The CMC and HEMC are not consistent in improving the water retention of mortar. With the increase of CMC content, the stratification degree is decreasing, but the decrease is not great. When the dosage is between 0.5% and 2.0%, the delamination degree exceeds 20mm.
Welcome to Semonova topic. The ability of fresh mortar to retain water is called water retention. Water retention also refers to the property that the constituent materials in the mortar are not easily separated. The water retention of mortar is expressed by the degree of stratification in the industry standard of "Masonry Mortar and Plastering Mortar for Autoclaved Aerated Concrete". Mortar with good water retention has less layering. The layering degree of masonry mortar and plastering mortar for autoclaved aerated concrete should be ≤20mm.
Analysis of the results of the effect of different dosages of HEMC on the fold-to-compression ratio of mortar. It can be seen that with the increase of HEMC content, the fold-to-compression ratio of both 7d and 28d increases. When the dosage is 0.3% , the fold-to-compression ratio reaches the maximum, indicating that after adding HEMC to the mortar. The flexural strength of the mortar decreased slightly, while the compressive strength decreased more, mainly because when HEMC was added. It increases the pores and flexible polymers in the mortar, when the mortar test block is folded. Pores will reduce the flexural strength of the mortar, while flexible polymers will increase the flexural strength of the mortar. Therefore, the combined effect of the two will reduce the flexural strength of the mortar to a smaller extent. When the mortar test block is under pressure, one reason is that the pores and flexible polymers cannot provide rigid support. The composite matrix is relatively weakened, resulting in a decrease in the compressive strength of the mortar; secondly, due to the water retention effect of HEMC, after the mortar test block is formed, most of the water remains in the mortar, and the actual water-cement ratio is much larger than that of the non-admixture. Therefore, the compressive strength of the mortar will be significantly reduced.
The CMC and HEMC are not consistent in improving the water retention of mortar. With the increase of CMC content, the stratification degree is decreasing, but the decrease is not great. When the dosage is between 0.5% and 2.0%, the delamination degree exceeds 20mm. However, only when the content is 2.5%, the layering degree is 19.5mm, which is just within the required range of the layering degree of the masonry mortar and plastering mortar for autoclaved aerated concrete, indicating that with the increase of the CMC content , the improvement of the water retention effect of the mortar is not very obvious.