الفهرس 
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Abstract
This study gives an evaluation of the local burnt clays, produced by different proportions and different calcinations temperatures, as a pozzolanic material in the production of blended cement. Testing was carried out on different types of local clays having different chemical composition and characterized by their low Al2O3 and high SiO2 contents. An optimum cement blend was made of ordinary Portland cement (OPC) and burnt clay (BC), which thermally treated at defined conditions then finely ground, as dry mixtures. This study consists of three main parts: the first part deal with the blended cement as paste to find out the optimum addition percentage, calcinations temperature and the phase composition of the hydrates. The cement paste specimens which were mixed with the optimum water consistency were first cured for different time intervals 1, 3, 7, 28, 90 and 180 days and the degree of hydration of the hardened cement pastes was measured by determination of the combined water contents and the free lime contents of the dried samples. In addition, the compressive strength was measured on the fresh cubic specimens at different curing ages up to 180 days. The results obtained indicated that the suitable calcinations temperature degree of kaolin is 700°C and the optimum addition is in the range of 25-30%. The phase composition of the formed hydration products was determined using XRD and DTA analysis. The second part can be considered as application of the optimum blends, concluded from the first part, on the concrete to test the effect of this artificial pozzolana, on the binder, on the mechanical properties of the concrete and also comparing with the Type (II) cement. The third part measures the durability of the optimum blends, in the paste form and concrete form, in aggressive media. The results obtained from this part illustrated that the incorporation of burnt clay as cement replacement showed excellent durability characteristics to sulfate-chloride environment over those made with OPC and type II cement.