e mechanical behavior of basaltic volcanic ash (VA) and fly ash (FA) as a cement replacement under elevated temperatures is mainly investigated in the current study. For this, cement content has been partially replaced with and without the presence of electric arc furnace slag (S). Four distinct ranges of temperatures (200°C, 400°C, 600°C, and 800°C) were selected, and the modified mixes were subjected to these gradually elevated temperatures. Samples were cured and cooled by using air-and water-cooling techniques. Test results were established by examining the sample weights and compressive strength before and after the exposure of each temperature level. e pozzolanic potential of volcanic ash and fly ash samples was identified using the strength activity index. After analyzing the test results, it has been found that there is a significant effect on the compressive strength of mortar mixes at the early ages of its strength gain. However, at the later ages of curing, samples modified with volcanic and fly ash with the presence of electric arc furnace slag have shown a better performance than control mix in terms of strength and weight loss.

In this study, the researchers investigated the potential use of locally available waste materials from the lime stone quarry and the granite industry as a partial replacement of cement. Quarry sites and granite industry in the eastern province of Saudi Arabia produces tons of powder wastes in the form of quarry dust (QD) and granite sludge (GS), respectively, causing serious environmental problems along with frequent dust storms in the area. According to ASTM C109, identical 50-mm3 specimens were cast throughout this study to evaluate the compressive strength development of mortars (7, 28 and 91 days) containing these waste materials. Experimental variables included different percentage replacement of cement with waste materials (GS, QD), fineness of GS, various curing temperatures (20, 40 and 60 °C as local normal and hot environmental temperatures) and curing moisture (continuously moist and partially moist followed by air curing). Finally, the results of mortar containing waste materials were compared to corresponding results of control mortar (CM) and mortar containing fly ash (FA). The test results indicated that under normal curing (20 °C, moist cured), the compressive strength of mortar containing the different percentage of waste materials (QD, GS, FA and their combinations) remained lower than that of CM at all ages. However, the compressive strength of mortar containing waste materials slightly increased with increased fineness of GS and significantly increased under high curing temperatures. It was recommended that more fineness of GS be achieved to use its high percentage replacement with cement (30% or more) incorporating local environmental conditions.

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In this study, the influence of mechanically activated electric arc furnace slag (EAFS) was investigated through compressive strength tests on 50 mm mortar cubes. The objective was to convert the wasteful EAFS into a useful binding material to reduce the cement content in concrete without compromising strength and economy. Four different groups of mortar were cast which include control mortar, reference fly ash mortar, mortar containing EAFS to determine its optimum fineness and replacement with cement, mortar blend containing fly ash and EAFS of optimum fineness. EAFS were identified with respect to its fineness as slag ground (SG), slag-fine (SF) 100% passing 75 µm sieve, and slag-super-fine (SSF) 100% passing 45 µm sieve. Compressive strength was measured according to ASTM C109. Specimens were cured under different temperatures and moisture to incorporate the effects of normal and hot environmental conditions. Compressive strength of mortars increases with fineness of EAFS and its strength activity index matches the ASTM C989 blast furnace slag (BFS) Grade 80 up to 30% cement substitution and Grade 100 when 10% cement substituted with SSF. The influence of curing temperatures was also significant in mortars containing SG or 10% SF where strength decreased with increasing curing temperature. However, a 20-30% and 20% cement substitution with SF produced strength comparable to control and reference fly ash mortars under moderate (40 • C) and high curing temperature (60 • C), respectively. The utilization of EAFS as binder in concrete may reduce needs for cement, as well as save environment and natural resources from depletion.