Pozzolanic reaction of fly ash modified by fluidized bed reactor-vapor deposition

This study aimed to introduce fluidized bed reactor-vapor deposition (FBR-VD) into the modification of fly ash (FA) using the activators of NaOH, Na2SO4, and NaCl. The compressive strength, non-evaporable water and the hydration degree fly ash (HDFA) were investigated. The scanning electron microscopy (SEM), and the X-ray powder diffraction (XRD) Rietveld analysis were also conducted. The results demonstrate that FBR-VD can benefit the compressive strength when the dosage rates of NaOH, Na2SO4 and NaCl are 0.1%, 0.5%, and 0.5%, respectively. The non-evaporable water and HDFA also increased at certain activator dosage rates. A modification layer consisting of nanometer-scale crystals forms on the surface of the FA beads, with NaOH or Na2SO4 applied. NaOH can react with FA and promote its pozzolanic activity. Na2SO4 and NaCl can benefit the HDFA by remaining undissolved, to increase their concentration around FA. The enhanced HDFA is also proved by the consumption of Ca(OH)(2). (C) 2016 Elsevier Ltd. All rights reserved.

本研究旨在将流化床反应器 - 气相沉积（FBR - VD）技术引入使用氢氧化钠（NaOH）、硫酸钠（Na₂SO₄）和氯化钠（NaCl）活化剂对粉煤灰（FA）的改性中。对粉煤灰的抗压强度、非蒸发水含量以及水化程度（HDFA）进行了研究。还进行了扫描电子显微镜（SEM）和X射线粉末衍射（XRD）的里特韦尔德分析。结果表明，当NaOH、Na₂SO₄和NaCl的用量分别为0.1%、0.5%和0.5%时，FBR - VD有助于提高抗压强度。在特定的活化剂用量下，非蒸发水含量和HDFA也有所增加。在使用NaOH或Na₂SO₄时，粉煤灰颗粒表面会形成一层由纳米级晶体组成的改性层。NaOH可与粉煤灰反应并促进其火山灰活性。Na₂SO₄和NaCl可通过保持不溶解的状态，提高其在粉煤灰周围的浓度，从而有利于HDFA。氢氧化钙（Ca(OH)₂）的消耗也证明了HDFA的提高。（C）2016爱思唯尔有限公司。保留所有权利。