MHEC chemical-Influence of the addition amount of hydroxyethyl methyl cellulose on the properties of mortar
Hydroxyethyl methyl cellulose HEMC can significantly improve the water retention of mortar, and the lower content of hydroxyethyl methyl cellulose HEMC can significantly improve the water retention of mortar. When the content is 0.02%, the water retention rate increases from 83 % rose to 88%; when the dosage was 0.2%, the water retention rate reached 97%. At the same time, the low content of HPMC also significantly reduced the stratification and bleeding rate of the mortar, which indicates that HEMC can not only improve the water retention of the mortar, but also significantly improve the cohesion of the mortar, which is important for the uniformity of the construction quality of the mortar. Very beneficial.
However, hydroxyethyl methyl cellulose HEMC has a certain negative effect on the flexural and compressive strength of mortar. With the increase of hydroxyethyl methyl cellulose HEMC content, the flexural strength and compressive strength of mortar tend to decrease gradually. At the same time, hydroxyethyl methyl cellulose HEMC can improve the tensile strength of mortar. When the content of hydroxyethyl methyl cellulose HEMC is within 0.1%, with the increase of HEMC content, the tensile strength of mortar increases continuously, while After the dosage exceeds 0.1%, the tensile strength will not increase significantly. Hydroxyethyl methyl cellulose HEMC can also significantly increase the compressive shear bond strength of the mortar. The addition of 0.2% HEMC can make the mortar bond strength from 0.72MPa. increased to 1.16MPa.
Studies have shown that hydroxyethyl methyl cellulose HEMC can significantly prolong the cooling time of mortar and significantly reduce the slip of mortar, which is very beneficial for tile construction. Without HEMC, the bond strength of mortar cooled for 20 min decreased from 0.72 MPa to 0.54 MPa, and the bond strength of mortar with 0.05% and 0.1% HEMC after cooling for 20 min was 0.8 MPa and 0.84 MPa, respectively. The slippage of the mortar without HEMC was 5.5mm. With the increase of HEMC content, the slippage continued to decrease. When the content of HEMC was 0.2%, the slippage of the mortar dropped to 2.1mm. Equal thin layer construction provides technical support.
In addition, hydroxyethyl methyl cellulose HEMC can effectively inhibit the formation of plastic cracks in mortar and reduce plastic cracks significantly. When the content of HEMC is low, the crack index decreases significantly with the increase of the content of HEMC. When the content of HEMC is 0.1% and 0.2%, the relative crack index of the mortar is 63% and 50%, respectively. When the content of HEMC exceeds 0.2%, the The plastic cracking of the mortar is no longer significantly reduced.