| The traditional mortar and the raw wall material are generally prone to cracking due to the inconsistent thermal expansion coefficient of the material,the large shrinkage rate of the mortar,the insufficient bond strength of the mortar and the poor toughness.In order to solve the above problems and better protect traditional dwellings,in this paper,from the point of view of materials,the research and development of raw soil wall interface bonding materials are carried out by adding some additives such as raw soil,cellulose ether,redispersible latex powder and polypropylene fiber into cement mortar.The main work and important achievements of this paper are as follows:(1)In the interface mortar with 20% soil content,The effects of the content of cellulose ether,redispersible latex powder and polypropylene fiber on the basic properties of interfacial mortar,such as water ratio,water retention and mechanical properties such as compressive,flexural and tensile bond strength were studied.Then a comprehensive analysis of the effect of various additives on the modification of interfacial mortar is carried out,the optimum dosage of various admixtures in interfacial mortar was obtained.: the cellulose ether content was 0.16%,the rubber powder content was 1%,and the polypropylene fiber volume was 0.2%.under this ratio,the interface mortar developed has a bond strength of 0.50 MPa and a compressive strength of 5.11 MPa.(2)By comparing and analyzing the mechanical properties of the interface mortar with 20% and 30% raw soil,Increasing the content of raw soil in interfacial mortar will reduce the compressive and flexural properties of mortar,but it can improve the toughness of interfacial mortar in a certain range;In addition,the addition of soil in interfacial mortar can reduce the difference of thermal expansion coefficient between mortar and soil wall materials,reduce the difference of deformation between mortar and soil wall materials caused by temperature,and thus reduce the cracking of interface bond between raw soil wall and mortar.In the interface mortar with 20% soil content,the shrinkage of mortar can be significantly reduced when various admixtures are mixed in the optimum amount.(3)The addition of cellulose ether can improve the bonding performance between the interfacial mortar and the wall matrix,but the optimum content of cellulose ether is different for different wall materials;In addition,the bond strength between outer mortar and interfacial mortar is greater than that between interfacial mortar and matrix material,which indicates that the interfacial mortar developed in this paper can also be well combined with outer mortar;The bond strength of interfacial mortar doped with cellulose ether is lower than that of interfacial mortar doped with polymer.By spraying water on the wall surface,the bond strength between the interface mortar with cellulose ether and the cement brick can be improved.At this time,the breakage form of the interface mortar and the matrix is the interfacial breakage;When cellulose ether,rubber powder and polypropylene fiber are mixed,the bond strength between the interface mortar and the wall will be reduced,and then the tensile bond failure between the interface mortar and the matrix will become matrix failure.(4)By studying the influence of the curing environment on the mechanical properties of the interfacial mortar,in different curing environments,the amount of cellulose ether corresponding to the maximum compressive strength of interfacial mortar is different;In the case where the amount of cellulose ether is determined,the optimum curing conditions for the mortar will also be different.In addition,the addition of cellulose ether has a significant effect on the adhesion strength of the mortar in a dry environment,but it is still lower than the bond strength of the equivalent cellulose ether interface mortar in a wet environment. |
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