Research On Cement Based Grouting Material Used In The Underwater Concrete Cracks

Concrete is easy to produce cracks in the process of production and use, because ofits low tensile strength, shrinkage, temperature difference, alkali aggregate reaction andso on. Not only the cracks affect the appearance, but the safety of the structure.Grouting method is a comprehensive repair technology, the advanced repair principleand excellent effect to make it become the important means to repair cracks in concreteat home and abroad. But for the underwater concrete cracks,thewater-saturatedenvironment requiresnot just the anti-dispersion of the repairingmaterials,which makes theordinarycement-basedgrouting materials encounter abottleneck.This paper is based on the underwater concrete and underwater mortar, using twousual kinds of flocculants: Polyacrylamide and Hydroxypropyl Methyl Cellulose. Toformulate the cement grouting material which can use under the condition of flowingwater environmentand to simulate the cracks are in the flowing water environment inthelabaccording to the requirements of the special environmental of underwatercracks.Providing reference for the construction of underwater concrete crackgroutingthrough the study of this type of cement based grouting materials, the testresults show that:1) Polyacrylamide and Hydroxypropyl Methyl Cellulose two Flocculantsthroughthe bridging role and charge neutralization in the cement pasteto make the paste antidispersion underwater;2) The fluidity of the cement slurry afer additionofPolyacrylamideFlocculant, asthe content increases,the fluidity first increase then decrease, having a “ritical point”.The larger the PolyacrylamideMecular weights,the more anti-dispersing capability it has,but it is negative to the slurry flow;3) Hydroxypropyl methyl cellulose can also lead to decreases of the fluidity ofcement paste, possessing air entrainingeffect at the same time, resulting in a lot of polesin the hardened slurry and decreasing the strength.The increase of thealkali(NaOH)content of slurry will destroy the anti dispersion effect of theflocculant;4) The final cement based grouting material Z has great mobility, which can’tdisperse in the flowing water. It can fill a big crack well, achieving the desiredrepair effect. The final filling body has a high early and later strength.