Fly Ash And Slag Powder Application Research On Concrete Of Expressway Engineering In Yunnan Province

As an important component of contemporary concrete,mineral admixture has been used in various types of housing construction and municipal engineering.In the practical application of highway engineering in national important infrastructure construction,standard and regional raw materials for the design and use of admixtures.The quality difference and the contradiction between supply and demand still exist.For the Yunnan-Guizhou Plateau,where the thermal power station and the steel plant are underdeveloped,the source of raw materials for admixtures is even scarcer.With the advancement of the construction of the “five nets” highway in Yunnan Province,it is limited by the traffic limitations of material procurement in mountainous highway projects.In the high proportion of bridges and tunnel stunneling ratio project,the technical requirements for the blending ratio of high-grade concrete above C50 are in great contradiction with the actual supply and demand.In order to realize the sustainable development of high-grade highway construction in Yunnan Province,for the production of Grade I fly ash and S95 grade slag powder in Yunnan Province with low production capacity and poor quality,research on application of concrete C50 and C55 in highway engineering of mineral powder and fly ash.The paper replaces the total amount of 5~20% of cementing materials in C50 and C55 with grade I and II fly ash and S75 and S95 grade slag powders,and determines the slump degree and expansion of fresh concrete by ensuring the matching ratio parameters.The performance was characterized by the compressive strength and static compressive modulus of 3d,7d and 28 d.The anti-freezing test and anti-cracking test were carried out to characterize the durability.The main findings are as follows:(1)when the content of grade II fly ash and S75 grade slag powder is within5%~15%,the concrete work performance is compared with pure cement.The chloride ion penetration resistance is improved significantly,especially in the crack resistance,the risk of cracking area is reduced by more than 10%,and the amount of cracking area is increased with the reduce of the amount of the material.The concrete is mixed with 15% of the grade II fly ash and the S75 grade ore powder.Compressive strength,static modulus,and frost resistance are less than the pure cement ratio(within 5%),and can meet the same level of evaluation with Class I fly ash or S95 durability specifications.(2)Class II fly ash or S75 grade slag powder has less workability difference,static modulus and 28-day strength under the same dosage of Class I fly ash or S95 grade slag powder within 15%.The reduction is within 1.7%,and the resistance to chloride ion penetration,crack resistance and frost resistance is reduced within 4%,which can meet the same level of evaluation with Class I fly ash or S95 durability specifications.(3)Combining the Grade II fly ash and S75 grade slag powder in Yunnan area in the C50 and C55 application cases of Yunnan Xiangli Expressway,Yuanman Expressway and Milu Xinji Expressway Project,the strength and durability indicators are all satisfied.Design and construction requirements.