Research On Contact Damage Of Concrete By Sphere Impact Method

Rock and concrete, degraded by environmental conditions easily, are the most important building materials. For any degradation of building materials, the surface is the position that the degradation appears. Thus, it is important to research the contact damage and damage regular for these materials. Some characteristics, such as damage mechanisms, expansion process of damage zone, realations of impact load-indentation size, impact load-time and impact stress-strain, of rock and concrete were investigated by sphere impact method aimed to explore a method to estimate the variety of rock and concrete surface esposed to corrosive environment. The equations of dynamic hardness and coefficient of restitution were also dudeced. The results can be listed as follows:(1) The relations of impact load-impact time for different materials and the material in corrosive environment didn't change on the whole. However, the impulse state after impact and the time for second impact was isochronous as the hardness and soundness degree of materials surface.(2) Within the limit of this experiment, impact load and indentation size of rock and concrete increased proportioned at the beginning. When the load arrived at the critical value, the increasing speed of indentation size was quicker than load. The whole curves were bilinear. With the process of corrosion, the impact load-indentaton size relation of granite and high strength concrete(HSC) after critical value didn't change obviously, but the slope of curves before critical load decreased with the process of corrosion. Furthermore, this characteristic for concrete at the harden stage was more and more plain instead of marble in corrosive environment.(3) The estimated results of dynamic hardness(HD) and coefficient of restitution(e) indicated that the values of HD and e of rock and concrete incorrosive were higher than that of corrosive at the same load level. With the process of corrosion, the values of HD and e for granite and concrete decreased by degrees and the marble's decreased intensively. For the concrete at the harden atage, the values of HD and e for concrete in water and standard curing room increased continuously regardless of the concrete in sulfate solution and outdoor with the process of harden. The characteristic wasn't achieved by compressive strength.(4) With the process of corrosion, the size of damage zone for granite and HSC existed damage zone increased continuously but the marble's intensively.In conclusion, it is feasible to estimate the contact damage and corrosive damage for rock and concrete by sphere impact method and these studies can be used in construction engineering.