The Effects And Mechanism Study Of Earthen Sites Reinforced By Sticky Rice Mortar

As an important part of cultural relics,earthen sites are significantly valuable in historical research,artistic research and scientific research.Because a large amount of earthen sites are exposed in natural conditions,earthen sites are vulnerable to various physical,chemical and biologic damage factors from natural environment.Therefore,we must take protective measures according to the principle of “protection is lord,rescue the first,reasonable exploitation,strengthen the management” so that they could be used for scientific research and exhibition in a long term.In northwestern area in China,the loess is distributed widely and used for earthen site as the main construction material,so the material used for the earthen sites repair should be loess as well.The loess has bad engineering features such as silt-based components and poor weather resistance,so the loess has to be modified before the earthen sites repair.At present,the reinforcing materials used in the relic protection include inorganic materials,organic materials and organic-inorganic composite materials.The lime as the reinforcing material has effective reinforced effect and strong practical experience.The survey shows that some earthen sites which mixed the repair materials with sticky rice have better strength and durability.In order to take advantages of this traditional material scientifically and apply it to earthen sites protection,this article studies the reinforced effects and the strengthening mechanism on the loess which is modified by the sticky rice mortar.In the research,the samples are designed to be reinforced by sticky rice slurry with different consistence(0%,1%,2%,3%,4%,5%)and lime with different lime-soil ratio(0%,2%,4%,6%,8%,10%).Then we test the strength,water resistance,colors exaggerated,breathability and salt resistance of the different sample,so that we could study the different reinforced effects due to different ratio.We observed the grain morphological features,contact relationships and pore structure by scanning electron microscope,after that we could understand the strengthening mechanism of sticky rice mortar.The conclusions from the research are shown as below:(1)After adding sticky rice and lime,the strength,water resistance and salt resistance the of loess increase,while the breathability decreases.The highest strength increased by more than 4 times.And the color does not change significantly.(2)With the increase of lime-soil ratio,the unconfined compression,water resistance and salt resistance of solidified loess increase,but breathability decreases.When lime-soil ratio exceeds 8%,the residual strength decreases.(3)With the increase of the sticky rice consistence,the unconfined compression of solidified loess increases firstly and then decreases,the residual strength also increases firstly and then decreases,the optimal concentration of sticky rice is 3%.Besides that,water resistance has little change,the breathability decreases firstly and then increases.When sticky rice consistence exceeds 3%,the salt resistance significantly decreases.(4)According to evaluation index system from the research results of this article,the optimal proportion is 8% lime-soil ratio and 3% sticky rice consistence.(5)The strengthening mechanism of sticky rice mortar includes the reaction between lime and loess and the improving function of sticky rice by means of influencing the calcium carbonate crystallization.The reaction between lime and loess included ion exchange,crystallization,cementation and pozzolanic reaction.The reinforcement mechanism of sticky rice slurry is mainly the control on the size and morphology of calcium carbonate crystallization and on the distribution of calcium ion,which would influences the structure and cementing power of soil particles.