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Effects of fibers on expansive shotcrete mixtures consisting of calcium sulfoaluminate cement,ordinary Portland cement,and calcium sulfate 被引量:6
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作者 H.Yu L.Wu +1 位作者 W.V.Liu Y.Pourrahimian 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2018年第2期212-221,共10页
The mining industry often uses shotcrete for ground stabilization. However, cracking within shotcrete is commonly observed, which delays production schedules and increases maintenance costs. A possible crack reduction... The mining industry often uses shotcrete for ground stabilization. However, cracking within shotcrete is commonly observed, which delays production schedules and increases maintenance costs. A possible crack reduction method is using expansive shotcrete mixture consisting of calcium sulfoaluminate cement(CSA), ordinary Portland cement(OPC), and calcium sulfate(CS) to reduce shrinkage. Furthermore, fibers can be added to the mixture to restrain expansion and impede cracking. The objective of this paper is to study the effects of nylon fiber, glass fiber, and steel fiber on an expansive shotcrete mixture that can better resist cracking. In this study, parameters such as density, water absorption, volume of permeable voids, unconfined compressive strength(UCS), splitting tensile strength(STS), and volume change of fiber-added expansive mixtures were determined at different time periods(i.e. the strengths on the 28 th day, and the volume changes on the 1 st, 7 th, 14 th, 21 st, and 28 th days). The results show that addition of fibers can improve mixture durability, in the form of decreased water absorption and reduced permeable pore space content. Moreover, the expansion of the CSA-OPC-CS mixture was restrained up to50% by glass fiber, up to 43% by nylon fiber, and up to 28% by steel fiber. The results show that the STS was improved by 57% with glass fiber addition, 43% with steel fiber addition, and 38% with nylon fiber addition. The UCS was also increased by 31% after steel fiber addition, 26% after nylon fiber addition, and16% after glass fiber addition. These results suggest that fiber additions to the expansive shotcrete mixtures can improve durability and strengths while controlling expansion. 展开更多
关键词 SHOTCRETE Restrained expansion Fibers calcium sulfoaluminate cement(CSA) Ordinary Portland cement(OPC) calcium sulfate(CS)
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Durability of calcium sulfoaluminate cement concrete 被引量:3
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作者 Bowen TAN Monday UOKORONKWO +1 位作者 Aditya KUMAR Hongyan MA 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2020年第2期118-128,共11页
Calcium sulfoaluminate cement(CSAC),first developed in China in the 1970 s,has received significant attention because of its expansive(or shrinkage-compensating)and rapid-hardening characteristics,low energy-intensity... Calcium sulfoaluminate cement(CSAC),first developed in China in the 1970 s,has received significant attention because of its expansive(or shrinkage-compensating)and rapid-hardening characteristics,low energy-intensity,and low carbon emissions.The production and hydration of CSAC(containing ye’elimite,belite,calcium sulfate,and minors)have been extensively studied,but aspects of its durability are not well understood.Due to its composition and intrinsic characteristics,CSAC concrete is expected to have better performance than Portland cement(PC)concrete in several aspects,including shrinkage and cracking due to restrained shrinkage,freeze-thaw damage,alkali-silica reaction,and sulfate attack.However,there is a lack of consensus among researchers regarding transport properties,resistance to carbonation,and steel corrosion protectiveness of CSAC concrete,all of which are expected to be tied to the chemical composition of CSAC and attributes of the service environments.For example,CASC concrete has poorer resistance to carbonation and chloride penetration compared with its PC counterpart,yet some studies have suggested that it protects steel rebar well from corrosion when exposed to a marine tidal zone,because of a strong self-desiccation effect.This paper presents a succinct review of studies of the durability of CSAC concrete.We suggest that more such studies should be conducted to examine the long-term performance of the material in different service environments.Special emphasis should be given to carbonation and steel rebar corrosion,so as to reveal the underlying deterioration mechanisms and establish means to improve the performance of CSAC concrete against such degradation processes. 展开更多
关键词 calcium sulfoaluminate cement(CSAC) DURABILITY CARBONATION CHLORIDE Steel corrosion
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Extending blending proportions of ordinary Portland cement and calcium sulfoaluminate cement blends:Its effects on setting,workability,and strength development
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作者 Guangping HUANG Deepak PUDASAINEE +1 位作者 Rajender GUPTA Wei Victor LIU 《Frontiers of Structural and Civil Engineering》 SCIE EI CSCD 2021年第5期1249-1260,共12页
This study extended blending proportion range of ordinary Portland cement(OPC)and calcium sulfoaluminate(CSA)cement blends,and investigated effects of proportions on setting time,workability,and strength development o... This study extended blending proportion range of ordinary Portland cement(OPC)and calcium sulfoaluminate(CSA)cement blends,and investigated effects of proportions on setting time,workability,and strength development of OPC-CSA blend-based mixtures.Thermogravimetric analysis(TGA)and X-ray diffraction(XRD)were conducted to help understand the performance of OPC-CSA blend-based mixtures.The setting time of the OPC-CSA blends was extended,and the workability was improved with increase of OPC content.Although the early-age strength decreased with increase of OPC content,the strength development was still very fast when the OPC content was lower than 60%due to the rapid formation and accumulation of ettringite.At 2 h,the OPC-CSA blend-based mortars with OPC contents of 0%,20%,40%,and 60%achieved the unconfined compressive strength(UCS)of 17.5,13.9,9.6,and 5.0 MPa,respectively.The OPC content had a negligible influence on long-term strength.At 90 d,the average UCS of the OPC-CSA blend-based mortars was 39.2±1.7 MPa. 展开更多
关键词 calcium sulfoaluminate cement cement blends hydration reaction SETTING WORKABILITY compressive strength
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Experimental study and field application of calcium sulfoaluminate cement for rapid repair of concrete pavements 被引量:7
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作者 Yanhua GUAN Ying GAO +2 位作者 Renjuan SUN Moon C. WON Zhi GE 《Frontiers of Structural and Civil Engineering》 SCIE EI CSCD 2017年第3期338-345,共8页
The fast-track repair of deteriorated concrete pavement requires materials that can be placed, cured, and opened to the traffic in a short period. Type III cement and Calcium Sulfoaluminate (CSA) cement are the most... The fast-track repair of deteriorated concrete pavement requires materials that can be placed, cured, and opened to the traffic in a short period. Type III cement and Calcium Sulfoaluminate (CSA) cement are the most commonly used fast-setting hydraulic cement (FSHC). In this study, the properties of Type III and CSA cement concrete, including compressive strength, coefficient of thermal expansion (CTE) and shrinkage were evaluated. The test results indicate that compressive strength of FSHC concrete increased rapidly at the early age. CSA cement concrete had higher early-age and long term strength. The shrinkage of CSA cement concrete was lower than that of Type III cement concrete. Both CSA and Type III cement concrete had similar CTE values. Based on the laboratory results, the CSA cement was selected as the partial-depth rapid repair material for a distressed continuously reinforced concrete pavement. The data collected during and after the repair show that the CSA cement concrete had good short-term and long-term performances and, therefore, was suitable for the rapid repair of concrete pavement. 展开更多
关键词 calcium sulfoaluminate (CSA) cement Type III cement coefficient of thermal expansion (CTE) shrinkage rapid repair
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Performance development of styrene-butadiene copolymer-modified calcium sulfoaluminate cement mortar under different curing conditions
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作者 Ru WANG Yu-sheng FAN +2 位作者 Zhao-jia WANG Tian-yong HUANG Tao ZHANG 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2021年第12期1005-1026,共22页
The purpose of this study was to investigate the change in the physical and mechanical properties of styrene-butadiene copolymer(SB)dispersion-modified calcium sulfoaluminate(CSA)cement mortar as it aged from 28 to 36... The purpose of this study was to investigate the change in the physical and mechanical properties of styrene-butadiene copolymer(SB)dispersion-modified calcium sulfoaluminate(CSA)cement mortar as it aged from 28 to 360 d,and cured at different temperatures and relative humidities.The results show that the mechanical properties of reference mortar(RM)of CSA cement,including its flexural,compressive,and tensile bond strength,showed a reduction after a certain time,but its water capillary absorption was hardly affected by age.When SB dispersion was added,there was no reduction in mechanical strength.The amount of SB added did matter.Addition of 5% SB had a negative effect on most properties compared with RM,except for tensile bond strength.However,the properties of SB-modified mortar(SBMM)were enhanced significantly as the amount of SB was increased from 5% to 20%.Temperature change had different effects on the properties of RM and SBMM.High temperature was beneficial to early flexural and compressive strength development of RM,but caused serious strength reduction at later stages.High temperature enhanced the development of tensile bond strength of RM.Increasing temperature enhanced properties of SBMM,including flexural,compressive,and tensile bond strength.Higher relative humidity improved all measured properties of all mortars.Scanning electron microscope(SEM)observations of the morphology of RM and SBMM at 360 d cured under different conditions accounted well for the changes in mechanical properties. 展开更多
关键词 calcium sulfoaluminate(CSA)cement Styrene-butadiene copolymer(SB)dispersion MORTAR Properties Curing temperature Relative humidity(RH)
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Effect of Superplasticizers on the Early Age Hydration of Sulfoaluminate Cement 被引量:1
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作者 袁晓辉 陈伟 YANG Mo 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2014年第4期757-762,共6页
The effects of two types of superplasticizers on the properties of CSA cement pastes during early hydration were studied. The influences of two types of superplasticizers on the properties of cement pastes, including ... The effects of two types of superplasticizers on the properties of CSA cement pastes during early hydration were studied. The influences of two types of superplasticizers on the properties of cement pastes, including the normal consistency, setting time, fl uidity, and compressive strength, were investigated by using various methods. The hydration products of the cement pastes cured for 1 day and 3 days were studied by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The results show that the PCE type superplasticizer retards the early age hydration while the FDN type superplasticizer accelerates the early age hydration of the CSA cement. Both types of superplasticizers have no infl uence on the further hydration of CSA cement, confi rmed by the calorimeter tests as well. The ultrasonic pulse velocity measurements were used to probe the influence of two types of superplasticizers on the hydration of CSA cement pastes at a high water-cement ratio(0.45). The results show that the PCE type superplasticizer retards the early age hydration of the CSA cement while the FDN type superplasticizer has little infl uence on the early age hydration of the CSA cement. 展开更多
关键词 calcium sulfoaluminate cement superplasticizer early age hydration
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INFLUENCE OF LATEX POLYMER ADDITION ON THE BEHAVIOR OF MATERIALS CONTAINING CSA CEMENT CURED AT LOW HUMIDITY
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作者 Joshua V.Brien Kevin R.Henke Kamyar C.Mahboub 《Journal of Green Building》 2013年第4期94-109,共16页
The present study assesses the hydration behavior of polymer modified and non-polymer containing calcium sulfoaluminate(CSA)cement pastes containing minor phase tri-calcium aluminate(C3A)when cured at ambient laborato... The present study assesses the hydration behavior of polymer modified and non-polymer containing calcium sulfoaluminate(CSA)cement pastes containing minor phase tri-calcium aluminate(C3A)when cured at ambient laboratory temperature with 50%relative humidity.The particular CSA cement is unique as it offers two potential paths for ettringite formation.In the presence of sufficient calcium sulfate,these two potential paths stem from either hydration of yeelimite or hydration of tri-calcium aluminate.The study assesses the microstructural behavior of cement pastes utilizing powdered x-ray diffraction(XRD)and thermogravimetric analysis(TGA/SDT).Additionally,the study utilizes direct tensile strength testing according to ASTM C307,Standard Test Method for Tensile Strength of Chemical Resistant Mortar,Grouts and Monolithic Surfacings to quantify relationships between microstructural characteristics and mechanical property performance for representative mortars.The present study is significant as it illustrates differences in microstructural behavior for CSA cement materials with and without polymer cured at constant 50%relative humidity.The present study suggests ettringite decomposition occurs within non-polymer containing CSA cement paste samples cured at constant low humidity.The present study presents polymer modification as an effective means for mitigating ettringite decomposition and subsequent strength loss in materials containing CSA cement cured at constant 50%relative humidity and 23℃. 展开更多
关键词 calcium sulfoaluminate cement latex polymer CSA cement strength loss ettringite decomposition
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