Study On Bonding Properties Of Wet Mixing Mortar And Building Wall

In the process of popularizing and applying wet plastering mortar,There were some engineering quality accidents such as empty drum,cracking and falling off.The bonding performance of wet plastering mortar and wall material is an important aspect that affects the quality of wet plastering mortar engineering.There are so many types of wall materials,and their properties are different.And wet plastering mortar is in mass production.If the mortar is produced according to the characteristics of the wall material,the production cost will be greatly increased.Therefore,it is very important to study the bonding performance of the wet plastering mortar from the interface between the wall material and mortar.The study can improve the quality of construction engineering and reduce quality accidents such as the empty drum,cracking and falling.In this paper,a test method for tensile bond strength of mortar was proposed.Superficial roughness and superficial coverage rate were used to characterize the degree of interface processing.The quality of limestone powder wet-mixed mortar is stable,so it is used as reference mortar.This paper systematically studied the effects of wall material type,moisture content,interface processing and curing environment to the bonding performance of wet plastering mortar.This paper provided theoretical support to the application of wet plastering mortar on new wall material,improvement of construction methods and reduction of engineering quality accidents.The main research contents of this paper were as follows:First,a kind of wet-mixed plastering mortar was prepared by using limestone powder,a stable inert admixture.When mortar was mixed with limestone powder,its performance indexes such as water retention rate,consistency,density,plastic viscosity and yield stress are stable.And the construction performance of mortar was good.So,this paper used the wet plaster limestone powder mortar as the standard mortar.Secondly,this paper had proposed a test method for tensile bond strength of mortar.In order to solve the problems on the test method of mortar tensile bond strength in the standard,such as the actual situation of the project cannot be truly reflected and the high discreteness of the test data.So,the bond strength test method was improved.The improved method used actual construction method,and used the self-made tensile bond strength test block sampling device to reduce error during the sampling process.That made data more stable.Thirdly,this paper had systematically studied the influence of wall material type and moisture content to the 14 days bonding performance of wet plastering mortar.The research showed that the moisture content of the wall material has a significant influence on the failure mode of mortar.When the moisture content of the wall material is low,the damage occurred in the mortar layer;when the moisture content at a high level,damage occurred on the interface or substrate.The moisture content of the wall material also had a significant effect on the tensile bond strength of mortar.On the wall materials with high water absorption such as autoclaved aerated concrete and concrete,the bonding performance of the wet plastering mortar was dependent on the wall moisture content.The strength increased with increasing content.On the wall materials with low water absorption such as calcium silicate board and ceramic brick,the bonding performance of the wet plastering mortar was basically not affected by the moisture content.But when the moisture content of the wall material was higher,the more easily the mortar fell off.Then,this paper had studied the influence of the interface treatment process(the spraying and patting method)to the bonding properties of wet plastering mortar with the wall material.And proposed the superficial roughness and superficial coverage to characterize degree of interface processing.The research showed that both two interface treatment processes can effectively improve the bonding performance of the plastering mortar with the wall material.The interface treatment of wall materials had an optimal degree of treatment.At the same time,the mortar bond strength is also the highest.When the degree of treatment exceeds the optimum value,the bonding strength of the plastering mortar would be reduced.The optimum roughness of the blasting treatment for concrete and autoclaved aerated concrete blocks is about 4.2 mm,and the best coverage for concrete patting is about 37%.Finally,the paper had studied the effects of curing condition to the 14 days bonding performance of wet plastering mortar.The curing conditions include two temperatures(20 ? and 40 ?)and two relative humidity(60% and 90%).The results showed that the curing temperature and curing humidity will significantly affect the bonding performance of the wet plastering mortar.Under the same curing temperature,the mortar bonding strength increases with the increase of humidity.And under the same curing humidity,the mortar bond strength decreases with increasing temperature.