Study On Fracture Mechanical Properties Of Crushed-stone Reactive Powder Concrete

In this thesis, the concept of Crushed-stone Reactive Powder Concrete (hereinafter referred to as Crushed-stone RPC) is presented as a kind of new composite materials for the first time. It is developed based on Reactive Powder Concrete (hereinafter referred to as RPC), but is also a good substitute for it. At present, few literatures have quantitatively analyzed the fracture parameters of RPC, and there is no literature researching on Crushed-stone RPC at home and abroad.RPC (866-1,666-1) and Crushed-stone RPC with different stone contents (866-2,866-3,866-4,666-2,666-3,666-4. The qualities of cementitious materials in mix proportion are expressed by 866 and 666 in the thesis.) three-point bending beams, totally forty beams are adopted for the test. The size of the beam is 400×100×100mm, and the ratio of slit and depth for the beam is 0.2. The curves of load-displacement and load-crack mouth opening displacement are measured; meanwhile, Two-parameter Fracture Model and Fictitious Crack Model are used as calculation theory to perform the analysis of data. The basic mechanical properties and fracture behaviors, affected by factors such as stone contents or elastic modulus are both studied in the thesis, comparing with the corresponding RPC. Then stress intensity factors from the same beams with different ratio of slit and depth are discussed by using software.The results show that Crushed-stone RPC and RPC have the similar fracture failure process, but the fracture surface of Crushed-stone RPC is more unsmooth; Of the 866 samples, the fracture performances of 866-4 are much better than 866-1. Compared with 866-1,fracture energy of 866-4 is 10.5% higher, fracture toughness is 50.5% higher, critical crack tip opening displacement is 54.2% larger, and effective crack length is 9.9% longer; In the 666 group, fracture performances of 666-2 and 666-3 are better than 666-1 too. The analysis also shows that 866-4 has the best fracture performance, compared with other groups, followed by 666-2 and 666-3; Different stone contents affect the fracture properties' rules of Crushed-stone RPC differently. Size effect of fracture toughness is verified by software, and KICS from Two-parameter Fracture Model reflects the fracture properties of structural more truly. There will be a lot of test-analysis before Crushed-stone RPC is applied instead of RPC.