Gel Composition and Strength Properties of Alkali-Activated Oyster Shell-Volcanic Ash: Effect of Synthesis Conditions
Gel Composition and Strength Properties of Alkali-Activated Oyster Shell-Volcanic Ash: Effect of Synthesis Conditions
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DOI：
10.1111/jace.14332
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发表时间：
2016-09-01
影响因子：
3.9
通讯作者：
Njopwouo, Daniel
中科院分区：
文献类型：
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作者：
Djobo, Jean Noel Yankwa;Tchakoute, Herve Kouamo;Njopwouo, Daniel
在不同NaOH浓度（8、12、15M）和养护温度（60℃、80℃）、湿、干条件下，研究了碱活化牡蛎壳火山灰的凝胶组成和力学性能。采用XRD、FTIR、SEM-EDS、TGA-DSC等方法对粘结剂进行了微观结构表征。结果表明，该体系的凝胶组成受NaOH浓度的影响，而固化温度在60 ~ 80℃范围内不受影响。所有碱活化的牡蛎壳-火山灰的主相为N， C- a - s - h，部分样品的副相为C- s - h，且含铁比例较高。FTIR光谱上nu(3) = 1400-1494 cm（-1）处的分裂对应于由于CO32-基团畸变引起的简并态的消除。高度的分裂表明这个碳酸盐基团与Ca2+相连。抗压强度受养护温度和二次相形成的影响。在干燥条件下，部分样品的抗压强度在28 ~ 180 d之间大致增加，而在潮湿条件下，部分硅酸盐相的Si-O-Si键的部分溶解导致强度降低。
The gel composition and mechanical properties of alkali-activated oyster shell-volcanic ash were investigated at different NaOH concentrations (8, 12, and 15M) and curing temperatures (60 degrees C and 80 degrees C) in wet and dry conditions. XRD, FTIR, SEM-EDS, and TGA-DSC were used for microstructural characterization of the binder. The gel composition of the system was found to be influenced by NaOH concentration and was not affected when curing temperature was varied from 60 degrees C to 80 degrees C. The main phase was N, C-A-S-H for all alkali-activated oyster shell-volcanic ash, with C-S-H as secondary phase for some samples and contains high percentage of iron. The splitting at nu(3) = 1400-1494 cm(-1) on FTIR spectra corresponded to the elimination of the degeneracy due to the distortion of CO32- group. The high degree of splitting indicated that this carbonate group is linked to Ca2+. The compressive strength was influenced by curing temperature and the formation of a secondary phase. The compressive strength in dry condition increased roughly between 28 and 180 d for some samples, while in wet condition, the partial dissolution of Si-O-Si bonds of some silicate phases resulted in a reduction of strength.