Study On Strength And Durability Of High Performance Concrete

As the leading engineering material in the world for nearly 200 years,concrete plays an extremely important role.Production application of the strength of the concrete is more and more high,the use of effective chemical admixture and highly active mineral admixture,even the ordinary concrete construction craft,also can more easily make up the concrete whose strength is more than 100 MPa,and apply it.Today,high rise buildings,sea crossing bridges,coal mines,high speed railways,submarine tunnels and other important concrete structures all impose various stringent requirements of concrete.With the improvement of performance requirements,self-compacting concrete,high temperature resistance concrete,refractory concrete and other special engineering characteristics and environment of high performance concrete are more and more widely used.By exploring and studying the content of mineral admixtures,chemical admixtures,the adaptability and the performance of concrete,high performance concrete should be able to meet the engineering needs,but also save resources,energy and capital,and improve the environment coordination.In this paper,by adding different admixtures,such as slag,fly ash,silica fume,coal gangue,replaces parts of cement,prepares the self-compacting concrete and study its properties,reduces the total alkali content of concrete by adding mineral admixture,partial groups join the NaOH,so that the total alkali content of concrete is controlled in 3.0kg/m³Na₂Oeq,then study the influence of concrete mechanical properties and durability on alkali content.The test results show that:1.With the addition of mineral admixture and high performance water reducer,the workability of concrete admixture is improved and the overall performance is good.The type and dosage of high performance water reducer are obvious to the workability of self-compacting concrete.The influence of the type and content of mineral admixtures on the compaction of concrete is greater than the water cement ratio.The slag is more conducive to the improvement of concrete compactness than fly ash.2.In the case of the same mineral content,the concrete with low water cement ratio has a higher strength but a slightly slower strength development.When the water cement ratio is the same,the strength of single mixed concrete is large,the early strength is high and the strength develops rapidly.The ultrasonic rebound method is not suitable for testing the strength of self-compacting concrete.If the sample data is sufficient,the strength correction coefficient between the actual strength can be obtained.3.The fluidity of the fresh paste,net pulp strength,ultrasonic wave are consistent with those of the concrete.The aggregate in the concrete contributes significantly to the overall compaction and strength.The early development of the net pulp compressive strength was rapid,and the strength of 28d was 80%of the corresponding concrete strength,which indicates that the aggregate has obvious influence on concrete strength.The water cement ratio and admixture have no obvious effect on the development of aggregate flexural strength.4.With the increase of alkali content,the strength of concrete decreases,and the frost resistance,carbonation resistance and erosion resistance are improved.If the fineness of admixture is greater,the degree of hydration and the strength of concrete are higher.5.Adding a lot of admixture makes the alkali content of concrete decrease,and its durability is adversely affected.The additive NaOH excits admixture,then concrete strength is increased,the strength loss caused by erosion,carbonization,and freeze are offsetted to a certain extent.Especially in the case of complex mixing,corrosion resistance is more obvious.6.Under the excitation of NaOH,with the same amount,the slag concrete has the greater strength and carbonation resistance than the coal gangue concrete,while the erosion resistance and frost resistance are slightly worse.