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An Investigation into the Performances of cement mortar Incorporating Superabsorbent Polymer Synthesized with Kaolin

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Fluid Dynamics & Materials Processing 2024年第6期20卷 1393-1406页

作者： Xiao Huang Jin Yang State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures and School of ResourcesEnvironment and MaterialsGuangxi UniversityNanning530004China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China School of Civil Engineering Architecture and EnvironmentHubei University of TechnologyWuhan430068China

cement-based materials are fundamental in the construction industry,and enhancing their properties is an ongoing challenge.The use of superabsorbent polymers(SAP)has gained significant attention as a possible way to improve the performance of cement-based materials due to their unique water-absorption and retention properties.This study investigates the multifaceted impact of kaolin intercalation-modified superabsorbent polymers(K-SAP)on the properties of cement mortar.The results show that K-SAP significantly affects the cement mortar’s rheological behavior,with distinct phases of water absorption and release,leading to changes in workability over time.Furthermore,K-SAP alters the hydration kinetics,delaying the exothermic peak of hydration and subsequently modifying the heat release kinetics.Notably,K-SAP effectively maintains a higher internal relative humidity within the mortar,reducing the autogenous shrinkage behavior.Moreover,K-SAP can have a beneficial effect on pore structure and this can be ascribed to the internal curing effect of released water from K-SAP.

关键词： Superabsorbent polymer kaolin cement mortar rheological behavior autogenous shrinkage

The Effect of Graphene Oxide on Mechanical Properties of cement mortar

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Research and Application of Materials Science 2024年第1期6卷 1-4页

作者： Lei FAN Jinhao ZHENG School of Civil Engineering and Architecture Zhejiang University of Science&TechnologyHangzhouZhejiang310023China Zhejiang-Singapore Joint Laboratory for Urban Renewal and Future City HangzhouZhejiang310023China

cement is widely used in engineering applications,but it has both the characteristics of high brittleness and poor bending resistance.In this paper,the effects of different amounts ofgraphene oxide on the flexural strength and compressive strength of cement mortar were studied by doping a certain amount of graphene oxide with cement mortar,and the strengthening mechanism of graphene oxide on cement mortar was obtained through microstructure detection.It is found that graphene oxide has a significant enhancement effect on the macroscopic mechanical properties of cement mortar,and graphene oxide provides nano-nucleation sites and growth templates for cement mortar,accelerates the hydration process,reduces the voids between hydration products,greatly increases the compactness,and improves the macroscopic properties of cement-based materials.

关键词： Graphene oxide cement mortar Mechanical properties Microscopic analysis

Experimental study on the seismic performance of masonry wall reinforced by cement mortar and polypropylene band

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Earthquake Engineering and Engineering Vibration 2023年第2期22卷 469-479页

作者： Zhao Wenyang Zhou Qiang Min Quanhuan Yang Lingyu Sun Baitao Song Guquan School of Infrastructure Engineering Nanchang UniversityNanchang 330031China Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationHarbin 150080China Key Laboratory of Earthquake Disaster Mitigation Ministry of Emergency ManagementHarbin 150080China

Since masonry structures are prone to collapse in earthquakes,a novel joint reinforcement method with a polypropylene band(PP-band)and cement mortar(CM)has been put forward.Compared with the common reinforcement methods,this method not only facilitates construction but also ensures lower reinforcement cost.To systematically explore the influence of joint reinforcement on the seismic performance of masonry walls,quasi-static tests were carried out on six specimens with different reinforcement forms.The test results show that the joint action of PP-band and CM can significantly improve the specimen′s brittle failure characteristics and enhance the integrity of the specimen after cracking.Compared with the specimen without reinforcement,each of the seismic performance indexes of the joint reinforced specimen had obvious improvement.The maximum increased rate about peak load and ductility of the joint reinforced specimen is 100.6%and 233.4%,respectively.

关键词： joint reinforcement masonry structure quasi-static test cement mortar seismic performance

Effect of Dry-Wet Cycles on the Transport and Mechanical Properties of cement mortar Subjected to Sulfate Attack

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Fluid Dynamics & Materials Processing 2023年第3期19卷 679-696页

作者： Wei Chen Weijie Shan Yue Liang Frederic Skoczylas School of Civil Engineering Architecture and EnvironmentHubei University of TechnologyWuhan430068China CNRS Centrale LilleUMR9013-LaMcube-Laboratoire de Mécanique Multiphysique et MultiéchelleUniversitéde LilleLilleF-59000France

This study deals with the analysis of the detrimental effects of a“sulfate attack”on cement mortar for different dry-wet cycles.The mass loss,tensile strength,and gas permeability coefficient were determined and analyzed under different exposure conditions.At the same time,nitrogen adsorption(NAD),scanning electron microscopy(SEM),and X-ray diffraction(XRD)techniques were used to analyze the corresponding variations in the microstructure and the corrosion products.The results show that certain properties of the cement mortar evolve differently according to the durations of the dry-wet cycles and that some damage is caused to the mortars in aqueous solution.The pores fill with corrosion products,increasing the mortar specimen mass and tensile strength while reducing the permeability coefficient and pore size distribution.As corrosion proceeds,the crystallization pressure of the corrosion products increases,resulting in a 16%reduction in tensile strength from the initial value and a 2.6-factor increase in the permeability coefficient,indicating sensitivity to sulfate attack damage.Furthermore,the main corrosion products generated in the experiment are gypsum and ettringite.Application of osmotic pressure and extension of the immersion time can accelerate the erosion process.

关键词： cement mortar dry-wet cycles gas permeability tensile strength microstructure

Performance Evaluation of MWCNTs Reinforced cement mortar Composites using Natural and Commercial Surfactants

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Journal of Wuhan University of Technology(Materials Science) 2022年第1期37卷 47-57页

作者： Qareeb Ullah Rao Arsalan Khushnood Sajjad Ahmad Muhammad Usman Shad Muhammad Jean-Marc Tulliani School of Civil and Environmental Engineering National University of Sciences and TechnologyIslamabad-44000Pakistan Department of Structural Geotechnical and Building EngineeringPolitecnico di TorinoTurin-10129Italy Department of Civil Engineering FE&TBahauddin Zakariya UniversityMultan-56000Pakistan Department of Applied Science and Technology Politecnico di TorinoTurin-10129Italy

An efficient and promising approach for effectively dispersing multi-walled carbon nanotubes(MWCNTs)in cementitious composites has been investigated.The naturally occurring organic extracts from species of indigenously known‘Keekar’trees scattered along tropical and sub-tropical regions;is found as an exceptional replacement to the non-natural commercial surfactants.In the initial phase of investigation,ideal surfactant’s content required for efficient dispersion of MWCNTs in solution was determined using ultra-violet spectroscopy.The experimental investigations were then extended to five different cement composite formulations containing 0.0,0.025,0.05,0.08 and 0.10%MWCNTs by weight of cement.It was observed that the natural surfactant produced efficient dispersion at much reduced cost(approx.14%)compared with the commercial alternate.The estimated weight efficiency factor f was found 6.5 times higher for the proposed sustainable replacement to the conventional along with remarkable increase of 23%in modulus of rupture on 0.08 wt%addition of MWCNTs.Besides strength enhancement,the dispersed MWCNTs also improved the first crack and ultimate fracture toughness by 51.5%and 35.9%,respectively.The field emission scanning electron microscopy of the cryofractured samples revealed efficient dispersion of MWCNTs in the matrix leading to the phenomenon of effective crack bridging and crack branching in the composite matrix.Furthermore,the proposed scheme significantly reduced the early age volumetric shrinkage by 39%.

关键词： MWCNTs acacia nilotica gum keekar triton X-100 fracture crack bridging cement mortar early age micro-cracking sustainability

THEORETICAL ANALYSIS ON THE NUCLEATION OF MICRO-DAMAGE IN cement mortar UNDER COMPRESSIVE LOADING AND SULFATE ATTACK

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Acta Mechanica Solida Sinica 2013年第1期26卷 53-61页

作者： Jiankang Chen Hui Song Minghua Zhang Jian Ye The Faculty of Mechanical Engineering and Mechanics Ningbo University State Key Laboratory of Turbulence and Complex Systems Jiangsu Provincial Water Resources Department

Effect of uniaxial compression on the nucleation of micro-damage in cement mortar under sulfate attack is investigated. Shape and size of micro-voids in cement mortar is detected using Micro Computed Tomography techniques. The formation of delayed ettringite crystal is analyzed using scanning electron microscope and energy disperse spectrum methods. Deformation of micro-voids and the distribution of stress at the surface of a micro-void are calculated. It is found that the nucleation of micro-cracks is caused by the tensile stress at the voids＇ surface, and such damage nucleation will be speeded up by the remote uniaxial compressive load.

关键词： sulfate attack uniaxial compression micro-damage cement mortar Eshelby＇smethod

Pozzolanic Activity of Burned Coal Gangue and Its Effects on Structure of cement mortar

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Journal of Wuhan University of Technology(Materials Science) 2006年第4期21卷 150-153页

作者：张长森 Material Engineering Department Yancheng Institute of TechnologyYancheng 224003China

The pozzolanic activity of coal gangue burned at different burning temperatures was investigated. The burned coal gangue was mixed with portland cement in different proportions （ 20% - 60% ）. The pozzolanic activity of coal gangue burned and the hydration products were examined, the compressive strengths of the pastes of the mixtures were tested, and the mechanism of the reaction was discussed. The experimental results slum, that the coal gangue burned at 750 ℃ has the optimum pozzolanic activity, and the burned coal ganguc with SiO2 and Al2 O3 is in an active form. When the coal gangue burned at 750℃ is mixed into portland cement, the content of calcium hydroxide in paste is significantly reduced, while the contents of hydrated calcium silk.ate and hydrated calcium aluminate are increased accordingly, hence resulting in the improvement of the microstructure of mortar. The compressive strength of cement paste decreases with increasing the content of burncd coal gangue. The decease in strength is small in the range of 20% - 30% coal gangue substitution and significant in 30%- 60% substitution.

关键词： coal gangue burn pozzolanic activity cement mortar strength

Effect of embedment length of untreated natural fibres on the bond behaviour in cement mortar

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Frontiers of Structural and Civil Engineering 2018年第4期12卷 454-460页

作者： Gudimella RAMAKRISHNA Sriraman PRIYADHARSHINI Department of Civil Engineering Pondicherry Engineering CollegePuducherry 605014lndia

The present investigation is focused on studying the effects of various matrices with 1:3, 1:4 and 1:5 mortars and fibre types of sisal and coir on the bond behavior at various ages of curing, i.e., 24 h, 3 d, 7 d and 28 d. The other parameters included in the investigation are water/cement (w/c) ratio, sand gradation and embedment length of fibres. In addition, the type of failure of sisal and coir fibres for different mixes of mortars at various curing ages is also reported. From the results, it is seen that the bond strength is improving with respect to age of curing in case of sisal fibres, but decreases in case of coir fibres. The failure of fibres due to fibre fracture is observed in sisal fibres and fibre pullout is observed in coir fibres. The other varying parameters such as mortar mixes, sand gradation, w/c ratio and embedded length also showed significant effect on bond behaviour of sisal and coir fibre with the cement mortar mixes.

关键词： bond strength cement mortar natural fibre pullout test type of failure

X-ray Microtomography of the Carbonation Front Shape Evolution of cement mortar and Modeling of Accelerated Carbonation Reaction

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Journal of Wuhan University of Technology(Materials Science) 2013年第2期28卷 303-308页

作者：韩建德孙伟 PAN Ganghua College of Civil Engineering Nanjing University of Technology School of Materials Science and Engineering Southeast University Jiangsu Key Laboratory of Construction Material

In situ monitoring of the microstructure evolution of cement mortar in accelerated carbonation reaction for different carbonation ages was carried out by X-ray computed tomography （XCT）. And the carbonation degrees of different time were measured by the volume fraction of uncarbonated and carbonated parts. Meanwhile, we presented a model for the carbonation of cement mortar by means of X-ray computed tomography （XCT）. Based on the principles of chemical engineering processes, the reacted products become a solid inert ash layer. Finally, the model was validated with results of accelerated carbonation of cement mortar. The model is thus able to reasonably predict the carbonation ohenomena for accelerated conditions.

关键词： XCT cement mortar carbonation in-situ monitoring gray values model validation