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When low-heat portland blast-furnace slag cement is used, the thermal expansion strain of concrete shows reversal deformation in spite of the continuous temperature rising as the result of rapid autogenous shrinkage greater than the thermal expansion. In this study, the autogenous shrinkage strain was investigated in terms of gypsum con-tent in cement. It was possible to reduce the autogenous shrinkage by increasing the gypsum content in cement. Prevention of the early-age rapid hydration development of granulated blast-furnace slag at high temperature was also examined. Moreover, the amount of transition from ettringite to monosulfate of hydration product was deter-mined. As the result, it affected autogenous shrinkage of blast-fumace slag cement concrete significantly.

Although the water-cement ratio of concrete for the prestressed concrete is low, deterioration due to salt attack of prestressed concrete structures has appeared in recent years. Blast-furnace slag is effective in resisting penetration of chloride ions. However, the influences of blast-furnace slag on the durability properties of high-strength concrete for steam-cured pretensioned elements are not clear. In this study, carbonation and chloride penetration of the high-strength concrete using blast-furnace slag were examined. As the result, the addition of blast-fumace slag increased the concentration of chloride ion near the surface, but decreased the penetration to the interior concrete. Blast-furnace slag improved the resistance to erosion by a calcium chloride solution. Moreover, it was found that carbonation of the concrete made with blast-furnace slag was slow and there was no problem in this respect.

It is well known that supplementary cementing materials can enhance the durability of concrete structures particularly in the hot and severe environment. In this study, concrete specimens containing different supplementary cementing materials, namely; silica fume, slag, a natural pozzolan (trass), and mixtures of cement and two pozzolans have been investigated. The tests conducted include, compressive strength, permeability, chloride diffusion, corrosion of reinforcing bars, and carbonation depth, all at different ages. The variables were cement types, supplementary cementing materials, water-cement ratio, and cover thicknesses. After standard curing, concrete specimens were transferred to the Gulf region and maintained in submerged, wetting and drying and coastal environments. For exposure to alternate cycles of wetting and drying, known as the most severe condition, the superior performance of silica fume was followed by the concrete mixture containing trass. However, all concrete mixtures containing natural or artificial pozzolans showed better performance compared with the portland cement control concrete mixtures.

A new type of high-performance, light colored pozzolan (LCP) has been investigated as an alternative supplementary cementitious material. The LCP is a by-product of the production of zirconium oxide from sand, unlike conventional gray silica fume (SF), which is a by-product derived primarily from the silicon metal/ferro-silicon industry. The LCP is predominantly an amorphous silicon dioxide, with minor amounts of zirconium oxide (zirconia) and zirconium silicate (zircon) present. The LCP provides similar strength enhancement and permeability reduction benefits to concrete as SF, without increasing the water demand of fresh concrete, which SF often does. As a result, it does not significantly increase the demand for high-range water reducer (HRWR) as compared to a reference concrete mixture. The LCP is white to off-white in color, which is an advantage as compared to SF when used in architectural, reflective or color-enhanced concrete applications. In addition, the cost of LCP is generally less than that of white silica fume.

A shortage of high quality natural sands and the environmental restrictions make the artificial aggregate to be used more available and more attractively for concrete industry. The fine aggregate of blast furnace slag, which is manufactured by grinding granulated slag, is similar in physical properties to natural sands. However, the aggregate grains are easily bonded together and hardened by hydration reaction, during storage. The authors have developed an anti-bonding agent that can extend the storage term safely more than 2 times, compared with the addition of conventional sodium gluconate to the aggregate. The performance was assessed by measuring aggregate grain size after various periods of curing at temperatures between 40 to 80°C in laboratory and was also confirmed by piling the aggregate outdoors in summer season. The effects of the agents on concrete properties were negligible.