Research On Flexural Property For Strength-Gradient Concrete Beams Consisting Of Recycled And High Strength Concrete

With the continuous development of the engineering, large-span and high strengthflexural member will be more and more common. The application and research onreinforced concrete flexural member at home and abroad are all with single strengthin the cross section. For high strength concrete flexural member, the high strength oftensile region is obviously not reasonable application, and in normal use condition, itscrack resistance and crack width are difficult to meet the current relevant nationalnorms and requirements, on the economy and engineering properties is not ideal. Forhigh strength concrete flexural member, if lower the strength of concrete in tensileregion and remain the strength of concrete in compressive zone unchanged will bemore reasonable from the perspective on the destruction mechanism of flexuralmember.At present our country each year engendered a lot of construction wastes due toengineering construction and the old building demolition and reconstruction etc. Andthose construction wastes always can’t get reasonable treatment. In addition, with theneed of modernization construction, coarse aggregate and fine aggregate demand isvery huge every year in our country. In some areas emerge some environment prob-lems such as a shortage of sand and gravel, soil and water loss etc. And promote theuse of recycled concrete can effectively solve the above two questions.Based on the above two aspects, this paper take the method of combining the expe-rimental research and theoretical analysis to research6strength-gradient recycledconcrete beams which have different strength in tension and compression zone. Expe-rimental shows that two kinds of concrete can be together to work as a whole aftermaintenance if the high strength concrete in compressive zone has been concretingbefore the recycled aggregate concrete in tensile region initial set. And there were nohorizontal slip cracks in the interface after beams damaged. This experiment is basedon the depth of compression zone under ultimate limit states which controlled by thereinforcement ratio. Strength-gradient recycled concrete beam section flexural per-formance experiment was carried out. The experimental results showed that strength-gradient recycled concrete beam is according with flat section assumption.Combined with the stress and strain distribution rule can reach cracking moment andultimate bearing capacity calculation formulas. Based on the experimental results, putforward the computing method of average crack spacing, average crack width, max-imum crack width and the deflection under the action of short-term load ofstrength-gradient recycled concrete beam. This paper created basic conditions forfurther research and application of strength-gradient recycled concrete beams.