Chemical changes and phase analysis of OPC pastes carbonated at different CO2 concentrations
Chemical changes and phase analysis of OPC pastes carbonated at different CO2 concentrations
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DOI：
10.1617/s11527-008-9399-1
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发表时间：
2009-05-01
影响因子：
3.8
通讯作者：
Alonso, Cruz
中科院分区：
文献类型：
--
作者：
Castellote, Marta;Fernandez, Lorenzo;Alonso, Cruz
对使用不同浓度的CO2（3%、10%和100%）加速碳化的OPC浆料进行了化学变化和物相分析，并与自然碳化（千分之一…0.03%）的浆料进行了比较。Si-29魔角旋转核磁共振（Si-29 m.a.s.n.m）R)，热重分析（TG）和x射线衍射（XRD）进行了表征。样品的碳化作用导致CSH的逐步聚合，从而形成钙修饰的硅胶和碳酸钙。CSH和波特兰铁矿的碳化同时发生，碳化后CSH的聚合随着CO2浓度的增加而增加。当使用0.03%和3%的CO2时，CSH凝胶的Ca/Si值低于未碳化样品，两种样品的Ca/Si值基本相同。当二氧化碳含量为10%和100%时，CSH凝胶完全消失。在每种情况下，由于CSH的脱钙作用，形成了聚合的ca改性硅胶。从这些结果可以推断，在测试的不同浓度的二氧化碳中，高达3%的二氧化碳碳化（也就是说，以100倍的比例）所产生的微观结构更类似于千分之0.03%的二氧化碳自然碳化，而不是10%和100%浓度的二氧化碳自然碳化。
Chemical changes and phase analysis of OPC pastes exposed to accelerated carbonation using different concentrations of CO2 (3%, 10% and 100%) have been undertaken and compared with those of natural carbonation (a parts per thousand...0.03%). Si-29 Magic Angle Spinning-Nuclear Magnetic Resonance (Si-29 M.A.S-N.M.R), Thermogravimetric analyses (TG) and X-Ray Diffraction (XRD) have been used for characterisation. The carbonation of the samples has resulted in a progressive polymerisation of CSH that leads to formation of a Ca-modified silica gel and calcium carbonate. The carbonation of CSH and portlandite occurs simultaneously and the polymerisation of the CSH after carbonation increases with the increase in concentration of CO2. When a parts per thousand...0.03% and 3% CO2 are used(,) CSH gel with a lower Ca/Si than that of the uncarbonated sample, and quite similar for both samples remained. When carbonating at 10% and 100% of CO2, the CSH gel completely disappears. For every condition, a polymerised Ca-modified silica gel is formed, as a result of the decalcification of the CSH. From these results it can be deduced that among the different concentrations of CO2 tested, carbonation up to a 3% of CO2, (that is to say, by a factor of 100) results in a microstructure much more similar to those corresponding to natural carbonation at a parts per thousand...0.03% CO2 than those at the 10% and 100% concentrations.