基于固废骨料刚度调控的混凝土及叠合梁性能研究

Performance of Concrete and Composite Beams with Stiffness-Regulated Solid Waste Aggregates

摘要:

为降低固废粗骨料混凝土叠合梁受弯叠合面开裂风险，采用高刚度铁矿废石粗骨料与低刚度自燃煤矸石粗骨料复合制备混配固废粗骨料，使其刚度接近天然粗骨料，研究其混凝土力学性能及制备叠合梁的受弯性能.结果表明：当高、低刚度粗骨料体积比为3:2时，混配固废粗骨料的刚度与天然粗骨料相当，两者所配制混凝土的弹性模量差异由28.03%降至2.37%.但当高刚度粗骨料占比超过68%和92%时，混凝土的抗压强度和弹性模量分别由极值开始下降.提出以骨浆弹比作为判断混凝土弹性模量和泊松比达到极值的判据.利用混配固废粗骨料混凝土制备叠合梁，可有效缓解叠合面应力集中，提高叠合面抗裂性能.

Abstract:

To reduce the risk of flexural cracking at the interface of composite beams made with waste coarse aggregate concrete, high-stiffness iron ore waste rock coarse aggregate (IRCA) and low-stiffness spontaneous combustion coal gangue coarse aggregate (SGCA) were combined to produce a hybrid waste coarse aggregate (HWCA) with stiffness comparable to that of natural coarse aggregate (NCA). The mechanical properties of HWCA concrete and the flexural performance of composite beams were investigated. Results indicate that when the volume ratio of high- to low-stiffness coarse aggregate is 3:2, the stiffness of HWCA is comparable to that of NCA, and the difference in elastic modulus between the concrete made with the two types of coarse aggregates decreases from 28.03% to 2.37%. However, when the proportion of high-stiffness coarse aggregate exceeds 68% and 92%, the compressive strength and elastic modulus of the concrete begin to decrease from their peak values. The elasticity ratio of aggregate to mortar was proposed as a criterion to determine whether the elastic modulus and Poisson’s ratio of the concrete have reached their peak values. The application of HWCA concrete in composite beams effectively mitigates stress concentration at the interface and improves the interface cracking resistance.