ORCID Profile
0000-0001-9985-3430
Current Organisation
University of Colorado at Boulder
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Elsevier BV
Date: 11-2021
Publisher: Elsevier BV
Date: 08-2022
Publisher: Elsevier BV
Date: 03-2022
Publisher: Elsevier BV
Date: 09-2021
Publisher: Elsevier BV
Date: 07-2021
Publisher: American Society of Civil Engineers (ASCE)
Date: 07-2021
Publisher: Elsevier BV
Date: 02-2022
Publisher: Hindawi Limited
Date: 19-02-2020
DOI: 10.1155/2020/8919681
Abstract: In this paper, the influence of graphene oxide (GO) on the microstructure of interfacial transition zone (ITZ) in cement mortar was investigated through image analysis (IA) of backscattered electron (BSE) micrographs. The results showed that the incorporation of GO significantly reduced the thickness of ITZ. The porosity in ITZ and bulk paste decreased due to the introduction of GO meanwhile, the compressive strength of the mortar s les was improved. The addition of GO also narrowed the gap between the porosity of ITZ and bulk paste, and therefore, the entire microstructure of mortar became more homogenous. Based on the above results, the model to predict the compressive strength of mortar was modified for better precision. The improved prediction model indicated that the difference between the compressive strength of ITZ and bulk paste was reduced upon the refinement of ITZ by GO.
Publisher: Elsevier BV
Date: 12-2021
Publisher: Elsevier BV
Date: 02-2022
Publisher: Elsevier BV
Date: 05-2021
Publisher: MDPI AG
Date: 16-08-2022
DOI: 10.3390/BUILDINGS12081252
Abstract: In this study, X-ray microcomputed tomography (XCT) and nanoindentation techniques were used to evaluate the synergistic action between sulfate and chloride ingress under cyclic drying–immersion conditions on steel-reinforced mortars. Three salt solutions, namely 3% NaCl (Sc), 5% Na2SO4 (Ss), and 5% Na2SO4 + 3% NaCl (Scs), were used and 24 drying–immersion cycles were applied. The results showed that the chloride caused more severe corrosion on steel reinforcement than the sulfate while under the influence of Scs, and the presence of sulfate suppressed the steel corrosion caused by chloride. In terms the damage to the mortar cover, after 24 drying–immersion cycles, the sulfate caused the most severe damage (volume loss of approximately 7.1%) while the chloride resulted in the least damage (volume loss of approximately 2.6%). By comparing Ss and Scs, it was also found that chloride suppressed the sulfate attack by reducing the damage to the mortar cover (volume loss of approximately 6.3% for Scs). Moreover, the degradation of mortar specimens was found to be layer-dependent, as was the distribution of micro-mechanics. Regarding the micro-mechanics, the specimens of the three solutions performed differently in terms of the aforementioned properties, depending on which underlying mechanism was analyzed. This research could allow for a more accurate assessment of the factors influencing building structures in a typical aggressive marine environment.
Publisher: Elsevier BV
Date: 11-2023
Publisher: Elsevier BV
Date: 12-2020
Publisher: MDPI AG
Date: 12-09-2018
DOI: 10.3390/MA11091697
Abstract: The present work aims to introduce a novel and eco-friendly method, i.e., a water-leaching pretreatment for extracting highly reactive biomass silica from rice husk (RH), for viability as a pozzolanic additive in cement. For comparison, the traditional acid pretreatment method was also employed throughout the experimental study. The silica from RH was extracted using boiled deionized water and acid solution as leaching agents to remove the alkali metal impurities, and then dried and submitted to pyrolysis treatment. The results indicated that potassium was found to be the major contaminant metal inducing the formation of undesirable black carbon particles and the decrease in crystallization temperature of amorphous RHA silica. The boiling-water-leaching pretreatment and acid-leaching pretreatment on RHs significantly removed the metallic impurities and reduced the crystallization sensitivity of RHA silica to calcination temperature. A highly reactive amorphous silica with purity of 96% was obtained from RH via 1 N hydrochloric acid leaching followed by controlled calcination at 600 °C for 2 h. The acid treatments increased the crystallization temperature of silica to 1200 °C and retained the amorphous state of silica for 2.5 h. In the case of water-leaching pretreatment, leaching duration for 2.5 h could yield an amorphous silica with purity of 94% and render the silica amorphous at 900 °C for 7 h. The RHA silica yielded by water-leaching pretreatment presented a comparable enhancing effect to that of acid leaching on hydration and improved the strength of cement. Furthermore, compared with the acid-leaching method, the water-leaching pretreatment method is more environmentally friendly and easier to operate, and hence more widely available.
Publisher: Elsevier BV
Date: 10-2023
Publisher: Elsevier BV
Date: 08-2019
Publisher: Elsevier BV
Date: 04-2019
Publisher: Elsevier BV
Date: 11-2022
Publisher: Elsevier BV
Date: 2020
Publisher: Elsevier BV
Date: 08-2023
Publisher: Elsevier BV
Date: 2023
Publisher: Elsevier BV
Date: 03-2021
Publisher: Elsevier BV
Date: 2022
Publisher: Elsevier BV
Date: 07-2022
Publisher: Elsevier BV
Date: 07-2019
Publisher: Elsevier BV
Date: 08-2021
Publisher: Elsevier BV
Date: 02-2022
Publisher: Elsevier BV
Date: 2022
Publisher: Elsevier BV
Date: 02-2021
Publisher: Frontiers Media SA
Date: 09-03-2022
DOI: 10.3389/FMATS.2022.845349
Abstract: This study compares the degradation behavior of the alkali-activated slag/fly ash (AASF) and ordinary Portland cement (OPC) mortars exposed to phosphoric acid with different pH values. The experimental results show that AASF mortars exhibit better resistance than OPC mortars against surface damage, although both systems get white deposits on the surface in phosphoric acid with a relatively high pH level. AASF mortars obtained lower mass loss than OPC mortars in phosphoric acid with pH at 2 and 3. The strength reduction in AASF mortars after immersion in phosphoric acid is more significant than that in OPC mortars. However, total degradation depth of AASF was smaller than that of OPC regardless of the pH of the acid solutions. Based on the experimental data, linear relationships were identified between the slope of degradation depth–mass loss curves and the Al/Si and Ca/Si ratios of the binders. This may indicate a new way to assess the degradation behavior of AASF and OPC based on their chemical compositions.
Publisher: MDPI AG
Date: 14-07-2022
DOI: 10.3390/MA15144913
Abstract: This paper proposes a new chemical combustion method for the synthesis of nano-low-carbon belite cement via a simple one-step process without using any oxidizers, and related mechanisms are briefly introduced. The starting materials used, including micro-silica (silica fume) as a byproduct of the metallurgic industry and CaCO3 powders, are of great abundance, and the processing parameters involved were optimized using a series of systematic experiments based on X-ray diffraction (XRD) and the Rietveld fitting method. Besides, the properties of the synthesized belite cement were characterized by the Brunauer–Emmett–Teller (BET) technique and scanning electron microscopy (SEM). Experimental results revealed that the optimized fuel agent was urea with a dosage of 4.902 times that of the starting materials by mass, and the corresponding holding temperature and time were 1150 °C and 2 h, respectively. In addition, the CaO/(SiO2 + CaO) for the starting materials should be set at 62.5% by mass ratio. BET and SEM results showed that the obtained belite cement had a specific surface area of 11.17 m2/g and a size of around 500 nm or even smaller in spherical shapes, suggesting that this method was successfully implemented. Thus, it can be a promising approach for the synthesis of nano-belite particles as a low-carbon construction material, which could be used more in the near future, such as for low-carbon concrete productions.
Publisher: American Chemical Society (ACS)
Date: 18-11-2022
Publisher: Elsevier BV
Date: 02-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1TA06594G
Abstract: A highly efficient composition screening protocol based on high throughput inkjet printing of perovskite films is developed to accelerate the discovery of novel tribromide perovskites for high-photovoltage solar cells.
Publisher: Elsevier BV
Date: 08-2022
Publisher: Elsevier BV
Date: 03-2022
Publisher: Elsevier BV
Date: 08-2023
Publisher: Wiley
Date: 05-2022
DOI: 10.1111/JACE.18515
Abstract: In this research, the effects of natural seawater (SW) on the properties of alkali‐activated slag/fly ash (AASF) are studied. AASF prepared with deionized water is set as the reference mixture. The results showed that the use of natural SW resulted in a prolonged setting time and lower heat release, but no obvious impact on the flowability of AASF specimens. The long‐term compressive strength became higher when SW was used, whereas the corresponding flexural strength and fractural toughness turned lower. The use of SW induced the formation of new products that were not identified in the reference mixture, such as Cl–hydrocalumite and gypsum. In addition, it is evidenced that the dissolution of fly ash (FA) particles was significantly delayed with the incorporation of SW. All these results were related to the various ions introduced by the natural SW and their interactions with the alkaline activator as well as the precipitation of salts on slag and FA surfaces or in the matrix.
Publisher: Elsevier BV
Date: 2020
No related grants have been discovered for JIE REN.