The Study Of High Performance Concrete Construction On Quality Control Technology In Wumeng Mountainous District

The concrete materials of large span continuous rigid frame bridge girder are supposed to have strong durability,high fluidity and good permeability.But during the building process of continuous rigid frame bridge recent years,a great many of cantilever cast-in-place main beam shows various degree of fissures after a short time of form removal.Even there are penetrating cracks on box girder after pouring within 2 to 3 days.Therefore,early cracks in the work process of continuous rigid frame bridge became a common problem,which contravened the designed principle of using High performance concrete material to improving Structural durability.In that case,current study which supported by Yunnan provincial transportation and transportation department scientific and technological plan,included in Construction project of niujia Gou Bridge project of mazhao Expressway in Yunnan have done these following works:(1)This study focused on the planing work of Mix ratio of high performance concrete depends on continuous rigid frame bridge.Applicable parameters was proposed by taking the desi gn plan of continuous rigid frame bridge as basis;combing the features of stereoscopic climate,large temperature difference between day and night in Wumeng mountainous district;improving the intensity of high performance concrete;using both of theoreti cal calculation and Orthogonal test method.And the applicability was proved after a series of high performance concrete durability test.(2)Current study researched the index analysis and pump control method of high performance concrete in the super high lift pumping process.At first,we developed a set of equipment to detecting the High performance concrete pump property rapidly and roundly(Type U,Type J and Type L),and drew up the analysis index and operation process.Secondly,we also discussed the disciplines of pressure loss along the path,and came up with the Pipeline layout scheme of high lift and low resistance.Lastly,combined with the scheme of high performance concrete pumping,we put forward the construction safety safeguard measures in pu mping process.(3)Besides above works,our study took the Spray control technology of Non-load type crack of main beam in continuous rigid frame bridge construction period.Primarily,this study discussed the critical reasons of early cracks of main beam i n continuous rigid frame bridge construction period.Next we came up with intelligent spray curing scheme,and the favourable effects of spray curing scheme on controlling Non-load type crack of high performance concrete was confirmed.In the end,based on the difficulties of high altitude mass concrete maintenance(especially the suspension at the bottom of the beam),we proposed a set of spray control technology aiming at box girder web and bottom plate in cantilever construction pe riod of continuous rigid frame bridge.These results could provide references for mix ration of high performance concrete design and pumping construction of High pier and large span continuous rigid frame bridge in mountain area.At the same time,there is also value for preventing the early Non-load type crack of box girder structure in cantilever construction period of continuous rigid frame bridge.