Review on Alternatives of Aggregates with Alternative Materials in Eastern Africa

Normal concrete, with bulky aggregate generally results to large amount of energy and natural resource requirement. Normal aggregates mining and river sand extraction, if done in unsustainably, potentially results in adverse environmental, health or hazardous impacts. There is therefore the need to research and utilize alternative more sustainable construction materials.

This main aim is to review properties of alternative aggregate or mixes with those aggregates within Eastern Africa. In this study, 23 reviews, at optimum aggregate replacement using volcanic materials, crushed rock sand and also fired bone generally indicated good strength performance. Majority of the alternative materials mixes presented indicated higher water absorption, lower slumps/workability and density, compared with the reference. Lower slump could affect compaction, strength or increase costs. Appropriate cost-effective admixtures or plasticizers are recommended while materials exhibiting lower strengths could be explored for non-structural use. Utilization of recycled waste for aggregate could help address resource scarcity and reduce construction environmental footprint.

There should be more research and development of proper procedures and techniques so as to ensure adequate bondage, optimal water/cement ratio and compaction and also use of cost-effective admixtures.