Thesis (M.Sc.) - Cairo University - Institute of African Research and Studies - Department of Natural Resources

Three commercial polynaphthalene sulfonate superplasticizers were used to study their effect on the slump behavior of cement pastes made of CEM I 42.5 N, sulfate resisting and portland limestone (CEM II / B - L) cements as well as on the respective concretes. The admixtures had similar characteristics with respect to their finger print infrared spectrograhs, the HPLC chromatographs, the differential thermogram DTA and the physical properties, The initial slump and the slump loss of the paste and concrete were measured by means of the minislump test and according to ASTM C - 143 - 08 respectively. The results obtained confirm the increased flowability of the pastes made of sulfate resisting and portland limestone cements compared to that of CEM I reported in the literature. The amount of C3A in the cement and the surface nature of limestone are factors determining the absorption process of the admixture on the cement hydrates and the consequent flowability. The fluidity start and slump retention capacities of concrete are found to follow the same trend of the pastes which suggests that the minislump test on pastes can be a successful indicator for the slump behavior of concrete

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