigues (2005) assert that plastics can be synthetic source or derived from natural substances. It is composed
of polymers, macromolecules from smaller and repeated structural units. Among several types are Polyethylene (PE) and Abrasion
Polypropylene (PP). Type Initial mass (g) Final mass (g) Lost mass (%)
(g)
Civil construction sector has caused major environmental impacts as large generators of waste. In addition, it is a large Mix 1 78,958 78,669 0,289 0,36
consumer of raw materials. According to data from ANEPAC (2015), in 2015, approximately 519 million tons of aggregates 0,84
Mix 2 71,414 70,809 0,605
were produced, in Brazil. Therefore, the search for alternatives to solve these problems is fundamental to reduce the
Mix 3 67,576 66,251 1,325 1,96
impacts, making it necessary to development of new products.
The substitution of natural aggregates for solid urban waste such as metals, plastic and glass are studied in several
investigations. Tiburcio (2018) reused plastic in masonry blocks. Gomes and Santos (2014) analyzed the glass in the It is possible to identify that abrasion wear increases with the substitution of fine aggregates increases. The loss of material
manufacture of pavers. Therefore, the present work aimed to evaluate the plastic waste that cannot be recycled as results from the adhesion between the plastic with the other components of the concrete, facilitating the material to be
aggregates when applied to pavers. Its viability can be an alternative in cases where the extraction and transport of fragmented. According (FUSCO, 1995) the adhesion, attrition and interlocking of the connection or mechanical adhesion of
natural aggregates is extremely reduced. the materials intervenes in connection with the other materials. Hypothetically the use of the plastic is greater than the fine
aggregate, justifying the growth of the wear mass.

MATERIAL AND METHODS Figure 2: Absorption of pavers

The specimens must have a water absorption no higher than 6% to accomplish the specifications of the NBR 9781 (ABNT, 2013).
Laboratory tests, dimensional evaluation, water absorption rate, compression strength and abrasion strength of the pavers,
The result indicates that specimens with plastic waste presented practically the same water absorption value than the reference The percentage of plastic in the concrete mixture increased, there was variation in the values of the tests in comparation with
were carried out in accordance with the guidelines and procedures established by the NBR 9781 standard - Concrete
mix, being 5.4% for the reference mix 5.63% and 5.76% for replacements of 10% and 20%. Regarding the percentages allowed, the conventional concrete pavers. Pavers with plastic did not have compressive strength necessary to comply with the
pieces for paving, specifications and methods (ABNT, 2013).
despite presenting values close to limit that standard requires for compositions made with substitution of fine aggregate by standard, because it was noticed that the plastic has little adherence to the concrete mixture. Compared to natural aggregate,
plastic waste to present a low permeability, demonstrating one of the main characteristics of polymers is impermeability. the compressive strength of the reference pavers was higher due to the fine particle size of the aggregate, which facilitates
Materials Therefore, it was noticed that increase in plastic in pavers increased slightly the water absorption, concluding that the more adherence to mixtures of concrete. Water absorption and dimensions met the regulatory requirements. Regarding to abrasion
Plastics used were Polyethylene (PE) and Polypropylene (PP) provided by a recycling company. The sand and gravel were plastic, the greater the porosity of material, preventing to use of higher percentages of replacement of washed sand. strength, the more plastic waste the more loss of material. It was concluded that the pavers produced with plastic waste
made available by construction material stores. Portland cement used was the CP-V-ARI high early strength cement. The reduces the efficient use of the raw materials.
granulometric curve of the plastic waste was compared with that of the fine aggregate. About 52% of the tested material Compressive strength
was retained in the 2.40 mm sieve and 48% in the 4.8 mm sieve. The fineness modulus was 6.45, higher common The values ​of the compressive strength variation test are shown in Figure 3 and in Figure 4 a specimen after testing from mix 3.
aggregate, because of the recycling process, presenting different distributions particle sizes.
The sand was retained in a greater proportion in the 0.3 mm sieve and 0.15 mm sieve, this being last in a volume greater
than 50% of the total weight of the sample. The coarse aggregate was characterized as gravel zero, due to its small
dimensions, being in a greater proportion between the 4.8 mm to 9.5 mm meshes, a usable value in the manufacture of REFERENCES
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reaching a value of 37.78 MPa, with an increase of 50.45% in relation to the strength value of the seventh day.
The 10% and 20% substitution mix for plastic also showed high strength values already on the seventh day, however, they showed Acknowledgements
a lower value in relation to reference mix. During the 7 days both mixes showed an average evolution of 1.77 MPa in their This work is financially supported by: Base Funding – UIDB/04708/2020 of the CONSTRUCT – Instituto de I&D em Estruturas e
strength value reaching the twenty-eighth day at a value well below the benchmark. While the 10% mix had a compressive Construções - funded by national funds through the FCT/MCTES (PIDDAC). This work is funded by national funds through FCT –
strength of 20.69 MPa, a strength 36.39% lower than the reference mix, the 20% mix had a compressive strength of 18.78 MPa, a Fundação para a Ciência e a Tecnologia, I.P., under the Scientific Employment Stimulus – Institutional Call –
Figure 1: (a) Mix 1; (b) Mix 2; (c) Mix 3. value less 52.09% than the reference mix. CEECINST/00049/2018.