Research On On-site Inspection And Application Of Dry Hard Concrete Precast Blocks In Water Conservancy Projects

Dry-hard concrete is a new type of concrete material with the slump less than 10 mm and the Vebe consistency value ranged 10s～30s.It possesses some good properties such as low water-cement ratio,low flowability,small contractility,high early strength and better forest resistance Besides,with the fast turnover rate and high productivity,it can be put into mass production for prefabricated concrete.At present,dry-hard concrete has been gradually developed and and has widely applied in the various fields,such as water conservancy project,highway construction,municipal works,airport flooring and so on.Nevertheless,a stander specification of dry-hard concrete is not formed and and the research on it is not perfect.In order to improve the promotion and application of dry-hard concrete in the field of water conservancy project,the comprehensive study on its structural behaviors and construction technique is of great significance.Therefore,based on previous studies at home and abroad and the actual demand of engineering practice,this thesis conducts a experimental study aiming at the mix ratio and testing method.Meanwhile,according to the application of river engineering,the pavement and construction technique of dry-hard concrete are analyzed in the study.The results are presented as followsThrough the study of the components of dry-hard concrete and their impacts on material strength,the reasonable values of components are obtained as follows:water cement ratio is 0.30,sand ratio is 0.35 and fly ash content is 15%or 20%。Through the field study of dry-hard concrete precast block in water conservancy project via the two nondestructive/semi-nondestructive testing methods:pin-penetration method and pull-out method.A significant correlation is found between the strength testing results and the traditional compressive testing results.The pin-penetration method has higher accuracy in testing low strength dry-hard concrete,but it is poor in testing high strength concrete.While the testing results of concrete strength by pull-out method are relatively stable.Through the analysis of the pavement process of dry-hard concrete with regard to the extension and dredging project of the Xinmeng River,the study forms a set of relatively perfect construction process,which provides a little experience and reference for further standardizing and promoting the application of dry-hard concrete in water conservancy projects.