The main factor affecting the durability of cement mortar is the water-cement ratio, which directly determines its impermeability, freeze-thaw resistance, and resistance to chemical corrosion by controlling the internal pore structure of the mortar.
In addition, the following key factors also significantly affect the long-term durability of mortar:
Water-cement ratio (core factor): An excessively high water-cement ratio leads to the formation of numerous pores after the excess water evaporates, reducing density and making the mortar more susceptible to freeze-thaw cycles, water penetration, and chemical corrosion, thus significantly weakening its durability. Controlling the water-cement ratio is the primary measure to improve durability.
Material quality and mix proportions
Cement quality: The mineral composition and corrosion resistance of cement directly affect durability. For example, sulfate-resistant cement can enhance resistance to chemical corrosion.
Sand mud content and gradation: High mud content or poor gradation will reduce mortar density and increase the risk of cracking.
Admixture Use:Appropriate addition of waterproofing agents and water-reducing agents can improve impermeability and density, but the dosage must be controlled.
Construction Process and Density: Uneven mixing, insufficient vibration, or excessive application can easily lead to hollow areas and cracks in the mortar layer, compromising its integrity and accelerating the intrusion of harmful external substances.
Cure Conditions (Key Guarantee): Cement hydration requires a continuously moist environment. Insufficient curing (such as lack of covering or untimely watering) can cause surface shrinkage cracks, affecting strength development and durability. Specifications require water curing to begin one day after construction and continue for at least seven days.
Environmental Effects: Long-term exposure to freeze-thaw cycles, alternating wet and dry conditions, chemical corrosion (such as acid rain and salt spray), or carbonization environments will gradually damage the mortar structure. Good initial density and impermeability are fundamental to resisting these damages.