Optimizing and Characterizing Geopolymers from Ternary Blend of Philippine Coal Fly Ash, Coal Bottom Ash and Rice Hull Ash.
Optimizing and Characterizing Geopolymers from Ternary Blend of Philippine Coal Fly Ash, Coal Bottom Ash and Rice Hull Ash.
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DOI：
10.3390/ma9070580
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发表时间：
2016-07-15
期刊：
影响因子：
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通讯作者：
Promentilla MA
中科院分区：
文献类型：
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作者：
Kalaw ME;Culaba A;Hinode H;Kurniawan W;Gallardo S;Promentilla MA
地质聚合物是由无定形铝硅酸盐材料的碱活化形成的无机聚合物，从而产生三维聚合物网络。作为一类材料，它被认为具有替代普通波特兰水泥（OPC）的潜力，一百多年来，普通波特兰水泥一直是结构和建筑应用的首选粘合剂。地质聚合物已成为维斯维斯OPC的可持续选择，原因有三：（1）它们的技术性能即使不是更好，也是相当的;（2）它们可以从工业废物中生产;（3）在合理的限制范围内，它们的生产需要更少的能源，排放的二氧化碳也明显减少。在菲律宾，使用煤灰作为富含氧化铝和二氧化硅的地质聚合物前体，被认为是对燃煤发电厂产生的煤灰进行可持续管理的选择之一。然而，大多数地质聚合物混合物（和流行的混合OPC）仅使用粉煤灰。煤底灰的用途很少，仍被弃置于垃圾场。来自生物质燃烧工厂的稻壳船体灰是另一种富含二氧化硅的地质聚合物前体材料，其来自该国另一种大量产生的废物，仅具有最小的利用率。在这项研究中，地质聚合物样品形成从煤灰的混合物，使用粉煤灰（CFA）和煤底灰（CBA），和水稻船体灰（RHA）。使用X射线荧光光谱（XRF）元素和X射线衍射（XRD）矿物组成的地质聚合过程中使用的原材料进行了表征。使用热重分析（TGA）和通过溶解测试和电感耦合等离子体质谱（ICP）分析的反应性来确定原材料的热稳定性和烧失量（LOI）。利用压缩试验、傅里叶变换红外光谱（FTIR）、扫描电子显微镜（SEM）和热重分析（TGA）分析了所形成的地质聚合物的机械、热和微观结构性能。使用基于Scheffé的混合物设计，目标是具有低导热性、轻质和中等强度的应用，并且考虑到所有三种组分的废物利用，允许最大5%的稻壳船体灰质量，已经确定，用80-20质量比的12 M NaOH和硅酸钠活化的85-10-5重量比的CFA-CBA-RHA（55%H2O，模量= 3）制备的地质聚合物当在80 °C下预固化24小时时，在28天固化下具有18.5MPa的抗压强度、1660 kg/m3的体积重量和0.457W/m-°C的热导率。在这项研究中，隐含能量和CO2的估计值分别低于1.7 MJ/kg和0.12 kg CO2/kg。
Geopolymers are inorganic polymers formed from the alkaline activation of amorphous alumino-silicate materials resulting in a three-dimensional polymeric network. As a class of materials, it is seen to have the potential of replacing ordinary Portland cement (OPC), which for more than a hundred years has been the binder of choice for structural and building applications. Geopolymers have emerged as a sustainable option vis-à-vis OPC for three reasons: (1) their technical properties are comparable if not better; (2) they can be produced from industrial wastes; and (3) within reasonable constraints, their production requires less energy and emits significantly less CO2. In the Philippines, the use of coal ash, as the alumina- and silica- rich geopolymer precursor, is being considered as one of the options for sustainable management of coal ash generation from coal-fired power plants. However, most geopolymer mixes (and the prevalent blended OPC) use only coal fly ash. The coal bottom ash, having very few applications, remains relegated to dumpsites. Rice hull ash, from biomass-fired plants, is another silica-rich geopolymer precursor material from another significantly produced waste in the country with only minimal utilization. In this study, geopolymer samples were formed from the mixture of coal ash, using both coal fly ash (CFA) and coal bottom ash (CBA), and rice hull ash (RHA). The raw materials used for the geopolymerization process were characterized using X-ray fluorescence spectroscopy (XRF) for elemental and X-ray diffraction (XRD) for mineralogical composition. The raw materials’ thermal stability and loss on ignition (LOI) were determined using thermogravimetric analysis (TGA) and reactivity via dissolution tests and inductively-coupled plasma mass spectrometry (ICP) analysis. The mechanical, thermal and microstructural properties of the geopolymers formed were analyzed using compression tests, Fourier transform infra-red spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Using a Scheffé-based mixture design, targeting applications with low thermal conductivity, light weight and moderate strength and allowing for a maximum of five percent by mass of rice hull ash in consideration of the waste utilization of all three components, it has been determined that an 85-10-5 by weight ratio of CFA-CBA-RHA activated with 80-20 by mass ratio of 12 M NaOH and sodium silicate (55% H2O, modulus = 3) produced geopolymers with a compressive strength of 18.5 MPa, a volumetric weight of 1660 kg/m3 and a thermal conductivity of 0.457 W/m-°C at 28-day curing when pre-cured at 80 °C for 24 h. For this study, the estimates of embodied energy and CO2 were all below 1.7 MJ/kg and 0.12 kg CO2/kg, respectively.