氧化镁膨胀剂在某桥梁主塔工程中的应用研究

Application of Magnesia Expansion Agent in Bridge Main Tower Project

研究了不同氧化镁膨胀剂掺量对混凝土力学性能及混凝土限制膨胀率的影响。并通过温度-应力试验对比了氧化镁膨胀剂掺量为6%的混凝土与空白混凝土的开裂温度、开裂应力。掺6%氧化镁膨胀剂的混凝土开裂温度为-18.5℃,明显低于空白混凝土。在约束条件下,掺氧化镁使得混凝土微膨胀,形成混凝土内部预压应力,最大压应力由1.35 MPa提高到3.15 MPa,应力储备从40%增加到69.7%。结合氧化镁膨胀剂在实际工程中的应用表明:氧化镁膨胀剂可提高混凝土的抗裂性能,能有效控制混凝土裂缝且降低大体积混凝土的开裂风险。

The effects of different amounts of magnesia expansion agent on the mechanical properties of concrete and the limited expansion ratio of concrete were studied.Through temperature-stress test,the cracking temperature and cracking stress of concrete with 6%magnesia expansion agent and blank concrete were compared.The cracking temperature of concrete mixed with 6%magnesia expansion agent is-18.5℃,which is significantly lower than that of blank concrete.Under the constraint conditions,the addition of magnesium oxide makes the concrete slightly expand,forming the internal precompression stress of the concrete.The maximum compressive stress is increased from 1.35 MPa to 3.15 MPa,and the stress reserve is increased from 40%to 69.7%.Combined with the application of magnesia expansion agent in practical engineering,it shows that magnesia expansion agent can improve the crack resistance of concrete,effectively control concrete cracks and reduce the cracking risk of mass concrete.