Journal of Cleaner Production
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2023
·
IF 11.1
Rongrong Zhang,Feng Li,Siqi Zhou,Yue Hou
Volcanic ash has several negative impacts on the environment and can be used in massive to synthesize geopolymers , which are considered quasi-brittle. Carbon nanofibers (CNFs) can reinforce the geopolymers, and the dispersion of CNFs directly determines the reinforcement effect. However, the dispersion of CNFs in alkali solutions is challenging. In this paper, the effect of surfactant type, dosage, and ultrasonic time on CNFs dispersion in aqueous and alkali solutions was investigated by the quantitive method of microscopic image processing to determine the preferred dispersion scheme. Zeta potential tests and visual observation were used to analyze the mechanism and stability. Based on this, volcanic ash-based geopolymer nanocomposites with 0.1 wt% contents of CNFs were synthesized. The mechanical properties were tested, and the microstructure was characterized using Scanning Electron Microscope coupled with Energy Dispersive Spectroscopy and Mercury Intrusion Porosimetry . The results showed that methylcellulose (MC), polycarboxylate superplasticizer (PC), and polyvinylpyrrolidone (PVP) could disperse CNFs in aqueous, but evident aggregations can be observed in the alkali solution. PC performed better than MC and PVP in alkali solutions, with 4.83% aggregation area of the whole image, 86% of 0–100 μm 2 aggregations, and an average aggregation area of 87 μm 2 , beneficial from the comb-like structures. Dispersed CNFs can improve the 28-d flexural and compressive strength of the resulting geopolymer nanocomposite by 23% and 16%, respectively, and refine the pore structure through filling, bridging, and nucleation effects, decreasing the average pore size and porosity by 33% and 15%. This paper will contribute to the resourceful use of volcanic ash to reduce pollution and the higher reinforcement of CNFs in alkali-activated geopolymers.
研究领域:
材料科学
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环境工程
✓ 已验证
产品关联
DOI
高影响因子
Materials
·
2023
·Vol. 16
·期 13
·4549
·
IF 3.4
Chuiyuan Kong,Bin Zhou,Rongxin Guo,Feng Yan,Rui Wang,Changxi Tang
Based on the physical and chemical properties of red sandstone (RS), RS is used to produce composite cementitious materials. The flowability, mechanical strength, and micromechanics of a red sandstone–cement binary cementitious material (RS-OPC) were investigated as functions of the amount of RS replacing the cement (OPC). Additionally, the feasibility of producing red sandstone–phosphogypsum–cement composite materials (RS-PG-OPC) using the phosphogypsum (PG)- enhanced volcanic ash activity of RS was investigated. The products of hydration and microstructures of RS-OPC and RS-PG-OPC were analyzed by XRD, FTIR, TG-DTG, and SEM. RS enhanced the flowability of RS-OPC relative to the unmodified cement slurry but lowered its mechanical strength, according to the experiments. When the quantity of OPC replaced was greater than 25%, the compressive strength after 28 days was substantially reduced, with a maximum reduction of 78.8% (RS-60). The microscopic mechanism of RS-OPC suggested that the active SiO2in the RS can react with Ca(OH)2to produce C-S-H but can only utilize small quantities of Ca(OH)2, confirming the low volcanic ash activity of RS. RS was responsible for dilution and filling. The incorporation of 5% PG into RS-PG-OPC slowed the hydration process compared with RS-OPC without PG but also increased the flowability and aided in the later development of the mechanical strength. This was primarily because the addition of PG provided the system with sufficient Ca2+and SO42−to react with [Al(OH)6]3−to form ettringite (AFt), therefore accelerating the dissolution of Al3+in RS to generate more AFt and C-(A)-S-H gels. To some extent, this excites the volcanic ash of RS. Therefore, if there is an abundance of waste RS in the region and a lack of other auxiliary cementitious materials, a sufficient quantity of PG and a finely powdered waste RS component can be used to replace cementitious materials prepared with OPC to reduce the mining of raw OPC materials.Keywords:red sandstone;phosphogypsum;flowability;mechanical strength;micromechanics;volcanic ash activity
研究领域:
建筑材料学
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材料科学
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产品关联
DOI
PubMed
高影响因子
APPLIED CLAY SCIENCE
·
2020
·
IF 4.605
Xiaohai Liu,Baoguo Ma,Hongbo Tan,Li Gao,Pian Chen
Metakaolin (MK) is a widely used admixture in chloride immobilization which is conducive to the durability of reinforced concrete. In this study, triisopropanolamine (TIPA) was added into cement-MK system to improve the chloride immobilization by expediting the pozzolanic reaction of MK. The effect of TIPA on hydration of binder composed of 90% Portland cement and 10% MK was investigated, and the hydration behavior was characterized by thermogravimetric analysis , X-ray diffraction, nuclear magnetic resonance spectroscopy , and mercury intrusion porosimetry , based on the evaluation of pozzolanic reaction of MK by ion dissolution. Results indicated that TIPA promoted the hydration of both MK and cement, and chloride immobilization was also improved. The mechanism for the improvement was involved in three aspects: a) TIPA facilitated the dissolution of aluminum from MK to obtain more chloroaluminate salts, strengthening chemical binding; b) TIPA accelerated hydration of cement and MK for more C-S-H gel, conducive to the physical adsorption; c) TIPA increased the amount of hydrates to refine the pore structure , hindering the migration of chloride ion. This investigation provided one new method for improving the pozzolanic reaction of MK to enhance chloride immobilization of cement-MK system.
研究领域:
建筑材料学
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化学工程
✓ 已验证
DOI
高影响因子
CEMENT & CONCRETE COMPOSITES
·
2024
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IF 10.8
Han Wang,Liguo Wang,Junlin Lin,Yali Li,Zeyu Lu,Jinyang Jiang
The random distribution of pozzolanic materials (PM) using direct mixing strategy reduces their contact possibility with hydration-released calcium hydroxide (CH), and limits the corresponding reinforcing efficiency to cement-based materials via pozzolanic reaction. In this study, a target dispersion strategy of PM nearby CH was proposed using super absorbent polymers (SAPs) as the carrier. On the one hand, nano silica (NS) and calcined clay (CC), two typical PM, can be encapsulated into SAPs through the hydrogen bonding interaction; on the other hand, the region around SAPs was enriched with more water and higher Ca 2+ concentration, which triggered the in situ crystallization of CH. In this case, the contact possibility between the NS or CC (NS/CC) and hydration-released CH was improved by the target dispersion strategy, and resulted in a 60 %–253 % increase in pozzolanic reaction degree (PRD) of NS/CC. Furthermore, the reinforcing effect of NS/CC on compressive strength of cement paste was enhanced by 25 % through this strategy. Therefore, the current study introduces a novel method for increasing the pozzolanic reinforcing efficiency of cement-based materials by turning the random to target dispersion of PM nearby CH.
研究领域:
土木工程
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材料科学
✓ 已验证
DOI
高影响因子
Journal of Building Engineering
·
2025
·
IF 7.4
Jielu Zhu,Bingzhi Xiang,Fanghua Liu,Lina Xiao,Yong Zhou,Junwei Song,Haijiao Xie
Functional materials represented by calcined layered double hydroxide (CLDH), nano-silica (SiO 2 ), and microcapsules are frequently incorporated into cement-based composites to accelerate cement hydration or autonomously heal matrix microcracks, thereby enhancing the chloride-binding quantity and inhibition performance of cementitious system. In this work, CLDH and SiO 2 were employed to target modify microcapsules (CLDH/SiO 2 -MC), aiming to achieve the functional coupling effects of three materials. The study revealed that CLDH and SiO 2 were successfully anchored within the microcapsule wall and improved the surface roughness of modified microcapsules. The targeted modification strategy is beneficial to improve the interfacial bonding between microcapsules and cement paste. Interestingly, the alkaline pore solution induced the hydration reaction of active SiO 2 component within the surface of modified microcapsules. Compared with the reference group, cement paste specimens incorporating 3 % and 6 % microcapsule demonstrated 30.76 % and 53.85 % enhancements in chloride binding capacity, respectively. The D RCM values of cement mortar with CLDH/SiO 2 -MC additions of 0 %, 3 %, 6 %, and 9 % were 19.95, 14.63, 17.00, and 19.52 × 10 −12 m 2 /s, respectively. The synergistic corrosion inhibition effects of microcapsules resulted in higher R ct value of steel electrode, and the highest inhibition efficiency of CLDH/SiO 2 -MC was 97.84 %. The density functional theory (DFT) calculations show that the charge exchange capacity between CLDH/SiO 2 and ethyl cellulose is 2.36 e – , with metal atoms serving as electron donors. The CLDH/SiO 2 targeted modified microcapsules achieved synergistic corrosion inhibition through self-healing of the core, chloride binding and pozzolanic activity of the wall, which is helpful to realize the sustainable development of steels.
研究领域:
材料科学
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腐蚀工程
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水泥化学
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纳米技术
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表面改性
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电化学
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计算材料科学
✓ 已验证
DOI
高影响因子
Journal of Environmental Chemical Engineering
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2025
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IF 7.2
Shixin Zhang,Jiahui Zhang,Dilin He,Yixin Zhang,Shiyu Yuan,Xiaomin Tang,Huaili Zheng,Sen Li,Yuxin Chen,Yu Qin
s In construction engineering, the disposal of waste slurries (particularly drilling-derived pile foundation sludge) poses significant environmental and resource challenges, necessitating efficient dewatering solutions. Conventional methods often prove inadequate for treating this inorganic-dominated sludge with poor natural separation capability. This study developed an amphoteric flocculant (PAAD) capable of auto-adapting to colloidal charges in sludge, coupled with a synergistic reagent combination strategy (PAAD/PAC/CaCl 2 : polyacrylamide/polyaluminum chloride/calcium chloride) to optimize dewatering performance. Systematic evaluation of key dewatering indicators including supernatant turbidity, specific resistance to filtration (SRF), sludge cake moisture content, floc settling velocity, and particle size distribution (d₅₀) demonstrated superior performance over conventional single-flocculant. The optimized system achieved remarkable metrics, turbidity: 6.5 NTU, SRF: 0.82×10¹¹ m·kg⁻¹, sludge cake moisture content: 30.28%, settling velocity: 0.54 cm/s, and particle size distribution (d₅₀): 70.77 μm. This tripartite strategy reduces chemical consumption by 66.7% compared to PAAD flocculant, offering sustainable sludge management for river channel engineering. Mechanism investigations revealed distinct roles of each component: PAAD dominated through charge neutralization and interparticle bridging, PAC enhanced charge neutralization via double-layer compression, while CaCl 2 exhibited multifunctional effects. Notably, CaCl 2 triggered pozzolanic reactions with inorganic constituents, generating high-density acicular solids that reinforced floc skeletons and created water-release channels. This tripartite synergy established a robust porous framework, significantly improving floc stability and dewatering efficiency.
研究领域:
土木工程
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环境工程
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化学工程
·
材料科学
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岩土工程
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DOI
高影响因子
JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2020
·Vol. 94
·期 2
·416-424
·
IF 2.008
Tian Wei,Du Bin,Shui Anze,Ke Shanjun,Shan Qingliang,He Chao,Ma Juan
In this work, a silica-based mesoporous oxide (SMO) was directly fabricated via a template-free method using the abundant and inexpensive volcanic ash as raw material. By alkali hydrothermal activation and acid hydrothermal etching of volcanic ash, the SMO with large mesopore size (7.94 nm), high specific surface area (459.5 m 2 /g), and total pore volume of 1.05 cm 3 /g was produced. The main ingredient of SMO is amorphous microporous silica. The structural evolutions of the mesoporous materials were revealed by X-ray powder diffraction, scanning electron microscope, Fourier transform infrared spectrometry, N 2 adsorption/desorption, and transmission electron microscopy techniques. The as-prepared SMO possessed excellent adsorption of water vapor as high as 616.0 g/m 2 at the relative humidity ranging from 33 to 75%. This SMO provides a platform for preparing high performance template-freely humidity self-regulating material.
This figure shows that silica-based mesoporous oxide (SMO) quickly adsorbs moisture at RH = 75% and reaches to 616.0 g/m 2 , and then the adsorbed water releases at 33% RH. These results suggest SMO have an excellent humidity self-regulating function in the RH ranging from 33 to 75%.
研究领域:
材料科学
·
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）