Study On Durability Of Modified Mortar

The durability of modified mortar is of great significance to the protection of modern excellent historical buildings.Architecture in modern Chinese history plays a role of connecting the preceding with the following and blending the East and the West.A large number of excellent historical buildings have been left in Chinese modern history,such as modern historical sites,religious buildings,former residences of celebrities,historical buildings of colleges and universities,industrial building sites,etc.In the natural state,the main damage forms of historical buildings include acid erosion,weathering,freeze-thaw,efflorescence and so on.Among them,the efflorescence of the mortar will affect the bond strength between the masonry,which will cause the mortar pulverization and spalling damage.The efflorescence will also reduce the strength of the decorative layer and the bonding layer,and even cause serious accidents.The common feature of these failure forms is that water is involved in them.Therefore,moisture isolation is also an important measure to improve the durability of materials.In order to improve the durability of the mortar of modern historical buildings and inhibit the occurrence of alkali phenomenon,a series of experimental studies have been carried out in this paper.First of all,through the exploration of microbial mineralization technology,the microorganism is introduced into the interior of the material,and the surplus salt alkali ions in the mortar are mineralized by using its own characteristics,so as to fix the salt alkali ions,inhibit the efflorescence and improve the mechanical properties of the material;in order to further improve the durability of the mortar material and reduce the influence of external moisture on the mortar,waterproof materials are introduced in the test By exploring the waterproof effect of different waterproof materials,as well as the waterproof depth and waterproof treatment method,the treatment process for the best waterproof effect of mortar materials is obtained;in this paper,the modification effect of the materials is tested by microbial mineralization and alkalization test,acid corrosion test,alkaline corrosion test,freeze-thaw cycle test and unconfined compression test.The experimental results show that:(1)By monitoring the change curve of sample quality,salinity,electrical conductivity and strength,it can be concluded that three times is the best mineralization cycle,and the strength growth rate after three mineralization cycles is 7.81%.EDS energy spectrum analysis shows that the content of calcium and magnesium is in a certain area The distribution and morphological characteristics of microbial mineralization were obtained by SEM analysis.(2)The acid-base corrosion resistance of the modified mortar was tested by acid-base corrosion tests at different p H.Under the condition of p H=2,the strength loss of 1 group of samples was 20.4%,that of 2 groups was 17%,and that of three groups was 4.9%.Under p H=4,the strength loss of group 1 is 11.5%,that of 2 groups is 7.6%,that of 3 groups is 3.3%,that of 1 group is 4.8%,that of 2 groups is 1.5%,and that of 3 groups is 0.37%.Under the condition of p H=13,the strength loss of 1 group of samples is 4.85%,the strength loss of 2 groups of samples is 4.28%,the strength loss of 3 groups of samples is 2.27%.Under the condition of p H=11,the strength loss of 1 group of samples is 3.25%,the strength loss of 2 groups of samples is 2.7%,and the strength loss of 3 groups of samples is 1.14%.Under the condition of p H=9,the strength loss of one group of samples is 3.26%;the strength loss of two groups of samples is 1.53%;the strength loss of 3 groups of samples is 0.2%.Under the same conditions,the strength loss of 3 groups of samples is less than that of 1 group and 2 groups,and the alkaline corrosion resistance is better than that of acid corrosion resistance.(3)The freeze-thaw resistance of the modified mortar was tested by the freeze-thaw cycle test.The changes of the appearance and morphology of the sample were recorded,and the changes of quality,salinity,conductivity and strength indexes were monitored.The strength of 0-100 freeze-thaw cycles of 1 group decreased by 2.3MPa,and the strength loss was 9%,the strength of 0-25 freeze-thaw cycles of 2 groups decreased slowly,the strength of 25-50 freeze-thaw cycles decreased rapidly,the strength of 50-100 freeze-thaw cycles decreased slowly,the strength of 0-100 freeze-thaw cycles decreased by 2.2MPa,and the strength loss was 8.3%,the strength of 0-50 freeze-thaw cycles of 3 groups decreased slowly the slope is the slowest,the decline slope of 50-75 freeze-thaw cycles is faster,the decline slope of 75-100 freeze-thaw cycles is slower,the strength of 0-100 freeze-thaw cycles is 1.4MPa,and the strength loss is 5.22%.The freeze-thaw resistance of 3 groups of samples is better than that of 1 group and 2 groups,and the strength loss of 0-100 freeze-thaw cycles is the least.The application of microbial mineralization can inhibit the alkali exudation of mortar and improve the mechanical properties of mortar,the introduction of waterproof materials can improve the durability of mortar;the combination of microbial mineralization and waterproof materials can slow down the damage of samples and improve the durability of mortar.