Slash Construction Costs and Boost Sustainability with Waste Foundry Sand in Concrete
This technical summary is based on the academic paper "Experimental investigation on waste foundry sand for effective utilization in building construction" by Manikandan A., Anandha Raj L. and Aravindh P., published in Research Journal of Chemistry and Environment (2020).
Keywords
- Primary Keyword: Waste Foundry Sand
- Secondary Keywords: Concrete Strength, Fine Aggregate Replacement, Cost-Effective Construction, Sustainable Building Materials, Metal Casting Waste, Concrete Cube
Executive Summary
- The Challenge: The global metal casting industry generates millions of tons of Waste Foundry Sand (WFS) annually, posing significant disposal costs and environmental challenges.
- The Method: Researchers conducted an experimental study replacing conventional fine aggregate (river sand) with WFS in proportions of 10%, 20%, 30%, and 40% within a standard concrete mix.
- The Key Breakthrough: Concrete incorporating up to 40% WFS as a fine aggregate replacement achieved over 86% of the compressive strength of conventional concrete after 28 days, proving its viability for construction applications.
- The Bottom Line: Waste Foundry Sand is a highly effective, cost-free alternative to expensive natural sand in concrete, offering a direct path to reduced material costs and more sustainable construction practices.
The Challenge: Why This Research Matters for HPDC Professionals
The Indian metal casting industry, a proxy for the global sector, produces nearly 10 million metric tons of castings annually from approximately 5,000 foundries. A major byproduct of this massive output is Waste Foundry Sand (WFS)—high-quality silica sand that has been degraded after repeated use in molding. Disposing of this material is not only a logistical burden but also an environmental concern.
Simultaneously, the construction industry relies heavily on natural river sand as a fine aggregate for concrete. This resource is becoming increasingly scarce and expensive due to mining regulations and high demand. This research directly addresses both problems by investigating a circular economy solution: can the waste stream of one industry become a valuable raw material for another? For HPDC managers, finding a viable, large-scale use for WFS can transform a costly liability into a sustainable output.
The Approach: Unpacking the Methodology
This study systematically evaluated the feasibility of using WFS as a direct replacement for natural fine aggregate in concrete. The methodology was robust, involving material characterization and comparative strength testing.
Method 1: Material Sourcing and Treatment
The Waste Foundry Sand was sourced from Sakthi Auto-Component Ltd, Erode, India. A critical step in the methodology was addressing the material's chemical composition. Chemical analysis (Table 4) revealed that the WFS had a higher content of magnesium and lime than is ideal for conventional concrete. To mitigate this, the researchers implemented a lime sludge treatment. The WFS was soaked in a lime solution for approximately six hours, a process that uses an exothermic reaction to remove residual resinous binders from the sand particles, making it more suitable for use in cementitious mixtures.
Method 2: Concrete Mix Design and Compressive Strength Testing
The researchers used a conventional concrete mix proportion of 1:1.5:3 (cement: fine aggregate: coarse aggregate). Five distinct batches were created:
* A control batch with 0% WFS (conventional concrete).
* Four experimental batches where the fine aggregate was replaced with WFS at 10%, 20%, 30%, and 40% by mass.
For each batch, concrete cubes (150mm x 150mm x 150mm) were cast. These cubes were then subjected to compressive strength tests at 7, 14, and 28-day intervals to measure strength development over time.
The Breakthrough: Key Findings & Data
The results demonstrate a clear and compelling case for the use of WFS in concrete, showing comparable performance and significant economic benefits.
Finding 1: WFS Concrete Achieves High Compressive Strength
The study found that concrete made with WFS performed remarkably well compared to the conventional control mix. As shown in the data below, even at high replacement levels, the concrete retained a significant portion of its structural strength.
The average 28-day compressive strength for the control concrete was 19.36 MPa (Table 4). In comparison, the WFS mixes achieved the following 28-day strengths:
* 10% WFS Replacement: 19.19 MPa (Table 5)
* 20% WFS Replacement: 19.5 MPa (Table 6)
* 30% WFS Replacement: 19.17 MPa (Table 7)
* 40% WFS Replacement: 18.36 MPa (Table 8)
Crucially, the 20% replacement mix slightly outperformed the conventional concrete, and the 40% mix retained nearly 95% of the control strength. The authors conclude that a 40% replacement level is efficient and provides 86% of the strength of conventional concrete, highlighting its suitability for various construction purposes.
Finding 2: A Clear Economic and Environmental Victory
The economic implications of this research are profound. The paper states, "The commercial rate of one ton of sand is Rs 8000 (Average). Waste foundry sand is freely available now." By replacing 40% of an expensive, mined resource with a free industrial byproduct, construction projects can realize substantial savings in material procurement costs. This not only improves project profitability but also reduces the environmental impact of sand mining and alleviates the landfill burden of WFS disposal.
Practical Implications for R&D and Operations
- For Process Engineers: This study suggests that replacing up to 40% of fine aggregate with properly treated WFS is a viable strategy for producing concrete. Attention must be paid to the pre-treatment of WFS, such as the lime sludge method described, to neutralize potentially reactive chemical binders.
- For Quality Control Teams: The data in Tables 5 through 8 provides clear benchmarks for the expected compressive strength of concrete with varying WFS percentages. These values can be used to establish new quality inspection criteria for projects incorporating this sustainable material.
- For Design Engineers: The findings confirm that WFS concrete can meet the strength requirements for many applications. This allows for the specification of WFS as a fine aggregate in designs, contributing to project sustainability goals (like LEED certification) and significant cost reductions without compromising structural integrity in appropriate applications.
Paper Details
Experimental investigation on waste foundry sand for effective utilization in building construction
1. Overview:
- Title: Experimental investigation on waste foundry sand for effective utilization in building construction
- Author: Manikandan A., Anandha Raj L. and Aravindh P.
- Year of publication: 2020
- Journal/academic society of publication: Research Journal of Chemistry and Environment, Vol. 24 (Special Issue I)
- Keywords: Metal casting, Waste foundry sand, Non-ferrous, Concrete cube, Cost effective.
2. Abstract:
The Indian metal casting industry is well established and producing estimated 9.99 million tons of various grades of casting as per international standards. There are an estimated 5000 foundries in India producing casting of Grey iron, Ductile iron, SG iron, Non-ferrous and steel totaling approximately 9.9 million metric tons annually. This work outlines the study of physical and chemical properties of the waste foundry (WFS) from Sakthi Auto-Component ltd, Erode and its effective utilization as a building material. The WFS sample along with fly-ash with different proportions are to be experimented into concrete cubes and its strength results are to be compared for identifying the optimum usage in constructions. Based cost comparison between conventional concrete and concrete with WFS shows economical aspect of effective utilization.
3. Introduction:
Foundry sand is a high-quality silica sand with uniform physical characteristics. It is a by-product of ferrous and non-ferrous metal casting industries, where sand has been used for centuries as a molding material due to its thermal conductivity. After continuous usage, it is ejected from industries and is known as waste foundry sand (WFS). This WFS consists of highly silica coated with a thin film of burnt carbon and residual binders (e.g., Bentonite, resins). The chemical composition of WFS depends on the casting process and industry type. Researchers have previously concluded that a 10% replacement of natural sand with WFS in concrete results in similar properties. This study aims to further investigate the effective utilization of WFS as a building material.
4. Summary of the study:
Background of the research topic:
The research addresses the dual challenges of managing the large volumes of waste foundry sand produced by the metal casting industry and the high cost and environmental impact associated with mining natural sand for the construction industry. The study proposes using WFS as a partial replacement for fine aggregate in concrete as a sustainable and economical solution.
Status of previous research:
The literature review indicates that WFS has been studied for use in structural fills, road construction sub-bases, paving units, self-compacting concrete, high-strength concrete, and masonry blocks. Previous studies generally found that replacing 10% to 30% of fine aggregate with WFS yielded good results. Research has shown that workability tends to decrease with higher WFS proportions and that freezing-thawing cycles can reduce the mechanical properties of WFS concrete. Some studies also explored the combined use of WFS with pozzolanic materials like fly ash.
Purpose of the study:
The primary purpose of this work is to study the physical and chemical properties of WFS from a specific source (Sakthi Auto-Component ltd, Erode) and to determine the optimum percentage of WFS that can replace natural fine aggregate in concrete without significantly compromising its compressive strength. The study also aims to highlight the economic benefits of this utilization.
Core study:
The core of the study is an experimental investigation where conventional concrete (mix proportion 1:1.5:3) was compared with concrete mixes in which fine aggregate was replaced by WFS at levels of 10%, 20%, 30%, and 40%. The physical properties of all constituent materials were tested, and the WFS underwent a chemical analysis and a lime sludge treatment. The compressive strength of concrete cubes from each mix was measured at 7, 14, and 28 days to evaluate performance.
5. Research Methodology
Research Design:
The study employed an experimental, comparative research design. A control group (conventional concrete) was tested against four experimental groups (concrete with varying percentages of WFS). The primary dependent variable was compressive strength, while the independent variable was the percentage of WFS replacement.
Data Collection and Analysis Methods:
Data was collected through standardized laboratory tests. Physical properties of cement, coarse aggregate, and fine aggregate were determined according to Indian Standards (IS). A chemical analysis was performed on the WFS samples. Concrete cubes (150mm150mm150mm) were cast for each mix design. Compressive strength testing was performed at 7, 14, and 28 days. The results were tabulated and averaged to compare the performance of the different concrete mixes.
Research Topics and Scope:
The research is focused on the utilization of WFS from a ferrous and non-ferrous metal casting industry as a partial replacement for fine aggregate in concrete. The scope is limited to a single concrete mix proportion (1:1.5:3) and the evaluation of one mechanical property: compressive strength. The economic aspect is considered based on the market price of natural sand versus the availability of WFS.
6. Key Results:
Key Results:
- Chemical analysis of the WFS showed high levels of magnesium and lime, which led the researchers to apply a lime sludge treatment to remove resinous particles and improve its suitability for concrete.
- The compressive strength of concrete with 10%, 20%, and 30% WFS replacement was found to be very similar to that of conventional concrete at 28 days, with the 20% mix showing slightly higher average strength (19.5 MPa vs. 19.36 MPa).
- The concrete with 40% WFS replacement achieved an average 28-day compressive strength of 18.36 MPa, which is approximately 95% of the strength of the conventional concrete control group.
- The study concludes that partial replacement of fine aggregate with WFS up to 40% is efficient and economically advantageous, as WFS is a freely available waste material while natural sand is a costly resource.
Figure Name List:
- Fig. 1: Comparison of concrete strength with WFS replacement
7. Conclusion:
Partial replacement of WFS sample up to 40% to fine aggregate proportion in concrete is found to be efficient and it gives 86% strength of conventional concrete at 28 days. By adding Fly-ash to this composition the strength may be improved after 28 days curing of the concrete specimen at later stages. By replacing the WFS sample to fine aggregate in concrete, the natural land resources can be served and also the waste utilization also can be effectively used in the concrete construction.
8. References:
- Tapkir R.R., Gholve N.N. and Jhadav V.P., Review of researches on replacement of fine aggregate by foundry sand in concrete, International Journal of Engineering Technology Science and Research, 5, 1696-1700 (2018)
- Mahima G., Sreevidya V. and Salim P.M., Waste Foundry Sand as a Replacement for Fine Aggregate in High Strength Solid Masonry Blocks, International Journal of Innovative Research in Science, Engineering and Technology, 5, 6879-6886 (2016)
- Dushyant R.B., Jayeshkumar P. and Jaydev J.B., Innovative ideas for manufacturing of the green concrete by utilising the used foundry sand and pozzocrete, International Journal of Emerging Science and Engineering, 1, 28-30 (2013)
- Mariana L.M., Jorg L., Rafael P., Raquel L.P. and Claudio O., Foundry sand for manufacturing paving units, 10th International Conference on Concrete block paving Shanghai, People Republic of China, 24-26 (2012)
- Saveria M., Daniela S. and Tittarelli F., Used Foundry Sand in Cement Mortars and Concrete Production, The Open Waste Management Journal, 3, 18-25 (2010)
- Mayudin S.A., Mohan M. and Reddy I.T., Strength behavior of concrete produced with foundry sand as fine aggregate replacement, International Journal For Technological Research In Engineering, 5 (2008)
- Siddique Rafat and Singh Gupreet, Utlization of waste foundry sand (WFS) in concrete manufacturing, Resources, conversation and Recycling, 55(11), 885-892 (2008)
- Naik T.R., Singh S.S., Tharaniyil M.P. and Wendrof R.B., Application of foundry By-product materials in manufacturing of concrete and mansory products, ACI Journal of Materials, 93, 41-50 (1996)
- Javed S. and Lovell C.W., Use of waste foundry sand in civil engineering, Transportation Research Board, 1486, 109-113 (1994).
Expert Q&A: Your Top Questions Answered
Q1: Why was a lime sludge treatment necessary for the Waste Foundry Sand before using it in concrete?
A1: The chemical analysis of the WFS (Table 4) showed higher than normal levels of magnesium and lime. More importantly, WFS contains residual chemical binders like resins from the casting process. The paper states the lime sludge treatment was used because the "Lime content at exothermic reaction removing the resinous particles present in the sample." This treatment is crucial to neutralize these binders, which could otherwise interfere with the cement hydration process and negatively impact the concrete's final strength and durability.
Q2: How did the strength development of WFS concrete compare to conventional concrete at earlier stages, like 7 days?
A2: The data shows interesting early-stage performance. The conventional concrete had a 7-day average strength of 14 MPa. The 40% WFS mix had a higher 7-day strength of 14.53 MPa, suggesting that the thermal properties of WFS might accelerate initial cement hydration, as mentioned in the paper's discussion. However, other mixes like the 20% WFS (12.18 MPa) and 30% WFS (13.14 MPa) showed slightly lower 7-day strength, indicating the relationship is complex and depends on the specific replacement percentage.
Q3: The literature review mentions that WFS can decrease the workability of concrete. Did this study address that factor?
A3: This study focused primarily on the final compressive strength of the hardened concrete. While the literature review acknowledges that higher additions of WFS can decrease the workability of fresh concrete, this specific paper does not detail any measurements of workability (like a slump test) or the use of admixtures like super-plasticizers to counteract this effect. The focus remained squarely on the viability of WFS from a strength perspective.
Q4: What is the primary economic driver for using Waste Foundry Sand in concrete?
A4: The economic driver is substantial and direct. According to the paper, the average commercial rate for one ton of natural sand is Rs 8000 (approximately $100 USD). In contrast, Waste Foundry Sand is described as "freely available." By replacing a significant portion of a costly raw material with a free industrial byproduct, construction projects can achieve significant material cost savings, directly impacting the project's bottom line.
Q5: The paper concludes that adding fly ash could further improve strength. What is the basis for this suggestion?
A5: The basis for this suggestion comes from both the cited literature and general principles of concrete technology. The literature review references a study by Dushyant et al. that specifically investigated using WFS in conjunction with "Pozzocrete P60," a quality-assured fly ash. Fly ash is a pozzolanic material, meaning it reacts with the byproducts of cement hydration to form additional cementitious compounds, which typically enhances the long-term strength and durability of concrete. The authors are suggesting that this synergistic effect could be leveraged to further optimize the performance of WFS concrete.
Conclusion: Paving the Way for Higher Quality and Productivity
This research provides compelling evidence that Waste Foundry Sand is not a waste product but a valuable resource. By replacing up to 40% of expensive natural sand in concrete, companies can maintain high structural strength while dramatically cutting material costs. This circular economy approach solves a critical disposal problem for the metal casting industry and provides a sustainable, cost-effective material for the construction sector. It's a clear win for both profitability and the environment.
At CASTMAN, we are committed to applying the latest industry research to help our customers achieve higher productivity and quality. If the challenges discussed in this paper align with your operational goals, contact our engineering team to explore how these principles can be implemented in your components.
Copyright Information
This content is a summary and analysis based on the paper "Experimental investigation on waste foundry sand for effective utilization in building construction" by "Manikandan A., Anandha Raj L. and Aravindh P.".
Source: Research Journal of Chemistry and Environment, Vol. 24 (Special Issue I), (2020), pp 56-59.
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