Effects of Methyl Cellulose in Dry Mortar in Construction
Molecular Formula of Methyl Cellulose (MC): [C6H7O2(OH)3-h(OCH3)n]x
Methyl Cellulose or MC
1.Methyl cellulose is soluble in cold water and may encounter difficulties when dissolved in hot water. The aqueous solution is very stable in the range of pH=3~12. It has good compatibility with starch, guar gum, and many surfactants. When the temperature reaches the gelling temperature, gelation may occur.
2.The water retention property of methyl cellulose depends on the adition amount, viscosity, particle fineness, and dissolution rate. Generally if the addition amount is great, the fineness is good, and the viscosity is large, then the water retaintion rate is high. Of these factors, the addition amount has the greatest impact on the water retention rate. The viscosity level is not proportional to the level of water retention rate. The dissolution rate depends mainly on the degree of modification of cellulose particle surface and particle fineness. Of the several cellulose ethers above, methyl cellulose and hydroxypropyl methyl has higher water retention.
3.Temperature changes will seriously affect the water retention of methyl cellulose. Generally the higher the temperature is, the worse the water retention will be. If the temperature of mortar exceeds 40℃, the water retention of methyl cellulose will significantly get worse, seriously affecting the workability of mortar.
4.Methyl cellulose has a significant effect on the workability and adhesion of the mortar. Here, “adhesion” refers to the adhesive force felt between the smudge tool of workers and the substrate of the wall, i.e., the shear resistance of the mortar. The greater the adhesion is, the larger the shear resistance of mortar, so in use process the strength required by the worker is also large and the workability of mortar is poor. In the cellulose ether products, the adhesive force of methyl cellulose is at the middle level.
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