Introduction With the continuous improvement of the construction industry’s requirements for concrete performance, the strength, durability and construction performance of concrete have received widespread attention. In terms of improving the performance of concrete, the use of admixtures is an important means. Hydroxypropyl Methylcellulose (HPMC), as a common cellulose chemical admixture, has been widely used in construction, coatings, gypsum, mortar and other fields. As a water-soluble cellulose ether, it has good thickening, water retention, film formation and improvement of construction performance. However, the effect of HPMC on concrete density is still a topic worth studying.

Basic properties of HPMC HPMC is a natural polymer compound soluble in water, usually obtained by chemically modifying cellulose, with certain hydrophilicity and adhesion. In concrete, HPMC mainly plays the role of thickening, water retention, improving fluidity, and extending working time. It can improve the fluidity and construction of cement paste, thereby improving the construction efficiency of concrete.

Effect of HPMC on Concrete Density

Water retention of HPMC on cement paste HPMC has strong water retention performance, which can effectively slow down the evaporation process of water and maintain the hydration environment of cement paste. Especially in high temperature or dry environment, the water retention effect of HPMC is particularly significant. The hydration reaction of cement paste requires sufficient water support. If the water evaporates quickly, the cement particles will not be fully hydrated, forming pores, which will affect the density of concrete. HPMC delays the evaporation of water to ensure that the cement particles can be fully hydrated, thereby improving the density of concrete.

Effect of HPMC on concrete fluidity HPMC, as a thickener, can improve the fluidity of concrete. An appropriate amount of HPMC can make concrete have good fluidity and reduce the segregation phenomenon of concrete during pouring. Concrete with better fluidity can better fill the mold during pouring, reduce the generation of bubbles and voids, and improve the density of concrete. However, if the HPMC dosage is too much, it may cause the viscosity of concrete to be too high, affecting the operability of concrete, making pouring difficult, and may even cause the voids in the concrete to be unable to be completely filled, thus affecting the density.

HPMC’s dispersibility of cement particles An appropriate amount of HPMC can improve the dispersibility of cement particles in water and make cement particles more evenly distributed in cement paste. Uniform distribution of cement particles helps reduce the agglomeration of large particles in concrete, thereby reducing porosity and improving the compactness of concrete. If the HPMC dosage is too large, it may cause the bonding force between cement particles to be too strong, resulting in excessive viscosity of cement paste, affecting the hydration of cement particles and the compactness of concrete.

Impact of HPMC on the hardening process of concrete HPMC plays a role in delaying the cement hydration reaction during the hardening process of concrete, especially in high temperature or dry environment, which can effectively prevent rapid evaporation of water and delay the cement hydration process, thereby improving the density of concrete. The slow progress of cement hydration reaction helps to form a finer cement gel, reduce the formation of pores, and improve the overall compactness of concrete. However, if the HPMC dosage is too high, it may cause excessive delay in the hydration process, affecting the strength development and structural stability of concrete.

Effect of HPMC on Concrete Impermeability Since HPMC has strong hydrophilicity, it can effectively reduce microcracks and pores in concrete, thereby improving the concrete’s impermeability. By optimizing the HPMC dosage, the structural density of concrete can be improved, the penetration of external media such as water and chemicals can be reduced, and the durability of concrete can be improved.

Optimal range of HPMC dosage According to experimental research, the effect of HPMC dosage on the density of concrete is bidirectional, and it cannot be too low or too high. When the dosage is too low, the thickening effect of HPMC is insufficient and it cannot effectively improve the fluidity and water retention of concrete; when the dosage is too high, it may cause excessive viscosity of concrete, affect construction performance, and even cause voids and holes. Therefore, the dosage of HPMC should be controlled within a reasonable range. According to different research data, the dosage of HPMC is generally controlled between 0.1% and 0.3%. Too high or too low dosage will have an adverse effect on the density and other properties of concrete.

The effect of HPMC dosage on the density of concrete is mainly reflected in its regulatory effect on the water retention, fluidity, dispersibility of cement particles and hardening process of cement paste. The right amount of HPMC can improve the construction performance of concrete, enhance the density of concrete, and improve its strength and durability. However, too high or too low dosage will have an adverse effect on the density of concrete. Therefore, in practical applications, the dosage of HPMC must be reasonably selected according to the use requirements and environmental conditions of concrete to achieve the best concrete performance.