Technical Feasibility Assessment of Masonry Blocks Manufactured with Recycled Concrete Aggregates

Abstract

The construction industry is among the highest consumers of natural resources worldwide, particularly stone aggregates such as sand and gravel. Urban growth and infrastructure expansion have substantially increased the demand for these materials, placing pressure on extraction sites and contributing to associated environmental impacts. At the same time, the industry generates large volumes of construction and demolition waste (CDW), which, when not properly managed, saturates landfills and contaminates the soil. This study evaluates the technical feasibility of using recycled aggregates from concrete waste in the manufacture of masonry blocks. The manufacturing process comprised eleven sequential stages: collection and sorting of CDW, crushing, granulometric classification, proportioning (water-to-cement ratio of approximately 0.45, Portland Type I cement), mixing, moulding, vibro-compaction, demoulding and 28-day wet curing. Masonry units with nominal dimensions of 12 × 20 × 40 cm and 15 × 20 × 40 cm were produced using 100% recycled concrete aggregate as a replacement for natural aggregate. Compressive strength was evaluated at 7, 14 and 28 days, yielding 11.26 N/mm² (114.87 kg/cm²), 12.80 N/mm² (130.56 kg/cm²) and 15.22 N/mm² (155.3 kg/cm²), respectively. The 28-day value exceeds the minimum of 14.71 N/mm² (150 kg/cm²) required by NMX-C-404-ONNCCE for low-demand structural applications. The results demonstrate that, under controlled processing and curing conditions, CDW can be successfully incorporated into masonry block production, contributing to a circular economy model and reducing dependence on virgin raw materials. Future research should address water absorption, dimensional variation, durability and varying replacement percentages to define optimal conditions for broader structural and non-structural applications.