Experimental Study On The Mechanical Properties Of The Tailing Sand Green Concrete Members

Iron tailing sand green concrete is a kind of new type energy-saving concrete material which take waste tailings as part of the fine aggregate,its presence not only solves a large pile of tailings pollution caused to the environment but also alleviate the shortage of natural sand,it can meet the environmental protection and sustainable development demand and have a significant social and economic benefits.A series mortar and concrete mix proportion design test was done base on iron ore tailings green concrete raw materials research with the SEM,XRD and XRF microscopic test method.And finaly iron ore tailings green concrete with good work performance and mechanical properties was made.With iron ore tailings replacement rate?0%,40%,50%,60%,70%?,reinforcement ratio,shear span ratio,plate thickness as parameters to forme the corresponding beam and plate specimen,then done shear and bending mechanical performance test separately to investigated the influence law of the share and bending mechanical performance of beam and plate specimen with multiscale parameters'change,and the specific results are as follows:?1?The tail of iron ore 40%replacement can been regarded as the limits replacement,when less than the value flexural strength and compressive strength of mortar reduce obviously,but greater than the value the strength reduction is limited.Coarse aggregate accumulation volume is less than 0.75,the slump and extend reduced slowly along with the accumulation of coarse aggregate volume down,but when greater than 0.75,the slump and extension degree fell sharply.The fluidity and extend degree of concrete is reduced with the increase of content of fine aggregate volume trend.Similar to ordinary concrete,iron ore of the green concrete hydration products mainly for C-S-H gel,Ca?OH?₂ and Ettringite,iron tailing sand green concrete has the same mechanical properties as the ordinary concrete,its compressive strength,tensile strength,elastic modulus,poisson ratio and ordinary concrete most close to the ordinary concrete is the rate of 40%concrete.?2?Systematically studied tailings concrete beams with ordinary concrete beam deflection,stress-strain curve,the average diagonal crack width,diagonal cracks and shear cracking load bearing capacity limit situation.Assuming that the study of the applicability of reinfoKJed concrete beams tailings,tailings failure modes of reinfoKJed concrete beams,the ultimate bearing capacity by solving the plane section,it can be seen tailings concrete beams diagonal crack in the initial formation,with the added load large,eventually extending obliquely Inclined cracks developed into a wide main crack-critical diagonal crack.Under the replacement rate of 40%of the cases,the shear capacity of tailings concrete beams with ordinary concrete beam or less,in the range of less than 1%;70%replacement rate,the shear capacity of larger difference between the range less than 10%.At the same time,combined with relevant experimental data at home and abroad,accumulation,and system processing test data,the establishment of a more reasonable shear capacity formula.?3?The bending mechanical performance of iron tailings sand green concrete beam with different iron tailings sand replacement rate was investaged,and analyze the difference in limit bearing capacity,cracking load,maximum crack width,cross deflection with ordinary concrete.The results show that:the two kinds of concrete beam with similar bending mechanical properties,the mechanical process obviously divided into four stages:elastic,cracking,yielding and ultimate,the calculation formula of flexural bearing capacity of normal section,cracking moment and crack width can refer the concrete structure design specification?GB 50010-2010?,but when the substitution rate is over 40%the crack width calculation need be corrected.?4?Bending mechanical properties of different substitution rate iron ore tailings green concrete one-way slab were studied,analyses the difference of cracking load,ultimate load,the maximum crack width and deflection to ordinary concrete one-way slab.The results of the study show that:iron ore green concrete one-way slab has the same bending mechanics performance as the ordinary concrete one-way slab,but its crack width is slightly larger than ordinary concrete slab at the same load,its mechanical properties can also refer the concrete structure design specification?GB,50010-2010?,but it should use the modified formula to caculate the crack width at high substitution rate.?5?Finite element analysis model of tailings green concrete beams and plates numerical simulation analysis,by reinforced concrete beams and plates of finite element analysis to describe the formation and development of cracks in concrete,and draw the whole process and undermine the process of developing the structure of the internal force and deformation of concrete and steel and the final failure modes.Calculated by the model of the cracking load and ultimate load test can be a good fit with the deflection curve can reflect the basic laws of deflection test specimen.