Influence of the addition amount of hydroxypropyl methylcellulose on the properties of mortar

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Influence of the addition amount of hydroxypropyl methylcellulose on the properties of mortar

Hydroxypropyl methyl cellulose HPMC can significantly improve the water retention of mortar, and the lower content of hydroxypropyl methyl cellulose HPMC 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 HPMC 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, hydroxypropyl methylcellulose HPMC has a negative effect on the flexural and compressive strength of mortar to a certain extent. With the increase of HPMC content of hydroxypropyl methylcellulose, the flexural strength and compressive strength of mortar decreased gradually. At the same time, hydroxypropyl methyl cellulose HPMC can improve the tensile strength of mortar. When the content of hydroxypropyl methyl cellulose HPMC is less than 0.1%, the tensile strength of mortar increases continuously with the increase of HPMC content. After the dosage exceeds 0.1%, the tensile strength does not increase significantly. HPMC can also significantly increase the compressive shear bond strength of the mortar. The addition of 0.2% HPMC can make the mortar bond strength from 0.72MPa. increased to 1.16MPa.

Studies have shown that hydroxypropyl methyl cellulose HPMC can significantly prolong the cooling time of mortar and significantly reduce the slip of mortar, which is very beneficial for tile construction. Without HPMC, the bond strength of mortar cooled for 20min decreased from 0.72MPa to 0.54MPa. After adding 0.05% and 0.1% HPMC, the bond strength of mortar cooled for 20min was 0.8MPa and 0.84MPa, respectively. The slippage of mortar without HPMC was 5.5mm. With the increase of HPMC content, the slippage decreased continuously. When the content of HPMC was 0.2%, the slippage of mortar dropped to 2.1mm. Equal thin layer construction provides technical support.

In addition, hydroxypropyl methylcellulose HPMC can effectively inhibit the formation of plastic cracks in mortar, which can significantly reduce plastic cracks. When the content of HPMC is low, the crack index decreases significantly with the increase of the content of HPMC. When the content of HPMC is 0.1% and 0.2%, the relative crack index of the mortar is 63% and 50%, respectively. When the content of HPMC exceeds 0.2%, The plastic cracking of the mortar is no longer significantly reduced.

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