摘要
混凝土收缩裂缝的形成与体系水化放热情况密不可分,优质矿物掺合料在水化期间可以有效推迟水化放热峰的出现时间,延缓水化放热速率,避免体系由于水化过快导致的高温度差,形成温度应力,导致裂缝出现。同时,优质矿物掺合料在改善混凝土基本性能方面具有重大作用,结合某大坝出现混凝土温度裂缝以及施工过程中基本性能较差等质量问题,引入品质优异的粉煤灰、矿粉、硅灰,研究取代率对于混凝土基本性能及收缩性能的影响。当粉煤灰掺量为15%、硅灰掺量为4.1%时,混凝土整体黏聚性、流动性、保水性得到显著改善;混凝土倒筒时间达到3.9s,初始扩展度达到660mm,1h扩展度达到665mm,2h扩展度达到670mm;混凝土和易性良好,易于施工,泵送阻力小,无泵送损失,表面无裂缝。
The formation of concrete shrinkage cracks is inseparable from the hydration and exothermic situation of the system.High quality mineral admixtures during hydration can effectively delay the emergence time of hydration and exothermic peak,delay the hydration and exothermic rate,and avoid the high temperature difference caused by the rapid hydration of the system,forming temperature stress,leading to the emergence of cracks.At the same time,high quality mineral admixtures play an important role in improving the basic properties of concrete.Considering the quality problems such as concrete temperature cracks and poor basic properties in the construction process of a dam,fly ash mineral powder silica fume with excellent quality was introduced to study the influence of substitution rate on the basic properties and shrinkage properties of concrete.When the fly ash content is 15%and the silica fume content is 4.1%,the cohesive fluidity and water retention of concrete can be significantly improved;the concrete pour time reaches 3.9s,the initial extension reaches 660mm,the 1h extension reaches 665mm,and the 2h extension reaches 670mm;concrete workability is good,easy to construct,low pumping resistance,no pumping loss,surface crack free.
作者
邵建新
SHAO Jian-xin(Zhejiang Provincial No.1 Hydropower Construction Group Co.Ltd.,Hangzhou 310051,China)
出处
《黑龙江水利科技》
2021年第6期18-20,共3页
Heilongjiang Hydraulic Science and Technology
关键词
大坝混凝土
矿物掺合料
基本性能
抗压强度
收缩性能
dam concrete
mineral admixtures
basic performance
compressive strength
contractility
