ABSTRACT

Waste utilization is an alternative to disposal, in that disposal cost and potential pollution problems are reduced or eliminated. The world is becoming susceptible to nuclear and radioactive rays attacks, and the study of how the use of heavy metal can produce concrete that can provide a shield against nuclear and radioactive rays is inevitable. The aim of this study was to investigate the performance and strength properties of composite concrete improved by blends of Rice Husk Ash and Iron Filings as aggregates. The objectives were to determine the optimum rice husk ash content that can be used as replacement for cement and the strength properties of rice husk ash and iron filings blend on the strength properties of concrete.

In this research, rice husk ash (RHA) was mixed with cement in various proportions to produce concretes having 28-day target strength of 40MPa. Various RHA contents to cement were utilized and it was observed that the optimum RHA content was 10%. As such, concrete cubes were prepared with a blended RHA cement (containing 90% Portland cement and 10% RHA), aggregates and water. The aggregates were comprised of fine aggregates incorporating Iron Fillings Aggregates (IFA) at replacement percentages of 10%, 20%, and 30% by weight of the fine aggregates, and coarse aggregates. The concrete cubes prepared were cured for 3, 7, 28, and 90 days. After that, various tests including compressive strength, Ultrasonic pulse velocity (UPV), flexural strength, and water absorption, were conducted on the concrete samples.

It was observed from the results that the addition of IFA to the fine aggregates resulted in an increase in the density of the concrete. At an IFA content of 20%, the strength as compared with the control (i.e. 0% IFA content) improved by 9.83% at 28 days. The UPV of the specimens showed consistency with the compressive strength of the same mix. The flexural strength of the concrete specimens was optimum when the IFA content was 20%. The water absorption tests conducted at 7 days and 90 days showed that the rate of water absorption in concrete with iron filings is lower compared to that without iron filings at 7 days, but this reverses at 90 days. The findings from this study have shown that the use of IFA as a partial replacement of sand in concrete production is one of the possible ways to improve environmental waste management and profitable utilization of industrial wastes like heavy metals.