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This research work investigates the durability-based properties of a ternary calcined clay and limestone powder blended Self Compacting Concrete by measuring the short- and long-term permeation properties using water absorption and sorptivity properties testing. Also, the variation of compressive strength with age was evaluated at 7, 14, 28 and 56 days, while the split tensile strength was determined at 7 and 28 days curing. The Mineralogy and morphology of the ternary SCC was evaluated using FT IR Spectroscopy, SEM imaging and EDS. The results obtained shows that the ternary SCC showed improved durability and strength properties with age with dense and improved microstructure.

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The failure of conventional concrete to have classical mechanical properties, reduced permeability and lead to sustainability in concrete production called for the use of supplementary Cementitious Materials (SCM) in concrete to improve its performance. This study investigates the effect of adding optimal dosage of an SCM called nanosilica (nS) on the tensile and compressive strengths, microstructural properties and cement hydration reaction for grade 30 concrete. The optimal dosage of the nS was determined to be 1.5% by weight of cement using compressive strength test. The influence of optimal nS dosage on the concrete properties was investigated using compressive strength test, splitting tensile strength test, Scanning Electron Microscopy (SEM) and Energy Dispersion Spectroscopy (EDS). Results revealed that optimal nS addition led to 30% and 23.3% respective increase in compressive and tensile strengths of conventional concrete at 7days of curing. SEM micrographs show better packing density in the nano-concrete at 90days of curing. EDS shows that addition of optimal nS dosage in concrete led to formation of more C-S-H gels at 90days curing period, and a corresponding reduction in Ca/Si ratio of the nano-concrete to 0.89; a ratio that is very close to that of 14Ǻ tobermorite reported in literature. The optimal nano-concrete can be used where strength improvement, especially at early age and reduction in concrete permeability are requirements. Keywords: Compressive strength, Tensile strength, Normal strength nano-concrete, SEM, EDS.

The objective of this study was to investigate the suitability of Nigerian, sourced Gypsum for the manufacture of Portland cement. Gypsum samples were obtained from eighteen deposits across Nigeria. These were classified into five purity groups based on their calcium sulphate content.Foreign Gypsum, imported from Morocco, was used as control. Six cement samples where produced for each of the five Gypsum purity groups by grounding and blending cement clinker with 3%, 4%, 5%, 6% and 7% Gypsum content. The group 1 cement mix (having not more than 65% calcium sulphate content) has displayed flash set and could not be moulded and therefore not used for further analysis. Cement mortar prisms were produced for the groups 2, 3, 4 and 5 cement mixes, and subjected to flexural and compressive strength tests at 7, 14, 21 and 28 day curing periods. The cement mortar prisms were also subjected microstructure analysis at 7 and 28 days curing period. The spongy, gel and whitish colouration observed from the  microstructure of the specimens indicated silicates enriched regions which have proven the strength increase from 7 to 28 day curing period. The optimum gypsum content of 5.5% was recommended. The results show that all but the class one gypsum with less than 65% purity content are suitable for cement manufacture. Keywords: Gypsum, clinker, mortar, microstructure, compressive strength, flexural strength