Introduction
1.1 General
Walls are the basic element in the construction of most buildings. They are often required to be load bearing, especially in low rise buildings (1-2 upper floors).
Sandcrete blocks are the most commonly used unit in wall construction in modern Nigeria and, indeed, the entire West Africa. The use of laterite and other forms of walling units, for the construction of modern residential buildings have not made much progress when compared to the use of sandcrete blocks. The same can also be said of bricks. The major advantage of sandcrete blocks is the ease of production and laying of the blocks
The structural properties of blocks of interest include compressive strength, flexural strength, water absorption, modulus of elasticity, shear modulus and split tensile strength. Others are density, fire resistance, durability and thermal conductivity. These properties are dependent to a very large extent on the relativeproportions of the constituents and the method of production process.
Sandcrete blocks are traditionally made of cement, natural river sand and water. The constituents are mixed and placed in a mould which is removed immediately after compaction and leveling of the top. The newly produced blocks are self-supporting; hence they are often referred to as zero slump concrete. Individual blocks are joined together, after curing, to form walls using cement-sand mortar. It is often the practice to partially replace the sand portion with other materials such as laterite, coarse aggregate or quarry dust.
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