シリカフュームを使用した高強度コンクリートの構造体強度補正値に及ぼす粗骨材種類の影響

 Strength correction values of concrete in structure (_mS_n) are necessary for inspections of compressive strength of concrete in structure using standard-cured specimens. _mS_n are determined by production of mock-up specimens for structural members. In the case of high strength concrete, the interior of concrete in structure gets very hot in the early stage. In the case of high strength concrete with a design strength below 60MPa, the influence of temperature conditions on _mS_n for each binder type has been clarified. Therefore, _mS_n for inspections may be set based on the result of experiment in the season (summer or winter) which _mS_n is expected to be largest. On the other hand, in the case of high strength concrete with a design strength over 60MPa, the influence of temperature conditions on _mS_n has not been clarified. Therefore, experiments in several seasons are necessary for setting _mS_n for inspections. For the purpose of resolution of such a problem, in this study, the tendency of the influence of temperature conditions on _mS_n for high strength concrete with a design strength over 60MPa was investigated.<br> 31 experiments were conducted with ready-mixed concrete plants. In all experiments, the binder for high strength concrete containing silica fume was used. Crushed stones and sands (andesite, hard sandstone, limestone) and natural sands were used as aggregates. Range of water-binder ratio of concrete was 0.14-0.38. Core specimens were collected from mock-up columns with a cross section of 950 × 950 mm or 1000 × 1000 mm. At the age of 56 days, tests for compressive strength with standard-cured specimens and core specimens were conducted to determine the differences between them (₅₆S₅₆).<br> In this study, the influence of temperature conditions on _mS_n was evaluated based on the ratio of ₅₆S₅₆ to compressive strength of standard-cured specimen (Sxy). In the case of using andesite crushed stones, Sxy of winter tended to be larger than Sxy of summer. On the other hand, in the case of using the other crushed stones (hard sandstone or limestone), the differences between Sxy of summer and Sxy of winter were small comparatively. In addition, in the case of using limestone crushed sands, Sxy tended to be large. However, rough tendency of the influence of temperature conditions on _mS_n can consider to be evaluated based on coarse aggregate types, because the influence of fine aggregate type on the relative relationship between Sxy of summer and Sxy of winter was small.<br> Such the influence of temperature conditions on _mS_n was evaluated quantatively by dividing into two factors (reaction of binder, coarse aggregate type). As a result, the same tendency as previous findings for the both elements was obtained. The influence of binder could be evaluated based on binder-water ratio and maximum temperature. The influence of coarse aggregate could be evaluated based on the amount of temperature change.