Test And Study On The Effect Of The Pretreatment Of Coarse Aggregate Interface On The Damping Property Of Concrete

Damping ratio is the important index representing the property of materials inreducing vibration, and it shows obvious influence to the dynamic response close tothe resonant frequency. Research to the damping property of concrete will affordfundamental criterion for both designers and confecting reducing vibration concrete.Currently, the research on enhancing the damping characteristics of structuresthrough the damping property of materials is seldom reported in our civilengineering's damping technique. Especially, study on the ordinary concretes'damping mechanism and influencing factors from the aspects of interface and innerfriction needs being more lucubrated.In this experiment,different size of the coarse aggregate were selected andcompounded C20,C30,C40 normal concrete, the surface of coarse aggregate waspretreatment (was soaked in the 10% NaOH solution,E44 epoxy resin was smeared,70and 90 grade asphalt was smeared), and adopted normal concrete mix proportioncompounded by a variety of coarse aggregate pretreatment of concrete. Hangingcuboid specimen(450mm×150mm×100mm) and free vibration method wasemployed to measure the damping ratio and relevant response frequency of theconcretes. Later the relationship between damping ratio and some parameters,such asviscoelastic treatment, chemical treatment, coarse aggregate size (total surfacearea),splitting tensile strength and splitting tensile strength difference,was studied.Experiment shows: the surface of coarse aggregate was viscoelastic treatmentand chemical treatment, coarse aggregate size(total surface area), splitting tensilestrength and splitting tensile strength difference all are zhe influencing factors todamping of concrete, viscoelastic treatment and coarse aggregate size are obviousfactors.The main conclusions of this research are follows: 1. Compared with normal concrete, the compressive strength and splitting tensilestrength of concrete has small increase after coarse aggregate was soaked in the 10%NaOH solution, the compressive strength and splitting tensile strength of concrete hasgreatly decreased after coarse aggregate was viscoelastic pretreatment.2. Compared with normal concrete, the damping ratio of concrete has a slightdecreased after coarse aggregate was soaked in the 10% NaOH solution.3. Compared with normal concrete, the damping ratio of concrete has improvedobviously after coarse aggregate was viscoelastic pretreatment.4. Under the same concrete mix proportion condition, the damping ratio ofconcrete showed decreasing along with the coarse aggregate size 's increase (totalsurface area's decrease) after coarse aggregate was viscoelastic pretreatment, thistrend with asphalt viscoelastic's enhance become more obvious,but other types ofconcrete has no obvious trend.5. The damping ratio of concrete showed decreasing along with splitting tensilestrength 's increase,and showed increasing along with splitting tensile strengthdifference 's increase.Finally, some analysis for the influencing factors of concrete are studied. Theprimary contents are the following:1. The cause of the concrete damping ratio as the coarse aggregate was chemicaltreatment;2. The interface between cement stone and aggregate's change as the coarseaggregate was viscoelastic treatment;3. Influence of coarse aggregates on the concrete damping ratio.