Study of Replacement of Sand with Electroplating Waste Sludge (EWS) in Manufacturing of Concrete Paver Blocks Using Different Binder Systems

Abstract

Electroplating waste sludge (EWS) is a hazardous industrial residue containing metal-bearing phases, while the growing demand for natural river sand creates a parallel resource-conservation challenge. This study evaluates processed EWS as a partial replacement of Zone II natural river sand in M40 concrete paver blocks manufactured with OPC 43 grade cement. Five mixes were investigated with 0, 5, 10, 15 and 20% sand replacement by mass. The experimental programme covered material characterization, dimensional tolerance, dry density, water absorption, compressive strength at 7, 14 and 28 days, 28-day splitting tensile strength, Böhme abrasion resistance, and heavy- metal leaching by Atomic Absorption Spectroscopy. A preliminary 50:50 EWS-waste-plastic thermal-fusion trial was also assessed. The 10% EWS mix achieved the highest 28-day compressive strength of 51.1 MPa, approximately 6.0% above the control, together with a splitting tensile strength of 4.05 MPa and water absorption of 4.88%. The 15% EWS mix retained a compressive strength of 42.8 MPa, water absorption of 5.65%, splitting tensile strength of 3.25 MPa and abrasion loss of 15,400 mm³/5,000 mm², and was identified in the source study as the maximum viable replacement level. At 20% replacement, strength and abrasion resistance decreased and water absorption increased to 6.72%. Leachate concentrations of Cr, Ni, Zn, Cu and Pb remained below the stated CPCB discharge limits up to 15% replacement, indicating effective immobilization in the hydrated cement matrix. The unformulated plastic-EWS thermal route produced a friable, non-cohesive material and was not carried forward. Overall, the results support low-to-moderate EWS utilization as a sand-conservation and hazardous-waste-management strategy for precast paver blocks.

Introduction

The study investigates the use of electroplating waste sludge (EWS) as a partial replacement for natural river sand in OPC-based M40 concrete paver blocks. The main motivation is to reduce the environmental problems caused by excessive river-sand extraction while providing a useful disposal route for industrial electroplating sludge.

Objective

The study replaces natural sand with processed EWS at 0%, 5%, 10%, 15%, and 20% by mass. The paver blocks are evaluated for:

• Density and water absorption
• Compressive strength
• Splitting tensile strength
• Abrasion resistance
• Dimensional stability
• Heavy-metal leaching
• Environmental suitability

A preliminary thermal process combining EWS with waste plastic was also explored as a possible non-hydraulic alternative.

Materials and methodology

The paver blocks were manufactured using OPC 43-grade cement, Zone II river sand, crushed granite aggregates, water, and superplasticizer. EWS was collected from an industrial effluent-treatment plant in Ludhiana, Punjab.

The sludge was:

1. Air-dried for 72 hours.
2. Oven-dried at approximately 105°C.
3. Pulverized and sieved through a 4.75-mm sieve.
4. Used as a fine-aggregate replacement.

Five mixes were prepared:

• S0: 0% EWS
• S5: 5% EWS
• S10: 10% EWS
• S15: 15% EWS
• S20: 20% EWS

The blocks were produced by vibro-hydraulic compaction and water curing.

Major findings

1. Density decreased with increasing EWS.
Density declined from 2385 kg/m³ for S0 to 2260 kg/m³ for S20, mainly because EWS has a lower specific gravity than natural sand.

2. Water absorption increased with EWS content.
Absorption rose from 3.42% in S0 to 6.72% in S20. Mixes up to S15 remained below the study's 6% criterion, while S20 exceeded it. The increase is attributed to the fine and relatively porous nature of EWS.

3. Compressive strength was highest at 10% replacement.

The 10% EWS mix performed best, achieving a 6.02% improvement over the control. This is attributed to micro-filler action, improved particle packing, and better nucleation of hydration products.

At higher replacement levels, strength decreased because of increased surface area, higher water/superplasticizer demand, and deterioration of the cementitious matrix.

4. Splitting tensile strength showed the same pattern.
It increased from 3.85 MPa for S0 to 4.05 MPa for S10, then decreased to 3.25 MPa for S15 and 2.68 MPa for S20. Thus, S20 failed to meet the 2.90 MPa criterion used in the study.

5. Abrasion resistance worsened as EWS increased.
Abrasion loss increased from 11,250 mm³/5,000 mm² for S0 to 18,900 for S20. This indicates that excessive EWS can reduce surface durability.

Overall conclusion

The study indicates that EWS can be successfully used as a partial replacement for natural river sand in concrete paver blocks, but the replacement level must be carefully controlled.

The 10% EWS replacement (S10) appears to be the optimum among the tested mixtures because it provides the highest compressive and splitting tensile strengths while maintaining acceptable water absorption and abrasion performance. Higher replacement levels, particularly 20%, negatively affect strength, water absorption, and abrasion resistance.

Conclusion

1) Processed EWS can be incorporated as a partial replacement of natural river sand in OPC-bound M40 paver blocks, provided the replacement level is controlled. 2) A 10% replacement (S10) produced the best mechanical performance, with a 28-day compressive strength of 51.1 MPa and splitting tensile strength of 4.05 MPa. 3) The source study identified 15% EWS (S15) as the maximum viable replacement level. At this dosage, 28-day compressive strength was 42.8 MPa, water absorption 5.65%, splitting tensile strength 3.25 MPa and abrasion loss 15,400 mm³/5,000 mm². 4) At 20% replacement, compressive strength decreased to 35.6 MPa, water absorption increased to 6.72%, splitting tensile strength decreased to 2.68 MPa and abrasion loss increased to 18,900 mm³/5,000 mm²; the mix was therefore rejected for the target application. 5) AAS leaching results showed Cr, Ni, Zn, Cu and Pb below the stated CPCB discharge limits through the 15% replacement level, supporting effective immobilization of heavy metals in the hydrated cement matrix. 6) The preliminary 50:50 waste-plastic/EWS thermal-fusion route at 270°C did not develop structural cohesion and was not suitable as a load-bearing paver-block binder system in the investigated form. 7) At the maximum recommended 15% replacement, the mix conserves 106.5 kg of natural river sand per cubic metre of concrete while providing a controlled beneficial-use route for electroplating sludge.

References

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Copyright

Copyright © 2026 Bharat Kaushik, Dr. Sanjay Sharma. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.