外掺氧化镁混凝土在硫酸盐、镁盐耦合作用下的抗侵蚀性能研究

氧化镁掺入普通混凝土中遇水溶解,生成氢氧化镁晶体,氢氧化镁晶体相互挤压,填充孔隙,并形成宏观膨胀,基本不与水泥浆体中的其他组分发生反应,从而达到降低普通混凝土的孔隙率,改善孔结构,提高密实性的目的,保障了体积稳定性,提高了抗渗性能及抗腐蚀性能。本文根据氧化镁膨胀剂不同掺量条件下的普通混凝土力学性能,并通过普通混凝土抗渗性能测试进行验证,最终确定了氧化镁膨胀剂的最佳掺量。通过对比试验,研究氧化镁膨胀剂在0掺量和同掺量两种条件下,对浸泡相同浓度不同离子(SO42-、Mg2+)、不同养护龄期下普通混凝土力学性能、膨胀性能的影响,分析外掺氧化镁膨胀剂混凝土在水泥水化初期后对降低普通混凝土的孔隙率、提高密实性的重要作用,得出外掺氧化镁膨胀剂混凝土较0掺量普通混凝土具有较好的抗离子侵蚀能力,在工程中具有广泛应用价值。

Study on corrosion resistance of concrete added MgO under coupling action of sulfate and magnesium salt

When mixed with ordinary concrete,MgO dissolves in water to form magnesium hydroxide crystals.Magnesium hydroxide crystals squeeze each other to fill the pores and form macroscopic expansion,which basically does not react with other components in the cement paste.It reduces the porosity of ordinary concrete,improves its pore structure and the compactness,ensuring the volume stability and improving the impermeability and corrosion resistance.According to the mechanical properties of magnesium oxide expansive agent under different dosage conditions,and through the test of permeability resistance of ordinary concrete,this paper finally determines the best dosage of magnesium oxide expansive agent.Through comparative tests,the effects of MgO expansive agent on the mechanical properties and expansion properties of ordinary concrete soaked in different ions(SO42-,Mg2+)with the same concentration and cured in different ages under the conditions of 0 and the same dosage are studied.The effect of adding MgO expansive agent on reducing the porosity and improving the compactness of ordinary concrete after cement hydration is analyzed.It is concluded that the concrete with magnesium oxide expansive agent has better ion erosion resistance than the ordinary concrete with 0 content,and has wide application value in engineering.