钢纤维沙漠砂混凝土梁受弯力学性能试验

Flexural mechanical properties of steel fiber desert sand concrete beams

适量沙漠砂作为细骨料制备混凝土可有效提高混凝土的抗压强度,而钢纤维的掺入对混凝土抗拉性能有显著的提升作用。为探究钢纤维沙漠砂混凝土梁受弯力学特性,设计11根试验梁,分别研究钢纤维体积掺量、沙漠砂替代率和配筋率对受弯梁的影响规律。试验研究表明,钢纤维沙漠砂混凝土梁相对于普通混凝土梁其受弯承载力提高了4%~22%,受弯梁裂缝数量随钢纤维掺量增加呈现降低趋势,钢纤维减小了混凝土表面的弹塑性变形,而“桥架作用”抑制了裂缝的产生和提高了试验梁的承载力;随着配筋率的增加,主裂缝宽度呈减小的趋势,但极限荷载则逐渐增加,表明配筋率是影响受弯梁承载力主要因素之一;沙漠砂的“填充作用”密实了混凝土,使构件整体性能呈现良好的状态。试验梁的开裂荷载、修正后的极限弯矩理论计算值和试验值吻合效果良好,误差均小于5%。沙漠砂替代工程用砂制备混凝土,可以充分发挥当地资源优势,节约河砂资源,保护河湖生态环境,达到绿色建筑目标。

Appropriate amount of desert sand as fine aggregate can effectively improve the compressive strength of concrete,and the incorporation of steel fiber has a significant effect on the tensile properties of concrete.In order to explore the flexural mechanical properties of steel fiber desert sand concrete beams,11 test beams were designed to study the influence of steel fiber volume content,desert sand replacement rate and reinforcement ratio on flexural beams.The result shows that the flexural bearing capacity of steel fiber desert sand concrete beam is increased by 4%-22%compared with that of ordinary concrete beam,and the number of cracks in the flexural beam decreases with the increase of steel fiber content.Steel fiber reduces the elastic-plastic deformation of concrete surface,and the‘bridge action’inhibits the generation of cracks and improves the bearing capacity of the test beam.With the increase of reinforcement ratio,the main crack width decreases,but the ultimate load increases gradually,which indicates that the reinforcement ratio is one of the main factors affecting the bearing capacity of the bending beam.The‘filling effect’of desert sand compacts the concrete and makes the overall performance of the component present a good state.The cracking load of the test beam and the corrected theoretical calculation value of ultimate bending moment are in good agreement with the test value,and the error is less than 5%.The preparation of concrete by desert sand instead of engineering sand can give full play to the advantages of local resources,save river sand resources,protect the ecological environment of rivers and lakes,and achieve the goal of green building.