The major problem associated with cassava starch stabilized bricks is the high rate of water absorption. The effect of high rate of water absorption make the bricks to be soluble in water and limits its use for only internal partition walls not out doors. This study therefore evaluates the effects of three binding media on compressed stabilized earth bricks. The three binding media are Makuba, Cassava Starch and Cement. The research entails a laboratory investigation in which three sets of compressed earth bricks were produced which sum up to a total of 107 bricks cured by open air dry method. The control (CO) and the addition of three binding media in the laterite mix were fixed at binder combination (C1) and binder combination (C2). The brick samples were tested for permeability, Sorptivity, water absorption, adsorption, compressive strength, abrasion resistance and density for the curing periods of 7, 14, 28 and 56 days. The results show that permeability of C2 has the minimum absorption rate of 7.90% at 56days. The Sorptivity of C2 had the least water rise of 5% at 10min. It was observed that the average water absorption of the test samples was 2.77% for C2 at 56days which conformed to ASTM C 62 (2010) Water Absorption test of brick samples. The compressive strength of C1 and C2 had increased the strength with 2.29 and 1.69 N/mm2 respectively. The setting time results confirmed that makuba has a significant effect on accelerating the setting time of cement while cassava starch decelerate the setting time of cement. This research was able to assess the effects of the three binding media on moisture movement in brick samples and the high rate of water absorption was reduced and the bricks produced are suitable for outdoors used. It is recommended therefore that for walls exposed to moisture such as external walls and walls of bathrooms and kitchen the C2 binder combination should be incorporated.
1.1 Background of the Study
In the modern brick construction practices, agricultural by-products are largely used as raw materials in laterite brick production. These have many benefits to the environment and bring about economic impact because of the cost of waste disposal which is increasing due to strict environment regulations. Waste utilization has been a common step taken in most countries in the world.Soil construction methods are used in 20%of urban buildings in Nigeria while this figure exceeds 90% in rural areas. Buildings are constructed entirely, or partially of soil, depending on location, climate, available skills, cost, building use and local tradition (Agib et al, 2001).
Laterite which is derived from the Latin word “later”meaning brick, was first used by Buchanan in 1807 for describing a red iron-rich material found in southern parts of India. The soil colour can vary from red, brown, and violet to black, depending on the concentration of iron oxides(Agib et al, 2001).Laterites are highly weathered soils which contain large, though extremely variable, proportions of iron and aluminium oxides, as well as quartz and other minerals. They are found in abundance in the tropics and subtropics, where they generally occur just below the surface of grasslands or forest clearings in regions with high rainfall (Starry, 2007).Laterite is defined by Encarta English Dictionary as red tropical soil: a reddish mixture of clayey iron and aluminium oxides and hydroxides formed by weathering of basalt under humid, tropical conditions. Fermor (1981) classified various forms of laterite soils on the basis of the relative contents of the constituents (Fe, Al, Ti, Mn) in relation to Silica.