C50大体积混凝土温度应力测试及抗裂性能研究
Temperature stress test and anti-crack properties of C50 massive concrete

为研究不同配合比条件下高强度大体积混凝土浇筑早期内部的温度、应力变化以及提高早期抗裂性能的技术途径，采用温度应力传感器分别测试尺寸为6.5 m×2.0 m×4.5 m的粉煤灰掺量为15%以及粉煤灰和矿粉双掺总量为33%的C50大体积混凝土早期的温度及应力变化。研究结果表明：以上2种混凝土在3 d龄期时抗压强度均不低于设计值的80%，劈拉强度均大于2.6 MPa。混凝土内外最大温差出现在3~4 d之间，最大拉应力也出现在大约3~4 d之间，采用粉煤灰和矿渣双掺的混凝土，掺合料掺量占胶凝材料30%以上，能够有效降低混凝土早期内外温差且3 d抗拉强度并未显著降低，有利于提高混凝土的抗裂性。
In order to study the early change of temperature and stress of high strength massive concrete with different mixtures and methods of anti-crack, test specimens of size 6.5 m×2.0 m×4.5 m were used and temperature and stress sensors were embedded. The specimens were made of design strength grade C50 concrete with addition of 15% fly ash and 33% mineral admixtures of fly ash and slog, respectively. Results show that compressive strength of these two kinds of concrete are beyond 80% of design strength grade and split tensile strength is also more than 2.6 MPa at 3 d ages. The improvement of early tensile strength of concrete is beneficial for anti-crack. Both the biggest temperature difference and the biggest tensile strength appear between 3 d and 4 d ages. Addition more than 30% mineral admixtures composed by fly ash slag into massive concrete can decrease temperature difference and keep high tensile strength, which is helpful for improving anti-crack properties of massive concrete