小浪底泄洪工程高标号混凝土裂缝产生的原因及防治

小浪底泄洪工程中采用了抗空蚀、耐磨性能好的C70高标号硅粉混凝土。孔板(导流)洞、排沙洞明流段、明流洞和溢洪道大体积、C70高标号硅粉混凝土中均出现早期和后期施工裂缝。早期裂缝主要与混凝土因水泥水化热引起的内外温差和干燥引起的内外湿差有关。后期裂缝主要由基础温差引起。采取掺加25-40%粉煤灰优化混凝土配合比、加强混凝土温度控制、缩短混凝土分块长度等措施能有效预防裂缝产生。工程修补时采用环氧树脂和特细水泥注浆法处理已出现的裂缝、效果良好。

The cause and prevention of cracking in high strength concrete of Xiaolangdi Project's outlet works

The cause of cracking in C70 silica fume concrete of outlet works in the Xiaolongdi Project is investigated.It is concluded that the cracking in early stage is mainly related to the temperature difference due to cement hydration heat and moisture difference due to drying.The cracking in later stage is due to the foundation temperature difference.The cracking can be effectively prevented if the fly ash is 20-40%,the temperature of the concrete is carefully controlled and the length of placement block is shortened.The epoxy resin injection and extra fineness cement grouting are adopted for cracking remedy and is proved to be very effective.