IMPACT OF PRODUCTION CHARACTERISTICS ON CONCRETE STRENGTH IN TROPICAL ENVIRONMENTS

Quality of concrete is an integrated function of the nature of the constituent materials, mix ratio, production method, curing age, water-cement ratio and the climate. Various standards and code of practices that regulate quality of concrete with the concerned production characteristics are in most cases not complied with in the area of the study; hence quality of concrete work becomes a suspect. To assess the effect of these production conditions, field survey and experimental designs were adopted. Data collected were analyzed using arithmetic mean and correlation to determine the mean strength values of different mix ratios and degree of ranking relationships among the strength values of each curing age in all the mix ratios respectively. It is therefore discovered that some major production conditions like mix ratio, aggregate type and curing age has significant effects on the quality of concrete. Strength of concrete produced with granite is higher than those produced with sedimentary aggregate; besides the strength increases as the curing age in all the experiments. Against the nominal mix ratios which are the standards, strength values of the prescriptive mix ratios commonly used in the area fall short of the standard values. Strength values of the pilot experiments conducted with nominal mix ratios show closeness to the standard strength but, with little lapse due to short fall in other production characteristics. It is also found that irrespective of the total quantity of the content of all the constituent aggregates in a mix, the proportional relationship between the fine and the coarse aggregates is germane. The study therefore recommends for a holistic research approach to designed mix of concrete production in order to develop templates in the form of nomogram, for easy and reliable production of desired concrete works. Other production conditions like aggregate type, water-cement ratio and curing age should as well be utilized optimally for improved quality of concrete works in the study area