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Hydration, microstructure and autogenous shrinkage behaviors of cement mortars by addition of superabsorbent polymers

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Frontiers of Structural and Civil Engineering 2020年第5期14卷 1274-1284页

作者： Beibei SUN Hao WU Weimin SONG Zhe LI Jia YU School of Civil Engineering Central South UniversityChangsha 410075China Magnel Laboratory for Concrete Research Department of Structural EngineeringGhent UniversityGhent 9052Belgium National Engineering Laboratory for High Speed Railway Construction Central South UniversityChangsha 410075China

Superabsorbent Polymer(SAP)has emerged as a topic of considerable interest in recent *** present study systematically and quantitively investigated the effect of SAP on hydration,autogenous shrinkage,mechanical properties,and microstructure of cement *** of SAP on hydration heat and autogenous shrinkage were studied by utilizing TAM AIR technology and a non-contact autogenous shrinkage test *** Electron Microscope(SEM)was employed to assess the microstructure *** SAP decreased the peak rate of hydration heat and retarded the hydration,it significantly increased the cumulative heat,indicating SAP helps promote the *** promotion caused by SAP mainly occurred in the deceleration period and attenuation *** can significantly mitigate the autogenous shrinkage when the content ranged from 0 to 0.5%.Microstructure characteristics showed that pores and gaps were introduced when SAP was *** microstructure difference caused by SAP contributed to the inferior mechanical behaviors of cement mortars treated by SAP.

关键词： Superabsorbent Polymer mechanical properties hydration heat autogenous shrinkage microstructure

Experimental Research on the autogenous shrinkage of MK High Performance Concrete

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Journal of Wuhan University of Technology(Materials Science) 2007年第3期22卷 551-554页

作者：王宝民 School of Civil and Hydraulic Engineering Dalian University of Technology

Calcine and mill kaolin were used under agreeable technological conditions to generate matakaolin （MK）. The autogenous shrinkage performance of high performance concrete added with MK was researched. It is shown that MK has an effective inhibitory action to early autogenous shrinkage of cement concrete, and the inhibitory action increases with the increase of MK. The autogenous shrinkage values from 24 hours after placement to 56 days are all higher than those of the contrasted concrete, among which, the value of the concrete with 5% MK is the highest. But the total shrinkage values in 56 days are all less than those of the contrasted test pieces. The total contraction after 24 h of placement decreases as the increase of MK, moreover, it is greatly less than that of the contrasted ones.

关键词： high performance concrete MK autogenous shrinkage

Surface Modification of Fly Ashes with Carbide Slag and Its Effect on Compressive Strength and autogenous shrinkage of Blended Cement Pastes

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Journal of Wuhan University of Technology(Materials Science) 2012年第6期27卷 1149-1153页

作者：郝成伟邓敏 MO Liwu LIU Kaiwei State Key Laboratory of Materials-Oriented Chemical Engineering College of Materials Science and EngineeringNanjing University of Technology College of Architecture and Civil Engineering West Anhui University

Surfaces of grade III fly ashes were modified through mixing with carbide slag and calcining at 850 ℃ for 1 h. Mineralogical compositions and surface morphology of fly ashes before and after modification were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）, respectively. Effect of surface-modified fly ashes on compressive strength and autogenous shrinkage of blended cement pastes was investigated. Microstructures of cement pastes were examined by backscattered electron （BSE） imaging and mercury intrusion porosimetry （MIP）. The experimental results showed that β-C2S was formed on the surfaces of fly ashes after modification. Hydration ofβ-C2S on the surface-modified fly ashes densified interface zone and enhanced bond strength between particles of fly ashes and hydrated clinkers. In addition, surface modification of fly ashes tended to decrease total porosity and 10-50 nm pores of cement pastes. Surface modification of fly ashes increased compressive strength and reduced autogenous shrinkage of cement pastes.

关键词： surface modification fly ash carbide slag autogenous shrinkage compressive strength

Effect of Pre-wetted Light-weight Aggregate on Internal RelativeHumidity and autogenous shrinkage of Concrete

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Journal of Wuhan University of Technology(Materials Science) 2006年第1期21卷 134-137页

作者：叶家军 School of Material Science and Engineering Wuhan University of Technology Wuhan 430070China

This research indicates that the gradient of internal relative humidity （IRH） decreases rapidly within 7-day curing age in HPC. The amount of water imported by pre-wetted light-weight aggregate can regulate IRH of concrete. By importing a proper amount of water, the process of the decline of IRH can be delayed and the autogenous shrinkage can be reduced. The relationship among the amount of water imported by pre- wetted lightweight aggregate, IRH and AS was established. The result provides a new method of reducing early AS and enhancing early cracking resistance of HPC.

关键词： autogenous shrinkage pre-wetted lightweight aggregate internal relative humidity high performance concrete

Characterisation of Early Age Deformations in Cement Paste: Case of Chemical and autogenous shrinkage

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Journal of Minerals and Materials Characterization and Engineering 2020年第4期8卷 223-239页

作者： Nkwenti Flavious Tanue Tubuo Fabian Fokwa Didier Tchemou Gilbert University of Douala Post Graduate Training Unit for Engineering Sciences Douala Cameroon University of Douala Higher Technical Teachers’ Training College Douala Cameroon

Concrete is commonly seen as a durable and long-lasting construction material. However, the long-term performance of a concrete structure can be greatly compromised by early-age cracking. This work is an experimental contribution to study early age deformations of cement paste. Its aim is, firstly, to develop an experimental dispositive for assessing chemical and autogenous shrinkage, and secondly, to measure these volumetric deformations in cement paste. The setup was done following the gravimetric method of measurement, which exploits the Archimedes’ principle. It is made up of an electronic balance, a data accusation unit, a temperature control unit and a buoyancy bath. Investigations were done on Portland cement (CPA-CEM II) at the following W/C ratios: 0.25, 0.3, 0.35, 0.4 and 0.5. It was noticed that the water-cement ratio does not influence the magnitude of the chemical shrinkage in a significant manner but had a kinetic effect;a lower W/C induces a faster rate of chemical shrinkage. autogenous shrinkage was discovered to be highly inversely proportional to the W/C and was also noticed to be in a function of chemical shrinkage within the first 2 to 4 hours when the paste was still liquid.

关键词： autogenous shrinkage Chemical shrinkage Volumetric Deformation Water-Cement Ratio

Mesocosmic study on autogenous shrinkage of concrete with consideration of effects of temperature and humidity

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Water Science and Engineering 2009年第4期2卷 85-94页

作者： Yan HAI Yue-ming ZHU College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 P. R. China

A study on the autogenous shrinkage （AS） of concrete from a mesocosmic perspective was carried out using numerical simulation technology. The temperature history and the autogenous relative humidity （ARH）, two factors that have been shown to have occasional influence on this process in previous studies, were introduced into this study. According to these concepts, a program for simulation of the temperature field, humidity field, and stress field based on the equivalent age method and a fully automatic aggregate modeling tool were used. With the help of these programs, the study of a small concrete specimen provided some useful conclusions： the aggregate and the matrix show distinct distribution properties in the temperature field, humidity field, and stress field; the aggregate-matrix interface has a high possibility of becoming the location of the initial cracking caused by AS of concrete; the distribution of random aggregates is extremely important for mesoscopical analysis; and the temperature history is the main factor affecting the AS of concrete. On the whole, inherent mechanisms and cracking mechanisms of AS of concrete can be explained more reasonably and realistically only by considering the different characteristics of material phases and the effects of temperature and humidity.

关键词： concrete autogenous shrinkage meso-analysis equivalent age temperature history autogenous relative humidity

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 *** 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 *** study investigates the multifaceted impact of kaolin intercalation-modified superabsorbent polymers(K-SAP)on the properties of cement *** 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 ***,K-SAP alters the hydration kinetics,delaying the exothermic peak of hydration and subsequently modifying the heat release ***,K-SAP effectively maintains a higher internal relative humidity within the mortar,reducing the autogenous shrinkage ***,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

Self-desiccation mechanism of high-performance concrete

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Journal of Zhejiang University Science 2004年第12期5卷 1517-1523页

作者：杨全兵张树青 ResearchLabofMaterialsEngineering CollegeofMaterialsScienceandEngineeringTongiiUniversityShanghai200433China

Investigations on the effects of W/C ratio and silica fume on the autogenous shrinkage and internal relative humidity of high performance concrete (HPC), and analysis of the self-desiccation mechanisms of HPC showed that the autogenous shrinkage and internal relative humidity of HPC increases and decreases with the reduction of W/C respectively; and that these phenomena were amplified by the addition of silica fume. Theoretical analyses indicated that the reduction of RH in HPC was not due to shortage of water, but due to the fact that the evaporable water in HPC was not evaporated freely. The reduction of internal relative humidity or the so-called self-desiccation of HPC was chiefly caused by the increase in mole concentration of soluble ions in HPC and the reduction of pore size or the increase in the fraction of micro-pore water in the total evaporable water (Tr/Tte ratio).

关键词： High-performance concrete autogenous shrinkage Self-desiccation Relative humidity

Early-Age Properties Development of Recycled Glass Powder Blended Cement Paste:Strengths,shrinkage,Nanoscale Characteristics,and Environmental Analysis

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Journal of Renewable Materials 2023年第4期11卷 1835-1852页

作者： Zhihai He Menglu Shen Jinyan Shi Jingyu Chang Víctor Revilla-Cuesta Osman Gencel College of Civil Engineering Shaoxing UniversityShaoxing312000China Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province Shaoxing312000China School of Civil Engineering Central South UniversityChangsha410075China Department of Civil Engineering Escuela Politécnica SuperiorUniversity of Burgosc/Villadiego s/nBurgos09001Spain Civil Engineering Department Bartin UniversityBartin74100Turkey

Recycling solid waste in cement-based materials cannot only ease its load on the natural environment but also reduce the carbon emissions of building *** study aims to investigate the effect of recycled glass powder(RGP)on the early-age mechanical properties and autogenous shrinkage of cement pastes,where cement is replaced by 10%,20%and 30%of *** addition,the microstructure and nano-mechanical properties of cement paste with different RGP content and water to binder(W/B)ratio were also evaluated using SEM,MIP and nanoindentation *** results indicate that the early-age autogenous shrinkage decreases with the increase of RGP content and W/B *** the mechanical strength deteriorates due to the addition of RGP,it can be compensated by reducing the W/B *** the addition of RGP increases the total porosity of the hardened paste,it reduces the small size porosity(shrinkage deformation that RGP is generating in cement pastes is encouraging for its use as a novel supplementary cementitious material that reduces the early-age cracking risk of cement-based ***,the life cycle assessments indicate that the RGP-cement component is an economical and eco-friendly novel engineering material.

关键词： Cement paste waste glass powder autogenous shrinkage microstructure nanoindentation