Abstract:Microporous concrete irrigation emitters were prepared with dry pressing method and then cured by an atomizing humidifying means. The effect of particle size of sand and cement content in raw material on the flexural strength, open porosity, pore size and hydraulic performance of the irrigation emitters was studied. By testing the hydraulic performance of the irrigation emitters, the variation of the water flow rate of irrigation emitters with time was analyzed, and the reason causing the variation was investigated. The particle size of sand has little effect on the flexural strength, open porosity and mean pore size of microporous concrete. As cement increases, the microporous concrete increases gradually in flexural strength, decreases obviously in open porosity and gradually in mean pore size. The water flow rate of irrigation emitters decreases obviously with the increase of cement in raw material, and decreases slightly as the particle size of sand decreases. When the cement content of raw material was 12%, the irrigation emitters are of high water flow rate but easy to be destroyed because of low strength. When the cement content of raw material was 21%, the irrigation emitters have good reliability due to their high strengths but are hardly to be used in practice because of very low water flow rate. When the cement content of raw material was 15%~18%, the irrigation emitters possess both good reliability and relative high water flow rate due to their suitable strengths, open porosities and mean pore sizes. During hydraulic performance testing, the soluble alkali in microporous concrete was dissolved and taken out by water, which makes the water flow rate with time of the irrigation emitters increase slightly because of the gradual increase of open porosity and mean pore size. Nevertheless, the slight increase of water flow rate has little impact on irrigation in practice. The microporous concrete irrigation emitters are promising good subirrigation emitters.
