风洞用高性能清水混凝土抗裂性能试验研究

Experimental study on crack resistance of high performance fair faced concrete used in wind tunnel

依托于某风洞工程,基于方圆抗裂模具试验方法,研究了矿物掺合料种类、水泥比表面积及水泥品种对清水混凝土抗裂性能的影响。结果表明:MgO膨胀剂和S105级矿渣均可延长清水混凝土的初裂时间,同时还可以减小裂缝总长度和总开裂面积,抗裂效果显著;石灰石粉对清水混凝土的初裂时间影响不大,但可减小裂缝总长度和总开裂面积,具有一定的抗裂效果;石英岩粉对清水混凝土抗裂性能的改善效果不佳,不仅会缩短初裂时间,而且会增大裂缝总长度和总开裂面积;应尽量使用比表面积较小的水泥,可降低清水混凝土的开裂敏感性;使用抗裂水泥可显著提高混凝土的抗裂性能,但对其早期强度会产生一定影响;清水混凝土中水泥用量不宜过多,否则会因为水化热过高而引起混凝土过早出现裂缝。

Relying on a wind tunnel project,based on the square and round anti crack mold test method,the anti crack performance of fair faced concrete with different mineral admixtures,different cement fineness and different cement varieties was studied.The results show that MgO expansive agent and S105 slag can extend the first crack time of fair faced concrete,and reduce the total crack length and total crack area,and the anti cracking effect is remarkable.Limestone powder has little effect on the first crack time of fair faced concrete,but it can reduce the total crack length and total crack area,and has a certain anti crack effect.The improvement effect of quartz powder on the crack resistance of fair faced concrete is not good,which not only shortens the first crack time,but also increases the total crack length and total crack area.Cement with smaller fineness should be used as far as possible,which can reduce the cracking sensitivity of fair faced concrete.The use of anti crack cement can significantly improve the anti crack performance of concrete,but may have a certain impact on the early strength.The amount of cement used in fair faced con-crete should not be too high,otherwise the concrete will crack prematurely because of too high hydration heat.