Increase in volume stability of RO phases in steel slag by combined treatment of alkali and dry carbonation
Increase in volume stability of RO phases in steel slag by combined treatment of alkali and dry carbonation
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DOI：
10.1016/j.conbuildmat.2023.132345
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发表时间：
2023-09
影响因子：
7.4
通讯作者：
Wenzheng Li;M. Cao;Dan Wang;Jun Chang
中科院分区：
文献类型：
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作者：
Wenzheng Li;M. Cao;Dan Wang;Jun Chang
RO相占钢渣的8.5- 16.9wt%，并表现出延迟水化活性，这可能导致钢渣（SS）的体积稳定性差。对合成的RO相进行碱激发剂（硅酸钠）处理，然后进行干法碳酸化技术（ADC），所述合成的RO相具有不同摩尔比的FeO、MgO和MnO以促进其早期水化活性。结果表明，掺ADC_SS的砂浆28 d抗压强度比未掺SS的砂浆提高19.67%，膨胀率降低26%。RO相的水化程度在碱处理过程中明显增加，从10.6%增加到21.7%（RO-6），并且随后的碳酸化进一步刺激水化程度（达到44.1%），两者都导致膨胀组分（即，MgO）。ADC_RO相/SS的加入促进了水泥的早期水化活性，这主要归因于水化和碳酸化产物的成核作用（即，Mg（OH）2、绿金矿和MgCO 3·3 H2O）。在碳酸化过程中产生的硅胶的碱激发反应以及单碳铝酸盐的形成进一步有助于强度增加。ADC_SS作为水泥混合材，与未处理的SS相比，具有强度高、水化速率快、放热低、膨胀率小等优点。ADC法是一种很有潜力的处理SS的方法，可以使SS用作波特兰水泥的混合材。
RO phases account for 8.5–16.9 wt% of steel slags and exhibit delayed hydration activity, which may result in poor volume stability of steel slags (SS). Treatment of alkali activator (sodium silicate) followed by dry carbonation technology (ADC) was conducted on synthetic RO phases with various molar ratios of FeO, MgO, and MnO to promote its early hydration activity. Results show that 28 d compressive strength of mortar added by ADC_SS is 19.67% higher than that of added untreated SS and 26% decrease in expansion rate. Hydration degree of RO phases increases obviously during alkali treatment from 10.6% to 21.7% (RO-6), and is further stimulated by subsequently carbonation (reaching 44.1%), both resulting in much consumption of expansive component (i.e., MgO) in RO phases. The early hydration activity of cement promoted by adding ADC_RO phase/SS, which mainly attributes to the nucleation effect of hydration and carbonation products (i.e., Mg(OH)2, pyoaurite, and MgCO3·3H2O). The alkali excitation reaction of silica gels produced during carbonation as well as the formation of monocarboaluminate further contribute to the strength gain. ADC_SS used as admixture for cement makes pastes have advantage of higher strength, higher hydration rate, lower heat release, and less expansion rate compared to the system contained untreated SS. ADC may be a potential method to treat SS and makes SS to be used as admixture for Portland cement.