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Copyright of Paint & Coatings Industry (0253-4312) is the property of Paint & Coatings Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transportation Science & Technolgy is the property of Transportation Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Accurate analysis of creep effects in finite element analysis depends on whether the exponential form of the creep coefficient can accurately reproduce the creep coefficient curve. This paper aims to develop a high-precision fitting method for arbitrary creep coefficient curves to achieve accurate finite element creep analysis. The core issue was examined, and an optimization algorithm was proposed. First, the simulated annealing algorithm was used to search for the global optimal solution, followed by the application of the Levenberg-Marquardt algorithm for precise calculations. Two examples were employed to verify the method. The results showed that: (1) The proposed creep coefficient curve fitting method could accurately fit the creep coefficient curve. (2) The case studies showed that the algorithm achieved a correlation coefficient ( R) above 0. 999 9 when fitting the creep coefficient curves according to highway and railway standards, indicating high fitting accuracy and strong general applicability. (3) The proposed algorithm featured a simple structure and clear hierarchy, allowing for easy implementation using common programming languages. This method provides valuable insights for the development of finite element program creep analysis modules or related scientific research on concrete creep behavior. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An investigation was undertaken to assess the potential for heavy metal leaching from gold tailings (GTs) when used GTs as fine aggregate for concrete. The leaching behavior in different pH leaching solutions and long-term leaching features of gold tailings concrete were studied. A kinetic model was used to predict the total amount of heavy metal leaching that will occur in next thirty years. The results reveal that the levels of Ba, Cd, Cr, Pb, Mn and Cu in GTs exceed the natural levels of these elements found in Chinese soil. Significantly, the leaching of Ba, Cd, Pb, Mn and Cu is more evident. GTs content shows a positive correlation with the leaching amount of heavy metals, and the cumulative leaching amount of heavy metals drops dramatically after 16 d. Based on 30 years leaching amount prediction, the leaching amount of Pb, Cu and Ba is 2 - 3 mg / L, while the leaching amount of Cd, Cr and Mn is less than 1 mg / L. These findings indicate that the GTs is sufficiently cured in concrete, thereby reducing the risk of long-term leaching of heavy metals. [ABSTRACT FROM AUTHOR]

In order to give full play to the particle filling advantage of desert sand and improve the mechanical properties of desert sand concrete, this paper carried out an experimental study on the mix proportion design method of polyvinyl alcohol fiber reinforced desert sand concrete based on Dinger-Funk close-packing theory. Firstly, applying the Dinger-Funk close-packing theory, the optimized sand rate is 42%, the optimized desert sand mass replacement ratio is 10%, 20% and 30%, the concrete aggregate particle gradation is improved, the fineness modulus of mixed fine aggregate is reduced from 3. 27 to 2. 92, 2. 81 and 2. 71, and the effective porosity is reduced from 2. 50% to 1. 65%, 1. 45% and 1. 51%, respectively. Secondly, the orthogonal test method was used to study the effects of water-cement ratio, desert sand mass replacement ratio, and the volume dosage of polyvinyl alcohol fiber on the workability, compressive strength, splitting tensile strength and flexural strength of concrete. The results show that, with the increase of desert sand mass replacement ratio and fiber dosage, the workability of concrete firstly increase and then decrease, and the compressive strength, splitting tensile strength and flexural strength show the trend of firstly increasing and then decreasing. Considering the test results of the workability and mechanical properties, the optimal mix proportion of C30 polyvinyl alcohol fiber reinforced desert sand concrete is determined to be 0.45 water-cement ratio, 20% of desert sand mass replacement ratio, and 0.10% of polyvinyl alcohol fiber volume dosage. [ABSTRACT FROM AUTHOR]

The correlations between compressive strength of UHPC and its mixture composition exhibit pronounced nonlinearity, presenting a challenge for analysis through conventional statistical approaches. In this study, an automatic machine learning (AutoML) technology was proposed to predict compressive strength of UHPC, and shapley additiveex planations (SHAP) was introduced to explain the AutoML model. The integration of AutoML and SHAP offered synergistic benefits, facilitating the development of a precise, efficient, and comprehensively interpretable model. Results demonstrate that AutoML model is automatically built with better accuracy and robustness than the base model. SHAP provides a global explanation, a single sample explanation, and a feature dependence explanation of characterization factors, which explains mechanism of the effect of each characterization factor on compressive strength. SHAP contributes to the understanding of mechanism of UHPC compressive strength development and the importance of characteristic factors, and can provide assistance in the design and application of UHPC. [ABSTRACT FROM AUTHOR]

This article was based on indoor simulated marine environment erosion tests using concrete, by analyzing the compressive strength, coating bonding strength and chloride ion diffusion behavior of marine cast-in-place concrete after erosion, and the effects of anti-corrosion coating / treating ages on the mechanical properties and durability evolution of marine cast-in-place concrete were studied. The results show that compared with concrete without anti-corrosion coating / treating, anti-corrosion coating / treating concrete using silane and polyurethane coating shows a decrease in compressive strength fc after erosion in marine tidal areas, and concrete fc gradually decreases with the increase of curing age tc . Anti-corrosion coating / treating can effectively improve the long-term chloride ion erosion resistance of marine cast-in-place concrete, and with the increase of curing age tc, the effects of anti-corrosion coating / treating on reducing the surface chloride ion content Cs and apparent chloride ion diffusion coefficient Da of concrete becomes more significant. Taking into account the development of mechanical properties of cast-in-place concrete in the marine tidal zone environment and the effectiveness of anti-corrosion coating / treating measures, it is recommended to use silane and polyurethane coatings for coating with a curing age of not less than 5 and 10 d, respectively. [ABSTRACT FROM AUTHOR]

Plant fibers have the characteristics of light weight, high specific strength and high elongation at break, which can improve the shortcomings of concrete such as easy cracking, low tensile strength and brittle damage. At the same time, plant fibers can improve the thermal insulation properties and durability of concrete. First of all, the chemical composition and mechanical characteristics of various commonly used plant fibers were analyzed, and the modification methods of plant fibers were also discussed. Then, the researches of domestic and foreign scholars on mechanical properties, hydration characteristics, thermal insulation properties and other properties of plant fiber reinforced concrete were analyzed and summarized in detail. And the following conclusions are drawn: when using plant fibers to enhance the strength of concrete, the long fiber lay-flat method has the best effect on the enhancement of tensile strength, while the short fiber in-mixing method has a wider range of applications, and at the same time, a variety of factors, such as fiber length, fiber content, and water-cement ratio, affect the mechanical properties of concrete; plant fibers can retard the release of heat of hydration by changing the hydration characteristics of cement, thus enhancing the crack resistance of mass concrete; plant fibers can improve the thermal insulation properties and durability of concrete, and reduce the cracking of concrete through the endotrophic effect of plant fibers on concrete. [ABSTRACT FROM AUTHOR]

Copyright of Paint & Coatings Industry (0253-4312) is the property of Paint & Coatings Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To investigate the effects of volume replacement rate of rubber coarse and fine aggregates on the stress-strain curve, the concept of volume replacement rate of rubber coarse and fine aggregates was defined. By collecting 110 existing experimental stress-strain curves from published literatures, the effects of rubber coarse and fine aggregate volume replacement rate on the key parameters of stress-strain relationship of fiber reinforced polymer (FRP) confined rubber concrete with different sections were analyzed. Based on the analysis results, the stress-strain relationship model and compressive strength model of FRP confined rubber concrete were established. The factor effects of the volume replacement rate of rubber coarse and fine aggregates and the cross-sectional shape of rubber concrete were considered in the proposed models. The model evaluation results show that the compressive strength ratio of FRP confined rubber concrete is increased with the increasing of the volume replacement rate of rubber coarse and fine aggregates, the FRP confinement stress ratio and the cross-sectional corner radius ratio. The proposed compressive strength model can accurately predict the compressive strength of FRP confined rubber concrete with rubber particles replacing part of fine aggregate or coarse and fine aggregate, and the average error value is 1.03. The predicted curves of the proposed stress-strain model are consistent with the experimental stress-strain curves of FRP confined rubber concrete. [ABSTRACT FROM AUTHOR]

By simulating the high-temperature service environment of tunnel lining concrete, this study investigates the compressive and impermeable properties of tunnel lining concrete at 20, 60, and ambient temperature of 80 ℃ for 3, 7, and 28 d, and analyzes the changes in compressive and impermeable properties of tunnel lining concrete under high-temperature environmental conditions, in order to provide theoretical support and empirical reference for the construction of tunnel lining concrete under high-temperature environmental conditions. The results indicate that a high-temperature curing environment can improve the compressive strength of tunnel lining concrete at 3 and 7 d, but an 80 ℃ high-temperature curing environment can reduce the compressive strength of tunnel lining concrete at 28 d；With the increase of ultrafine powder content, the compressive strength of tunnel lining concrete first increases and then decreases. When the content is 30%, the compressive strength of concrete is the highest；With the increase of temperature and the addition of ultrafine powder, the electrical flux of tunnel lining concrete generally shows a downward trend. In the same mix, the modal chord length of concrete specimens does not show a significant change with the increase of curing temperature, but the average chord length decreases with the increase of curing temperature. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Construction measures and material failures at expansion joints of utility tunnels often lead to concrete cracking and water leakage issues. The use of superhydrophobic concrete can effectively prevent water leakage at these expansion joints. By dripping a mixture of silicone and turpentine onto pre-cured concrete and using a rapeseed oil soot deposition method,the surface is transformed to possess superhydrophobic properties. The prepared silicone-soot composite material inhibits the absorption of water and corrosive ions,provides thermal insulation to the original concrete,and can resist mechanical abrasion,heavy rainfall,and dynam ic impact from sulfuric acid droplets. Thereby enhancing the waterproofing capabilities of underground utility tunnels. [ABSTRACT FROM AUTHOR]

For the improvement of asphalt-based waterproofing membrane bonding effect on the concrete surface,this paper systematically studied the changes in surface functional groups after surface oxygen,nitrogen and air plasma treatment and molecu lar grafting of waterproofing membranes. The surface functional groups established through plasma treatment are further modified with polyhydroxy or silyl functional molecules,such as silane reagents,dopamineand lignin,to optimize molecular branching and concrete bonding capacity.Through the contact angle measurement,infrared spectroscopy,XPS and other means,it found that the plasma treatment of modified asphalt-based waterproofing membrane surface shows obvious hydrophilicity changes and the corre sponding chemical functional group absorption peaks,proving the realization of the plasma treatment of modified surface groups and the success of the branching molecules. It can enhance the bonding effect between waterproof membrane and concrete. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: To effectively address the disposal issues of gold tailings and alleviate the shortage of sandstone resources,this study investigated the potential of utilizing gold tailings as a partial replacement for natural sand in the production of gold tailings concrete. Method: Through a series of cube compressive strength tests and orthogonal experimental methods,this research conducted a comprehensive analysis of the impacts of four factors: water-binder ratio, go Id tailings substitution rate, sand ratio, and fly ash content, on the 28-day compressive strength of gold tailings concrete. The systematic analysis was performed using range and variance analysis methods, which determined the relative importance of each factor in influencing the 28-day compressive strength of the concrete. Furthermore,a multiple regression equation was established for predicting the compressive strength of gold tailings concrete based on the orthogonal experimental data. Conclusion: The results indicated that the water-binder ratio had the most significant effect on the compressive strength, followed by the gold tailings substitution rate, fly ash content,and sand ratio. The regression equation,with an R2 value of 0. 872,can predict the compressive strength to a considerable degree. Significance: The research results can provide some reference value for the comprehensive utilization of gold tailings resources. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This is an article in the field of ceramics and composites. Taking ilmenite ore as the research object, the possible phase transformation of FeTiO3 in concrete liquid phase environment was analyzed in order to provide a basis for the utilization of ilmenite tailings. The thermodynamic stability of ilmenite (FeTiO3) was analyzed by thermodynamic calculation. Ilmenite ore powder was soaked in simulated concrete pore solution at 20 ℃ and 80 ℃ for 28 d and 270 d, XRD and SEM/EDS were used to detect mineral transformation. Using ilmenite ore to replace part of the gravel to prepare concrete, the influence on concrete strength at 20 ℃ and 80 ℃ was studied respectively. The results of thermodynamic calculations show that FeTiO3 is unstable in the environment of O2 and converts into Fe3O4 or Fe2O3 and TiO2. The immersion experiment of ilmenite in the simulated concrete pore solution shows that ilmenite has no obvious changes. The concrete strength test shows that at 20 ℃ and 80 ℃, when ilmenite ore replaces 5% crushed stone, the compressive strength of concrete increases, and when the replacement is 15%, the compressive strength decreases, the reason is that the quartz in the ilmenite ore has undergone an alkali aggregate reaction.

This is an article in the field of ceramics and composites. Alkali-activated Slag-fly Ash-based Geopolymer (ASFG) has excellent properties such as high early strength, acid and alkali resistance, but its large brittleness and poor toughness affect its popularization and application. In order to improve the properties of ASFG and broaden the types of mineral admixtures that can be used for ASFG modification, six kinds of mineral admixtures, including metakaolin, zeolite powder, bentonite, wollastonite powder, light calcium carbonate and silica fume, are used as modified materials, and their modification effects on ASFG are studied. The optimum modified material is silica fume. In order to further explore the improvement effect of silica fume on the mechanical properties of ASFG, the effect of the content of silica fume on the mechanical properties of ASFG is studied, and the optimal content of silica fume is determined. Finally, Alkali-activated Slag-fly Ash-silica Fume-based Geopolymer Concrete (ASFSGC) is prepared, and its workability, quasi-static mechanical properties and impermeability are studied. The results show that bentonite, wollastonite powder, light calcium carbonate and silica fume can significantly improve the flexural strength of ASFG. Wollastonite powder and silica fume can significantly improve the compressive strength of ASFG. For ASFG, silica fume is a premium mineral admixture. With the increase of silica fume content, the mechanical properties of ASFG first increase and then decrease, and the optimal content of silica fume is 4%. ASFSGC has good workability and excellent impermeability, and the ductility of ASFSGC is 14.1% larger than that of ordinary Portland cement concrete.

This is an article in the field of ceramics and composites. To achieve the resource utilization of fly ash and accurately assess the compressive strength of fly ash concrete, three predictive models for compressive strength were constructed using machine learning modeling techniques, including traditional linear regression, decision tree, and support vector machine models. These models were utilized to model and analyze the compressive performance of the concrete. Firstly, a corresponding experimental database was established, with seven input parameters including cement, fly ash, water reducer, coarse aggregate, fine aggregate, water, and curing age, and the compressive strength as the output parameter. Based on 10-fold cross-validation, the performance of the three models on the training set was evaluated using root mean square error (RMSE), mean absolute error, and correlation coefficient, and their performance on the test set was compared. The results showed that curing age had a high correlation with compressive strength (0.60), and the correlation of fly ash with compressive strength was higher than that of cement. The traditional linear regression model exhibited an RMSE of 7.27 and 5.91 on the training and test sets, respectively. The decision tree model showcased an RMSE of 2.72 and 9.23 on the respective sets, while the support vector machine model yielded an RMSE of 5.34 and 4.09. Overall, the support vector machine model exhibited good accuracy and robust performance in predicting the compressive strength of fly ash concrete. This research can provide strength design guidance for concrete using fly ash and promote the resource utilization of fly ash.

In order to utilize the huge stock of coal gasification slag (CGS) as an alternative to river sand, the feasibility of coal gasification slag concrete for road construction is studied, and the influence of CGS on the performance of cement-based material is investigated. Using the CGS (particle size below 4.75 mm) as fine aggregate, the CGS mortar is made by replacing river sand with the same mass CGS. Replacement ratios are 0%, 20%, 40%, 60%, and 80%, respectively. Through the mortar fluidity test, compressive strength test, X-ray diffraction analysis, mercury intrusion analysis, scanning electron microscopy, and energy spectrum analysis, the influence of CGS replacement ratio on the rheological property, mechanical property, hydration product, pore structure and micro morphology of the mortar are systematically studied. The optimal substitution rate of CGS is determined through comprehensive comparison and selection, and the mix design of CGS concrete for road construction is carried out using this substitution rate. The mechanical performance reliability of CGS concrete is evaluated based on 28 d flexural tensile strength. The results show that as the substitution rate of CGS increases, the flowability of CGS mortar gradually decreases and the compressive strength at 28 days gradually increases. Taking into account the fluidity and mechanical properties of the mortar, the optimal substitution rate for CGS is 80%, and the corresponding compressive strength of CGS mortar is 34 MPa. The microscopic analysis shows that the CGS can promote the cement hydration reaction of CGS mortar, increase the relative content of C—S—H gel, and reduce the content of C2S and C3S. The addition of CGS reduces the critical pore size, average pore size, and median pore size of mortar, increases the proportion of small pore size, improves its pore size distribution type, and thus increases the proportion of small pore size, resulting in a decrease in pore connectivity and higher compactness. After adding CGS, the CGS mortar does not produce new hydration products, which reduces the calcium silica ratio of C—S—H gel, enhances the crystallinity of gel, and improves the durability of mortar. With variation coefficient 0.1, the CGS concrete with a substitution rate of 80% can ensure the use of cement concrete pavement for rural road without standard axle load for 10 years.

To investigate the direct shear behavior of residual soil-concrete interface under different roughness coefficients, ovendried residual soil samples were prepared at different water contents (13%, 19%, 25%) to form remolded soil samples, which were then subjected to a series of monotonic direct shear tests using a pneumatic direct shear apparatus against 3D-printed concrete blocks with varying roughness coefficients under normal stresses of 30, 60, 90 kPa. The effects of different factors on the shear stress-shear displacement characteristics was examined at the residual soil-concrete interface, as well as the vertical displacement-shear displacement patterns and strength indicators. The experimental results indicate that the interface shear strength increases with the increase of contact surface roughness coefficient, initially rises and then decreases with increasing water content, reaching a peak around 19% water content. The interface friction angle shows little variation with increasing roughness coefficient, while it tends to increase initially and then decreases with increasing water content. The interface cohesion increases with the roughness coefficient initially and then stabilizes, while it increases initially and then decreases with increasing water content. The fitting results of the roughness coefficient, water content, and shear strength suggest that the peak values of interface shear strength are achieved at water content ranging from 15% ~ 20% and contact surface roughness coefficients ranging from 16 ~ 18. [ABSTRACT FROM AUTHOR]

In order to investigate the high-temperature performance of graphene oxide modified concrete and the effect of different cooling methods on concrete performance, FIB-SEM microscopic observation was performed on the benchmark group and the test group with 0.05% graphene oxide. The effects of natural cooling, immersion cooling, and spraying cooling at different high-temperature nodes on the concrete mass loss rate, mechanical characteristics of the samples, and uniaxial compressive stress-strain constitutive equation were studied. The results show that the peak stress and modulus of elasticity of the benchmark group and graphene group are gradually decreasing with the increase of heat treatment temperature, and the mass loss rate and peak strain are gradually increasing, but the graphene oxide improves the mechanical properties and high temperature resistance of concrete by refining the pore size and adjusting the microstructure of cement hydration products, and thus showing better mechanical properties. Different cooling methods have different effects on the mechanical properties, which are positively correlated with the cooling rate, i.e., immersion cooling > spraying cooling > natural cooling, and the uniaxial compressive stress-strain relationship can be described by the segmental equation. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Mechanics is the property of Chinese Journal of Applied Mechanics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To realize the resource utilization of solid waste of iron tailings, steel slag and phosphorus slag, reduce the amount of cement and reduce the adverse impact of iron tailings powder as admixture on concrete, three admixtures of phosphorus slag powder, desulfurization ash powder and steel slag powder were introduced based on high-silicon iron tailings powder. The compressive properties of iron tailing powder-phosphorus slag powder-desulfurization ash powder (IPD), iron tailing powder-phosphorus slag powder-steel slag powder (IPS) and iron tailing powder-steel slag powder-desulfurization ash powder (ISD) concretes were investigated. Mercury injection test and backscattered electron were used to test and analyze the internal pores and interfacial transition zone of concrete. The results show that the 28-day compressive strengthes of IPD system, IPS system and ISD system respectively reach 80.1%, 92.4% and 82.5% of that of pure cement concrete, and the interfacial transition zone between aggregate and cement is more dense after the addition of the admixture with reduced porosity to different degrees. The filling effect of the admixture is well exerted, and the adverse influence of internal porosity on concrete is alleviated. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The effects of single and compound fly ash and plastic waste on the mechanics and durability of concrete modified with fly ash and polypropylene particles are studied. The results show that the appropriate amount of fly ash has no obvious effect on the mechanical properties of concrete at late age, and the appropriate amount of fly ash can improve the durability of concrete at late age. Single-doped polypropylene plastic particles reduce the mechanical properties and durability of concrete. The mechanical properties and durability of concrete in the late stage can be effectively improved by adding fly ash and polypropylene particles in appropriate amount. When the mass ratio of fly ash and polypropylene particles is 1:1, the mechanical properties and durability of concrete are better under the condition that the total content is 30%. [ABSTRACT FROM AUTHOR]

Copyright of Multipurpose Utilization of Mineral Resources / Kuangchan Zonghe Liyong is the property of Multipurpose Utilization of Mineral Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Multipurpose Utilization of Mineral Resources / Kuangchan Zonghe Liyong is the property of Multipurpose Utilization of Mineral Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To study the influences of fire extinguishing agents on the mechanical performance of concretes after high temperatures, specimens of different curing ages were heated to different temperatures at 5 °C/ min and 10 °C / min heating rates, and then they were maintained at different constant temperatures of 200 °C, 400 °C, 600 °C and 800 °C for one hour. The mass loss rate of specimens of different curing ages and heating temperatures were tested. Specimens were moved into a tempered glass frame. Water, Halon 1211, CO2 and HFC-227ea were used to treat these specimens. The results showed that the mass loss rates of the specimen with 7 d and 14 d curing age were significantly higher than that in 28 d curing age at 400 °C . Fire extinguishing agents did not affect the compressive strength of the specimens at room temperature. Water, Halon 1211, and HFC-227ea could reduce compressive strength of the specimens after high temperature treatment at 400 °C and 600 °C . However, water cooling treatment at 600 °C could increase the compressive strength of the specimen with 7 d and 14 d curing age by 9.14% and 9. 18%. Curing age did not affect the experimental results of Halon 1211 and HFC-227ea, and the compressive strength of the specimen was relatively low at 800 °C, which could not reflect the influence of different treatment methods on the compressive strength. Water, Halon 1211, and HFC-227ea fire extinguishing agents could reduce the splitting tensile strength of concrete at 400 °C. CO2 had no influence on the compressive strength and splitting tensile strength of concrete. [ABSTRACT FROM AUTHOR]

In order to explore the mechanical properties of undisturbed sea sand concrete with high chlorine concentration and high shell content, taking the chloride ion content and shell content of sea sand as variables, nine groups of sea sand concrete were designed and prepared to carry out concrete cube compressive strength test and uniaxial compressive stress-strain curve test, and compared with ordinary concrete. The results show that with the increase of chloride ion content, the pore structure of concrete becomes finer, the early strength increases, the peak stress of uniaxial compressive stress-strain complete curve increases, the peak strain decreases, and the elastic modulus increases. With the increase of shell content, the slump of concrete decreases significantly, the pore structure of concrete becomes looser, the strength decreases, and the peak stress of uniaxial compressive stress-strain complete curve decreases, the peak strain increases, and the elastic modulus decreases. Finally, based on the existing models, the formula for calculating the model parameters of chloride ion content and shell content is put forward. [ABSTRACT FROM AUTHOR]

Using manufactured sand, extra fine sand and other materials to prepare chloride resistance concrete is of great significance to reduce production costs and improve the service life of bridges in coastal areas. In this study, the chloride resistance of concrete was improved by optimizing aggregate design and cement paste composition. The effects of aggregate gradation, extra fine sand content, sand ratio, water-binder ratio and cementitious material type on concrete performance were studied. The results show that the chloride diffusion coefficient decreases from 4.0 x 10-12 m²/s to 2.9 x 10-12 m²/s when the mass fraction of 8 ~ 16 mm gravel increases from 50% to 80%. When 50% (mass fraction) manufactured sand is replaced by extra fine sand, the chloride diffusion coefficient is 3.6 x 10-12 m²/s, which can still meet the design requirements. With the increase of sand ratio, the chloride diffusion coefficient decreases first and then increases. The water-binder ratio is controlled in the range of 0.36 ~ 0. 38, and the chloride diffusion coefficient is less than 3.5 x 10-12 m²/s. The hydration of slag component improves the pore structure of concrete, and forms more AFm and C-S-H, which improves the chloride binding capacity. The chloride diffusion coefficient of concrete with slag cement is 40% lower than that of OPC. [ABSTRACT FROM AUTHOR]

In response to the problem of reduced durability of concrete structures in the northwest region of China under salt frost erosion, this study selected concrete specimens with different polypropylene fiber contents (0, 0. 6, 0.9, 1.2, 1.5 kg ⋅ m-3) and placed them in clear water, 3% NaCl, and 5% Na2SO4 solutions for freeze-thaw cycle testing. The changes in mass loss rate, dynamic elastic modulus and compressive strength of specimens were analyzed, and standard models were established based on Weibull theory and grey theory to predict the maximum service life of polypropylene fiber reinforced concrete structures. At the same time, SEM was used to analyze the mechanism of polypropylene fiber reinforced concrete. The results show that the damage caused by clear water freeze-thaw conditions to concrete is lower than that caused by salt freeze-thaw erosion with chloride salt causing the most severe erosion damage to mechanical properties of concrete. The infiltration of polypropylene fibers can effectively slow down the degradation rate of mechanical properties of concrete under freeze-thaw erosion and weaken the impact of external erosion on compressive strength. The optimal effect is achieved when the fiber content reaches 1.2 kg ⋅ m-3. The life prediction results of grey prediction model and Weibull model are roughly similar. The grey prediction model can only make large-scale inferences based on data currently contained, while Weibull model has more accurate prediction results. This result can provide theoretical guidance and basis for studying the mechanical properties of concrete and selecting the best model to predict the service life of concrete. [ABSTRACT FROM AUTHOR]

In order to study the compressive properties of desert sand concrete (DSC) after high temperature, desert sand was used to replace medium sand with replacement rate of 0%, 20%, 40%, 60%, 80% and 100% (by mass) to make DSC. The effects of fire temperature and desert sand replacement rate (DSRR) on the rebound value, ultrasonic velocity and compressive strength of DSC were analyzed. The grey prediction strength model of DSC after high temperature was established. Ultrasonic-rebound comprehensive method for measuring strength curve of DSC and formula of fire temperature were deduced. The results show that with the increase of fire temperature, the ignition loss rate of DSC increases gradually, specimen surface colour gradually changes from deep to shallow, and the compressive strength, rebound value, ultrasonic velocity of DSC increase first and then decrease. With the increase of DSRR, the rebound value and compressive strength of DSC increase first and then decrease. When DSRR is equal to 40%, the compressive strength and rebound value of DSC reach the maximum. The NSGM (1,3) model has excellent prediction performance with an average relative error of 8.6%, which can be used to predict the medium and long-term compressive strength of DSC after high temperature. The prediction accuracy of DSC ultrasonic-rebound comprehensive method for measuring strength curve meets the requirements of specification. [ABSTRACT FROM AUTHOR]

To explore the influences of different coarse aggregate replacement ratios on the high-temperature performance of recycled concrete with manufactured sand (RCM), RCM specimens were prepared with varying coarse aggregate replacement ratios (0%, 20%, 40%, 60%, 80%, 100%, mass fraction). The surface morphology, mass loss rate, compressive strength, load-deformation curve, and microscopic morphology of RCM were investigated after exposure to high temperatures. Results indicate that the RCM performs well in high-temperature tests below 600 °C when the coarse aggregate replacement ratio is between 40% and 60%. At 200 °C, the specimens in each group show minimal morphological changes, small mass loss rate, and a slight increase in compressive strength. At 400 °C, cracks begin to appear on the surface of the specimens, with mass loss rate ranging from 4. 35% to 6. 47%, and compressive strength starts to decline. At this point, the coarse aggregate replacement ratio has a minor impact. At 600 °C, significant changes in surface morphology are observed, with mass loss rate increasing to 6. 42% ~ 8.70%, and compressive strength eventually decreasing to around 80% of the baseline strength. Specimens with coarse aggregate replacement ratio of 40% ~ 60% perform well under these conditions. At 800 °C, the surface morphology of specimens in all groups intensifies further. The impact becomes particularly pronounced for coarse aggregate replacement ratio exceeding 60%. Simultaneously, various performance parameters indicate that the concrete has experienced a complete loss of effectiveness at this temperature. [ABSTRACT FROM AUTHOR]

The organic isooctyltriethoxysilane (TS) and inorganic nanosilicon dioxide (nano-SiO2) were combined to prepare monolithic superhydrophobic hydraulic concrete by "binary synergistic" biomimetic method, and the effects of TS dosage and curing conditions on the mechanical properties and hydrophobicity properties of concrete were investigated. The microscopic morphology, phase composition and hydrophobic modification mechanism of materials were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and fourier transform infrared spectrometer (FT-IR). The results show that the curing conditions have a large influence on the hydrophobicity of concrete. Under natural curing conditions, when TS dosage reaches 3% (mass fraction), the concrete all exhibits superhydrophobicity, with a maximum contact angle of 155.6°. The incorporation of nanoparticles promotes cement hydration and enhances compressive strength of specimens. The modified hydraulic concrete has good hydrophobicity, and the water absorption rate decreases by 68.8% in 288 h immersion. [ABSTRACT FROM AUTHOR]

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In the internal support system of foundation pit engineering, concrete support has been widely used in foundation pit engineering due to its advantages of high bearing capacity, unrestricted layout, cast-in-place end nodes and good integrity. However, the disadvantages of concrete support in design and construction are also very obvious, with problems such as large design section, long construction time, heavy pollution, high cost and serious waste. Therefore, in view of the advantages and disadvantages of concrete support in foundation pit engineering and combined with the characteristics of deep foundation pit engineering of metro open cut station, the prefabricated composite concrete filled steel tube internal support is designed in this paper. From the perspective of improving the stiffness and strength of end joints and achieving fixed connection at the end, a fixed end composed of long bolts and mold bag concrete is proposed, which is suitable for the prefabricated composite steel tube concrete internal support of metro foundation pit. The design scheme, structural characteristics and working principle of the fixed end are explained and compared with the cast-in-place concrete support node, which shows that the fixed end plays the role of fixed support in the support system, which is composed of special components such as embedded steel plate, hollow flange, bag concrete and long bolt. In order to establish the theoretical basis for the design and check of the fixed end, the analytical method of the compression and bending load-bearing capacity of the fixed end is obtained by analyzing the mechanical mechanism, failure mode and evolution law of the fixed end. In order to verify the feasibility of the theoretical analysis method of the bearing capacity of the fixed end, the theoretical and numerical results are verified and analyzed by numerical simulation, and the main factors affecting the bearing capacity of the fixed end are parameterized. [ABSTRACT FROM AUTHOR]

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Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Beijing University of Civil Engineering & Architecture is the property of Journal of Beijing University of Civil Engineering & Architecture Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)