Research On The Influence Of Acid Rain On Construction Mortar Performance

Since the 1980s,with the rapid development of economy,the use of industrial fuel such as coal,oil and vehicle exhaust emissions which produce much nitrogen oxides and sulfides,and emissions into the atmosphere.And then it form acid rain.It is the main factor of atmosphere in a long time.At present China's acid rain environment is mainly for sulphuric acid rain,but has a trend of sulphuric acid and nitric rain mixed.Building mortar is an important part of building structure and widely used in all kinds of engineering construction.Due to its own alkaline,so under the environment of acid rain,durable performance of cement base material will be in a big test.As a result,the author take a research on the effects of acid rain on building mortar performance below.Completely immerse rapid corrosion method is adapt,according to the acid rain erosion intensity equivalent to simulated acid rain solution and three kinds of different acidity of sulphuric solution of pH 1.0,pH2.5,pH4.0 are prepared which is used in the early immersion.Then we can use nitric acid to adjust the pH to simulate the acid rain environment.By simulated acid rain erosion of cement mortar test block,the test block apparent erosion,quality loss,compressive strength loss,bond strength loss degradation rule are explored.And on the basis of diffusion and mass transfer theory,the cement mortar test block neutralization depth prediction model is established.In special to the effects of acid rain mortar,under different simulated acid rain environment through different corrosion time of cement mortar are studied.The results shows that:(1)The apparent change of cement mortar test block is obvious after the simulated acid rain solution erosion.(2)The quality of cement mortar briquette in group of pH 1.0 has been always declined from early corrosion.The quality of cement mortar briquette in group of pH2.5 and pH4.0 has a little increase.With the increase of corrosion time,the quality is gradually begin to fall.And the fall point of the group of pH2.5 is early than the group of pH4.0.(3)The compressive strength of cement mortar briquette in group of Ph1.0 has been on a downward trend from the beginning of the corrosion.The compressive strength of cement mortar briquette in group of pH2.5 and pH4.0 increase slightly at the beginning of the corrosion.With the increase of corrosion time,the compressive strength is begin to fall gradually.(4)The bonding strength of in group of pH1.0 has been always fall.The bonding strength of cement mortar test block in group of pH2.5 increase slightly at the beginning of the corrosion.With the increase of corrosion time,the bonding strength is begin to fall rapidly.The bonding strength in group of pH4.0 remained a slight growth trend all the time.(5)The neutralization depth of cement mortar test block has been increasing all the time,because of the SO42-in the solution invade into mortar test block taking crystalline curing effect which reduce the porosity of mortar test block.So this makes its internal more dense as a result neutralization depth rise speed gradually slow down.(6)The forecast model of three kinds of neutralization depth of cement mortar briquette in acid environment is established and compare the experimental values to the calculated values.The result shows that the values agree with experimental values well.Through the conclusion get in this paper,that provides a base for the further study of cement basis materials under acid rain environment which is advantageous to the solution of how to extend and predict the life of concrete structure under acid rain environment.