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在约束混凝土工程(如桥面板)中,可通过选择低裂水泥减少开裂,正如德国巴伐利亚的Rudolphstein桥。RILEM TC119TCE3试验是专门用来测定由热收缩和自收缩造成的开裂风险。除此之外,没有等效的ASTM测试方法。AASHTO3498作为新的干燥开裂测试方法,不能直接用于桥面板的早期开裂问题,因为这种开裂是由热收缩和自收缩引起的。本文介绍的两种方法在估计水泥开裂趋势方面比RILEM测试更为简单,即12小时半绝热抗压强度测试和12小时化学收缩测试。同时介绍了应用于水泥浆体的简单干燥收缩测试方法。强度测试和化学收缩测试可以测定水泥的热开裂趋势,也可以用于对约束混凝土在内的重大工程中低裂水泥种类选择。,应该考虑将这些测试方法列入ASTM C1157中水泥的标准规范中,尤其是化学收缩测试,这是至关重要的。因为美国面临的开裂问题比其它一些国家要多,如德国就不存在桥面板开裂这一问题[1],他们使用粗水泥并限制水泥含量。
In constrained concrete works such as bridge decking, cracking can be reduced by choosing low-cracking cements, just as the Rudolphstein Bridge in Bavaria, Germany. The RILEM TC119TCE3 test is designed to measure the risk of cracking caused by heat shrinkage and self-shrinkage. In addition, there is no equivalent ASTM test method. AASHTO3498, as a new dry cracking test, can not be used directly for early cracking of bridge deck because this cracking is caused by thermal shrinkage and self-shrinkage. The two methods presented in this paper are simpler than the RILEM test in estimating trends in cement cracking, namely a 12-hour semi-thermal insulation and a 12-hour chemical shrinkage test. At the same time, the simple drying shrinkage test method applied to cement paste is introduced. Strength test and chemical shrinkage test can determine the trend of thermal cracking of cement, can also be used for the selection of low-cracking types of cement in major projects, including confined concrete. , It is crucial that these test methods be included in the standard specifications for cement in ASTM C1157, especially the chemical shrinkage test. Because there are more cracking problems in the United States than in some other countries, Germany does not have the problem of delamination of deck slabs [1]. They use coarse cement and restrict the cement content.