Effect of Composite Thickener on Performance of Large-Flow Thin Layer Mortar and Its Anti-Cracking Mechanism

Abstract

Abstract: For the characteristics of the two thickeners, welan gum (WG) and hydroxypropyl methyl cellulose (HPMC), they were added to solve the problem of easy cracking of cement-based large-flow mortar for thin layer construction under harsh environments. By comparing the effects of WG, HPMC, and composite thickener, the influence law of the composite thickener on the workability, mechanical properties and anti-cracking of large-flow mortar was elaborated. The mechanism of anti-cracking action of the composite thickener was also explained by cryo-scanning electron microscopy. The results show that neither WG nor HPMC alone can solve the problem of mortar cracking under harsh environments. The composite thickener performs better in water retention and anti-cracking, and the modulus of elasticity of mortar becomes lower, and the flexibility is improved, so that it will not crack in outdoor exposure in summer. The anti-cracking mechanism is considered as that the composite thickener combines the respective advantages of WG and HPMC. It forms the superposition of three-dimensional network structure and film structure in the system slurry space. The three-dimensional network structure can greatly enhance the stability of slurry, while the film effect again enhances the stability of slurry and greatly improves the water retention of mortar, which in turn significantly reduces water diffusion and evaporation to achieve the purpose of mortar anti-cracking.

Key words: welan gum, hydroxypropyl methyl cellulose, large-flow mortar, anti-cracking, fluidity, mechanical property

CLC Number:

TU525

YANG Wenxiu, ZHAO Qinglin, ZHOU Mingkai, WU Defan, WU Miaomiao, SHEN Weiguo. Effect of Composite Thickener on Performance of Large-Flow Thin Layer Mortar and Its Anti-Cracking Mechanism[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2023, 42(6): 1938-1949.

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