为探索粗水泥用于提高碾压混凝土(RCC)抗裂性的可行性,首先要研究水泥比表面积对RCC力学性能的影响.测试了5种比表面积(258~413m。/kg)的P·I水泥胶砂强度等物理性能,分析了这5种水泥配制的三级配RCC力学性能及极限拉伸值的差异.结果表明,比表面积为258m。/kg的粗P·I水泥仍满足42.5水泥强度要求;RCC抗压强度、轴心抗拉强度基本不随水泥比表面积的变化而变化;粗水泥配制的RCC的28d抗拉弹模较低且极限拉伸值较大,90d、180d的抗压强度增长率、轴心抗拉强度增长率及抗拉弹模增长率均较大,说明粗水泥有助于提高RCC的抗裂性能.
To investigate the possibility of improving cracking-resistance of RCC by using coarse cement, it is necessary to study relationship between specific surface area (SSA) of cement and mechanical properties of RCC. Physical properties of cements with five different SSAs (258 -413 m2/kg) are tested, such as mortar strength. Mechanical properties and ultimate tensile strain capacity of five kinds of RCC mixed in cements with different SSA are compared. Results show that at 28 d, the compressive strength of mortar made with type P · I cement, of which SSA is 258 m2/kg, still meets the requirements (42. 5 MPa); the difference of compressive strength and the difference of axial tensile strength among the five kinds of RCC are not remarkable. After 90 d, the growth rates of compressive strength, axial tensile strength and tensile elastic modulus of RCC are higher; at 28 d, the coarser the cement is, the lower the tensile elastic modulus of RCC becomes and the higher the ultimate tensile strain is. All this shows that the cracking-resistance of RCC can be improved by using coarse cement.