The effect of hydroxypropyl methylcellulose on the properties of concrete materials!

Hydroxypropyl methylcellulose (HPMC) has excellent thickening properties and can be used as an excellent anti-dispersant for concrete. In the past, this material was a chemical product that was in short supply in China, and its cost was high. Due to various reasons, its use in The application in my country’s construction industry, in recent years, with the continuous development of external wall insulation technology, the lack of progress in cellulose production technology, and the excellent characteristics of HPMC principal and interest, HPMC has been widely used in the construction industry.

One: Anti-dispersion test:

Dispersion resistance is an important technical index to measure the quality of the separation. HPMC is a water-soluble polymer compound, also known as water-soluble resin or water-soluble polymer. It increases the mixture scheduling by increasing the viscosity with water. It is a pro- Water-based polymer materials can dissolve in water to form solutions or dispersions. Experiments show that when the amount of naphthalene-based high-efficiency water reducers increases, the addition of water reducers will reduce the dispersion resistance of freshly mixed cement. This is because the naphthalene-based high-efficiency water reducer is a surfactant. When the water reducer is added to the mortar, the water reducer is oriented on the surface of the cement particles so that the surface of the cement particles has the same charge. This electric repulsion makes the cement particles The formed flocculation structure is dismantled, and the water contained in the structure is released, which will cause the loss of part of the cement. At the same time, it is found that with the increase of the HPMC content, the dispersion resistance of the freshly mixed cement mortar is getting better and better.

Two: the strength characteristics of concrete:

(1) The addition of hydroxypropyl methylcellulose has an obvious slowing effect on the mortar mixture. With the increase of the amount of HPMC, the retarding time of the mortar is extended successively. Under the same amount of HPMC, the underwater molding The setting time of the mortar in the air is longer than that in the air, which is beneficial to the pumping of water-based concrete.

(2) The freshly mixed cement mortar mixed with hydroxypropyl methylcellulose has good cohesive properties and almost no bleeding.

(3) The amount of hydroxypropyl methylcellulose and the water demand of mortar decreased first and then increased obviously.

(4) The incorporation of water reducing agent improves the problem of increased water demand for mortar, but its dosage must be controlled reasonably, otherwise the underwater anti-dispersion of freshly mixed cement mortar will sometimes be reduced.

(5) Adding hydroxypropyl methylcellulose underwater non-dispersible concrete admixture, controlling the dosage is beneficial to the strength. The test shows that the strength ratio of water-formed concrete and air-formed concrete is 84.8%, and the effect is compared significantly.