Requirements for grouting material for prestressed plastic corrugated pipeRequirements for grouting material for prestressed plastic corrugated pipe
In the pre-stressed reinforced concrete technology, the grouting material of the post-tensioned pre-stressed plastic corrugated pipe is a key material that protects the stress steel bars from corrosion and connects the post-tensioned pre-stressed steel bars to the entire structure. The primary function of post-tensioned pre-stressed grouting material is to protect the pre-stressed steel bars from showing corrosion, and to ensure the useful stress transfer between the pre-stressed steel bars and concrete members. Next, follow the footsteps of the prestressed plastic corrugated pipe equipment manufacturers to look at the requirements of the grouting material for prestressed plastic corrugated pipes:
Requirements for grouting material for prestressed plastic corrugated pipe
The requirements of grouting material for prestressed plastic corrugated pipes meet the following requirements: the water-to-glue ratio is 0.40～0.45, and the water-cavity ratio can be reduced to 0.35 when an appropriate amount of water reducing agent is added; the bleeding rate of the grouting material should not exceed 3, The bleeding rate for 3 hours after stirring should be controlled at 2, and the bleeding should be completely sucked back from the beginning within 24 hours; the consistency of the grouting material should be controlled between 14S～18S, which has good fluidity and is suitable for construction pouring; the grouting material is solidifying The front has a certain swelling effect, so that the slurry fills the entire tunnel after being poured, especially the special-shaped parts of the steel strands, the corners of the tunnel and the vertical grouting parts; the grouting material should have the middle of cement hardening (about 14d). Expansion function, the well compensates the natural shrinkage of the cement paste in the middle and late stages, but its free expansion rate should be less than 10, and it is not suitable to cause large expansion internal stress in the concrete; the strength of the grouting material should not be less than 30MPa, so as to be suitable for concrete The integrity of the structure satisfies the useful stress transfer between prestressed steel bars and concrete members.
When the post-tensioned pre-tensioned steel bar is in a non-horizontal skewed position, multi-span tortuous and vertical conditions, the bleeding of the grouting material of the pre-stressed plastic bellows will cause the voids after the bleeding transpiration to lose the passivation protection of the cement, and the steel strand The abnormal shape of the line will also cause some parts of the grouting to be insufficient and lose passivation protection. However, the corrosion of steel bars is easy to develop under stress, resulting in cross-sectional defects at the corrosion parts of the steel bars, which inhibits the guarantee and reliability of the prestressed structure. Tian this, in recent years, the functional assurance of post-tensioned pre-stressed grouting materials has attracted increasing attention from engineers and technicians.