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本文是针对国产回转窑烧结法矾土水泥配制的混凝土,在通过大量的实验室快速试验和不同自然条件地区长期龄试验结果的基础上写成的。与前人已发表的采用电炉熔融所制得的高铁矾土水泥混凝土所得的结论相近似。文章论述了强度下降的原因是由于低钙铝酸盐水化物转化成高钙铝酸盐水化物和铝胶结晶,造成晶体间结合力降低,孔隙率增加。强度下降的速度与环境温湿度等条件有关,高温高湿时强度下降速度加快。指出矾土水泥混凝土强度下降不是无止境的,存在着最低强度值。提出决定该值大小的主要因素是水灰比,也与水泥矿物组成等有关。并建议用50℃水热养护法确定该值。还提出了国产回转窑烧结法矾土水泥混凝土最低强度值估算的数学表达公式。
This article is based on the domestically produced rotary kiln sintering concrete made of alumina cement, written on the basis of a large number of laboratory rapid tests and long-term age test results in different natural conditions. The results obtained with previous published high-iron alumina cement concretes produced by electric furnace melting are similar. The article discusses that the reason for the decrease in strength is due to the conversion of low-calcium aluminate hydrates into high calcium aluminate hydrates and aluminum colloidal crystals, resulting in reduced intercrystalline bonding and increased porosity. The speed of the decrease in strength is related to the conditions such as the temperature and humidity of the environment, and the decrease in the strength is accelerated at high temperatures and high humidity. It is pointed out that the decrease in the strength of alumina cement concrete is not endless and there is a minimum strength value. The main factor for determining the value of this value is the water-cement ratio, which is also related to the composition of cement minerals. It is recommended to use the 50 °C hydrothermal curing method to determine this value. The mathematic expression formula for estimating the minimum strength value of cement concrete made by rotary kiln made in China is also proposed.