Eco-friendly paver blocks: repurposing plastic waste and foundry sand

ABSTRACT

This study investigates the use of waste plastic (polyethylene and polypropylene) and foundry sand to manufacture eco-friendly paver blocks, providing a sustainable alternative to conventional materials. The project aims to address the challenges of plastic waste disposal and environmental damage caused by sand mining. Twelve paver block samples were prepared with varying proportions of plastic (30%–60%) and foundry sand, with or without coarse aggregate. The mechanical properties, including compressive strength, flexural strength, water absorption, and fire resistance, were tested following ASTM standards. The optimal mix, FPA-2 (40% plastic, 40% foundry sand, 20% coarse aggregate), exhibited a compressive strength of 27 N/mm² and a flexural strength of 6.7 N/mm², comparable to traditional paver blocks. Water absorption rates were below 7%, and the blocks met fire resistance criteria. Cost analysis revealed that plastic-based paver blocks are up to 25% cheaper than conventional ones, enhancing their economic feasibility. By repurposing waste materials, this study offers a sustainable solution for reducing natural resource dependency and mitigating environmental harm. The findings highlight the potential for plastic-based paver blocks to promote circular economy practices, maintain performance standards, and provide cost-effective alternatives for the construction industry.

Keywords:
Paver block; Waste plastic; Foundry sand (Fs); Sustainable construction; Recycling

1. INTRODUCTION

The construction industry, known for its massive consumption of raw materials, has long relied on traditional resources such as cement, coarse aggregate, and fine aggregate. These materials are integral to producing a wide range of structural elements, including bricks, paver blocks, tiles, and other critical components. However, the continuous use of these conventional materials has raised concerns due to their rising costs, environmental footprint, and demand for specific compositions to achieve desired mechanical properties [¹]. As construction continues to expand globally, so does the need to explore sustainable alternatives to traditional materials.

One approach that has garnered attention in recent years is the incorporation of waste materials into construction processes. In this project, the focus is on manufacturing paver blocks using waste plastic and foundry sand, two abundant materials that often pose significant environmental challenges when disposed of improperly. The construction industry, known for its vast consumption of resources, presents an opportunity to leverage waste materials in innovative ways to reduce environmental degradation [²]. Recycling plastic waste, in particular, offers numerous benefits due to its omnipresence and long service life. Plastic waste is one of the most problematic materials in waste management systems globally because of its persistence in the environment. Repurposing plastic waste into paver blocks not only diverts it from landfills and oceans but also helps in mitigating the environmental impact associated with the disposal of plastic [³].

Paver blocks, also referred to as brick paving, are increasingly being adopted in the construction sector for a variety of applications, including pavements, walkways, and hard standings. They have gained popularity as a decorative, durable, and easy-to-install alternative to traditional concrete pavements [⁴]. The rise in the use of paver blocks can be attributed to several key factors. First, they offer unparalleled design versatility, allowing intricate patterns to be incorporated into urban landscapes or private projects. Their aesthetic appeal has made them a preferred choice for residential, commercial, and public infrastructure projects. Second, paver blocks are known for their durability, withstanding heavy loads and adverse weather conditions, making them suitable for a wide range of applications. Their durability and minimal maintenance needs have added to their popularity, further driving their adoption in the construction industry [⁵].

The focus on waste plastic and foundry sand as key ingredients in the production of paver blocks not only addresses the sustainability aspect of modern construction but also contributes to cost savings. Cement, one of the primary materials used in paver block manufacturing, has a considerable environmental impact due to the energy-intensive processes required for its production. By partially replacing cement with waste plastic, this project offers a dual benefit. First, it reduces the environmental footprint of cement production, which is a major contributor to CO₂ emissions globally. Second, it provides a valuable solution for managing plastic waste, turning a liability into a resource [⁶]. This circular approach—where waste materials are reused in construction—aligns with sustainable development goals aimed at reducing waste and conserving natural resources.

Foundry sand, another key material in this project, is a byproduct of the metal casting industry. It consists primarily of high-quality silica sand, which is used to create moulds for both ferrous and non-ferrous metal castings. The metal casting process, particularly in the automobile sector, generates large quantities of foundry sand. While the sand is initially pure, it becomes contaminated with impurities after repeated use in the casting process [⁷]. Traditionally, foundry sand is discarded after it has served its purpose in the casting industry, contributing to waste management challenges. However, by incorporating foundry sand into the production of paver blocks, we can reuse this material effectively while reducing the strain on natural sand resources [⁸].

The incorporation of waste plastic and foundry sand into paver blocks represents a promising development in sustainable construction. This project addresses not only the environmental challenges posed by waste materials but also seeks to reduce the reliance on traditional construction materials, which are becoming increasingly costly and scarce. By integrating these waste materials into the manufacturing process, we are taking a significant step towards creating more eco-friendly construction solutions [⁹].

The environmental implications of cement, combined with the global plastic waste problem, present a critical need for alternative materials in construction. Unlike other waste materials, plastic does not break down easily, which has made it a significant problem for waste management systems [¹⁰]. Waste plastic, due to its durability and resistance to degradation, is an ideal candidate for repurposing in construction materials. However, this same property makes it valuable when integrated into long-lasting construction elements like paver blocks. In the case of foundry sand, its reuse provides a solution for industries struggling with the disposal of large amounts of sand contaminated during metal casting processes [¹¹].

This project showcases the transformative potential of waste materials in the construction industry, demonstrating how they can positively impact both the economy and the environment. By shifting from traditional construction materials to sustainable alternatives like waste plastic and foundry sand, the project addresses pressing issues such as the depletion of natural resources and the environmental harm caused by conventional construction methods [¹²]. This shift is crucial for mitigating the long-term effects of unsustainable practices, and it represents a step toward more eco-conscious construction techniques.

Furthermore, the project emphasizes the role of innovation in green building and sustainable construction practices. By reducing dependence on traditional materials such as cement and aggregates and instead repurposing waste, this initiative aligns with the broader goals of resource conservation and environmental responsibility. The success of this project not only demonstrates the feasibility of using alternative materials in paver blocks but also opens the door for further exploration of other waste products that can be utilized in construction.

2. MATERIALS

2.1. Foundry sand

Foundry sand, is collected from the metal casting industry. Foundry sand is a by-product of metal casting processes and typically consists of high-quality silica sand that has been used in the production of metal parts. The main constituent of foundry sand is silica sand that has been lightly covered with dust, leftover materials, and burned carbon. It is the byproduct of metal casting processes, particularly sand casting systems commonly preferred by most metal industries. Foundries often recycle & reuse the sand multiple times during the casting process [¹³]. However, after multiple uses, the sand is eventually discarded, becoming what is known as waste foundry sand. In the construction industry, waste foundry sand can be utilized in paver block manufacturing to enhance its strength and other durability factors. This sustainable approach not only reduces the environmental impact of waste foundry sand disposal but also contributes to the development of durable construction materials [¹⁴]. Table 1 and Table 2 shows the physical and chemical properties of foundry sand respectively.

Table 1
Physical properties of foundry sand.

S.NO	PARAMETERS	SPECIFICATION
1	Specific gravity	2.5–2.65
2	Sieve Analysis	Zone III
3	Water absorption	1.5

Table 2
Chemical properties of foundry sand.

S.NO	PARAMETERS	SPECIFICATION
1	Silica	56.8%
2	Ferric Oxide	0.37%
3	Magnesium Oxide	0.21%
4	Sodium Oxide	NIL
5	Aluminium Oxide	NIL

2.2. Plastic

Cement, a binding material, is commonly used in construction to set and harden other materials, binding them together. It is one of the most widely used materials globally, second only to water. However, in this project, an alternative to cement is explored, utilizing plastic, which possesses good binding properties [¹⁵].

Waste plastic, specifically high-density polyethylene (HDPE) and polypropylene (PP), are sourced from plastic scrap industries. HDPE is selected for its beneficial properties, such as durability, resistance to moisture, and ability to withstand significant mechanical stress, making it an ideal component for paver blocks. Plastic, a waste material widely used in the construction industry, offers a solution to the disposal of large amounts of the recycled plastic material through reuse [¹⁶]. Despite the presence of many recycling plants worldwide, recycled plastic tends to lose its strength with each cycle. Consequently, recycled plastic often ends up as landfill, contributing to environmental issues [¹⁷]. Table 3 shows the physical properties of plastic.

Table 3
Physical properties of plastic.

S.NO	PARAMETERS	SPECIFICATION
1	Melting Point	150°C
2	Thermal Co-efficient	100–200 × 10-6°C
3	Density	1–0.945 kg/m3
4	Tensile Strength	0.25–0.45(N/mm2)

2.3. Preparation of paver block

2.3.1. Manufacturing process

The manufacturing of the paver block begins with the melting of the waste plastic. The plastic heater machine is used to heat the HDPE and PP to a temperature of 150°C. This heating process is crucial because the plastic needs to reach a molten state to mix properly with the other materials. The plastic is kept in the heater for a few minutes until it is fully liquefied.

Once the plastic has melted and is in a molten liquid state, the foundry sand and coarse aggregate are added. The materials are combined in the correct proportions and mixed thoroughly. Achieving a uniform mixture is essential to ensure that the plastic coats the sand and aggregate evenly, which contributes to the overall strength and durability of the paver block. Figure 1 shows the Plastic heater machine.

Figure 1
Plastic heater machine.

2.3.2. Mix proportions of paver blocks

The paver blocks are manufactured using various proportions, as shown in Table 4. These paver blocks consist of plastic, foundry sand, and coarse aggregate. The first nine samples are made using high-density polyethylene (HDPE) plastics, while the next three samples utilize high-grade polypropylene (PP) plastics. In the initial three samples, 20% of coarse aggregate is maintained in a constant proportion. The subsequent three samples contain 10% of coarse aggregate in a constant proportion. The following three samples are made without coarse aggregate, maintaining a constant proportion of plastic and FS. The proportions of plastic and foundry sand in the paver blocks vary from 30% to 60%, with different ratios tested to determine the optimal combination. Table 4 contains the various proportions of paver block.

Table 4
Mix proportions of paver block.

S.NO	SAMPLE	PLASTIC (%)	FOUNDRY SAND (%)	AGGREGATE (%)
1	FPA 1	50	30	20
2	FPA 2	40	40	20
3	FPA 3	30	50	20
4	FPA 4	50	40	10
5	FPA 5	45	45	10
6	FPA 6	40	50	10
7	FP 1	60	40	0
8	FP 2	50	50	0
9	FP 3	40	60	0
10	PP 1	50	30	20
11	PP 2	40	40	20
12	PP 3	30	50	20

2.3.3. Mould preparation

While the mixture is being prepared, the metal moulds used for shaping the paver blocks are cleaned and prepped. Cleaning the mould ensures that no debris or residue is left from previous batches, which could affect the shape or surface finish of the new blocks. After cleaning, oil is applied to the interior surfaces of the mould to act as a release agent, preventing the mixture from sticking to the mould and ensuring easy removal of the block once it has hardened.

2.3.4. Pouring and compaction

After preparing the moulds, the molten plastic mixture, combined with the foundry sand and coarse aggregate, is poured into the mould. Compaction is a crucial step in the manufacturing process, as it ensures that the material is densely packed into the mould, reducing internal pores and air voids that can compromise the strength of the final product. The block is compacted using manual or mechanical methods to achieve the required density and uniformity. Failure to compact the block properly can result in poor strength and durability, as voids within the block can lead to structural weaknesses.

2.3.5. Drying and hardening

Once the block has been properly compacted, it is left to dry and harden. The paver blocks are allowed to dry in an open space for 24 hours. During this time, the block cools down and begins to solidify, transitioning from its molten state to a solid form. The drying process is important because it allows the block to attain its initial hardness, making it stable enough for handling and further processing.

2.3.6. Removal from mould

After the 24-hour drying period, the hardened paver block is carefully removed from the mould. The application of oil during the mould preparation stage ensures that the block can be released easily, without damaging its shape or surface. The block is inspected for any defects, such as cracks, uneven surfaces, or incomplete compaction. Once the block has passed this initial inspection, it is ready for further curing or testing. The width of the paver block is 12cm on each side and its height is 5 cm. The weight of each paver block is 3.5 kg. Figure 2 and Figure 3 shows the casted paver block.

Figure 2
Paver block.

Figure 3
De-Moulding of paver block.

2.3.7. Final testing

After the blocks are removed from the mould, they undergo a series of tests to evaluate their strength and durability. The blocks were tested for compressive strength, flexural strength, water absorption, and other important properties to ensure they meet the required standards for use in construction projects. Only after passing these tests are the paver blocks deemed suitable for use in practical applications, such as pavements, driveways, or landscaping projects.

3. METHODS

3.1. Compressive strength testing

The testing procedure adhered strictly to the guidelines set forth in ASTM C109/C109M, a globally recognized standard that specifies the method for determining the compressive strength of hydraulic cement mortars, although it can be applied to other materials like paver blocks. Following these standards ensures that the test results are accurate, reliable, and comparable with other studies and industry benchmarks. In line with these guidelines, the CTM was set to apply pressure at a consistent loading rate of 20 MPa per second. This loading rate is crucial for maintaining uniform stress distribution across the sample, preventing localized failures that might result from uneven loading [¹⁸].

These blocks were subjected to the compressive strength test after curing. The blocks were carefully placed in the testing chamber of the CTM, ensuring that they were aligned properly to prevent any irregularities in load distribution, which could affect the outcome of the test. The casted paver blocks were prepared in such a way that the testing procedure would mimic the conditions they would experience in real-world applications, providing practical insights into their performance. The compressive strength test continued with the machine applying increasing levels of stress to the block until failure occurred, which is defined as the point at which the material can no longer sustain the applied load and fractures. This point of failure is recorded as the maximum compressive strength of the material, a key indicator of its load-bearing capacity. The results of these tests were used to assess the structural integrity of the paver blocks made from waste plastic and foundry sand and to compare them with traditional paver blocks made from conventional materials.

3.2. Flexural strength testing

The flexural strength test was conducted in accordance with ASTM C78/C78M, a globally recognized standard that outlines the procedure for determining the flexural strength of concrete using a simple beam with third-point loading, although it can be applied to other materials like paver blocks. Adhering to ASTM guidelines ensures consistency, accuracy, and comparability with other studies and industry standards [¹⁹].

For this test, paver blocks were placed on two supporting rollers, ensuring the proper alignment to avoid irregular stress distribution. A load was then applied at two points along the top of the block, between the supports, to create bending stress. This method allows for the uniform application of the load across the span of the block, mimicking the forces that blocks would encounter in use, such as when heavy loads are placed on uneven surfaces. The load was applied steadily until the block reached its failure point, defined as the moment the block fractures or cracks under the applied bending stress.

The flexural strength, recorded at the point of failure, provides a critical measure of the block’s resistance to tensile stresses and its overall durability in service. The results of this test were used to evaluate the performance of paver blocks made from waste plastic and foundry sand, comparing their flexural strength with that of traditional blocks made from conventional materials. This data is crucial for determining the suitability of these paver blocks for various applications where resistance to bending is essential.

3.3. Water absorption

To assess water absorption, the test was performed in accordance with the ASTM D570 standard, which is widely recognized for evaluating water absorption in materials [²⁰]. The procedure began by thoroughly drying the paver block samples in an oven at a controlled temperature for 24 hours. After drying, the samples were weighed, and this initial dry weight was recorded as W1.

Following the drying process, the samples were fully immersed in water for 24 hours. After soaking, the blocks were removed and brought to a saturated surface-dry condition, meaning any excess water on the surface was wiped off, ensuring that only the water absorbed into the material was accounted for. The blocks were then weighed again, and this second weight was noted as W2.

The water absorption percentage, which provides a measure of how much water the paver blocks absorbed, was calculated using the following formula:

$$\text{Water Absorption}\left(\%\right)=\left[\left(\text{W1}–\text{W2}\right)/\text{W2}\right]\times \text{1}00$$

Here:

• W1 is the dry weight of the sample before immersion.

• W2 is the weight of the saturated sample after immersion.

This test offers insights into the material’s porosity and its suitability for various applications, especially in environments where moisture exposure is prevalent. Low water absorption values typically indicate higher durability and resistance to weathering, making such blocks more suitable for long-term use in construction projects.

3.4. Fire resistance test

A fire resistance test for plastic paver blocks assesses their ability to withstand high temperatures without significant damage or structural failure. During the test, samples are exposed to intense heat, typically between 500°C and 1000°C, for a specified duration to simulate real fire conditions. After exposure, the blocks are evaluated for any cracking, deformation, or weight loss, and their residual compressive strength was measured.

Blocks with higher plastic content are likely to degrade faster under fire due to plastic’s lower melting point, potentially leading to warping or melting. In contrast, blocks with more foundry sand and aggregate are expected to show better fire resistance, as these materials are non-combustible and help slow heat penetration. Overall, the plastic composition in these blocks can limit their fire resistance, but adjustments in material ratios or adding fire retardant agents could improve their performance [²¹].

4. RESULTS AND DISCUSSION

4.1. Compressive strength

By incorporating plastic waste into concrete, four different types of cubes were casted using varying proportions of plastic waste (PW) and foundry sand (FS), along with different percentages of coarse aggregate (CA). Initially, a concrete mix with 20% coarse aggregate, and 50%, 45%, and 40% plastic waste (PW) combined with 30%, 40%, and 50% foundry sand (FS) was used. The compression strength of this mix, named FPA2, demonstrated an optimal level of strength due to the even distribution of PW and FS within the concrete mix, resulting in enhanced strength. Subsequently, another mix with 10% coarse aggregate, and 50%, 45%, and 40% plastic waste (PW) combined with 40%, 45%, and 50% foundry sand (FS) was used, the values are listed in Table 5. The compression strength of this mix, named FPA5, exhibited an optimal level of strength. Following that, a mix with 0% coarse aggregate, and 60%, 50%, and 40% plastic waste (PW) combined with 40%, 50%, and 60% foundry sand (FS) was used. The compression strength of this mix Table 4, named FP2, showed an optimal level of strength. Lastly, a mix using polypropylene, with 50%, 40%, and 30% plastic waste (PW) combined with 30%, 40%, and 50% foundry sand (FS), was utilized. The compression strength of this mix named PP2, demonstrated an optimal level of strength.

Table 5
Compressive strength of paver block.

S.NO	SAMPLE	PLASTIC (%)	FOUNDRY SAND (%)	AGGREGATE (%)	COMPRESSIVE STRENGTH (n/mm2)
1	FPA 1	50	30	20	20.3
2	FPA 2	40	40	20	27
3	FPA 3	30	50	20	13.6
4	FPA 4	50	40	10	18.55
5	FPA 5	45	45	10	26.4
6	FPA 6	40	50	10	17.4
7	FP 1	60	40	0	22.6
8	FP 2	50	50	0	25
9	FP 3	40	60	0	18.2
10	PP 1	50	30	20	15.4
11	PP 2	40	40	20	18.6
12	PP 3	30	50	20	12.3

The provided data from Table 5 and Figure 4 presents the compressive strength of various plastic paver block samples with different proportions of plastic, foundry sand, and aggregate. The results demonstrate that the composition of these materials significantly influences the strength of the pavers. Notably, FPA 2, with a composition of 40% plastic, 40% foundry sand, and 20% aggregate, achieved the highest compressive strength at 27 N/mm², indicating an optimal balance between materials.

Figure 4
Compression strength graph.

In contrast, FPA 3, containing 30% plastic, 50% foundry sand, and 20% aggregate, had the lowest strength at 13.6 N/mm², suggesting that a higher sand content with lower plastic weakens the structure. Meanwhile, samples with 60% plastic and 0% aggregate, such as FP 1 and FP 2, also displayed relatively high-strengths (22.6 N/mm² and 25 N/mm², respectively), indicating that aggregate content is not always essential for achieving strength when plastic content is high. Balanced compositions, such as PP 2 (40% plastic, 40% foundry sand, 20% aggregate), yielded moderate compressive strength (18.6 N/mm²), emphasizing the importance of optimizing the mix for durability and performance. These findings suggest that varying the plastic and foundry sand percentages while maintaining some aggregate can lead to diverse strength outcomes, depending on the specific application and performance requirements of the paver blocks.

4.2. Flexural strength

The compositions of the samples varied in their content of plastic, foundry sand, and aggregate, and the corresponding flexural strengths were measured. Sample FPA-2 exhibited the highest flexural strength at 6.7 N/mm², comprising 40% plastic, 40% foundry sand, and 20% aggregate. Generally, samples with a higher percentage of plastic, such as FP-1 and FP-2, showed relatively high flexural strengths of 5.8 N/mm² and 6.0 N/mm² respectively, indicating a positive influence of plastic content up to a certain percentage. Conversely, samples with higher foundry sand content, like FP-3 with 60% foundry sand, displayed varying flexural strengths, suggesting that while foundry sand contributes to strength, achieving an optimal balance with other components is essential.

Table 6 and Figure 5 presents the flexural strength of various plastic paver block samples, categorized by their composition of plastic, foundry sand, and aggregate. Flexural strength, measured in Newtons per square millimeter (N/mm²), indicates the ability of a material to withstand bending forces without breaking. Among the samples, FPA 2 demonstrates the highest flexural strength at 6.7 N/mm², with a composition of 40% plastic, 40% foundry sand, and 20% aggregate, suggesting that this particular blend provides an optimal balance of materials for enhanced performance. Conversely, FPA 3 has the lowest flexural strength at 4 N/mm², with a higher foundry sand content (50%) and reduced plastic content (30%), indicating that excessive sand may compromise the block’s ability to withstand bending forces.

Table 6
Flexural strength of paver block.

S.NO	SAMPLE	PLASTIC (%)	FOUNDRY SAND (%)	AGGREGATE (%)	COMPRESSIVE STRENGTH (n/mm2)
1	FPA 1	50	30	20	5.3
2	FPA 2	40	40	20	6.7
3	FPA 3	30	50	20	4
4	FPA 4	50	40	10	5
5	FPA 5	45	45	10	6.3
6	FPA 6	40	50	10	4.5
7	FP 1	60	40	0	5.8
8	FP 2	50	50	0	6
9	FP 3	40	60	0	4.8
10	PP 1	50	30	20	4.3
11	PP 2	40	40	20	5
12	PP 3	30	50	20	3.9

Figure 5
Flexural strength graph.

Additionally, samples such as FP 2 (50% plastic and 50% foundry sand) show a competitive flexural strength of 6 N/mm², illustrating that higher plastic content can still yield significant strength, even with varying aggregate percentages. The PP samples generally exhibit lower flexural strengths, with PP 3 recording the lowest at 3.9 N/mm². This trend suggests that higher plastic content alone, especially without sufficient foundry sand and aggregate, may not be sufficient to achieve desirable mechanical properties. Overall, the data indicates that a well-balanced composition of plastic and foundry sand is critical for optimizing the flexural strength of plastic paver blocks, impacting their suitability for various construction applications.

4.3. Water absorption

After casting, the paver blocks were immersed in water for 28 days of curing. The wet weight of the paver blocks, noted as W1, was recorded. Subsequently, the specimens were dried in an oven at a specific temperature for 24 hours, and their dry weight, noted as W2, was noted. The water absorption percentage was also calculated, ensuring it did not exceed 7% of the paver block’s weight.

Table 7 and Figure 6 shows following measurements and records were made about the various samples’ rates of water absorption: FPA–5.6%, FP–5.25%, and PP–3.2%. These values indicate the amount of moisture absorbed by the paver blocks when submerged in water. Among the samples, PP demonstrated the lowest water absorption rate at 3.2%, indicating that it retained the least amount of moisture. On the other hand, FPA exhibited the highest water absorption rate at 5.6%. These results suggest that the composition of plastic waste and sand in the paver blocks significantly influences their water absorption properties. Lower water absorption rates are desirable as they indicate better resistance to moisture penetration, enhancing the durability and longevity of the paver blocks.

Table 7
Water absorption of paver block.

SL.NO	SAMPLE	WATER ABSORPTION %
1	FPA	5.6
2	FP	5.25
3	PP	3.2

Figure 6
Water absorption (%).

The provided table summarizes the water absorption characteristics of three different categories of plastic paver block samples—FPA, FP, and PP—each showing varying levels of water absorption. FPA, with a water absorption percentage of 5.6%, has the highest moisture uptake among the samples, indicating that it absorbs more water compared to the other two types. FP follows closely with a water absorption of 5.25%, showing slightly better resistance to water absorption but still relatively high. On the other hand, PP demonstrates the lowest water absorption at 3.2%, making it the most water-resistant among the three. These results suggest that the composition of the PP samples likely results in a denser, less porous structure, which can enhance durability by reducing the potential for water-induced damage. Lower water absorption, as seen in PP, generally correlates with better long-term performance, especially in environments where moisture exposure is common, as it minimizes the risk of degradation caused by freeze-thaw cycles and other weathering effects.

In regions with heavy rainfall or flooding, paver blocks with higher water absorption rates, such as the FPA samples, may face challenges in maintaining their structural integrity. For these areas, additional treatments could be beneficial to enhance the water resistance of the blocks.

4.4. Fire resistance test

The fire resistance test is crucial for assessing the safety and performance of paver blocks made from plastic, particularly because plastic is known to be highly susceptible to fire. Understanding the melting point of the plastic is essential, as it determines how the material will behave under high temperatures. To enhance fire resistance, foundry sand—which consists of silicon and magnesium—is mixed into the paver block formulation, as these materials possess inherent properties that resist combustion.

The testing process begins by placing the paver block in an oven at a controlled temperature of 180°C for 24 hours, allowing for thorough heat exposure. After this period, the dimensions of the paver block was measured to assess any changes resulting from the heat. If the dimensional change is not greater than 1 cm, the block is deemed suitable for construction work, indicating it has maintained its structural integrity. In this particular case, since the dimensional change is less than 1 cm, the paver block meets the necessary criteria and can be confidently used for site work. This evaluation ensures that the blocks are not only durable but also safe for various applications, particularly in environments where fire resistance is a significant concern.

5. CONCLUSION

The following conclusions were reached after consideration of the Results & discussion:

• Utilizing waste plastic and foundry sand in the production of paver blocks offers an effective solution for the disposal of plastic and foundry waste.

• This method helps reduce the demand for natural and conventional materials such as fine aggregate and cement, which are majorly used in construction.

• By replacing cement with plastic and fine aggregate with foundry sand, the manufacturing cost of paver blocks can be significantly reduced.

• The cost of concrete paver block is Rs.30 to 45 per square feet. The cost of one plastic paver block is Rs.5.25 and the cost of plastic paver block per square feet is Rs.21. When compared to the conventional paver block the rate will be reduced upto Rs.10 per square feet.

• Paver blocks manufactured using the FPA-2 sample, consisting of 40% plastic, 40% foundry sand, and 20% coarse aggregate, demonstrate a compressive strength of 27 N/mm², which is comparable to that of normal paver blocks.

• Sample FPA-2, with 40% plastic, 40% foundry sand, and 20% aggregate, exhibited the highest flexural strength at 6.7 N/mm². This suggests that achieving the right balance of plastic, foundry sand, and aggregate is crucial for maximizing strength.

• The FPA sample of paver blocks exhibits a water absorption rate of 5.6%, which is within acceptable limits and comparable to that of concrete paver blocks.

• Since the dimensional change is less than 1 cm, in fire resistance test, the paver block meets the necessary criteria and can be confidently used for site work. The paver block shows fire resistance because the foundry sand consists of silicon, magnesium and iron oxide proportion which are good at heat resistance.

• Considering its properties, the FPA-2 sample of plastic paver blocks is recommended for use in non- traffic areas, offering a sustainable and cost-effective alternative for construction projects.

While the results of this study demonstrate the potential of plastic-based paver blocks as a sustainable construction material, several limitations must be considered like long-term durability and environmental impacts. Addressing these limitations requires further research to optimize material formulations, improve durability, and assess the environmental impacts of widespread adoption. Such investigations would ensure the safe and sustainable integration of plastic-based paver blocks into construction practices.

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Publication Dates

• Publication in this collection
  20 Jan 2025
• Date of issue
  2025

History

• Received
  18 Oct 2024
• Accepted
  22 Nov 2024