关于水泥强度标准评价方法的探讨.docVIP

关于水泥强度标准评价方法的探讨 ISO水泥标准强度性能评价方法的局限性。通过对不同窑型生产的相同强度等级水泥的抗压强度—与水灰比关系的试验研究，表明在较高和较低的水灰比范围内，相同等级的不同水泥强度可能存在显著的差别。通过对掺矿渣、粉煤灰和沸石水泥在不同掺量和不同水灰比条件下强度发展的研究，进一步说明了矿物混合材对这种强度差异的影响。理论分析和试验结果说明，由单一水灰比确定的水泥强度等级既不能全面表征水泥强度取决于水灰比的特性，也不能区别相同强度等级的不同水泥。本文最后对水泥强度标准评价方法的改进提出了建议。 Limits of Standard Evaluating Method of Cement Strength Grade and its Improvement Xu Yongmo1 Bai Xianming2 Guo Junping2 China Building Materials Industries Association, 2.China Building Materials Academy Abstract: This paper experimentally shows the limits of the present standard methods of evaluating cement strength grade. The results demonstrate that cements with the same strength grade but produced by different calcinating processes, such as shaft kilns and rotary kilns showed significant differences in strength at lower water/cement ratios. Different mineral blends such as slag, flyash and zeolite also displayed its important influence on the strength difference. The cement strength grade determined by a single water/cement ratio at 0.5 might neither provide correct information on strength properties that depend on water/cement ratios, nor make difference in strength properties between different cements that have the same strength grade. In view of the nonlinear relationship between the strength and water/cement ratio, ever-increasing use of mineral additives which have different effects on strength development, and the development of high performance concretes, it is suggested that the strength evaluation at a lower cement ratio is needed at least to reliably indicate the strength behavior both at higher and lower water/cement ratios and the difference between different cements. 前言 ?与许多结构材料一样，水泥硬化浆体的力学性能取决于材料的密实程度或孔隙率大小。对硬化水泥浆体而言，其力学性能主要决定于水灰比大小和其它影响密实度的因素[1]。在实际应用中，由于水泥仅仅是混凝土的胶凝材料组分，对其工程力学性能评价又不得不引入集料和集灰比等影响因素。以标准砂浆试体确定的水泥强度等级是工程混凝土设计的重要依据。纵观水泥强度标准测试方法的发展历程，不断提高水泥品质以满足混凝土工程对水泥材料的需要是水泥标准的发展主线。从硬练法到软练法，从国标到ISO标准，水泥力学性能的评价方法越来越接近水泥混凝土的实际，例如级配标准砂和振动成型方法的采用等[2]。但遗憾的是，在水泥的物理和力学性能的评价和表征方法中我们仍能看到许多落后于现代科技水平和工程实际的方面