The influence of VAE powder on the basic properties of waterproof mortar
VAE/RDP powder can significantly enhance the adhesion of mortar, increase the bonding force and adhesion of materials, reduce the water absorption rate of materials, lower the elastic modulus of materials, enhance the flexural strength, impact strength, wear resistance and durability of materials, improve the workability of materials, and increase the impermeability and waterproofing ability of mortar, while also increasing its flexural and compressive strength.
As the dosage of VAE/RDP powder increases, the water requirement of the mortar mixture increases and the fluidity decreases. This is because the polymer latex powder, when dissolved in water, has a large molecular weight and strong adhesion, which leads to an increase in the adhesion of the mortar and a decrease in its fluidity. It can be seen from the figure that as the dosage of the redispersible latex powder (VAE/RDP powder) increases, the bond strength of the mortar increases. When the dosage is 0.25%, the bond strength of the mortar is nearly three times that when the dosage is 0.15%. It can be seen from the figure that as the dosage of the latex powder increases, the impermeability pressure of the mortar gradually increases, but the change is not significant. When the dosage increases from 0.15% to 0.3%, the impermeability pressure increases by 0.22 MPa. Due to the reduction in cement usage while the water usage of the mortar remains unchanged, the water-cement ratio of the mortar increases accordingly, resulting in a higher content of coarse capillary pores in the cement stone. Although the polymer has a certain film-forming property and can fill, cut off and refine some of the coarse capillary pores, the content of large pores in the mortar matrix is still relatively high, ultimately failing to fully demonstrate the improvement effect of the redispersible latex powder on the impermeability of the mortar. As the dosage of the redispersible latex powder increases, the early expansion of the mortar increases and the later shrinkage decreases, indicating that the modified waterproof mortar with redispersible latex powder can promote the expansion value of the expansive agent, ultimately reducing the shrinkage of the waterproof mortar and improving its crack resistance.
The influence of VAE emulsion on the basic properties of mortar. It can be seen from the figure that the impermeability pressure shows an increasing trend, and the change rate tends to level off when the dosage is 0.44%. The impermeability performance increases from the initial 1.42 MPa to 1.96 MPa at a dosage of 0.44%, an increase of 38%. This figure is quite encouraging and can meet the impermeability requirements of most engineering and construction projects. It indicates that the addition of VAE plays a significant role in improving the impermeability of mortar, with a very obvious effect. Moreover, the dosage of VAE is not large. When the dosage reaches 0.7%, the impermeability only increases by 0.08 MPa. From an economic perspective, it is not cost-effective. Due to the addition of polymers, some air bubbles are introduced, reducing the density of the mortar and causing a decrease in its compressive and flexural strength. Considering all factors, when the dosage of VAE is 0.44%, its 28-day compressive strength, 28-day flexural strength and bond strength all reach relatively high values, achieving the purpose of improving dry-mixed mortar and playing a role in impermeability and waterproofing. From a cost perspective, it is also relatively economical and has a high cost-performance ratio.