Experimental investigation and optimization of cellular light weight concrete using foam content and prediction using response surface methodology

Abstract

This study investigates the mechanical and physical behavior of Cellular Lightweight Concrete (CLC) incorporating fly ash as a partial cement replacement, with a focus on density, water absorption, compressive strength, and split tensile strength. Experimental evaluation was conducted through both destructive and non-destructive testing (NDT) methods, supported by statistical modeling using Response Surface Methodology (RSM) to optimize mix designs. CLC was produced with varying foam contents (25%, 50%, 75%, and 100%) and foam-to-water–cement (w/c) ratios (1:25, 1:30, and 1:40), aiming to determine the optimal blend for enhanced performance. The results revealed that increasing foam content significantly reduced density and compressive strength due to increased pore volume, with 25% foam yielding the highest strength (12.68 N/mm2) and lowest water absorption (5.02%). In contrast, 100% foam content led to ultra-lightweight concrete with a density of 580 kg/m3 but experienced a drastic strength reduction to 3.65 N/mm2 and water absorption exceeding 13%, indicating high porosity. The incorporation of fly ash improved workability and sustainability while maintaining structural performance when used in balanced proportions. NDT outcomes from rebound hammer and ultrasonic pulse velocity showed a strong correlation with destructive test data, validating the integrity of the specimens. RSM provided robust predictive models with R2 values > 0.99, confirming high model accuracy. The significance of model terms was validated using ANOVA with low P-values and high F-values, while 3D Surface plots also analyzed and supported the optimization outcomes. This research confirms CLC with fly ash as a sustainable, lightweight construction material with optimized performance.