The Carbonation Resistance Measures Research Of High-flowing Concrete

today, with the aggravation of deterioration prematurely of the concrete structure and environmental problems, the problem of concrete durability has attracted wide attention from the society. Carbonation is an important index of concrete durability, how to reduce the harm of carbonation and improve the performance of carbonation resistance of concrete has become an important research topic of many scholars. The dosage of mineral admixture and curing methods are two important factors that influence the performance of carbonation resistance of concrete. This paper research the measures that make sure the high-flowing concrete reach level T-IV carbonation resistance performance by the dosage of admixture and curing methods,through compressive strength and carbonation experiment of high-flowing concrete that mixed only with fly ash, powder slag and composite of ratio 1:2. The main conclusions are as follows:(1) With different water-binder ratio, the accelerated carbonation depth of high-flowing concrete that mixed with fly ash,powder slag or composite of fly ash and powder slag by ratio 1:2 increased at different ages with the increase of dosage of admixture.(2) When the water-binder ratio is 0.4, 0.45, 0.5 and 0.55 respectively,in order to ensure the concrete reach level T-IV carbonation resistance performance,The concrete shall meet the following dosage conditions with different water-binder ratio: ① Mixed with fly ash,the dosage limit are 50%, 30%, 30% and 20%; ②Mixed with powder slag,the dosage limit are 70%, 60%, 60% and 45%; ③Mixed with composite of fly ash and powder slag by ratio 1:2,the dosage limit are 60%, 45%, 40% and 30%.(3) When the water-binder ratio is 0.4, 0.45 and 0.5 respectively and the dosage of admixture is between 32% and 70%,it has little effect to the performance of the carbonation resistance of high-flowing concrete that using sodium silicate solution, waterborne curing liquid and lime water solution for the curing of concrete, but has gradually increased of effect to the carbonation depth of concrete during different age,while the accelerated carbonation depth of high-flowing concrete increased with the increase of dosage of admixture when the water-binder ratio is 0.5. When using the same dosage, the negative effect of the three kinds of coating curing measures increases gradually with the increase of water-binder ratio to carbonation depth of high-flowing concrete at different ages, especially the age of 28 d. When using the three kinds of coatings for curing of concrete,we need to reduce the maximum dosage under different water-binder ratio if we want concrete to meet the level T-IV carbonation resistance performance.(4) In order to ensure the concrete reach level T-IV carbonation resistance performance, the selection condition of every curing methods as follows: We can use the natural curing method when the dosage is between 45% and 60% with the water-binder ratio of 0.4 and the dosage is between 39% and 45% with the water-binder ratio of 0.45.We can use the sodium silicate solution, waterborne curing liquid and lime water solution curing methods when the dosage is between 45% and 50% with the water-binder ratio of 0.4.When the dosage is between 45% and 60% with the water-binder ratio of 0.4, the dosage between 39% and 45% with the water-binder ratio of 0.45 and the dosage between 32% and 40% with the water-binder ratio of 0.5, We can use the standard curing method.(5) With different water-binder ratio and dosage of admixture, the compressive strength and performance of carbonation resistance of high-flowing concrete are overall best when we use standard curing method, followed by natural curing method, but it is rather poor by sodium silicate solution, waterborne curing liquid and lime water solution which is more obvious differences when the water-binder ratio is 0.5 and dosage of admixture is greater. Between the three kinds of coating curing method, the effect of sodium silicate solution is relatively better.