INVESTIGATING THE PERFORMANCE OF CLASS A HCB MANUFACTURED WITH PARTIAL REPLACEMENT OF SCORIA POWDER AS A CEMENT AND PROCESSED CONSTRUCTION WASTE AS A FINE AGGREGATE

Abstract

Hollow concrete blocks (HCBs) are widely used in Ethiopian housing developments. However, the production of HCBs using traditional materials such as cement, river sand, water, and light aggregates. They are made of concrete and moulded into moulds in order to obtain the necessary physical strength and dimensions for the criteria and standards. The manufacturing of cement releases carbon dioxide into the atmosphere, contributing to global warming. Construction waste is also disposed of at landfill sites, causing environmental problems. Therefore, alternative materials for HCB production are needed. This study aims to investigate the possibility of using construction waste (CW) and scoria powder as alternative materials for river sand and cement, respectively, in the production of class A HCBs. The objective was to partially substitute scoria powder for cement and CW for sand in different proportions. Tests were conducted to determine the appropriateness of the materials used and how well they performed in terms of engineering qualities. Microstructural investigations were also carried out using XRD and SEM, while the oxide content in scoria powder was determined using XRF. The compressive strength, density, and water absorption of HCBs made from different proportions of scoria powder and CW were measured. The compressive strength of HCBs decreased with increasing replacement rates, except for CW (75%) and scoria (30%). However, the blocks still achieved the target strength for class A blocks. The strength values of a mixture of 50% CW as sand and 30% scoria powder as cement were either greater or comparable to the standard limit. The density and water absorption of HCBs made from scoria powder and CW remain within Ethiopian standards. The study concludes that construction waste and scoria powder can be used as alternative materials for river sand and cement, respectively, in the production of class A HCBs. However, the substitution rates should be carefully considered to ensure that the blocks meet the required strength standards. The use of alternative materials can help reduce the environmental impact of HCB production and waste disposal. Further research is recommended to investigate the long-term durability and performance of HCBs made from alternative material