A natural analogue study of CO2 -cement interaction: Carbonation of calcium silicate hydrate-bearing rocks from Northern Ireland
A natural analogue study of CO2 -cement interaction: Carbonation of calcium silicate hydrate-bearing rocks from Northern Ireland
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CO2 - 水泥相互作用的自然模拟研究：北爱尔兰含硅酸钙水合物岩石的碳化
DOI：
10.1016/j.egypro.2011.02.502
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
Milodowski A
中科院分区：
文献类型：
--
作者：
Milodowski A
波特兰水泥的天然类似物可以深入了解在二氧化碳封存性能评估感兴趣的时间范围内运行的碳化过程。北爱尔兰的两个这样的地点（Scawt Hill 和 Carneal Plug）已经被调查，在那里可以观察到天然存在的水泥矿物的碳化反应。在过去的一万到两万年里，部分水合的富含镁铁矿的结核一直在低温下与大气中的二氧化碳或溶解的碳酸氢根离子发生反应。这在水合低温硅酸钙 (CSH) 矿物周围产生了碳酸盐矿物边缘，包围着原生高温变质硅酸钙和铝酸钙（主要是硅灰石，通常伴有硅灰石、硫锌矿、副硅钙石、褐铁矿、钙镁石、钙铁钙石）的残余核心，碳化作用从结核的外缘逐渐进行。方解石和方解石是主要的次生碳酸钙矿物，但也形成了球霰石和文石。碳化作用产生致密、低孔隙率的碳酸盐边缘。这与体积的减少有关，并伴随着下面残留的结晶不良的 CSH 凝胶及其富含二氧化硅的蚀变产物的收缩和微破裂，这在蚀变材料中产生了显着的次生孔隙度。尽管一些次生碳酸钙反应产物可能部分矿化裂缝，但它们不会完全密封裂缝，从而导致二氧化碳/碳酸氢盐进一步进入。也就是说，即使在几千年后，进入速度也不足以完全碳化结核。在量化碳酸化反应速率和 CO2/HCO3 通量方面仍然存在不确定性，需要进一步的工作来了解这些可能非常有用的类似物。
Natural analogues of Portland cement can provide insights into carbonation processes operating over timescales of interest to performance assessments of CO2storage. Two such sites in Northern Ireland (Scawt Hill and Carneal Plug) have been investigated, where carbonation reactions of naturally-occurring cement minerals can be observed. Here, partially hydrated larnite-rich nodules have been reacting with atmospheric CO2or dissolved bicarbonate ions at low temperatures over the last 10–20 thousand years. This has produced rims of carbonate minerals around hydrated low-temperature calcium silicate (CSH) minerals enclosing residual cores of primary high-temperature metamorphic calcium silicates and calcium aluminates (dominated by larnite, and often accompanied by wollastonite, spurrite, paraspurrite, brownmillerite, bredigite, andradite-grossular) with carbonation proceeding progressively from the outer margins of the nodules. Calcite and scawtite are the dominant secondary calcium carbonate minerals, but vaterite and aragonite have also formed. The carbonation produces dense, low-porosity carbonate rims. This is associated with a reduction in volume, accompanied by shrinkage and microfracturing of the underlying residual poorly crystalline CSH gel and its silica-rich alteration product, which has created significant secondary porosity in the altered material. Although some secondary calcium carbonate reaction products may partially mineralise the fractures, they do not seal the fractures completely, allowing further ingress of CO2/bicarbonate. That said, the ingress rate has not been sufficient to completely carbonate the nodules, even after several thousand years. Uncertainties remain in terms of quantifying carbonation reaction rates and the CO2/ HCO3-flux, and further work is needed to understand these potentially very useful analogues.