Objective
This project investigates the challenges and develops remedies for replacing natural sand with bottom ash in concrete and mortar mixes. The research focuses on optimizing workability, strength, and water balance to ensure effective utilization of bottom ash as a sustainable alternative to natural sand.
Key Findings & Remedies
Water Absorption
Issue: Bottom ash absorbs more water than sand, decreasing workability of concrete and mortar mixes.
Remedy: Maintain Saturated Surface Dry (SSD) condition and use superplasticizers to control workability effectively.
Water Retention
Issue: Lower water retention leads to bleeding in concrete mixes.
Remedy: Carefully adjust water content to avoid slump reduction and bleeding issues.
Specific Gravity
Issue: Bottom ash (1.4–2.1) is lighter than sand (2.65–2.7), reducing concrete density and complicating batching processes.
Remedy: Use factored percentage replacement (below 40%) for balanced performance and density.
Gradation
Finding: Natural sand (Zone II) helps improve gradation and strength consistency in concrete mixes. Proper gradation is essential for optimal performance.