Experimental Study On Reinforced Concrete Curshing Using Static Cracking Agent

Static cracking technology is a special blasting method with a lot of advantages,such as no noises,no flying stone,no toxic gas,no dust,and no blasting vibration,which has solved a lot of building demolition problems under difficult construction conditions.With the exist of steel,it is difficult to dismantle reinforced concrete structures using static cracking agent compared with plain concrete.In the present study,a series of static cracking tests are conducted to study the cracking migration regular of reinforced concrete structures for the selecting of optimize parameters.The tests of expansion property of static cracking agent are conducted under different ambient temperatures(i.e.14,22,and 30 ?)and water ratios(i.e.0.28,0.30,and 0.32).The test results show that the volume expansion rate of static cracking agent show the maximum value of 4.84 at 14 ? and water ratio of 0.32.The static cracking tests are conducted on reinforced concrete with a size of 200 mm X 200 mm X 200 mm under different borehole arrangements and borehole diameters.In addition,the comparison of the failure modes between the reinforced concrete and plain concrete are analyzed.The compare results show that there has an evenly stress distribution within the reinforced concrete compared with the plain concrete because of the restraint effect of stirrup.Three crack characteristics are observed in failure process of reinforced concrete compared with plain concrete:more cracks,smaller crack width and later cracking initiation time.The initiation time of cracking is almost the same to two borehole arrangements,yet the fracture effect with two boreholes is better than that of single borehole.The static cracking tests are conducted on the reinforced concrete beam(1020 mm X360 mm X 650 mm)with the test methods of reserved boreholes and embedded strain brick to investigate the failure mode and strain regular during the fracture process,and the laws of strain and the process of cracking migration are studied.The test results show that(1)the crack firstly appears at the minimum resistance line with the increase of expansion stress inside the borehole.(2)the values and the law of strain in the same row are similar to each other.(3)the reinforced concrete beams are successfully fractured with quincunx mode for the pour patterns of both row by row and every other row.(4)there has a better failure effect with pour pattern of row by row compared with that of every other row,and the corresponding crack width is 11.8 mm.