Strength and Durability Properties of Bacterial Rice Husk Ash Concrete

Abstract

Concrete is most widely used construction material used all over the world and usually considered as indestructible because of their longer service life as compared with the most constructional products. However, continuous exposure of hard weathering leads to an increase of the porosity of concrete and as a result, the mechanical features decreases. The permeability of the concrete depends on the porosity and on the connectivity and /or structure of the pores. A unique way of concrete design crossbreed between biology and engineering study of concrete called microbial concrete has been introduced, which involves the utilization of bacteria to increase the strength and durability of concrete. These microorganisms are used for calcium carbonate precipitation in concrete, it is highly desirable because the calcite precipitation induced as a result of microbial activities is pollution free and natural. The Calcite precipitation occupies the voids between cement matrixes and therefore leads to denser concrete. The approach does not deplete any natural resources since the bacteria used can be easily reproduced by cultivation process. The use of biological approach in concrete is also considered as a green technology as its production does not involve greenhouse gas emission. The significant objective of the research work further involved the use of bacteria. The bacteria present in the concrete rapidly sealed freshly formed cracks through calcite production. In concrete mix, 0, 5, 10, 15 and 20% cement weight was replaced with rice husk ash. The experiments were carried out to evaluate the effect of bacteria of concentration 105cfu/ml on the compressive strength, water absorption, water porosity, abrasion and rapid chloride permeability of concrete made with rice husk ash up to the age of 7, 28 and 56 days.