シリカフユームを使用した高強度コンクリートの強度発現に及ぼす高温温度履歴の影響

抄録

High strength concrete with the compressive strength in excess of 80MPa has recently been a matter of concern in its application to the column or core wall of high-rise reinforced concrete building. High strength concrete can potentially generate high hydration temperature at early ages due to its relatively high cement conctent. It has been pointed out that a high temperature profile at early ages has a detrimental effect on the strength of high strength concrete, reducing long-term strength development and increasing thermal cracking risk.
In this study, a temperature matched curing system (TMC) which can simulate in-situ temperature profiles of the column was developed in order to investigate the influence of high hydration temperature at early ages on the strength development of high strength concretes with and without silica fume. It was found that under sealed conditions, a high temperature of 70°C at early ages in high strength concretes with silica fume led to a little higher 7-day strength but no increase in strength beyond 28 days, whilst it had no significant detrimental effect on the strength development in those without silica fume. The evaporable and non-evaporable water content data showed that both the hydration of cement and the pozzolanic reaction of silica fume almost completed after 3 days TMC due to the shortage of water in concrete when high strength concretes with silica fume were subjected to a high temperature of 70°C at early ages.