|
, Concrete has become the largest amount of building materials in the construction projects , the development experience of ordinary concrete , high strength concrete, has been toward the direction of high performance development . Concrete to obtain high-strength , high-performance purposes , you must reduce the water-cement ratio and increase the amount of cementitious material , which directly increases the possibility of shrinkage cracking of concrete early . High performance concrete , its contraction is large and occurs mainly in the early days , more importantly, the contraction of the contraction of the early than late . In recent years , countries shrinkage cracking in concrete at early a lot of research , but the study is not a standard test method for shrinkage cracking of concrete at early constraint , the researchers based on the object of study and research content using different research methods or test procedures. Early shrinkage of the concrete is mainly affected by the impact of cement hydration rate and water vapor loss rate due to the concrete internal contraction uneven , resulting in shrinkage stress gradient layer constraints exist , in order to reduce the concrete due to constraints on the stress gradient layer concrete restrained shrinkage test , improved layered ring restrained shrinkage test device within the steel ring constraints . In this paper, a hierarchical ring constraints early restrained shrinkage of the the shrinkage test device for ordinary concrete tested to study the water-cement ratio , ratio of pulp set , fly ash , steel fiber and basalt fiber ash on concrete early contraction the impact of , and research on early shrinkage of self-compacting concrete . Environmental conditions on early shrinkage of the concrete impact , especially temperature , wind speed , and solar radiation . In addition to a similar environment in the laboratory simulation tests , still in the natural environment of the outdoor test, differences in test results through the comparison of the two conditions , and to provide a basis for concrete outdoor maintenance system . The experimental results show that , compared with the conventional test method , improved hierarchical annular constraint test in the early shrinkage of concrete test , prediction of concrete cracking sensitivity and higher accuracy .
|