1.1 Introduction
Lateritic soils are reddish brown in colour, which have been used as blocks for buildings without any cement content. Recently, modern builders started introducing some percentage of cement to laterite for moulding stronger blocks, because of high cost of sandcrete blocks. The compressive strength of laterite-cement blocks increased steadily with increase in percentage of cement content up to 20% but decreased at cement contents above 20% (Aguwa, 2009). A major advantage of the use of laterite instead of sand in moulding building blocks is the low cost, due to small quantity of cement required to produce blocks with adequate compressive strengths as well as low cost of transporting laterite. The rapid changes in the use of brick to block in Nigeria have encouraged the investigations into the use of sandcrete blocks to be more elaborate (Abdullahi, 2005).
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitations of the Study and Definition of technical terms.
1.2 Background of Study
The roman first invented what today is called hydraulic cement – base concrete. They build numerous concrete structures, including the Pantheon in Rome, one of the finest architecture that survived to the day. The name concrete comes from Latin word “concretus” which means to grow together.
In many countries, the need for locally manufactured building materials can hardly be overemphasized because there is an imbalance between the demands for housing and expensive conventional building materials coupled with the depletion of traditional building materials. To address this situation, attention has been focused on low-cost alternative building materials.
Chemical hydration process which mainly occurs over the time scale of hours and days causes the material to grow together from a viscoelastic moldable liquid into a hard, rigid solid. In our world today, concrete has become ubiquitous and in fact, it is hard to imagine modern life without it about five billion tones at concrete are sued around the world each year. The cement used mostly in today’s concrete is called port land cement. The process to produce port land cement was invented by Joseph Aspdin in the early 1800’s in England.
In Makurdi, the capital of Benue State of Nigeria and its surrounding towns, the most common walling materials are the conventional sandcrete blocks and fired clay bricks. The cost of sandcrete blocks coupled with the low strength properties of commercially available blocks necessitated the search for an alternative that was fired clay bricks. These are smaller than sandcrete blocks and therefore require more bonding mortar.
The production of fired clay bricks is labour intensive and the process of firing is usually carried out using given species of trees (prosopis Africana and melicia excelsa) which could lead to their extinction and deforestation. Firing of bricks requires great quantities of firewood and energy loss in the form of heat is about 40-50%. In addition to the environmental problem, clay bricks can only be produced in locations where suitable clay soil deposits exist.
In Makurdi and other locations within Benue State, abundant lateritic soil deposits exist which can be harnessed for brick production. This potential is not being maximized. Compared to sandcrete blocks, it is economic to use laterite for brick production because very little cement is required and the cost of transportation is eliminated as production takes place on site. Compared to fired clay bricks, the production of laterite bricks does not involve the firing process. To cure the laterite bricks, they are by covered with tarpaulin and waterproof devices thereby making the process to be more environmental friendly. Laterite bricks are fire resistant and bulletproof.
Laterite stabilized with cement was used successfully to produce bricks in Sudan (Adam, 2001). Three pressure ranges: 2 to 4 N/mm2, 8 to 14 N/mm2 and 6 to 20 N/mm2 which were designated low, high and hyper respectively were used in the production of bricks. With cement content of 5 to 8% and a brick size of 290 x 140 x 90 mm, compressive strength ranging from 3 to 3.5 N/mm2 was achieved using a compactive effort that ranged from 8 to 14 N/mm2. The study showed that the strength of bricks was dependent on the pressure applied during production, percentage of cement used, and the particle size distribution of the laterite.
Therefore, in Nigeria where the research was carried out, the activities that was conducted is to know the Use of Cement Sand Admixture in Laterite Blocks Production for Low Cost Housing.
1.3 Statement of Problems
Investigation revealed that concrete is an excellent material, but it is not perfect. You don’t have to look very far to identify the real life concrete problem. However, most of the problems are avoidable or fixable unfortunately most concrete problems are the result of error with the finisher. And builder, to maximize profit, take the lowest bidder. The lowest bidder uses the latest amount of man power to get the job done and was cheaper, lower quality concrete with low compressive strength and inexpensive admixture filler (fly-ash). Most problems associated with concrete arise from the inability of the finisher to finish the concrete slab correctly, because of production rate and manpower.
1.4 Aim and Objectives of Study
The aim of the study is to examine the Use of Cement Sand Admixture in Laterite Blocks Production for Low Cost Housing. In achieving this aim, the following specific objectives were laid out as follows:
- To ascertain if the utilization of cement sand admixture result to low cost housing;
- To evaluate the performance of laterite-cement blocks as walling materials; and
- To investigate the use of cement and sand admixed with laterite for brick production.
1.5 Research Questions
The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:
- Does the utilization of cement sand admixture result to low cost housing?
- Is cement and sand admixed with laterite used for brick production?
- What is the performance of laterite-cement blocks as walling materials?
1.6 Significance of Study
This study will be of immense benefit to other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.7 Scope of Study
The scope of the research is focused on the Use of Cement Sand Admixture in Laterite Blocks Production for Low Cost Housing.
1.8 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet).
1.9 Definition of Terms
Concrete: A mixture of cement, sand, stone (coarse aggregate) and water.
Reinforcing Steel Bar: They are used for reinforcement of concrete structures, manufacture of anchor bolts etc
Super Structure: That part of the structure that is above the ground level.
Sub-Structure/Foundation: Is the lower portion of the structure usually located below the ground level.
