In this research, an attempt has been made to study the velocity of ultra-sonic pulse Velocity (UPV) transmitted through self-compacting lightweight concrete (SCLC) with and without steel fiber (SF) for different specimen lengths (i.e. 100 mm cubes and 200 mm cylinders). Two volume fractions of SF “0.4%” and “0.8%”(as an indication to steel fiber content (SFC) were also studied to explore their contributor role. It was found that, for the (100 mm) cubic specimens and the (200 mm) cylindrical specimens, the UPV increment with increasing SFC, but the percentage of increase is higher in cylinders than in cubes. It was also found that, for the same SF volume fraction, the UPV in the SCLC, increases with the decreasing of specimen length, from (200 mm) cylinders to (100 mm) cubes. The percentage of this increase decreases with the increment of SFC. The influence of SF on three mechanical properties of the SCLC (namely: the compressive strength, the splitting tensile strength, and the bulk density) was also studied. It was found that the three mentioned properties are enhanced with the increment of SFC, but this increase is moderately in compressive strength, extremely in tensile strength, and slightly in bulk density.

Geopolymer concrete was presented to produce alternative binder to cement. This study considered the influence of silica fume on the properties of metakaolin based geopolymer mortar exposed to high temperature up to 800 °C. Five mortar mixes were used with silica fume replacing level of 0, 10, 20, 30 and 40% of weight of metakaolin. The results demonstrated that the compressive and splitting tensile strength increased with increasing the silica fume replacing level up to 40% of weight of metakaolin for all burning temperature and the absorption was decreased with it. The outcomes also demonstrated that for the same mix the compressive and splitting tensile strength improved with increment burning temperature up to 400 °C and reduced with increasing the temperature above it until 800 °C.

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This work study the effect of partial replacement of cement by hydrated cement on some properties of cement paste and cement mortar such as normal consistency, initial and final setting time, compressive strength, and length change. The results show that pastes containing hydrated cement require more water than reference paste to give normal consistency. The results also show that the replacement by hydrated cement delay the initial and final setting time of cement paste. The delay in setting time increased with increasing the partial replacement by hydrated cement.Compressive strength test was carried out on (54) cubes of (50) mm side dimensions of mortars containing (5, 10, 15, 20, and 25%) of hydrated cement at (3, 7, and 28) days. They were then compared with reference mortar. The compressive strength results show that the compressive strength decreases with increasing the replacement percentage by hydrated cement at all ages. The decreases in compressive strength reached (23.05 %) when (25%) of cement was replaced by hydrated cement in (28) days.The results also show that the replacement of cement by hydrated cement increases the length change of mortars compared with reference mortar.