Study On The Inhibitory Effect Of Diethylenetriaminepenta (Methylenephosphonic) Acid On The Salt Damage Of Sodium Sulfate In The Rammed Earth

The crystallization of sodium sulfate can cause serious damage to the earthen site,so it is of great significance to study how to restrain the crystallization of sodium sulfate in the earthen site.Diethylenetriaminepenta(methylene-phosphonic acid)(DTPMP)has been proved to have a significant effect on the inhibition of sodium sulfate crystallization in the petroleum chemical industry,sewage treatment and other fields.we chose DTPMP as the research object,through the simulation experiment,studied the inhibitory effect of DTPMP to the rammed earth containing sodium sulfate samples.we analyzed the impact of DTPMP on mineral composition of soil,crisp base,salt and water transport and the performance of rammed earth.The main conclusions are as follows:(1)When the sodium sulfate content was 1%,2%,3%,adding DTPMP could inhibit the crystallization of sodium sulfate in the rammed earth.The content of DTPMP was higher the inhibitory effect was more obvious,the sodium sulfate content in rammed earth was low,the inhibitory effect of DTPMP was more obvious.(2)When DTPMP content was higher than 0.1%,DTPMP moved to the surface of rammed earth with water,this prevented evaporation and Soil Water and Salt Movement,it affected the color of the surface of the rammed earth,it caused the surface of rammed earth shell and other diseases.Therefore,the DTPMP content of 0.1%was more appropriate.(3)No matter when the sodium sulfate content was 1%,2%,3%,with the increase of DTPMP content,the time of crystallization was getting longer and longer.(4)Sodium sulfate crystals was irregular surface shape when they were crystallized in the rammed earth surface.When DTPMP was added,the crystal shape of sodium sulfate was changed into small volume particles,this was the primary cause of the inhibitory effect of DTPMP.DTPMP reduced the surface tension of sodium sulfate solution,decreased the rate of capillary action,and prolonged the time of crystallization.DTPMP could reduce the aperture of rammed earth,it affected the transport of water and salt in the earth.(5)The inhibitory effect of DTPMP was closely related to the pore size distribution of rammed earth.The rammed earth density was too large or too small willed affect the inhibitory effect of DTPMP,the suitable density of rammed earth was a necessary condition for DTPMP function.(6)Jioning DTPMP:Mineral composition of rammed earth soil has not changed;The rammed earth surface has little effect on color;It improved the corrosion resistance of rammed earth disintegration;It reduced the permeability coefficient of rammed earth;It has little effect on the liquid limit moisture content,plastic limit moisture content and plasticity index;It improved the tensile compressive strength of rammed earth;It significantly reduced rainfall on earth damage,improved the performance of the rammed earth rain erosion.The low content of DTPMP can be used in the conservation of the earthen sites.The optimum content of DTPMP is 0.1%.