透水砖吸水及保水性能研究

Study on Water Absorption and Water Retention Performance of Permeable Bricks

吸水及保水性能是影响透水砖蒸发降温效果的重要因素。现今多采用整体浸泡实验获得的浸泡饱和质量含水率来描述透水砖在自然状态下所能保存的最大水量,但采用何种实验方法及指标描述透水砖的吸水性能仍然有所欠缺。本文以烧结陶瓷透水砖(陶瓷砖)、再生骨料混凝土透水砖(再生砖)和普通混凝土透水砖(普通砖)为研究对象,采用整体浸泡实验、单面浸泡实验和人工模拟降雨实验,测试了砖体含水率随时间的变化规律,并比较了3种实验方法测试结果差异。结果表明:可采用毛细吸水系数Aw描述透水砖的吸水性能,陶瓷砖、普通砖和再生砖的Aw值分别为2.1 kg/(m^2·s^(0.5)),0.07 kg/(m^2·s^(0.5))和0.03 kg/(m^2·s^(0.5)),表明陶瓷砖吸水速度比再生砖快70倍;应采用单面浸泡饱和质量含水率W_(sat)描述透水砖的保水性能,陶瓷砖,再生砖和普通砖的W_(sat)值分别为7.15%,10.25%和6.27%,表明饱和状态时,再生砖蓄留的水分是陶瓷砖的1.43倍;透水砖的吸水及保水性能并无一定关联性,故从蒸发降温角度考虑透水砖吸水特性时,应采用毛细吸水系数Aw及单面浸泡饱和质量含水率W_(sat)共同作为砖体吸水及保水性能指标;W_(sat)与透水砖开放孔隙率呈正相关关系,而Aw与透水砖开放孔隙率和孔径尺寸均有重要关联性。

Water absorption and water retention performance is one of the most important factors that affect evaporative cooling process of permeable bricks. Nowadays, the maximum water content of permeable bricks can be described by saturated mass water content from soaking experiment, but the experiment method and indicators to describe the water absorption of permeable bricks is still missing. In this paper, three typical permeable bricks were chosen to study the water absorption characteristics, including sintered ceramic permeable bricks （TC） , recycled aggregate concrete permeable bricks （ZS） and ordinary concrete permeable bricks （PT）, the change law of moisture content varies with time of these bricks were measured by soaking experiment, partial immersion experiment and artificially-simulated rainfall experiment. The results show that the water absorption capacity of permeable bricks can be described by water absorption coefficientAw, the value is TC 2. I kg/（m2· s0.5） , PT 0.07 kg/（ m2· s0.5） , ZS 0.03 kg/（ m2· s0. 5）, indicating that TC is 70 times faster than ZS; the water retention capability of permeable bricks should be described by partial immersion saturated moisture contentWsat, the value is TC 7.15% ,ZS10.25% and PT 6.27% , indicating that water retention capability of ZS is 1.43 times of TC ; the water absorption and water retention performance of permeable brick is not necessarily related, therefore, from theperspective of evaporative cooling, water absorption coefficient and the partial immersion saturated moisture content should be both used as evaluation index to measure water absorption and water retention capability of permeable bricks; Wsat has a positive correlation with open porosity, while, the open porosity and pore size have significant effect on Aw.