Experimental Study On Physical Mechanics Of Aerated Concrete And Its Engineering Application

This paper first analyzes the current situation of the use of domestic air-entrained concrete,and concludes that the life of the air-entrained concrete is short,and the reason for the easy destruction is the lack of gas content when entering the mold.After systematic analysis,the cause of insufficient gas content of concrete may be caused,and the air entraining agent selection test is carried out according to the site conditions.The test of the relationship between the concrete slump and the gas content of the fresh concrete,the cement stability monitoring test,and the gas volume to the gravel/Comparative test of strength and frost resistance of pebble concrete,influence of proportion of admixture on gas content of concrete,design experiment of air-entraining concrete mix ratio of unqualified raw materials.The following conclusions were drawn:(1)The type of air entraining agent has a great influence on the slump and air entrainment of concrete mix and the loss of time with respect to both.This may be related to the adaptability of air entraining agent and raw materials,and should be verified before use.(2)The amount of bleed air of the air-entrained concrete increases first and then decreases with the change of slump.The concrete content of the concrete mixture is the highest in the slump range of 140-220mm.The 1h gas content loss rate of the concrete mixture reached a minimum within the initial slump of 160-220 mm.When the initial slump of concrete is below 160mm,the workability of the concrete mixture is poor.When the initial slump of concrete is above 220mm,the bubble is easy to overflow and break due to the low viscosity of the slurry;the gas content is reduced due to the above reasons.Controlling the slump between 160-220mm will result in a better concrete inlet gas content;(3)In the range of 3?10%of air entrainment,the compressive strength of concrete decreases with the increase of air entrainment,and the frost resistance increases with the increase of air entrainment.When the design strength is low,both the crushed aggregate and the pebble aggregate can reach the design strength.The frost resistance of the gravel concrete is better than that of the pebble concrete.The performance gap between the two is less as the air entrainment increases.At the same time,the strength of the concrete prepared by the cobble aggregate is lower than that of the gravel aggregate,and the strength of the pebble concrete decreases more as the amount of bleed air increases.The frost resistance of the pebble concrete is lower than that of the gravel concrete.With the increase of the air entrainment,the frost resistance of the pebble concrete generally increases,but the fluctuation is large,and the antifreeze performance has an upper limit.(4)In the actual project,the quality of commercially available cement has a certain fluctuation.The preparation of air-entrained concrete should use the cement of the large factory as much as possible,and the quality is relatively stable.Under the low temperature environment in the northern region,the solution of low concrete air entrainment can be improved.The proportion of cement used in the rubber material,thickening of the admixture,increasing the amount of concrete slurry,reducing the particle size of the aggregate,increasing the sand rate,increasing the system temperature,etc.,adjusting the ratio of the air-entrained concrete,so that the gas content of the concrete is reached.Design requirements.In this paper,the main factors causing the air content of the air-entrained concrete in the construction stage are systematically studied,and the targeted tests are carried out.Based on the test,some inferences are obtained,and the sand and stone are simulated based on the actual situation on site.When some indicators are unqualified,the main precautions for preparing air-entrained concrete are proposed for the construction application of air-entrained concrete.