ABSTRACT
This study investigated the structural characteristics of chikoko mud-cement concrete. The structural characteristics of chikoko mud-cement concrete investigated were compressive strength, flexural strength, shear strength and split tensile strength while the elastic properties investigated were static modulus of elasticity, poisson’s ratio and shear modulus. The water absorption of chikoko mud-cement concrete as a reflection of concrete durability was also investigated. Ninety (90) 150mmx150mmx150mm cube specimens were produced for the compressive strength test, ninety (90) 450mmx150mmx150mm prototype beam specimens were produced for the flexural strength test, ninety (90) cylinder specimens of 300mm long and 150mm diameter were produced for the split tensile strength test and 180 prototype beam specimens were produced for poisson’s ratio test. Models were fitted to data obtained on various properties tested for. Two mathematical models were developed for each structural property, elastic property and water absorption based on Scheffe’s and Osadebe’s models, making a total of sixteen (16) mathematical models. Cost models were also developed for the chikoko mud-cement concrete using Scheffe’s and Osadebe’s technique, based on the most current market prices of the component materials. A total of sixteen (16) computer programs coded in BASIC language were written based on Scheffe’s and Osadebe’s techniques for quick prediction of structural properties, elastic properties, water absorption and cost of chikoko-cement concrete. The formulated models for structural properties, elastic properties and water absorption were tested for adequacy at 95% level of confidence using t-statistic and were all found to be adequate. The cost models were tested for adequacy at 95% level of confidence using F-statistic and were found to be adequate.. The computer programs can predict the mix ratios corresponding to any desired value of structural property, elastic property, water absorption, cost and vice versa. The maximum value of compressive strength predictable by Scheffe’s model is 17.511N/mm2 , the maximum value of flexural strength predictable by Scheffe’s model is 4.933N/mm2 , the maximum value of shear strength predictable by Scheffe’s model is 0.822N/mm2 , the maximum value of static modulus of elasticity predictable by Scheffe’s model is 26.530GPa, the maximum value of poisson’s ratio predictable by Scheffe’s model is 0.245, the maximum value of shear modulus predictable by Scheffe’s model is 11.188GPa, the maximum value of split tensile strength predictable by Scheffe’s model is 2.117N/mm2 and the maximum value of water absorption predictable by Scheffe’s model is 1.608%. The optimum percentage replacement of cement with chikoko mud was found to be 5% for all the structural properties. The maximum value of compressive strength obtained showed that it can be used for plain concrete works, lean concrete, simple foundations, masonry walls and other simple construction works in low-cost housing construction in Nigeria. Structural properties were also tested for at 90 days of curing in water using separate concrete specimens and were found to improve considerably showing that pozzolanic reaction increases with age of curing.
