Preparation Of Self-waterproofing Concrete And Its Frost Resistance And Impermeability

Durability is one of the important research contents of concrete,and its frost resistance and impermeability are closely related.In the alpine region,concrete frost resistance and impermeability are the main factors leading to poor durability of concrete damage,especially in underground engineering,due to concrete will be infiltrated by water in the ground,extremely prone to concrete seepage phenomenon,when this problem occurs,reworking is not only difficult but also a waste of unnecessary manpower and resources.So it is necessary to make a thorough study of this problem.Therefore,in-depth study of this issue is necessary.The effect of self-made waterproofing components on the frost resistance and permeability of concrete was studied.The compressive strength loss and mass loss rate of concrete after freezing were tested,As well as the impact of waterproofing components on concrete permeability,The microstructure characteristics of concrete specimens were tested by XRD and SEM.The research draws the following conclusion:The self-made waterproofing components have great influence on the frost resistance of concrete.The appropriate amount of waterproofing components has a great influence on the frost resistance of concrete.With the increase of the amount of waterproofing components,after 28d curing 100 freeze-thaw cycles experiments,concrete compressive strength first increased,when the content of the waterproofing component is 8%,the compressive strength reaches the maximum(41.37MPa),and then the compressive strength decreases.Compressive strength loss and mass loss first decreased and then increased,when the dosage is 8%,the compressive strength loss and mass loss reach the minimum at the same time.Fly ash helps to improve the frost resistance of concrete with water repellent components.When the amount of fly ash gradually increased,after 100 freezing thawing,the compressive strength of the concrete specimen is gradually reduced.However,the compressive strength loss and mass loss first decreased and then increased,the compressive strength loss and mass loss are the lowest when the volume is 20%(12.03%and 1.091%respectively).Superfine mineral powder is used to replace fly ash,it helps to improve the strength and impermeability of concrete.With the increase of the amount of superfine mineral powder,the compressive strength of concrete shows an increasing trend.When the concrete freeze-thaw cycles are different,the degree of compressive strength loss is different.When the number of freeze-thaw of concrete increases gradually,its compressive strength loss rate and mass loss rate first reducedand then increased,when the amount of superfine mineral powder is 20%,the strength loss and mass loss of the concrete that freeze-thawed 100 times at the age of 28 d were the least.X-ray(XRD)and scanning electron microscopy(SEM)studies have shown that,The waterproofing components make the hydration speed of the cementitious material quicker.The hydrated products are filled in the pores of the capillary,it makes the interior of the concrete more dense,the proper amount of infiltration crystal water-proofing component reduces the ettringite crystal,the pore size is reduced,the pore are refined,the structure is compact and the frost resistance is improved.However,excessive content of waterproofing components,resulting in the pore structure of the concrete structure becomes larger,the formation of ettringite crystal is thick,the frost resistance of concrete is poor.The amount of crystallizing inside the concrete structure varies with the composition of the permeable crystalline waterproofing components and the change of the amount of mixing.The effect of waterproofing components on the permeability of concrete is greater,and the change of crystallization is more obvious.