Experimental Research On Expansive Deformation And Mechanical Properties Of Shringkage-compensating Steel Fiber Reinforced Shotcrete

The main outlet of concrete sustainable development is prolong its service life. And the main factor of reducing concrete service life is crack. In this paper, steel fiber reinforced shotcrete as the base, expansive agents uniformly dispersed in this shotcrete which made of shrinkage-compensating steel fiber reinforced shotcrete. Expansive deformation, mechanical properties and crack resistance were studied through test.Percentage of free expansive and percentage of restrained expansive under restrained of steel bar alone,steel fiber alone and combine the two factor. The expansive percentage of all concrete were significantly decreased under the steel fiber and steel bar separately restrained,and the best effects is on the situation of consociation-limit;Restrictive of 1.6% steel fiber alone to concrete is close to the steel bar which reinforcement ratio is 0.79%.The addition percentage of expensive agent and the fraction of steel fiber by volume as variable to carry out orthogonal test for mechanical properties,design 16 groups concrete mix proportion,288 specimens,7d and 28d compressive strength, splitting tensile strength, flexural strength were measured separately.For shrinkage-compensating shotcrete,6% expansive agent is the best,but continue to increase the addition percentage of expensive agent,the strength beginning to reduce;For steel fiber reinforced shotcrete,the best ideal range of fraction of steel fiber by volume is 0.8%～1.2%,compared with plain concrete,the most increasing rate of compressive strength, splitting tensile strength and flexural strength is 4.0%,43.4% and 28.0% separately;Double mixed steel fiber and expansive agent, with the increase of fraction of steel fiber by volume,the strength will decrease,and superior to steel fiber enhanced alone,with the increase of expensive agent dosage,concrete strength increase at first than decrease,under the 8% expansive agent reached the maximum,the most increasing rate of three strength is 11.7%,53.2% and 40.0% separately,obviously superior to steel fiber incorporation alone.And he best match dosages of expansive agent and steel fiber are 8% and 1.2% for shrinkage-compensating steel fiber reinforced shotcrete.When the percentage of free expansive of shrinkage-compensating shotcrete exceed 0.035%,the strength of concrete beginning to greatly decrease; When the percentage of unite restrained expansive reacher to 0.021%, for shrinkage-compensating steel fiber reinforced shotcrete with 1.2% steel fiber, the strength beginning to ruduce.As expansive deformation test and mechanical properties for foundation,comparison test of early crack were studied under the best match dosages of expansive agent and steel fiber.The cofficient of crack decreased of steel fiber reinforced shotcrete, shrinkage-compensating shotcrete and shrinkage-compensating steel fiber reinforced shotcrete were 58.4%,91.6% and 96.8%,early anti-crack grade were second-grade,first grade, first grade,and the best effect of anti-crack is shrinkage-compensating steel fiber reinforced shotcrete.Figure 63 table 27 references 74...