Test On Brick Improvement In Old Building

As the artistic treasure of the Chinese nation,ancient architecture contains rich historical and cultural values.For example,all kinds of pavilions,ancient city walls,ancient dwellings and so on.These historical buildings are mostly built by brick masonry,because there are a large number of tiny connected pores inside the brick,with strong water absorption,resulting in the brick wall is easy to appear powder,crystalline bloom and other adverse phenomena.As a result,these magnificent historical sites are rapidly disappearing,or are undergoing varying degrees of damage,and urgently need to be restored and preserved.This dissertation is to Kaifeng ancient city wall pulverization falls off phenomenon as the research background,put forward the method of vacuum preloading on brick infiltration method of modified organosilicon waterproofing agent,waterproofing agent used in concentration 0%,1%,2% and 3% respectively,by the capillary water absorption test,acid-proof alkaline test,freeze-thaw cycling test to explore the improvement of water sample properties,durability,mechanical property and frost resistance;Scanning electron microscopy was used to analyze the internal morphological changes and reveal the action mechanism of silicone water-repellent improved brick.The following conclusions were drawn:(1)The effectiveness of the brick improvement method was verified by water absorption test.The average water absorption rate of the sample within 5h gradually decreased with the increase of the concentration of the water-proofing agent.The water absorption rate of the sample with the concentration of 1% water-proofing agent was not significantly different from that before the improvement.The water absorption rate of the sample with the concentration of 3% water-proofing agent was 4.61% lower than that before the improvement.The internal structure density and waterproof of the improved sample were improved to some extent.The internal structure of the improved sample was denser after the concentration of 3% waterproofing agent was improved,and the water drop presented lotus leaf rolling phenomenon,effectively improving the water resistance of the sample.(2)The durability of improved brick was verified by acid and alkali erosion test.The improved sample can significantly improve the acid and alkaline resistance,the appearance and morphology are complete,without obvious damage,the water absorption is reduced,the mass growth rate is reduced,the compressive strength is effectively improved,the maximum loss rate is only 8.47%,the sample can maintain a good appearance and strength.(3)The freezing-thawing cycle test of the improved brick verified its frost resistance.The improved sample still maintained good morphology,low water absorption and mass growth rate,and its compressive strength was improved.The compressive strength loss rate of the improved sample with a concentration of 3% waterproofing agent was only 8.26%,which still maintained high strength and showed good frost resistance.(4)The microstructure of brick was analyzed by SEM.The results showed that the internal structure of the sample changed,the intergranular pores decreased,and the structure became denser.This is because organic silicon molecules through hydrolysis,condensation,gel adsorption in the internal pores of the sample,forming a waterproof film,enhance the waterproof and mechanical properties of the sample,so that the stability of the sample greatly improved.Silicone waterproof agent can change the internal microstructure of brick,reduce internal pores,increase the density of skeleton particles,the formation of waterproof film can improve the surface tension of hydrophobic characteristics,and then effectively improve the brick water resistance,acid and alkali erosion,mechanical properties and durability.The 3% silicone water repellent can effectively resist the erosion of capillary water,acid and alkali solution and the damage of freeze-thaw cycle.