1.1 BACKGROUND OF STUDY
Earth as a building material is available everywhere. In developing countries, earth construction is economically the most efficient means to house the greatest number of people with the least demand of resources (Al-Sakkaf, 2009). Traditional earth construction materials such as adobe bricks suffer from moisture attack and cracks, thus the need to continuously maintain them in order to keep them in good condition. According to Adam and Agips (2001), traditional earth construction technology has undergone considerable developments that enhance earth’s durability and quality as a construction material for low-cost buildings. Such methods include rammed earth and machine pressed compressed stabilized earth bricks. Stabilization of these earth bricks is achieved using various methods that often involve the use of a variety of stabilizers. Adam and Agip (2001) identified these stabilizers to include artificial ones such as Portland cement and lime and the natural ones such as agricultural waste amongst others.
Cassava starch which is the stabilizer in view in this research was recently evaluated for its suitability as stabilizer and found to improve some mechanical properties of selected soil types (Khalil 2005). Incidentally the abundance of the cassava crop in Nigeria is not in doubt. Phillips et al (2004) pointed out that Nigeria is the highest cassava producer in the world.
The effects of soil grain sizes in imparting changes in mechanical behavior of soils have also been pointed out by researchers like Wang, Lu and Shi. (2010), Rahardjo et al (2002) and many more.
This research work intends to evaluate the
possibility of further improving the strength and durability characteristics of
the cassava starch stabilized compressed earth bricks through the exploration
of mechanical behavior of different grain size range of a selected soil type.
1.2 STATEMENT OF RESEARCH PROBLEM
Despite the diverse number of policies and programme adopted by the Nigerian Government, housing delivery has remained a major challenge leading to deficits in delivery. Oluwakiyesi (2011) puts the housing shortfall at between 16 and 18 million housing units. Ajanlekoko
(2011) pointed out that the National housing programme launched by the Nigerian Government in1994 had a delivery target of 121,000 units to be distributed throughout the states of the Federation. Only 1,367 were completed and another 17,792 units were under construction. The National Rolling Plan (NRP) on the other hand, puts the housing requirement of Nigeria at a conservative annual estimate of between 500,000 and 600,000 thus needing an estimated 250 to 300 million Naira to make up for the shortfall. It can therefore be inferred that initiatives at enhancing housing delivery need not be limited to housing policies and programs of Government alone but should more importantly include reduction in overall construction cost particularly amongst the rural populace. Ajanlekoko (2001) asserted that the rapid up-swing in the prices of building materials in the last five years has further reduced the affordability for most Nigerians. Oresegun (2011) noted high cost of building materials and labour to be amongst major problems affecting housing delivery in Nigeria. Satprem (2009) recommended among other measures, a reduction in the amount of cement for brick making in other to enhance cost effectiveness.
THE EFFECT OF VARYING RANGE OF SOIL GRAIN SIZES ON CASSAVA STARCH STABILIZED COMPRESSED EARTH