摘要：
Nowadays, geopolymer coatings have been studied a lot due to their green and sustainable properties, and they have a great potential to partially replace traditional coatings in terms of corrosion resistance and economy. In this study, metakaolin-based geopolymer coating was used as the control group, and anticorrosive coatings were prepared by adding different dosages (2–8 wt%) of ZnO fillers to study the effect of ZnO on physical properties and anticorrosion properties of metakaolin-based geopolymer anticorrosive coatings. The results showed that when the mass fraction of the zinc oxide was 8%, it had the optimum effect on physical performance. The water absorption was 12.4%, and the toughness was 3 mm. In addition, the anticorrosive properties of the coating were studied by sodium chloride (NaCl) solution immersion test, wet–dry cyclic test, salt spray test, and electrochemical test. In sodium chloride (NaCl) solution immersion, wet–dry cycle, and salt spray test, a reduction of 43.8%, 50.6%, and 74.2% in corrosion area ratio, respectively, were achieved with a coating of 8% ZnO filled as compared with pure geopolymer coatings. The results indicated that the addition of ZnO enhanced the anticorrosion performance of the coating. The macroscopic test results were verified by SEM. This study lays a foundation for the subsequent research and performance improvement of metakaolin-based geopolymer anticorrosive coatings.
摘要：
Phase change energy storage technology using phase change materials (PCMs) is a viable solution to effectively address the heat dissipation problems of electronic devices. Herein, we proposed to prepare a modified PCM using CH3COONa center dot 3H(2)O (SAT) as main PCM, 9 wt% DL-Alanine (DL) as temperature modifier, and 2 wt% Na2HPO4 center dot 12H(2)O as nucleating agent. Calculations using density functional theory method confirmed that the adjustment of DL on phase change temperature of SAT was originated from the hydrogen bond between them. Then, the modified PCM was loaded into 14 wt% expanded graphite (EG) to obtain a composite PCM with a suitable phase change temperature of 52.9 degrees C, phase change enthalpy of 227.4 J/g as well as supercooling degree of 6.6 degrees C, and the thermal conductivity of the composite PCM was as high as 11.52 W.m(-1).K-1. SEM and pore structure analyses showed that the modified PCM was successfully loaded into the pore structure of EG, and their combination was verified by XRD and FT-IR as a physical interaction. After 200 heating-cooling cycles, the phase change temperature and enthalpy of the composite PCM was basically unchanged along with consistent crystal structure and chemical composition, showing an excellent thermal reliability. A comparative analysis applied in a testing system showed that with loading of the composite PCM temperature control module, the critical time of the electronic chip was extended by 4670 s and the thermal equilibrium temperature was decreased by 20.4 degrees C, presenting a good thermal management performance. Therefore, the prepared composite PCM had great potential for application in thermal management of electronic devices.
摘要：
This study investigates the influence of polyvinyl alcohol (PVA) fiber dosage and length on the porosity, mechanical strength, and toughness of fly ash -based geopolymer composites. The experimental data are analyzed to examine the deflection -load relationship in the flexural toughness tests of fiber -reinforced geopolymer composites (FRGPC) with different PVA fiber parameters. The results indicate that the addition of a certain amount of PVA fibers effectively enhances the flexural resistance of FRGPC. Particularly, the optimal performance is achieved with the addition of 2.0 vol% of 9 mm PVA fibers, where the 28 -day flexural strength reaches 13.16 MPa, representing a 150.95 % increase compared to the control group, and the deflection at peak load increases by 308.00 %. However, the compressive strength of FRGPC with PVA fiber dosage at 1.6 vol%, 2.0 vol%, and 2.4 vol% decreases by 0.89 %, 6.39 %, and 10.13 %, respectively. Microscopic observations of FRGPC indicate that an increase in fiber dosage and length results in larger pores and uneven distribution of fibers. Notably, 12 mm PVA fibers exhibit significant aggregation, confirming the findings from mechanical property tests. This study, through an indepth exploration of the mechanical properties of PVA fiber -reinforced fly ash -based geopolymer composites, provides crucial experimental data and a theoretical foundation for the development of sustainable construction materials.
作者机构：
[Cong Li] School of Civil Engineering and Architecture,Wuhan Polytechnic University,Wuhan 430023,China;[Fangling Xu; Xiaowei Wang; Cong Li] Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources,Yangtze River Scientific Research Institute,Wuhan 430010,China;[Fangling Xu; Xiaowei Wang] Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,Hohai University,Nanjing 210098,China;[Xiaoke Shen; Bo Lu; Jiebing Zhu] 长江水利委员会长江科学院;[Weizhen Cai; Rongtang Zhang; Jiesheng Liu] 武汉理工大学
通讯机构：
[Cong Li] S;School of Civil Engineering and Architecture, Wuhan Polytechnic University, Wuhan, China<&wdkj&>Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources, Yangtze River Scientific Research Institute, Wuhan, China
摘要：
Weathered rock (especially granite) slopes are prone to failure under the action of rainfall， making it necessary to study the response of weathered rock slope to rainfall infiltration for landslide prevention. In this study， a series of model tests of weathered rock slope under different conditions were conducted. The matric suction， volumetric water content， earth pressure and deformation of slope were monitored in real time during rainfall. The response of the slope to rainfall infiltration， failure process and failure mode of slope under different conditions were analyzed， and the early warning criterion for the failure of weathered rock slope caused by rainfall was studied. The results show that the slope deformation evolution process under rainfall condition was closely related to the dissipation of matric suction. When the distribution of the matrix suction (or water content) of slope met the condition that the resistance to sliding of the slip-mass was overcome， the displacement increased sharply and landslide occurred. Three factors including rainfall process， lithologic condition and excavation condition significantly affect the response of weathered rock slope to rainfall. It can be found from the test results under different conditions that compared with intermittent rainfall condition， the rainfall intensity and infiltration depth were smaller when the slope entering accelerated deformation stage under the condition of incremental rainfall. The accumulated rainfall when weathered clastic landslide occurring was greater than that of weathered granite， which results in greater disaster risk. The excavation angle and moisture distribution of a slope were the main factors affecting the stability of a slope. In addition， the evolution processes and critical displacement velocities of slopes were studied by combining the deformation curves and matrix suction curves， which can be used as reference for early warning of rainfall-induced weathered rock landslide.
通讯机构：
[Jiesheng Liu] S;School of Civil Engineering and Architecture, Wuhan Polytechnic University, 68 Xuefu S. Rd., Changqing Garden, Wuhan 430023, China<&wdkj&>Author to whom correspondence should be addressed.
摘要：
Nowadays, energy saving, and green sustainability are influencing the development of all industries, including the construction industry. In recent years, geopolymeric cement and concrete have become hot topic materials as a replacement for traditional OPC; this work carried out orthogonal experiments to identify four potential factors affecting the basic properties of the metakaolin-geopolymeric cement specimens. The results showed that the metakaolin and activator contents were the two primary influencing factors. Given the importance of studying the durability of building restoration materials in harsh environments, this experiment focused on testing the bond strength, permeability resistance, sulphate corrosion resistance, and freeze-thaw resistance of metakaolin geopolymer pastes with different proportions of metakaolin dopant and alkali activator content. The findings are that durability of the formed specimens significantly improved when suitable metakaolin and activator contents were incorporated, and bond strength was also improved. Moreover, the microscopic tests, including SEM and FT-IR experiments, were used to better reflect the changing durability of pattern. The experiments showed that the best durability of the metakaolin geopolymeric cement was achieved when the ratio of metakaolin to cement was 1.5 and the ratio of activator to cementitious material was 0.3. It can be concluded that the appropriate content of metakaolin and activator can give the geopolymer excellent performance under harsh conditions, which will contribute to the wide application of geopolymer.
作者机构：
[Li Cong; Zhang Rong-tang; Wu Liang-liang; Liu Jie-sheng; Zhang Xin-zhou] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Peoples R China.;[Lu Bo; Li Cong; Zhu Jie-bing; Shen Xiao-ke; Wang Xiao-wei] Changjiang River Sci Res Inst, Minist Water Resources, Key Lab Geotech Mech & Engn, Wuhan 430010, Peoples R China.;[Wang Xiao-wei] Hohai Univ, Minist Educ Geomech & Embankment Engn, Key Lab, Nanjing 210098, Peoples R China.
通讯机构：
[Cong Li] S;School of Civil Engineering and Architecture, Wuhan Polytechnic University, Wuhan, China<&wdkj&>Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources, Changjiang River Scientific Research Institute, Wuhan, China
关键词：
Rock slope;Fractured rock mass;Freeze-thaw cycle;Model experiment;Stability degradation mechanism;Failure mode
摘要：
The stability of slope rock masses is influenced by freeze-thaw cycles in cold region, and the mechanism of stability deterioration is not clear. In order to understand the damage and progressive failure characteristics of rock masses under the action of freezing and thawing, a model test was conducted on slope with steep joint in this study. The temperature, frost heaving pressure and deformation of slope rock mass were monitored in real-time during the test and the progressive failure mode was studied. The experimental results show that the temperature variations of cracking and the rock mass of a slope are different. There are obvious latent heat stages in the temperature-change plot in the crack, but not in the slope rock masses. The frost heaving effect in the fracture is closely related to the constraint conditions, which change with the deformation of the fracture. The frost heaving pressure fluctuates periodically during freezing and continues to decrease during thawing. The surface deformation of the rock mass increases during freezing, and the deformation is restored when it thaws. Freeze-thaw cycling results in residual deformation of the rock mass which cannot be fully restored. Analysis shows that the rock mass at the free side of the steep-dip joint rotates slightly under the frost heaving effect, causing fracture propagation. The fracture propagation pattern is a circular arc at the beginning, then extends to the possible sliding direction of the rock mass. Frost heaving force and fracture water pressure are the key factors for the failure of the slope, which can cause the crack to penetrate the rock mass, and a landslide ensues when the overall anti-sliding resistance of the rock mass is overcome.
摘要：
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<jats:title content-type="abstract-subheading">Purpose</jats:title>
<jats:p>The purpose of this paper is to develop a high-performance composite emulsion cement waterproof coating. The coating has excellent durability and is effective in protecting cement mortar substrates from harmful ions.</jats:p>
</jats:sec>
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<jats:title content-type="abstract-subheading">Design/methodology/approach</jats:title>
<jats:p>The polymer cement waterproof coatings with different emulsion compounding ratios were tested for mechanical properties and water resistance after alkali immersion, water immersion, thermal aging and UV aging, and the coatings were analyzed by infrared spectroscopy after aging to evaluate its durability. Meanwhile, the coating that presents favorable durability was applied to cement mortar test blocks. The protective effect of the coating on the test blocks was tested by immersion method, and X-ray diffraction analysis was performed on the eroded test blocks.</jats:p>
</jats:sec>
<jats:sec>
<jats:title content-type="abstract-subheading">Findings</jats:title>
<jats:p>The coating with neoprene latex/acrylate latex weight ratio of 90/10 presents favorable durability and has superior overall performance. Besides, when it is applied to cement mortar blocks, the coatings effectively reduced the erosive effect of harmful ions on cement mortar blocks, resulting in much lower mass change ratios and less internal structural damage of the blocks significantly.</jats:p>
</jats:sec>
<jats:sec>
<jats:title content-type="abstract-subheading">Originality/value</jats:title>
<jats:p>The obtained coating will be of great application potential for use in building waterproofing construction. Moreover, the coating can practically prevent chloride ions and sulfate ions from penetrating cement-based materials.</jats:p>
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