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Peng Zhang
Center for Durability & Sustainability Studies of Shandong Province, Qingdao University of Technology, 266033 Qingdao, P. R. China

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Journal article
Published: 21 July 2021 in Journal of Materials Research and Technology
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Solid waste building material treatment is an essential means of disposal and an active research area. Despite this, the multisource characteristics, large volumes and complex compositions of solid waste necessitate new requirements for its treatment. In this paper, a typical resource-based coastal city is considered the research object. Fly ash (FA), furnace slag (FS) and mineral powder (MP) are taken as samples to investigate the influence of admixtures on the properties, pore structure and durability of foam concrete by three-factor and three-level orthogonal tests. Results indicate that foam concrete with different admixtures can have various mechanical and thermal insulation properties. The compressive strength of foam concrete can increase to 3.90 MPa, and its thermal conductivity can reach 0.1347 W/ M·k. MP has the largest apparent effect on the compressive strength, while FS has the most obvious impact on the thermal conductivity. The durability analysis shows that the number of freeze-thaw cycles foam concrete can withstand is 25∼100 cycles. The collaborative disposal of multisource inorganic solid waste has high potential for being applied as inner partition walls and thermal insulating components in buildings. This paper provides valuable guidance for the sustainable and clean utilization of multisource inorganic solid waste.

ACS Style

Qiang Song; Jiuwen Bao; Shanbin Xue; Peng Zhang; Mu Shining. Collaborative disposal of multisource solid waste: Influence of an admixture on the properties, pore structure and durability of foam concrete. Journal of Materials Research and Technology 2021, 1 .

AMA Style

Qiang Song, Jiuwen Bao, Shanbin Xue, Peng Zhang, Mu Shining. Collaborative disposal of multisource solid waste: Influence of an admixture on the properties, pore structure and durability of foam concrete. Journal of Materials Research and Technology. 2021; ():1.

Chicago/Turabian Style

Qiang Song; Jiuwen Bao; Shanbin Xue; Peng Zhang; Mu Shining. 2021. "Collaborative disposal of multisource solid waste: Influence of an admixture on the properties, pore structure and durability of foam concrete." Journal of Materials Research and Technology , no. : 1.

Journal article
Published: 16 July 2021 in Measurement
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Neutron radiography was employed to observe and quantify water exchange between fresh and old cement mortars. The influence of the initial moisture conditions (dry, water-saturated, and partially saturated) in the old mortar on water exchange at the interfaces was studied. The dynamic water content profiles in the repair and old mortars were determined as a function of time. The time-dependence of the water infiltration depth in the old mortar was analyzed. A desorption coefficient was defined to describe the water loss rate for the repair mortar. The results indicated the prewetting of the old mortar significantly decelerated its extraction of water from the repair mortar. A reversal of water migration was even found after the casting of repair mortar onto a water-saturated old mortar for a period of time. In addition, visual and quantitative investigation was performed for the influence of cracks on water redistribution in repair and old mortars.

ACS Style

Shanbin Xue; Peng Zhang; E.H. Lehmann; J. Hovind; F.H. Wittmann. Neutron radiography of water exchange across the interface between old and fresh mortar. Measurement 2021, 183, 109882 .

AMA Style

Shanbin Xue, Peng Zhang, E.H. Lehmann, J. Hovind, F.H. Wittmann. Neutron radiography of water exchange across the interface between old and fresh mortar. Measurement. 2021; 183 ():109882.

Chicago/Turabian Style

Shanbin Xue; Peng Zhang; E.H. Lehmann; J. Hovind; F.H. Wittmann. 2021. "Neutron radiography of water exchange across the interface between old and fresh mortar." Measurement 183, no. : 109882.

Journal article
Published: 26 June 2021 in Measurement
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Appling fresh mortar onto the surface of old concrete has been a common repair and reinforcement method. In this work, the influence of initial moisture conditions of old mortar on the microstructure of repair mortar was checked. Two types of composites were prepared by bonding fresh repair mortar with a pre-dried or a water-saturated old cement mortar. By analyzing X-ray CT images, severe shrinkage cracking was found in the repair mortar bonded with a pre-dried old mortar. A large discontinuity was revealed between repair mortar and pre-saturated old mortar by X-ray CT images. Various porosities in the repair mortar were identified by Mercury Intrusion Porosimetry tests. Dynamic water imbibition in the two types of composites was followed by neutron radiography. Shrinkage cracks in repair mortar can significantly promote water infiltration in both repair mortar and substrate, which poses a threat to the durability of the repair system.

ACS Style

Shanbin Xue; Fanqiang Meng; Peng Zhang; Junjie Wang; Jiuwen Bao; Linfeng He. Influence of substrate moisture conditions on microstructure of repair mortar and water imbibition in repair-old mortar composites. Measurement 2021, 183, 109769 .

AMA Style

Shanbin Xue, Fanqiang Meng, Peng Zhang, Junjie Wang, Jiuwen Bao, Linfeng He. Influence of substrate moisture conditions on microstructure of repair mortar and water imbibition in repair-old mortar composites. Measurement. 2021; 183 ():109769.

Chicago/Turabian Style

Shanbin Xue; Fanqiang Meng; Peng Zhang; Junjie Wang; Jiuwen Bao; Linfeng He. 2021. "Influence of substrate moisture conditions on microstructure of repair mortar and water imbibition in repair-old mortar composites." Measurement 183, no. : 109769.

Journal article
Published: 24 June 2021 in Journal of Building Engineering
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Triethanolamine (TEA) is known as a widely-used cement additive for regulating setting time, hydration process and mechanical strength. However, the working mechanism of TEA on blended cement with various kinds of minerals, has not yet thoroughly explored. This invesitigation focused on effects of TEA on the strength enhancement and hydration properties of the blended cementitious materials, containing fly ash, slag, limestone. Hydration heat evolution of the composite binder was studied by isothermal calorimetry. Pore size distribution was analyzed through mercury injection porosimetry (MIP), and the evolution of hydration products in the function of TEA was investigated by X-ray diffractometry (XRD), differential thermal analysis (DTA) and thermogravimetric analysis (TG). Microstructure and composition characteristics of hydration products were studied through scanning electron microscopy (SEM) equiped with energy dispersive X-ray spectroscopy (EDX). Results showed that strength enhancement effect of TEA varied when the component and proportion of cementitious materials altered. Containing 30% fly ash and 10% limestone, the composite binder got the optimal strength-enhancing effect to nearly 15%. When containing 30% slag and 10% fly ash, the composite binder obtained the worst strength-enhancing effect with about 5%. The addition of TEA prolonged the induction period, and enhanced the formation of AFt. With high aluminate glass phases, fly ash was vulnerable to be influenced by the complexation of TEA, and hence the pozzolanic reaction of fly ash was accelerated significantly, resulting in reduced content of Ca(OH)2 (CH) as well as increased production of hydrates. Limestone participated to accelerate the hydration of C3A, and provided microcrystals for the growth of hydrates. Slag was mainly composed of high calcium glass phases and was rarely impacted by the complexation of TEA. The findings would gain a comprehensive insight of TEA in affecting the hydration process of blended materials, and would provide expedient information on the technique to control the hydration progress of composite binder.

ACS Style

Yan He; Shuhua Liu; Xiong Zhang; Wenbin Liu; GaoYu Liao; Mingfeng Xu. Influence of triethanolamine on mechanical strength and hydration performance of blended cement containing fly ash, limestone and slag. Journal of Building Engineering 2021, 44, 102879 .

AMA Style

Yan He, Shuhua Liu, Xiong Zhang, Wenbin Liu, GaoYu Liao, Mingfeng Xu. Influence of triethanolamine on mechanical strength and hydration performance of blended cement containing fly ash, limestone and slag. Journal of Building Engineering. 2021; 44 ():102879.

Chicago/Turabian Style

Yan He; Shuhua Liu; Xiong Zhang; Wenbin Liu; GaoYu Liao; Mingfeng Xu. 2021. "Influence of triethanolamine on mechanical strength and hydration performance of blended cement containing fly ash, limestone and slag." Journal of Building Engineering 44, no. : 102879.

Journal article
Published: 12 May 2021 in Construction and Building Materials
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The exploration of sustainable and green cement-based materials prepared from industrial solid wastes is an important research direction in the development of new building materials. This paper carried out a quantitative comparative study of the influences of different composite mineral admixtures prepared with fly ash, steel slag, and ground granulated blast furnace slag (GBFS) as supplementary cementitious materials (SCMs) on the early hydration, long-term (360 d and 720 d) mechanical properties and penetrability of cement-based systems. The results show that adding GBFS and steel slag has the greatest influence on the early hydration of cement due to their synergistic reactions. Over time, it becomes increasingly apparent that adding composite admixtures containing GBFS and fly ash can refine the long-term pore structure, reduce the brittleness, improve the long-term strength and chloride ion penetrability resistance of concrete to the greatest extent. However, adding composite admixtures containing steel slag and fly ash has no positive impact on the long-term properties of concrete. From a comprehensive perspective, considering early hydration, long-term properties and economic costs, composite admixtures containing GBFS and steel slag have potential for wide popularization and applications which can promote the sustainable utilization of steel slag and cleaner production of green concrete.

ACS Style

Jianwei Sun; Peng Zhang. Effects of different composite mineral admixtures on the early hydration and long-term properties of cement-based materials: A comparative study. Construction and Building Materials 2021, 294, 123547 .

AMA Style

Jianwei Sun, Peng Zhang. Effects of different composite mineral admixtures on the early hydration and long-term properties of cement-based materials: A comparative study. Construction and Building Materials. 2021; 294 ():123547.

Chicago/Turabian Style

Jianwei Sun; Peng Zhang. 2021. "Effects of different composite mineral admixtures on the early hydration and long-term properties of cement-based materials: A comparative study." Construction and Building Materials 294, no. : 123547.

Journal article
Published: 19 April 2021 in Sustainability
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Cement-based materials prepared with activated water induced by a magnetic field or electric field represent a possible solution to environmental issues caused by the worldwide utilization of chemical admixtures. In this contribution, electric- and magnetic-activated water have been produced. The workability and mechanical properties of cement mortar prepared with this activated water have been investigated. The results indicate that the pH and absorbance (Abs) values of the water varied as the electric and magnetic field changed, and their values increased significantly, exhibiting improved activity compared with that of the untreated water. In addition, activated water still retains activity within 30 min of the resting time. The fluidity of the cement paste prepared with electric-activated water was significantly larger than that of the untreated paste. However, the level of improvement differed with the worst performance resulting from cement paste prepared with alternating voltage activated water. In terms of mechanical properties, both compressive strength and flexural strength obtained its maximum values at 280 mT with two processing cycles. The compressive strength increased 26% as the curing time increased from 7 days to 28 days and flexural strength increased by 31%. In addition, through the introduction of magnetic-activated water into cement mortar, the mechanical strength can be maintained without losing its workability when the amount of cement is reduced.

ACS Style

Kaiyue Zhao; Peng Zhang; Bing Wang; Yupeng Tian; Shanbin Xue; Yuan Cong. Preparation of Electric- and Magnetic-Activated Water and Its Influence on the Workability and Mechanical Properties of Cement Mortar. Sustainability 2021, 13, 4546 .

AMA Style

Kaiyue Zhao, Peng Zhang, Bing Wang, Yupeng Tian, Shanbin Xue, Yuan Cong. Preparation of Electric- and Magnetic-Activated Water and Its Influence on the Workability and Mechanical Properties of Cement Mortar. Sustainability. 2021; 13 (8):4546.

Chicago/Turabian Style

Kaiyue Zhao; Peng Zhang; Bing Wang; Yupeng Tian; Shanbin Xue; Yuan Cong. 2021. "Preparation of Electric- and Magnetic-Activated Water and Its Influence on the Workability and Mechanical Properties of Cement Mortar." Sustainability 13, no. 8: 4546.

Journal article
Published: 16 April 2021 in Journal of Cleaner Production
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Industrial and construction solid waste regarded as a hazardous material has given rise to the potential threats of environmental pollution. The ferronickel slag (FNS) as an industrial by-product and recycled concrete aggregates (RCAs) derived from construction and demolition wastes have potential for sustainable use as the fine and coarse aggregate in concrete, respectively. However, less information regarding the re-utilization of FNS as fine aggregate in recycled aggregate concrete (RAC) and the effects on transport properties can be found in the previous literature. The aim of this study is to investigate the compressive strength and transport behavior of RAC incorporating FNS as fine aggregate. In this study, several groups of specimens with different replacement ratios of FNS as fine aggregate (0, 20%, 40% and 50%) and RCAs (0, 50% and 100%) as coarse aggregate were prepared. The compressive strengths of FNS-RAC specimens at curing age of 3, 7 and 28 days were measured. The coupled effects of FNS and RCAs on the resistance to water absorption and chloride penetration of concrete were discussed. To explore the effect of microstructure on transport behavior, the tests of scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) were further conducted. Overall, the sorptivity and chloride diffusion coefficient increase as the RCA replacement ratio increases, but they generally decrease with increasing of FNS content. The mixtures containing 40%–50% FNS fine aggregate in RAC exhibit the greater compressive strength and better resistance to transport behavior.

ACS Style

Jiuwen Bao; Zihao Yu; Licheng Wang; Peng Zhang; Xiaomei Wan; Song Gao; Tiejun Zhao. Application of ferronickel slag as fine aggregate in recycled aggregate concrete and the effects on transport properties. Journal of Cleaner Production 2021, 304, 127149 .

AMA Style

Jiuwen Bao, Zihao Yu, Licheng Wang, Peng Zhang, Xiaomei Wan, Song Gao, Tiejun Zhao. Application of ferronickel slag as fine aggregate in recycled aggregate concrete and the effects on transport properties. Journal of Cleaner Production. 2021; 304 ():127149.

Chicago/Turabian Style

Jiuwen Bao; Zihao Yu; Licheng Wang; Peng Zhang; Xiaomei Wan; Song Gao; Tiejun Zhao. 2021. "Application of ferronickel slag as fine aggregate in recycled aggregate concrete and the effects on transport properties." Journal of Cleaner Production 304, no. : 127149.

Journal article
Published: 08 April 2021 in Sustainability
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Chloride binding capacity and its effect on the microstructure of mortar made with marine sand (MS), washed MS (WMS) and river sand (RS) were investigated in this study. The chloride contents, hydration products, micromorphology and pore structures of mortars were analyzed. The results showed that there was a diffusion trend for chloride ions from the surface of fine aggregate to cement hydrated products. During the whole curing period, the free chloride content in the mortars made by MS and WMS increased firstly, then decreased and stabilized finally with time. However, the total chloride content of three types of mortar hardly changed. The bound chloride content in the mortars made by MS and WMS slightly increased with time, and the bound chloride content included the MS, the WMS and the RS arranged from high to low. C3A·CaCl2·10H2O (Friedel’s salt) was formed at the early age and existed throughout the curing period. Moreover, the volume of fine capillary pore with a size of 10–100 nm increased in the MS and WMS mortar.

ACS Style

Congtao Sun; Ming Sun; Tao Tao; Feng Qu; Gongxun Wang; Peng Zhang; Yantao Li; Jizhou Duan. Chloride Binding Capacity and Its Effect on the Microstructure of Mortar Made with Marine Sand. Sustainability 2021, 13, 4169 .

AMA Style

Congtao Sun, Ming Sun, Tao Tao, Feng Qu, Gongxun Wang, Peng Zhang, Yantao Li, Jizhou Duan. Chloride Binding Capacity and Its Effect on the Microstructure of Mortar Made with Marine Sand. Sustainability. 2021; 13 (8):4169.

Chicago/Turabian Style

Congtao Sun; Ming Sun; Tao Tao; Feng Qu; Gongxun Wang; Peng Zhang; Yantao Li; Jizhou Duan. 2021. "Chloride Binding Capacity and Its Effect on the Microstructure of Mortar Made with Marine Sand." Sustainability 13, no. 8: 4169.

Journal article
Published: 02 April 2021 in Construction and Building Materials
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Water transport in the heat-damaged cement mortar is closely related to the evaluation of durability for structures exposed to fire and the recycling of thermally damaged cement-based materials. In this study, the influence of microstructure on water transport in unsaturated and saturated heat-treated cement mortar was analyzed based on experimental results from neutron radiography, water permeability, mercury intrusion porosimetry (MIP) and X-ray computed tomography (CT) tests. Neutron radiography was employed to track the dynamic wetting front in real time during water imbibition in the heat-treated mortar specimens exposed to a series of temperatures (105°C, 200°C, 400°C, 600°C, 800°C). The evolution of the wetting front was analyzed according to the square root of time based on neutron images. A deviation from the standard t1/2 pattern of the wetting front was found when water imbibition in the cement mortar specimens treated by a temperature ≥400°C. The absorptivities of different imbibition stages were determined for heat-damaged cement mortar. Mechanisms for the change of typical absorptivities with the evolution of thermal damage were discussed from the perspective of microstructure. In addition, causes for the occurrence of anomalous water absorption were explored by considering the role of thermal cracks and potential physicochemical reactions. Methods were proposed to estimate the effective tortuosity of water channels in the cement mortar damaged by different temperatures. The representative size of water channels was estimated with the calculated tortuosity. The estimated water channels size was compared with the pore aperture determined by MIP. At last, the estimated water channels size and tortuosity from imbibition data were utilized to predict the water permeability of the heat-treated mortar using a capillary model. By comparing the predicted and measured permeabilities, the correlation and difference between unsaturated and saturated water transport in the heat-treated cement mortar were analysed. Future work for modeling water transport in heat-damaged cement mortar was discussed.

ACS Style

Shanbin Xue; Peng Zhang; Junjie Wang; Jiuwen Bao; Songbai Han; Linfeng He. Influences of thermal damage on water transport in heat-treated cement mortar: Experimental and theoretical analyses. Construction and Building Materials 2021, 288, 123100 .

AMA Style

Shanbin Xue, Peng Zhang, Junjie Wang, Jiuwen Bao, Songbai Han, Linfeng He. Influences of thermal damage on water transport in heat-treated cement mortar: Experimental and theoretical analyses. Construction and Building Materials. 2021; 288 ():123100.

Chicago/Turabian Style

Shanbin Xue; Peng Zhang; Junjie Wang; Jiuwen Bao; Songbai Han; Linfeng He. 2021. "Influences of thermal damage on water transport in heat-treated cement mortar: Experimental and theoretical analyses." Construction and Building Materials 288, no. : 123100.

Journal article
Published: 16 March 2021 in Construction and Building Materials
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Recently, there has been an ongoing interest in the use of fly ash as an alternative to reduce cement content in cementitious composites. The addition of high-volume fly ash (HVFA) into strain hardening cementitious composites (SHCCs) as a strengthening layer for concrete not only improves the flexural performance, but also provides a sustainable approach to address a severe environmental concern. In this contribution, an experimental program was undertaken to determine the influence of SHCCs containing high-volume fly ash (HVFA-SHCC) working as a strengthening layer in a plain concrete beam on the flexural behavior of the layered structure, considering the layer thickness, re-curing conditions and curing time. The crack patterns, mid-span strain distributions, and load deflection curves were obtained based on a four-point bending test. Compared to that for the plain concrete, the specimens containing the HVFA-SHCC layer exhibited excellent crack control, and their failure mode gradually changed from flexure failure to shear failure with increased layer thickness. Moreover, a remarkable improvement in the strain hardening behavior was also found as increasing the layer thickness. Furthermore, an ultimate flexural toughness ratio was proposed, which has proven to be a valuable method to evaluate the flexural toughness of plain concrete beams containing HVFA-SHCC layers under different deformation conditions. The present study suggests that the optimal layer thickness of HVFA-SHCC is in the range of 25%-35% of the beam height in view of the flexural performance and cost. In addition, an improved flexural performance of a plain concrete beam containing an HVFA-SHCC layer is expected in an alkali environment.

ACS Style

Jun Shang; Kaiyue Zhao; Peng Zhang; Weina Guo; Tiejun Zhao. Flexural behavior of plain concrete beams containing strain hardening cementitious composite layers with High-Volume fly ash. Construction and Building Materials 2021, 286, 122867 .

AMA Style

Jun Shang, Kaiyue Zhao, Peng Zhang, Weina Guo, Tiejun Zhao. Flexural behavior of plain concrete beams containing strain hardening cementitious composite layers with High-Volume fly ash. Construction and Building Materials. 2021; 286 ():122867.

Chicago/Turabian Style

Jun Shang; Kaiyue Zhao; Peng Zhang; Weina Guo; Tiejun Zhao. 2021. "Flexural behavior of plain concrete beams containing strain hardening cementitious composite layers with High-Volume fly ash." Construction and Building Materials 286, no. : 122867.

Review article
Published: 07 January 2021 in Materials Characterization
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Cement hydration is a key process to determine most properties of cementitious materials. A deep understanding of cement hydration is thus favourable for the improvement of the overall properties of these materials and for providing solutions to the technique problems for concrete applications in terms of durability and sustainability. The conversion of water states is a fundamental process associated with cement hydration. Quasi-elastic neutron scattering (QENS) has recently emerged as a powerful non-destructive technique for studying the conversion of water states during cement hydration. The free water index and correlation parameters describing the states of the bound water and confined water can be quantitatively given. Compared with conventional methods of cement hydration characterization, QENS has a unique advantage. This paper summarizes the application of QENS for hydration in cement-based materials. In this review, the focus is first placed on the mechanism of the QENS method and the development of QENS spectrum analysis models to provide insight into the new technique. Then, the focus is shifted to its application for hydration and hydration kinetics in cement-based materials. Recent improvements in QENS facilities have allowed unexpected possibilities for studying complex hydration processes in cementitious materials. The potential of this promising technology for further research is outlined.

ACS Style

Kaiyue Zhao; Peng Zhang; Shanbin Xue; Songbai Han; Harald S. Müller; Yinguo Xiao; Yu Hu; Lijie Hao; Longwei Mei; Qingbin Li. Quasi-elastic neutron scattering (QENS) and its application for investigating the hydration of cement-based materials: State-of-the-art. Materials Characterization 2021, 172, 110890 .

AMA Style

Kaiyue Zhao, Peng Zhang, Shanbin Xue, Songbai Han, Harald S. Müller, Yinguo Xiao, Yu Hu, Lijie Hao, Longwei Mei, Qingbin Li. Quasi-elastic neutron scattering (QENS) and its application for investigating the hydration of cement-based materials: State-of-the-art. Materials Characterization. 2021; 172 ():110890.

Chicago/Turabian Style

Kaiyue Zhao; Peng Zhang; Shanbin Xue; Songbai Han; Harald S. Müller; Yinguo Xiao; Yu Hu; Lijie Hao; Longwei Mei; Qingbin Li. 2021. "Quasi-elastic neutron scattering (QENS) and its application for investigating the hydration of cement-based materials: State-of-the-art." Materials Characterization 172, no. : 110890.

Journal article
Published: 08 October 2020 in Construction and Building Materials
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Electrical capacitance tomography (ECT) is a novel non-destructive testing technology that can monitor the moisture content in cement-based materials with the application of a capacitive sensor. In this study, three types of ECT array capacitive sensors were developed, and a series of experiments was implemented using the designed sensors to investigate the influence of the relative humidity of a porous material on the capacitance. The experimental results indicate that the non-homogeneity of the sensitive field is improved within the measurement field by an external electrode sensor. Capacitive sensors with internal electrodes demonstrated more sensitivity to changes in moisture content under the same excitation conditions. In addition, the capacitance signals of sand and cement mortar increased exponentially as the relative humidity increased. Finally, a two-dimensional finite element method (FEM) was used to model the electromagnetic field distribution around capacitive sensors, and the numerical results agreed well with the experimental results, which indicated the feasibility of developing capacitive sensors. These findings may provide theoretical guidance for the engineering applications of capacitive sensors in the non-destructive testing of cement-based materials in the future.

ACS Style

Wentao Wang; Kaiyue Zhao; Peng Zhang; Jiuwen Bao; Shanbin Xue. Application of three self-developed ECT sensors for monitoring the moisture content in sand and mortar. Construction and Building Materials 2020, 267, 121008 .

AMA Style

Wentao Wang, Kaiyue Zhao, Peng Zhang, Jiuwen Bao, Shanbin Xue. Application of three self-developed ECT sensors for monitoring the moisture content in sand and mortar. Construction and Building Materials. 2020; 267 ():121008.

Chicago/Turabian Style

Wentao Wang; Kaiyue Zhao; Peng Zhang; Jiuwen Bao; Shanbin Xue. 2020. "Application of three self-developed ECT sensors for monitoring the moisture content in sand and mortar." Construction and Building Materials 267, no. : 121008.

Journal article
Published: 22 September 2020 in Journal of Analytical and Applied Pyrolysis
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In this paper, to investigate the catalytic pyrolysis behavior of coal (XJ) volatiles over two hematite (HA and HB), a double-layered fixed-bed reaction apparatus, which was easy to separate coal and catalysts was employed to measure the pyrolysis tar yield, and the composition of pyrolysis tar and gas was investigated by GC-MS and GC. The results indicated that both hematite A and hematite B reduced the tar yield and caused an increase in CH4, CO2 and H2 output. Analysis of the chemical composition of tar indicated that XJ had a high content of pitch (46.39 %). At the same time, the addition of HA and HB decreased the pitch content by 7.59 and 8.88 %, respectively. Then, the change in the hematite chemical composition and physical structure after catalytic pyrolysis was characterized by XRD, TEM, XPS, SEM and N2 adsorption-desorption. Furthermore, a catalytic mechanism was proposed to illustrate the transformation of pyrolysis tar over hematite. Fe atoms and lattice oxygen are the decisive factors in the bond cleavage of pyrolysis tar. Fe atoms can break the CC and CH bonds of aliphatic hydrocarbons, while lattice oxygen can promote CO bond cleavage and produce CO2.

ACS Style

Qiang Song; Hongyu Zhao; Shengqiang Chang; Li Yang; Fang Zou; Xinqian Shu; Peng Zhang. Study on the catalytic pyrolysis of coal volatiles over hematite for the production of light tar. Journal of Analytical and Applied Pyrolysis 2020, 151, 104927 .

AMA Style

Qiang Song, Hongyu Zhao, Shengqiang Chang, Li Yang, Fang Zou, Xinqian Shu, Peng Zhang. Study on the catalytic pyrolysis of coal volatiles over hematite for the production of light tar. Journal of Analytical and Applied Pyrolysis. 2020; 151 ():104927.

Chicago/Turabian Style

Qiang Song; Hongyu Zhao; Shengqiang Chang; Li Yang; Fang Zou; Xinqian Shu; Peng Zhang. 2020. "Study on the catalytic pyrolysis of coal volatiles over hematite for the production of light tar." Journal of Analytical and Applied Pyrolysis 151, no. : 104927.

Journal article
Published: 18 September 2020 in Journal of Materials Research and Technology
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Water repellent treatment is one of the effective means to improve the durability of concrete. This paper aims to investigate the water repellency of cement-based materials treated with silane-based water repellent agent under different exposure environments. Five different exposure conditions were applied in this experiment, namely, standard moist curing room, in-door laboratory atmosphere, pre-oven-dried condition, and out-door natural environment with or without shelter. Three different types of mortars with water-to-cement ratios of 0.4, 0.5 and 0.6 were prepared. And three different dosages (200, 400, 600 g/m2) of silane gel were utilized on the surface of specimens. The impregnation depth and water absorption after hydrophobic treatment have been measured. Results indicate that the initial moisture condition of mortar has a significant influence on the efficiency of surface silane impregnation. The depth of silane impregnation gradually decreases with the increase of initial moisture condition. The water repellency of surface impregnation of cement-based materials was well exhibited under the condition of about 50% relative humidity. It illustrated that the moisture within the cement-based materials affects the hydrolysis reaction process and the formation of hydrophobic membrane. Thus, the water repellency of cement-based materials greatly depends on the initial moisture content and the thickness of hydrophobic layer.

ACS Style

Jiuwen Bao; Shuguo Li; Peng Zhang; Shanbin Xue; Yifei Cui; Tiejun Zhao. Influence of exposure environments and moisture content on water repellency of surface impregnation of cement-based materials. Journal of Materials Research and Technology 2020, 9, 12115 -12125.

AMA Style

Jiuwen Bao, Shuguo Li, Peng Zhang, Shanbin Xue, Yifei Cui, Tiejun Zhao. Influence of exposure environments and moisture content on water repellency of surface impregnation of cement-based materials. Journal of Materials Research and Technology. 2020; 9 (6):12115-12125.

Chicago/Turabian Style

Jiuwen Bao; Shuguo Li; Peng Zhang; Shanbin Xue; Yifei Cui; Tiejun Zhao. 2020. "Influence of exposure environments and moisture content on water repellency of surface impregnation of cement-based materials." Journal of Materials Research and Technology 9, no. 6: 12115-12125.

Journal article
Published: 14 September 2020 in Construction and Building Materials
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Water re-curing has been recognized as a potential method to recover the mechanical strength and durability of heat-damaged cement-based materials, which benefits from the improvement of its microstructure due to the rehydration and carbonation of dehydration products. In this contribution, the influence of water re-curing on the microstructure of heat-damaged cement mortar was evaluated by combining Mercury Intrusion Porosimetry (MIP) with low-field Nuclear Magnetic Resonance (LF-NMR). The heat-damaged cement mortar specimens were prepared through exposing to a series of ascending temperatures (105 °C, 200 °C, 400 °C, 600 °C, 800 °C). First, the influence of water re-curing on the porosity and pore size of the heat-damaged cement mortar was analysed with the results of MIP tests. Then, the microstructural evolution of the heat-damaged cement mortar was monitored by means of LF-NMR in the process of water re-curing. At last, a conversion of T2 spectra into pore size distribution (PSD) curves was performed. Causes for the difference in the PSD curves determined by LF-NMR and MIP were discussed. Results demonstrated that LF-NMR was a powerful tool to follow the microstructural evolution of heat-damaged mortar specimens during water re-curing. When combined with MIP tests, the LF-NMR technique can provide quantitative information with respect to the evolution of PSD in a nondestructive way. Capillary pores can be segmented into smaller pores due to the filling of products generated by the rehydration of dehydrated products. The microdamage was partially healed after 10.5 days of water re-curing. The original exposure temperature has a noteworthy impact on the recovery rate and level of the heat-damaged mortar during water re-curing.

ACS Style

Shanbin Xue; Fanqiang Meng; Peng Zhang; Jiuwen Bao; Junjie Wang; Kaiyue Zhao. Influence of water re-curing on microstructure of heat-damaged cement mortar characterized by low-field NMR and MIP. Construction and Building Materials 2020, 262, 120532 .

AMA Style

Shanbin Xue, Fanqiang Meng, Peng Zhang, Jiuwen Bao, Junjie Wang, Kaiyue Zhao. Influence of water re-curing on microstructure of heat-damaged cement mortar characterized by low-field NMR and MIP. Construction and Building Materials. 2020; 262 ():120532.

Chicago/Turabian Style

Shanbin Xue; Fanqiang Meng; Peng Zhang; Jiuwen Bao; Junjie Wang; Kaiyue Zhao. 2020. "Influence of water re-curing on microstructure of heat-damaged cement mortar characterized by low-field NMR and MIP." Construction and Building Materials 262, no. : 120532.

Journal article
Published: 02 July 2020 in Materials Today Communications
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This contribution presents the self-healing performance of cracks in strain-hardening cement-based composites (SHCCs) containing different amounts of magnesia expansive agents (MEAs) with different reactivities. Specimens were preloaded under a four-point bending test to induce cracks and then exposed to water fog curing conditions. The changes in the crack width before and after curing were measured with a digital microscope, and a water absorption test was also performed to measure the sealing ability of the cracks. The test results show that three reactive MgO expansive agents can significantly improve the crack healing efficiency of SHCC under water fog curing conditions. However, the self-healing effect of the 10% dosage was not as good as that of the 5% dosage when the reactivity of the MEA was the same, and the MgO expansive agent with a reactivity value of 110 s shows the most promising effect on crack healing. Moreover, it should be noted that the 10% dosage was too high for the 110 s MgO expansive agent, resulting in poor volume stability.

ACS Style

Peng Zhang; Yuqing Dai; Wentao Wang; Jinbo Yang; Liwu Mo; Weina Guo; Jiuwen Bao. Effects of magnesia expansive agents on the self-healing performance of microcracks in strain-hardening cement-based composites (SHCC). Materials Today Communications 2020, 25, 101421 .

AMA Style

Peng Zhang, Yuqing Dai, Wentao Wang, Jinbo Yang, Liwu Mo, Weina Guo, Jiuwen Bao. Effects of magnesia expansive agents on the self-healing performance of microcracks in strain-hardening cement-based composites (SHCC). Materials Today Communications. 2020; 25 ():101421.

Chicago/Turabian Style

Peng Zhang; Yuqing Dai; Wentao Wang; Jinbo Yang; Liwu Mo; Weina Guo; Jiuwen Bao. 2020. "Effects of magnesia expansive agents on the self-healing performance of microcracks in strain-hardening cement-based composites (SHCC)." Materials Today Communications 25, no. : 101421.

Journal article
Published: 20 June 2020 in Advances in Materials Science and Engineering
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The fracture energy of the high-performance fiber-reinforced cement-based composite (HPFRCC) can be modified within wide limits by the variation of the amount of steel fibers added to the fresh mix. First of all, considering the actual engineering conditions in Qingdao, the materials commonly used in Qingdao were selected. The optimal reference mix proportion of the HPFRCC cementing material was proposed through determination of fluidity and flexural strength. Based on the optimal mix proportion, the uniaxial tensile, fracture, and dry shrinkage properties of HPFRCC with different steel fibers are systematically studied. Stress-strain diagrams of the different samples were measured under the uniaxial tensile test, wedge splitting test, and three-point bending test. The steel fiber content was varied between 0 and 200 kg/m3. The load bearing capacity and the fracture energy were determined experimentally. In addition, moisture loss as a function of time and shrinkage was determined in an environment of 20°C and 50% RH (relative humidity). The results indicate that the maximum load increases significantly in the HPFRCC series reinforced by 150 and 200 kg/m3 of steel fibers. Both have a hardening branch developed after the first crack deflection due to the high percentage of fibers bridging the crack surfaces. The load bearing capacity and fracture energy increased almost linearly with the steel fiber content. It was found that the three-point bending test is more applicable in measuring the fracture energy of HPFRCC than the wedge splitting test. The addition of steel fibers decreased the moisture diffusion and consequently the drying shrinkage of HPFRCC, and there was minimum weight loss and deformation when the steel fiber content was 150 kg/m3. The results obtained will be presented and discussed.

ACS Style

Weina Guo; Peng Zhang; Yupeng Tian; Bing Wang; Wan Ma. Influence of the Amount of Steel Fibers on Fracture Energy and Drying Shrinkage of HPFRCC. Advances in Materials Science and Engineering 2020, 2020, 1 -15.

AMA Style

Weina Guo, Peng Zhang, Yupeng Tian, Bing Wang, Wan Ma. Influence of the Amount of Steel Fibers on Fracture Energy and Drying Shrinkage of HPFRCC. Advances in Materials Science and Engineering. 2020; 2020 ():1-15.

Chicago/Turabian Style

Weina Guo; Peng Zhang; Yupeng Tian; Bing Wang; Wan Ma. 2020. "Influence of the Amount of Steel Fibers on Fracture Energy and Drying Shrinkage of HPFRCC." Advances in Materials Science and Engineering 2020, no. : 1-15.

Journal article
Published: 10 June 2020 in Construction and Building Materials
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The evaporation of water from chloride-contaminated concrete during drying process causes reverse convection of chloride ions, resulting in chloride ions to accumulate on the concrete surface, thus affecting concrete durability and service life. In this contribution, the pre-dried treatment, capillary absorption test, free diffusion test, drying test were carried out to experimentally investigate the influence of diffusion and convection on chloride transport. RCM test, isothermal adsorption and desorption test and constant permeability test were used to determine the simulation parameters, thus allowing an accurate simulation of the experiment results. Chloride transport was dominated by the inward diffusion in the free diffusion test, whereas chloride migration in the drying test was affected by the coupling effect of inward diffusion and outward convection. The shorter test days led to a more prominent effect of the reverse convection. The chloride diffusion coefficients varied with the pre-dried days, water-to-cement-ratio and diffusion test type with the best chloride resistance coming from specimens with lower water-to-cement-ratio and shorter pre-dried days. The numerical results agreed fairly well with experimental results obtained from the capillary absorption test, diffusion test and drying test.

ACS Style

Kaiyue Zhao; Yun Qiao; Peng Zhang; Jiuwen Bao; Yupeng Tian. Experimental and numerical study on chloride transport in cement mortar during drying process. Construction and Building Materials 2020, 258, 119655 .

AMA Style

Kaiyue Zhao, Yun Qiao, Peng Zhang, Jiuwen Bao, Yupeng Tian. Experimental and numerical study on chloride transport in cement mortar during drying process. Construction and Building Materials. 2020; 258 ():119655.

Chicago/Turabian Style

Kaiyue Zhao; Yun Qiao; Peng Zhang; Jiuwen Bao; Yupeng Tian. 2020. "Experimental and numerical study on chloride transport in cement mortar during drying process." Construction and Building Materials 258, no. : 119655.

Research article
Published: 21 April 2020 in Advances in Materials Science and Engineering
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Geopolymer concrete has been regarded as one of the most important green construction materials, which has been restrained in engineering applications partially due to a lack of bond studies. The structural performance of the reinforced concrete components primarily relies on the sufficient bond between the concrete and the reinforcing bars. Before being utilized in any concrete structure, GPC must demonstrate that it possesses understandable bond behaviour with commercial steel reinforcements. This work presents an experimental investigation on the bond stress of steel bars in reinforced geopolymer concrete (GPC) structures. Standard beam-end pull-out tests were conducted on GPC specimens reinforced with 16 mm plain and ribbed bars that were equipped with electrical resistance strain gauges. The longitudinal variation in the bond stress in the GPC beams during the pull-out tests was calculated and plotted, as well as the stress in steel bars. The cracks on the bond area of the GPC were compared with those of the corresponding ordinary Portland cement concrete (OPC), as well as the steel stress and bond stress. The results showed that the relative slip between plain bar and geopolymer concrete varies from 30–450 microns from the loaded end to the free end when the bond stress decreased by 83%. The relative slip between ribbed bar and geopolymer concrete varies from 280–3,000 microns from the loaded end to the free end when the bond stress decreased by 57%. Generally, GPC is different from OPC in terms of bond stress distribution.

ACS Style

Yifei Cui; Peng Zhang; Jiuwen Bao. Bond Stress between Steel-Reinforced Bars and Fly Ash-Based Geopolymer Concrete. Advances in Materials Science and Engineering 2020, 2020, 1 -11.

AMA Style

Yifei Cui, Peng Zhang, Jiuwen Bao. Bond Stress between Steel-Reinforced Bars and Fly Ash-Based Geopolymer Concrete. Advances in Materials Science and Engineering. 2020; 2020 ():1-11.

Chicago/Turabian Style

Yifei Cui; Peng Zhang; Jiuwen Bao. 2020. "Bond Stress between Steel-Reinforced Bars and Fly Ash-Based Geopolymer Concrete." Advances in Materials Science and Engineering 2020, no. : 1-11.

Research article
Published: 09 April 2020 in Advances in Materials Science and Engineering
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Concrete mixtures consisting of nanomaterials and fly ash have been shown to be effective for improving the performance of concrete. This study investigates the combined effects of nano-CaCO3 and fly ash on the mechanical properties and durability of concrete; the mix proportion is optimized through orthogonal experiments. In the first phase, nine concrete mixtures were prepared with three water-to-binder ratios (0.4, 0.5, and 0.6), three fly ash contents (15%, 20%, and 25% replacement of the cement weight), and three nano-CaCO3 contents (1%, 2%, and 3% replacement of the cement weight). Based on the orthogonal analysis, the optimal concrete mix proportion was determined as a water-to-binder ratio of 0.4, 20% fly ash, and 1% nano-CaCO3. In the second phase, further investigations were carried out to examine the superiority of the optimal concrete and evaluate the synergistic effect of nano-CaCO3 and fly ash. The results showed that nano-CaCO3 contributed to increasing the compressive strength of fly ash concrete at the early ages, but its effect was quite limited at later ages. Furthermore, the scanning electron microscopy analysis revealed that the seeding effect, filling effect, and pozzolanic effect were the primary mechanisms for the improvement of concrete performance.

ACS Style

Yanqun Sun; Peng Zhang; Weina Guo; Jiuwen Bao; Chengping Qu. Effect of Nano-CaCO3 on the Mechanical Properties and Durability of Concrete Incorporating Fly Ash. Advances in Materials Science and Engineering 2020, 2020, 1 -10.

AMA Style

Yanqun Sun, Peng Zhang, Weina Guo, Jiuwen Bao, Chengping Qu. Effect of Nano-CaCO3 on the Mechanical Properties and Durability of Concrete Incorporating Fly Ash. Advances in Materials Science and Engineering. 2020; 2020 ():1-10.

Chicago/Turabian Style

Yanqun Sun; Peng Zhang; Weina Guo; Jiuwen Bao; Chengping Qu. 2020. "Effect of Nano-CaCO3 on the Mechanical Properties and Durability of Concrete Incorporating Fly Ash." Advances in Materials Science and Engineering 2020, no. : 1-10.