Properties of Calcium Sulfoaluminate Cement Mortar Modified by Hydroxyethyl Methyl Celluloses with Different Degrees of Substitution.

Shaokang Zhang,Linglin Xu,Andreas Hecker,Peiming Wang,Ru Wang,Horst-Michael Ludwig

doi:10.3390/molecules26082136

Shaokang Zhang, Linglin Xu + Show 4 more

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https://doi.org/10.3390/molecules26082136

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Abstract

This paper studies the influence of hydroxyethyl methyl cellulose (HEMC) on the properties of calcium sulfoaluminate (CSA) cement mortar. In order to explore the applicability of different HEMCs in CSA cement mortars, HEMCs with higher and lower molar substitution (MS)/degree of substitution (DS) and polyacrylamide (PAAm) modification were used. At the same time, two kinds of CSA cements with different contents of ye’elimite were selected. Properties of cement mortar in fresh and hardened states were investigated, including the fluidity, consistency and water-retention rate of fresh mortar and the compressive strength, flexural strength, tensile bond strength and dry shrinkage rate of hardened mortar. The porosity and pore size distribution were also analyzed by mercury intrusion porosimetry (MIP). Results show that HEMCs improve the fresh state properties and tensile bond strength of both types of CSA cement mortars. However, the compressive strength of CSA cement mortars is greatly decreased by the addition of HEMCs, and the flexural strength is decreased slightly. The MIP measurement shows that HEMCs increase the amount of micron-level pores and the porosity. The HEMCs with different MS/DS have different effects on the improvement of tensile bond strength in different CSA cement mortars. PAAm modification can improve the tensile bond strength of HEMC-modified CSA cement mortar.

Highlights

The cement industry is responsible for 5% of global anthropogenic greenhouse gas emissions [1,2]
It seems that Hydroxyethyl methyl cellulose (HEMC) with higher molar substitution (MS)/degree of substitution (DS), lower MS/DS and PAAm modification have the same impact on water-retention capacity
This means that HEMCs exhibit excellent water retention when it is used in calcium sulfoaluminate (CSA) cement mortars

Summary

Introduction

The cement industry is responsible for 5% of global anthropogenic greenhouse gas emissions [1,2]. It consumes 10–11 EJ of energy resources annually, which accounts for 2–3% of the use of global primary energy [3]. CSA cement can be used as cementitious material in self-leveling mortar, concrete grouting material, ceramic tile adhesive, rapid repair material, etc. In those areas, cellulose ether is usually regarded as a good water-retention and thickening agent, and it is widely applied to improve water retention and cohesion. It has been confirmed that HEMC has effects on the workability [6], rheological properties [7], mechanical properties [8], hydration [9]

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