Assessment of Mechanical and Durability Properties of Sandcrete Blocks Incorporating Recycled Construction and Demolition Waste as Partial Replacement Materials

Abstract

Aim: The study investigates the mechanical and durability properties of sandcrete blocks when recycled construction and demolition waste (C&DW) are incorporated into the constituent materials as a partial substitute for natural aggregates. Methodology: Recycled aggregates were processed and characterized through comprehensive laboratory testing, including physical and mechanical assessments in accordance with ASTM and BS standards. Mix proportions were developed using Fuller’s maximum density law to ensure optimal particle packing, while chemical oxide composition was determined using X-ray fluorescence (XRF) analysis to verify material compatibility. Sandcrete blocks were produced with varying replacement levels and tested for compressive strength, tensile strength, water absorption, dry density, and carbonation resistance Results: The results revealed that sandcrete blocks incorporating 50% recycled aggregates achieved compressive strength values ranging from 8.4 to 8.8 N/mm², exceeding the NIS 87:2014 minimum requirement of 3.45 N/mm² by over 120%, while maintaining acceptable tensile strength, density, water absorption (≤8.1%), and carbonation depth (<8 mm). Although full replacement resulted in marginal strength reductions, all mixtures satisfied Nigerian standard specifications. Conclusion: The study demonstrates that recycled construction and demolition waste can be effectively utilized as aggregate replacements in sandcrete block production without compromising structural performance or durability. An optimal replacement level of 50% provides a balance between strength, durability, and sustainability. The findings support the adoption of recycled aggregates in Nigeria’s construction industry to reduce landfill waste, conserve natural resources, and promote environmentally sustainable building practices.