Research On Concrete's Corrosion Resistance To Saline Soil Under Condition Of Inadequate Early Wet Curing

Salts in inland saline soil have serious corrosion effect on the concrete in engineering,and the corrosive salts are mainly chloride and sulfate.In the saline soil area of the western part of China,due to the harsh environment and limited construction conditions,the concrete is not properly cured,which exacerbates the degree of concrete's corrosion.Based on this background,this thesis studied the effects of mineral admixtures such as fly ash,ground granulated blast furnace slag(GGBS),limestone powder on the properties of concrete such as sulfate resistance and chloride ion permeability under condition of inadequate early wet curing.Through these experimental studies,the law of salt corrosion resistance of concrete under condition of inadequate early wet curing is explored,and the mix proportions for effectively improving the salt corrosion resistance of concrete will be found and applied to engineering.The main research contents and conclusions are as follows:(1)The resistance to sulfate attack and chloride ion permeability of concrete mixed with fly ash were investigated at the early wet curing time of 3 days,7 days,and 28 days.Fly ash is highly sensitive to the early wet curing time.When the early wet curing is not sufficient,fly ash cannot improve the resistance to sulfate attack and chloride ion permeability of the concrete.Decreasing the water-to-binder ratio can reduce its sensitivity to early wet curing time,but fly ash still does not improve the salt corrosion resistance of concrete.(2)The resistance to sulfate attack and chloride ion permeability of concrete mixed with GGBS powder were investigated at the early wet curing time of 3 days,7 days,and 28 days.The concrete with GGBS addition can even improve the resistance to sulfate attack and chloride ion permeability of the concrete when the early wet curing is insufficient.In addition,the reducing of water-to-binder ratio can significantly reduce the sensitivity of the concrete's salt corrosion resistance to early wet curing time.(3)The resistance to sulfate attack and chloride ion permeability of concrete mixed with limestone powder were investigated at the early wet curing time of 3 days,7 days,and 28 days.Limestone powder,under the condition of a constant water-to-binder ratio(W/B = 0.45),will deteriorate the resistance to sulfate attack and chloride ion permeability of concrete,but it can reduce the sensitivity of limestone powder concrete performance to early wet curing time as well as improve the salt corrosion resistance of concrete under the condition of a constant 28-day compressive strength.(4)The resistance to sulfate attack of mortar mixed with ultra-fine GGBS and metakaolin was investigated with the early wet curing time of 3 days and 7 days.When the early wet curing is not sufficient,the addition of ultra-fine GGBS has a poor effect on improving the sulfate resistance of the mortar,while the mixing of metakaolin can effectively improve the sulfate resistance of the mortar,and as the amount increases(less than 20%),the improving effect is more significant.