A cement-based dam grouting process with double expansion agent and its construction method

Abstract

The invention discloses a grouting process for cement-based dam with double-doping of expansive agents and a construction method therefor. In the grouting process, a dam body is subjected to surface treatment and joint cleaning, and then a cement-based grouting material doped with both a light calcined magnesia expansive agent and an ettringite-type expansive agent is grouted, from bottom to top, into the dam body, until the whole joint is filled fully. The construction method includes the steps of: 1) performing surface cleaning to the joint in the dam body; 2) performing joint sealing treatment, and embedding grouting sprues from bottom to top along the joint; 3) cleaning the joint and discharging the water in the joint completely; 4) blending the cement-based grouting material with double-doping of the expansive agents; and 5) from the lowest grouting sprue, grouting the joint from bottom to top until the whole joint is filled fully. The grouting process with the double-doping expansive agents can significantly improve stability, groutability, strength, anti-seepage property and interface binding effect of the grouting material, thereby prolonging the durability and improving process quality. The grouting process also increases construction speed and efficiency, reduces work period, saves cost and increases engineering benefit.

Description

technical field [0001] The invention relates to a cement-based dam grouting process and a construction method of a double-mixed expansion agent. Background technique [0002] The dam concrete produces a large amount of heat of hydration due to the hydration of cement, which causes the internal temperature of the dam concrete to rise significantly in the early stage, and reaches the highest temperature (maybe more than 50°C) at a certain age, as the hydration rate of cement decreases, The hydration heat release rate decreases, and the internal temperature of the concrete also decreases. The volume of the concrete shrinks due to thermal expansion and contraction. At the same time, the volume shrinkage of the concrete is constrained by the bedrock and the underlying concrete to generate tensile stress inside. Low tensile strength and small tensile deformation capacity are prone to temperature cracking, destroying the integrity and stress state of the dam body, and endangering t...

AI Technical Summary

Problems solved by technology

[0003] The traditional dam joint grouting material does not contain expansion agent, often due to the late shrinkage of the grouting material, it will lead to debonding and cracking, resulting in new cracks, resulting in leakage and dissolution, and changing the stress state of the concrete dam. Water is often stored, and due to the water pressure in the gap, the secondary grouting effect is often difficult to achieve good results

Without water reducing agent, the water consumption per unit will be large, the plastic shrinkage of the slurry will be large, the strength will be low, and the bonding effect will be poor.

Without fly ash, lack of secondary hydration, the micro cracks at the interface are difficult to heal themselves, and the impermeability cannot be effectively improved

If compressed air is not used to clean the joints, the water in the joints will be difficult to remove, and the grouting effect will be greatly reduced in the joints filled with water