(CO2) to form Calcium Carbonate (CaCO3) with the rate
of carbonation of concrete increasing with an increase in
concentration of CO2. Carbonation could have some positive
consequences because CaCO3 occupies greater volume
than Ca(OH)2 which it replaces and in turn reduces
the porosity of concrete since it is generally accepted that
the durability of concrete is related to the characteristics of
its pore structure. proportions of mix, the method of compaction
and other controls during placing, compaction and
curing. The supply of sand is being threatened by a number
of factors on one hand while its demand is increasing
at alarming rate on the other hand. Increasing environmental
consideration are among other factors besides being
the only conventional fine aggregate that militate against
supply of sand. It has been observed that based on the
availability of laterite, a fine aggregate, laterite could either
partially or wholly replace sand as fine aggregate.
The criterion for concrete strength requirement is always
based on the characteristic compressive strength obtained
after 28-day curing. The compression strength of concrete
is usually determined by performing compression test on
standard sizes of concrete blocks (i.e., 150mm x 150mm x
150mm).The strength of concrete is affected partly by the
relative proportion of cement and of the fine and coarse
aggregates but the water-cement ratio is another important
factor.
Significance of study
With the fast depleting state of natural resources like river
sand and aggregates, it is time to look for alternative
cheap materials (marginal materials) for making concrete,
particularly when strength is not a primary parameter. One
of the potential marginal materials for use in concrete is
laterite. Laterite is a product of intense sub aerial weathering.
Laterisation process involves leaching of alkalis, basis
and silica with complimentary enrichment of alumina,
iron and some trace elements. This type of weathering