Associate professor of civil engineering and manager, Research Institute, University of Petroleum and Minerals, Dhahran,
Lecturer, King Faisal University, Dammam,
Research assistant, Research Institute, University of Petroleum and Minerals, Dhahran,
Professor of civil engineering, University of Petroleum and Minerals, Dhahran,
The low durability of concrete construction in the Middle East caused by corrosion of reinforcement, sulfate attack, environmental cracking, and aggregate-cement reactivity necessitates that mix design techniques be formulated to yield dense and impervious concrete with as little heat of hydration as possible; it should also have enhanced resistance to salt attack and possible cement-aggregate reactivity. These objectives present fly ash as a potentially useful admixture from the standpoint of improving the durability of concrete construction in the aggressive service environment of the Gulf seaboard.
This investigation presents data on the strength, general quality, and durability performance of fly-ash portland-cement concrete against sulfate/chloride attack. The variables used for this study are fly ash additions as cement replacement from 0 to 40%, cement factors of 300, 360 and 450 kg/m3 (500, 600, and 750 lb/yd3) and tricalcium aluminate (C3A) phase ranging from 0 to 9.5%. Results show that 20% replacement by fly as shows the best performance in terms of rate of strength gain, ultimate strength, absorptive characteristics, and resistance to sulfate/chloride attack. The strength gain is superior in lean mixes, and the effect of fly ash addition on sulfate resistance of concrete is more pronounced for higher C3A cements. An increase in the cement factor without attendant changes in water/cement ratio does not necessarily provide better durability performance.
Paper ID: CCA10061J