Proceeding of the 1st International Conference on Infrastructure Development in Africa (ICIDA) Conference Kumasi, Ghana, 22-24 March 2012 Pages 285-299 COMPARATIVE STUDY ON SHEAR STRENGTH OF REINFORCED CONCRETE BEAMS MADE FROM PHYLLITE AND GRANITE AGGREGATES WITHOUT SHEAR REINFORCEMENT Adom-Asamoah,M., Afrifa, R.O. and Ampofo, J.W Department of Civil Engineering, Kwame Nkrumah University of Science and Technology, Kumasi-Ghana The experimental shear strength of twenty (20) RC beams; 10 each of phyllite concrete and granite concrete without shear reinforcement were investigated. Five different beam cross-sections with similar shear span to depth ratios and two flexural tension reinforcement ratios (1% and 2%) were investigated. Higher amount of flexural tension reinforcement (2%) in each concrete type indicated an increase in the shear capacity and enhanced flexural strength. The RC beams made from phyllite aggregates exhibited lower ultimate shear capacities, lower diagonal cracking shear capacities, wider crack widths and lower ultimate displacement capacities as compared to the corresponding granite concrete beams. This is probably because the granite concrete showed effective bonding to longitudinal reinforcement resulting in adequate load transfer to increase beam strength and stiffness of granite beams. For the limited test results obtained from the study of the shear behaviour of phyllite concrete beams without shear reinforcement, ACI 18 was the most conservative whilst EC 2 appeared to be the most accurate. Keywords: Phyllite aggregate; granite aggregates; reinforced concrete; shear strength prediction; conservative design. 1.0 INTRODUCTION Civil infrastructural development is an important aspect of the Millennium Development Goals (MDGs) set for developing countries in a bid to eradicate the rampant springing up ofslum dwellings in cities. In this regards, research is on-going in order to optimize the cost and use of local materials used in the construction of buildings in Ghana. The most common building material used in most Ghanaian cities and towns is reinforced concrete. Concrete consists of cement, fine aggregates, coarse aggregates and water with or without admixtures in the appropriate proportions. The percentage of coarse aggregates may vary from about 50-75% of the total concrete volume. The major contribution of coarse aggregate to the strengthof reinforced concrete members is in shear. The type of concrete can influence the shearstrength characteristics of reinforced concrete members. Concrete made from phylliteaggregate is being used for structural construction works in certain parts of Ghana especiallythe gold mining areas. Phyllite aggregate which is a by-product of underground miningactivity has become convenient in its use as a construction material as a result of itsavailability. This is because long haulage distances often result in additional cost to the priceof aggregates. In addition to a reduction in material cost, one important factor that contributesto the decision to use an unconventional coarse aggregate in concrete is to adequatelycharacterize its structural behavior. An important step in studying the shear behaviour of reinforced concrete is to study RC beams without shear reinforcement. Available literature show that RC beams made from nonconventional aggregate