不同养护条件下丁苯乳液改性水泥砂浆的物理性能

研究了丁苯乳液在水泥砂浆中的减水和保水作用,以及该乳液在不同养护条件下对砂浆物理性能的影响,发现丁苯乳液在砂浆中有良好的减水和保水作用.当聚灰比达13%时,其在砂浆中的减水率达到50%.固定流动度为(170±5)mm且聚灰比大于7%时,改性砂浆的保水率达99%.固定水灰比,丁苯乳液改性砂浆的体积密度在聚灰比10%左右出现极小值,而孔隙率和平均孔径的变化与之相反.但固定流动度为(170±5)mm时,丁苯乳液对砂浆体积密度和孔隙率及孔径的影响不显著.湿养改性砂浆的孔隙率和平均孔径比混养的低.丁苯乳液显著降低了砂浆的毛细孔吸水率.

PHYSICAL PROPERTIES OF SBR LATEX-MODIFIED MORTAR UNDER DIFFERENT CURING CONDITIONS

The water-reduction and water-retention of styrene-butadiene rubber (SBR) latex in mortar and the influence of the latex on the physical properties of mortar at a certain water-cement ratio (m_w/m_c) of 0.4 or flow (170±5) mm were investigated. Two curing methods (wet curing and mixed curing) were evaluated. The results show that the SBR latex has the effect of the water-reduction and water-retention in mortar. The water-reduction rate increases to about 50% when the SBR latex-cement ratio (m_p/m_c) increases up to 13%. The water-retention rate reaches 99% when the m_p/m_c is 7% at a constant flow. With a constant m_w/m_c, the bulk density of the SBR latex-modified mortars decreases to a minimum at the m_p/m_c of 10%, and its porosity and the mean pore diameter change con-trarily. However, the effect of the m_p/m_c on the bulk density, porosity and pore diameter is insignificant at a constant flow of (170±5) mm. The porosity and the pore diameter of wet-cured SBR latex-modified mortars are lower than those of mixed-cured ones. The capillary water adsorption of mortar is bated effectively by the addition of the SBR latex.