How to use hydroxypropyl methylcellulose correctly in cement slurry
1. The addition of HPMC has a significant retarding effect on the mortar mixture. With the increase of HPMC content, the setting time of mortar is prolonged. Under the same amount of HPMC, underwater molding mortar is better than air. Molding takes longer to set. This feature is advantageous for pumping underwater concrete.
2. Fresh cement mortar mixed with hydroxypropyl methylcellulose has good cohesive properties and hardly bleeds.
3. The amount of HPMC and the amount of water used in mortar showed a significant increase after the first decrease.
4. The addition of water reducing agent improves the problem of increasing the water demand of the mortar. However, the amount of mortar must be reasonably controlled. Otherwise, the underwater dispersion resistance of the freshly mixed cement mortar is sometimes reduced.
5. There is no significant difference in the structure of the cement slurry samples mixed with HPMC and blank samples. The structure and density of the grout samples placed in water and poured into the air were not significantly different. Underwater molded 28d test pieces were slightly brittle. The main reason is that the addition of HPMC greatly reduces the loss and dispersion of cement in the cast cement, but also reduces the density of the cement stone. In the case of ensuring underwater non-dispersive effects in the project, the number of HPMCs can be minimized.
6. Using HPMC underwater non-dispersible concrete admixture, controlling the admixture is beneficial to the strength. Tests show that the strength ratio of concrete formed in water to that of molded objects in air is 84.8%, and the effect is remarkable.