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Adsorption Mechanism of Polycarboxylate-Based Superplasticizer in CFBC Ash-Portland Cement Paste 被引量:4
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作者 宋远明 GUO Chuanchuan +2 位作者 QIAN Jueshi LIU Yiquan CAO Aizhi 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2014年第5期945-949,共5页
Circulating fluidized bed combustion (CFBC) ash exhibits the desirable pozzolanic activity which makes it a potential supplementary cementitious material to replace cement for concrete production. However, the high ... Circulating fluidized bed combustion (CFBC) ash exhibits the desirable pozzolanic activity which makes it a potential supplementary cementitious material to replace cement for concrete production. However, the high unburnt carbon content and porous surface structure of CFBC ash may adsorb water reducer and thereby significantly reduce the efficiency of water-reducing agents. The adsorption mechanism of polycarboxylate superplasticizer in CFBC ash-Portland cement paste was investigated by ultraviolet-visible spectrophotometer, and the conception of "invalid adsorption site" of CFBC ash was presented. The results show that the adsorption behavior of polycarboxylate superplasticizer in coal ash-Portland cement paste can be described by Langmuir isothermal adsorption equation. The adsorption capacity of CFBC ash-Portland cement paste is higher than that of pulverized coal combustion (PCC) fly ash-Portland cement paste. Moreover, the adsorption amount of polycarboxylate superplasticizer increases with the ratio of ash-to-cement in the paste. At last, the fluidity of CFBC ash-Portland cement paste is lower than that of the PCC fly ash paste. This work suggests that when CFBC ash is used as concrete admixture, the poor flowability of the cementitious system due to the high adsorption of water and water-reducing agent should be taken into consideration. 展开更多
关键词 CFBC ash concrete admixture adsorption polycarboxylate superplasticizer invalid adsorption site
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Synthesis and Performance Characterization of a Low Adsorption Clay-resistant Polycarboxylate Superplasticizer 被引量:2
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作者 ZHANG Ying WANG Pengshuo +2 位作者 SUN Guowen YANG Jianming GAO Rui 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2021年第3期446-455,共10页
A low adsorption clay-resistant polycarboxylate superplasticizer(KN-PC)was synthesized using acrylic acid and isopentenol polyoxyethylene ether as the main reaction materials.The structural characterization and clay-r... A low adsorption clay-resistant polycarboxylate superplasticizer(KN-PC)was synthesized using acrylic acid and isopentenol polyoxyethylene ether as the main reaction materials.The structural characterization and clay-resistant mechanism of the KN-PC were explored using Fourier transform infrared spectroscopy and X-ray diffraction,and the effect of the KN-PC on the performance of composite paste with various montmorillonite(MMT)contents was analyzed.Compared with ordinary polycarboxylate superplasticizer(PC),the KN-PC has a low sensitivity to the MMT.By the action of the MMT,the adsorption dosage of the KN-PC on the MMT is much smaller than that of the PC. 展开更多
关键词 polycarboxylate superplasticizer clay-resistant MONTMORILLONITE performance SYNTHESIS
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Influences of Soluble Salts on Adsorption Properties of Polycarboxylate Superplasticizers
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作者 王栋民 程佩福 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2012年第4期684-688,共5页
Polycarboxylate(PC) superplasticizers with different chemical structures were synthesized through free radical co-polymerization reaction.A total organic carbon analyzer was used to investigate adsorption behaviors ... Polycarboxylate(PC) superplasticizers with different chemical structures were synthesized through free radical co-polymerization reaction.A total organic carbon analyzer was used to investigate adsorption behaviors of PCs,and to evaluate influences of soluble salts on absorption properties of PCs.It is found that adsorption ratios of PCs on cement particles decrease greatly with the addition of Na2SO4;the adsorption ratio of ethers PC with Hydroxyethyl methacrylate(HEMA) group first increases then decreases with the addition of NaCl;the adsorption ratio of esters PC with short side chains first decreases then increases,while the adsorption ratio of ethers PC with HEMA group decreases with the addition of CaCl2;the adsorption ratio of esters PC with short side chains decreases with the addition of Ca(NO3)2;AlCl3 causes the decrease of the adsorption ratio of ethers PC with HEMA group. 展开更多
关键词 soluble salts polycarboxylate superplasticizer adsorption property
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Influence of High-Robustness Polycarboxylate Superplasticizer on the Performances of Concrete Incorporating Fly Ash and Manufactured Sand
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作者 Panpan Cao Xiulin Huang +1 位作者 Shenxu Bao Jin Yang 《Fluid Dynamics & Materials Processing》 EI 2023年第8期2041-2051,共11页
Using ethylene glycol monovinyl polyoxyethylene ether,2-acrylamido-2-methylpropane sulfonic acid(AMPS)and acrylic acid as the main synthetic monomers,a high robustness polycarboxylate superplasticizer was prepared.The... Using ethylene glycol monovinyl polyoxyethylene ether,2-acrylamido-2-methylpropane sulfonic acid(AMPS)and acrylic acid as the main synthetic monomers,a high robustness polycarboxylate superplasticizer was prepared.The effects of initial temperature,ratio of acid to ether,amount of chain transfer agent,and synthesis process on the properties of the superplasticizer were studied.The molecular structure was characterized by GPC(Gel Permeation Chromatography)and IR(Infrared Spectrometer).As shown by the results,when the initial reaction temperature is 15℃,the ratio of acid to ether is 3.4:1 and the acrylic acid pre-neutralization is 15%,The AMPS substitution is 10%,the amount of chain transfer agent is 8%,and the performance of the synthesized superplasticizer is the best.Compared with commercially available ordinary polycarboxylate superplasticizer in C30 concrete prepared with manufactured sand and fly ash,the bleeding rate decreases by 52%,T50 decreases by 1.2 s,and the slump time decreases by 1.1 s.In C60 concrete prepared with fly ash and river sand,the bleeding rate decreases by 46%,T50 decreases by 0.8 s,and the slump time decreases by 3.2 s. 展开更多
关键词 polycarboxylate superplasticizer EPEG ROBUSTNESS WORKABILITY
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Study on the Hydration and Physical Properties of Cement by M18 Polycarboxylate Superplasticizer Modified Graphene Oxide
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作者 Dalong Liao Dongxu Li +2 位作者 Shun Zhou Xiaotao Zhang Ying Fang 《Journal of Renewable Materials》 SCIE EI 2023年第2期625-641,共17页
Graphene oxide(GO)as a new nano-enhancer in cement-based materials has gained wide attention.However,GO is easy to aggregate in alkaline cement mortar with poor dispersibility.This hinders its application in practical... Graphene oxide(GO)as a new nano-enhancer in cement-based materials has gained wide attention.However,GO is easy to aggregate in alkaline cement mortar with poor dispersibility.This hinders its application in practical infrastructure construction.In this work,GO-M18 polycarboxylate compound superplasticizer(GM)were obtained by compounding the M18 polycarboxylate superplasticizer with GO solution at different mass ratios.The dispersion of GM in alkaline solution was systematically studied.The phases and functional groups of GM were characterized by XRD and FTIR.The effects of GM on the cement mortar hydration and the formation of microstructure were investigated by measuring the heat of hydration,MIP,TG/DSC,and SEM.The results show that the long-chain structure of the M18 polycarboxylate superplasticizer can increase the interlayer spacing of GO and weaken the force between GO sheets.The modified GO can be uniformly dispersed in the cement slurry.GM can accelerate the early hydration process of cement,which can increase the content of Ca(OH)2 and decrease the grain size.It can optimize the pore size distribution of cement-based materials,increase the density of harmless and less harmful pores,thereby improving mechanical properties.Such methods can transform traditional cement-based materials into stronger,more durable composites,which prolong the life of cement-based materials and reduce the amount of cement used for later maintenance.This provides an idea for achieving sustainability goals in civil engineering. 展开更多
关键词 Modified graphene oxide CEMENT polycarboxylate superplasticizer hydration properties me-chanical performance
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Effects of CFB Ash on the Adsorption Mechanism of Polycarboxylate Superplasticiser
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作者 LIU Juanhong GAO Meng SONG Shaomin 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2018年第6期1323-1333,共11页
The effects of circulating fluid bed(CFB) ash on the adsorption performance of polycarboxylate superplasticiser and the mechanism of this influence on the dispersive property of the polycarboxylate superplasticiser we... The effects of circulating fluid bed(CFB) ash on the adsorption performance of polycarboxylate superplasticiser and the mechanism of this influence on the dispersive property of the polycarboxylate superplasticiser were investigated by determing the cement paste fluidity, total organic carbon adsorption, infrared spectroscopic analyses and ζ potential test. The experimental results show that the addition of an inorganic salt into the mixture to change the content of SO42-and Fe2O3can improve the adaptability between the CFB ash and polycarboxylate superplasticiser. Adsorption may occur between the polycarboxylate superplasiciser and Fe2O3, SO42-or other components in CFB ash, leading to a significant reduction in paste fluidity. As the content of Na2SO4in CFB ash reaches 3% or Fe2O3reaches 9%, the paste loses its liquidity. The organic carbon content in the liquor decreases with an increase in Na2SO4or Fe2O3content. Adding some Ba(NO3)2and Na2S to the liquor can recover the organic carbon content to a certain extent, and the absolute value of ζ potential will increase. The addition of Ba(-NO3)2or Na2S reduces the adsorption property of Na2SO4or Fe2O3in CFB ash on the polycarboxylate superplasticiser. 展开更多
关键词 CFB ash polycarboxylate superplasticiser FLUIDITY TOC adsorption
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Effect of Competitive Adsorption between Sodium Tripolyphosphate and Naphthalene Superplasticizer on Fluidity of Cement Paste 被引量:7
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作者 谭洪波 MA Baoguo +2 位作者 LI Xiangguo JIAN Shouwei YANG Hu 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2014年第2期334-340,共7页
The adsorption amount, ξ-potential of cement particles and fluidity of cement paste were tested to research the competitive adsorption between naphthalene superplasticizer (FDN) and STPP. The experimental results s... The adsorption amount, ξ-potential of cement particles and fluidity of cement paste were tested to research the competitive adsorption between naphthalene superplasticizer (FDN) and STPP. The experimental results showed that the presence of STPP could significantly improve the fluidity of cement paste and reduce the fluidity loss with FDN. There existed a competitive adsorption between STPP and FDN. STPP and calcium ions formed complexes; they preferentially adsorbed onto surface of cement particles and preempt adsorption points of FDN; and it reduced adsorption amount of FDN. In the absence of STPP, saturation adsorption amount of FDN was 5.93 mg/g; but when the dosage of STPP was 0.1%, it reduced to 4.3 mg/g (about 72.5%). The adsorption amount of FDN was reduced by STPP, but ξ-potential of cement particles enhanced and fluidity of cement paste increased because of strong negative charge effect of the complexes. Adsorption of the complexes would delay Ca^2+ into liquid and inhibit formation of active adsorption points. Then, content of FDN in liquid increased with the addition of STPP and ξ-potential of cement particles became stable. In this way, fluidity loss of cement paste reduced. 展开更多
关键词 sodium tripolyphosphate naphthalene superplasticizer ξ-potential COMPLEX competitive adsorption
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Effects of Molecular Structure of Polycarboxylate-type Superplasticizer on the Hydration Properties of C_3S 被引量:5
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作者 丁庆军 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2012年第4期768-772,共5页
Effects of polycarboxylate-type superplasticizer(PC) molecular structure on the hydration heat of tricalcium silicate(C3S) paste and polymerization degree of hydration products(C-S-H gel) were researched by usin... Effects of polycarboxylate-type superplasticizer(PC) molecular structure on the hydration heat of tricalcium silicate(C3S) paste and polymerization degree of hydration products(C-S-H gel) were researched by using TAM AIR isothermal microcalorimetry(TA) and 29Si nuclear magnetic resonance(NMR).Methoxy polyethylene glycol-methacrylates-based polycarboxylate superplasticizers with different side chain lengths and main chain lengths were employed.PC molecules with shorter main chain or longer side chains caused stronger retardation of C3S early hydration and lesser increase of C3S 3 d hydration degree.NMR measurement indicated that the incorporation of PC increased the hydration degree of C3S paste and the polymerization degree of silicon-oxygen tetrahedron of C-S-H gel.The tendency for C3S 7 d hydration degree to improve was more pronounced while PC molecules with longer main chain or shorter side chain were added.Whereas,PC molecules with longer main chains or longer side chains increased the 7 d polymerization degree of C-S-H gel. 展开更多
关键词 tricalcium silicate polycarboxylate superplasticizer C-S-H gel HYDRATION NMR
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Effect of Crosslink Structure of Bridge Polycarboxylate Superplasticizers on Dispersion Ability 被引量:5
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作者 毕耀 雷家珩 +1 位作者 DU Xiaodi ZHANG Anfu 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2013年第2期339-342,共4页
Bridge polycarboxylate superplasticizers(PCs) with crosslink structure were synthesized by using polyethyleneglycol di-acrylate(PEGdA), replacing partial polyethyleneglycol mono-acrylate (PEGmA) as crosslinking ... Bridge polycarboxylate superplasticizers(PCs) with crosslink structure were synthesized by using polyethyleneglycol di-acrylate(PEGdA), replacing partial polyethyleneglycol mono-acrylate (PEGmA) as crosslinking agent. Structures of bridge PCs were analyzed by gel permeation chromatography, and dispersion ability was evaluated by cement paste dispersity variation on time and rheology test. The experimental results showed that, molecular weight(MW) of bridge PCs increased with increase of PEGdA proportion, and MW distribution curve changed from Gaussian to fiat like, which meant notable increase of highly crosslinked copolymer. Bridge PCs led to decreased initial cement paste dispersity and better dispersity retention due to slow releasing. Further research showed that, PEGdA proportion had slight effect on polymerization degree of backbone, MW distribution of backbone deviated from Gaussian distribution and shoulder peaks appeared on distribution curve when PEGdA increased. 展开更多
关键词 bridge polycarboxylate superplasticizers cement paste dispersity crosslink structure polyethyleneglycol di-acrylate
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Influence of Polycarboxylate Superplasticizer on Rheological Behavior in Cement Paste 被引量:3
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作者 何燕 ZHANG Xiong +3 位作者 KONG Yaning WANG Xiaofu SHUI Liangliang WANG Haoren 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2018年第4期932-937,共6页
Molecular structures of polycarboxylate(PCE) superplasticizer significantly affect the rheological properties of cement paste. Consequently, we employed self-synthesized PCE copolymers with different carboxylic dens... Molecular structures of polycarboxylate(PCE) superplasticizer significantly affect the rheological properties of cement paste. Consequently, we employed self-synthesized PCE copolymers with different carboxylic densities to investigate their influence on the rheological behavior of cement paste. Three typical rheological models were applied to analyze the rheological properties, including Power-law model, Bingham model as well as Herschel-Buikley model. In addition, the thixotropical performances of cement paste in the presence of PCE with different carboxylic densities were investigated. The results show that the carboxylic density of PCE greatly influences the dispersing performance of PCE superplasticizers. As carboxylic density increases, the dispersing capability of PCE improves, and P(PEG1-AA6) possesses the strongest dispersing capability, the initial fluidity and 1 h fluidity of cement paste are both the highest, and cement paste has the lowest viscosity and the smallest hysteresis loop. 展开更多
关键词 polycarboxylate superplasticizer carboxylic density FLUIDITY RHEOLOGY THIXOTROPY
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Adsorption of Superplasticizers in Fly Ash Blended Cement Pastes and Its Rheological Effects 被引量:2
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作者 陈伟 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2012年第4期773-778,共6页
The adsorption of superplasticizers in fly ash blended cement paste and its rheological effects were investigated.It is shown that the absorption of superplasticizer on portland cement particles is very different from... The adsorption of superplasticizers in fly ash blended cement paste and its rheological effects were investigated.It is shown that the absorption of superplasticizer on portland cement particles is very different from that on fly ash particles.The fly ash particles have smooth surfaces and are negatively charged,so its adsorption capacity is weaker than the portland cement particles.The amount of adsorbed SP in the fly ash blended cement paste depends highly on the replacement proportion of portland cement with fly ash,and to a much less extent on the nature of the fly ash.However,the amount of adsorbed superplasticizer does not correspond well the ζ-potential of the solid particles,due the strong adsorbing capacities of the Portland cement particles.When fly ash replaces portland cement in the paste,the rheological behavior is radically changed,which is closely related to the fineness and density of the ash.The packing and agglomeration of the solid particles are the controlling factors on the rheological parameters of the fresh paste,instead of the amount and type of adsorbed superplasticizer. 展开更多
关键词 adsorption fly ash superplasticizer ζ-potential rheology
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Synthesis of New Polyether Polycarboxylate Superplasticizer 被引量:2
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作者 麻秀星 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2010年第5期799-802,共4页
The effects of various factors on the synthesis process and the performances of product, including batch feeding way and the dosage of the radical initiator, the system concentration, the reaction temperature and the ... The effects of various factors on the synthesis process and the performances of product, including batch feeding way and the dosage of the radical initiator, the system concentration, the reaction temperature and the reaction time were discussed. A kind of polycarboxylate superplasticizer with allyl alcohol polyethylene glycol, maleic anhydride and methacrylic acid sulfonic sodium as main raw materials has been synthesized. Their relative effectiveness as dispersants was evaluated in cement paste by measuring paste fluidity. The optimum parameters of technology and the appropriate proportion of raw materials were obtained. As a result,the new high performance superplasticizer suitable for high-performance concrete has been synthesized. The structure of copolymer was characterized and analyzed by FT-IR spectra. Results indicated that product copolymer structure was consistent with the ideal molecular structure designed. 展开更多
关键词 polycarboxylate maleic anhydride high-performance superplasticizer free radical polymerization
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Effects of Clay on Properties of Polycarboxylate Superplasticizer and Solutions 被引量:5
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作者 王林 WANG Dongmin 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2015年第6期1167-1171,共5页
The infl uence law of clay on mortar fluidity mixed with polycarboxylate superplasticizer was studied. Several methods of inhibiting clay adsorption of polycarboxylate superplasticizer were discussed. The experimental... The infl uence law of clay on mortar fluidity mixed with polycarboxylate superplasticizer was studied. Several methods of inhibiting clay adsorption of polycarboxylate superplasticizer were discussed. The experimental results show that clay has signifi cant effect on the dispersion of polycarboxylate superplasticizer and montmorillonite clay has more signifi cant impact on mortar fluidity than other clays. The pH value and the salts of the solution can affect the adsorption of clay to polycarboxylate superplasticizer. The incorporation of a small amount of sodium hydroxide solution, sodium silicate or cationic surfactants can improve the effect of the clay on the dispersion of polycarboxylate superplasticizer. 展开更多
关键词 clay polycarboxylate superplasticizer fluidity adsorb
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Preparation of Polycarboxylate-based Superplasticizer and Its Effects on Zeta Potential and Rheological Property of Cement Paste 被引量:4
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作者 刘明 雷家珩 +3 位作者 BI Yao DU Xiaodi ZHAO Qinglin ZHANG Xuqing 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2015年第5期1008-1012,共5页
A series of polycarboxylate-based superplasticizers(PCs) with different structures were synthesized and the effects of chemical structure on zeta potential and rheological property of cement paste were studied. Residu... A series of polycarboxylate-based superplasticizers(PCs) with different structures were synthesized and the effects of chemical structure on zeta potential and rheological property of cement paste were studied. Residual monomers in each sample of PCs were quantitatively determined. The property of the polymers in cement was tested by micro-electrophoresis apparatus and R/S rheometer. Results showed that the zeta potential and its rheological properties are related with the side-chain length and density of PCs. The PCs having shorter side chain and lower side chain density exhibit higher anionic charge density, thus resulting in higher zeta potential. The effect of side chain density on zeta potential is more notable compared with that of side-chain length, and thus affecting the initial shear yield stress and apparent viscosity of the cement paste. In addition, although increasing the side chain length will result in reduction of the anionic charge density, the steric hindrance effect is obvious, which can effectively improve the dispersion of the cement particles, and reduce the viscosity and shear yield stress of slurry. 展开更多
关键词 comb polymer polycarboxylate-based superplasticizers zeta potential cement dispersant rheological property
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Determination of Residual Monomers in Polycarboxylate Superplasticizer Using High Performance Liquid Chromatography 被引量:1
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作者 郭丽萍 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2011年第3期439-442,共4页
A procedure was developed for the determination of residual monomers in polycarboxylate superplasticizer (PCs) by reversed-phase high performance liquid chromatography (RP-HPLC).Four kinds of residual monomers wer... A procedure was developed for the determination of residual monomers in polycarboxylate superplasticizer (PCs) by reversed-phase high performance liquid chromatography (RP-HPLC).Four kinds of residual monomers were well separated and determined on a SinoChrom ODS-BP (C18) column with mobile phases composed of acetonitrile and phosphate buffer solution.The monomers were detected by UV detector at 205 nm and quantitatively analyzed with an external standard method.For those residual monomers,the linear response ranged from 4.0×10-6 mol·L-1 to 2.0×10-3 mol·L-1.The determination limit of acrylic acid,sodium methylallyl sulfonate and 2-Acrylamido-2-methylpropane sulfonic acid was 0.02×10-5 mol·L-1,while that of methoxy-polyethylene glycol monoacrylate was 0.1×10-5 mol·L-1.The relative standard deviation (RSD) of high concentration samples was less than 1%,while that of the low concentration samples was between 1%-4%.The standard (additional) recovery ratio was 97.4% -104.2%. 展开更多
关键词 polycarboxylate superplasticizer monomer HPLC copolymerization
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Influences of Polycarboxylate Superplasticizers on Rheological Behavior of Low-cement Castables
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作者 LI Zhukai HE Tingshu HUANG Xiaoyan 《China's Refractories》 CAS 2013年第2期33-37,共5页
Influences of different superplasticizers ( STP. KSJSTO and LMS-P) on rheological behavior of low-cement castables and the mechanisms were analyzed. The shear stress and viscosity under different shear rates of matr... Influences of different superplasticizers ( STP. KSJSTO and LMS-P) on rheological behavior of low-cement castables and the mechanisms were analyzed. The shear stress and viscosity under different shear rates of matrix slurry were determined using a NXS-I IA rotary viscometer. Effects of different admixtures on the rheological properties of slurry was analyzed theoretically. Sodium tripolyphosphate and poly'carboxylate superplasticizers KS-JSTO and LMS-P) can improve the fluidity and initial setting time. With STP. the slurry is plastic flow. With KS-JS70 or LMS-P increasing, the slurrv changes from plastic.flow, pseudoplastic flow to dilatant flow successively. Th, e optimum dosages of STP. KS-JSTO and LMS-P are 0. 15%. 0. 25% and 0. 40%, respectively. KS-JS70 and LMS-P can significantly reduce the slurry viscosity and shear stress to improve the workability of construction. Both shear stress and viscosity shall be taken into account for on-site construction. 展开更多
关键词 polycarboxylate superplasticizer theological behavior apparent viscosity shear stress
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Effect of molecular structure and slump loss resistance of polycarboxylate superplasticizers on self-compacting concrete
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作者 兰自栋 《Journal of Chongqing University》 CAS 2016年第1期35-42,共8页
A new kind of polycarboxylate superplasticizer with high slump loss resistance was obtained by designing scheduled molecular structure.The number average molecular mass of the polymer was characterized by the gel perm... A new kind of polycarboxylate superplasticizer with high slump loss resistance was obtained by designing scheduled molecular structure.The number average molecular mass of the polymer was characterized by the gel permeation chromatography measurements.And chemical structure of the polymer was observed by the Fourier transform infrared spectroscopy(FT-IR).The results show that the good workable maintaining of self-compacting concrete could be achieved through direct adjustment of number average molecular mass and different unsaturated monomer in synthetic process.The FT-IR analysis illustrated that the high slump loss resistance of polycarboxylate superplasticizers with ester and carboxyl group and expectations of molecular structure were designed. 展开更多
关键词 high slump loss resistance of polycarboxylate superplasticizers self-compacting concrete number average molecular mass WORKABILITY
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The Competitive Adsorption Characteristics of Welan Gum and Superplasticizer in Cement Mortar
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作者 赵青林 ZHANG Yulin +2 位作者 LIU Ciqi ZENG Luping CHEN Shihua 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2016年第1期131-138,共8页
Welan gum has been widely used in oil cement and grouting materials for its excellent rheological properties and anti-bleeding,and most of all,being friendly to the environment.However,when welan gum was added,the flu... Welan gum has been widely used in oil cement and grouting materials for its excellent rheological properties and anti-bleeding,and most of all,being friendly to the environment.However,when welan gum was added,the fluidity of mortar decreased sharply,so it should be used together with a superplasticizer to enable good workability.With its powerful charge density in the molecular structure,the competitive adsorption between welan gum and other admixtures happened remarkably during the addition process.Consequently,we experimentally studied on the bleeding rate and rheological properties of cement slurry,fluidity and mechanical properties of mortar with welan gum mixed with superplasticizer,aiming at understanding the competitive adsorption phenomenon by application of welan gum mixed with superplasticizer.By measuring the hydration heat and zeta potential,the mechanism of interaction of welan gum with superplasticizer was deduced and explained.The results showed that it could ensure a good dispersion effect when welan gum is mixed with the two kinds of superplasticizer.Welan gum had little impact on the naphthalene superplasticizer,but did have a substantial influence on polycarboxylate.In practice,adding welan gum after PCE acted with cement for 2 min could effectively avoid the competitive adsorption and then achieve better performance.On this viewpoint for mortar with PCE,new delay release welan gum needs further research and development. 展开更多
关键词 welan gum superplasticizer competitive adsorption properties
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Chemical Structures and Adsorptive Behaviors of Superplasticizers on β-C_2S
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作者 王子明 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2007年第2期337-340,共4页
The chemical structures of four types of superplasticizers (SPs) and their adsorptive behaviors on β-C2S were investigated. The adsorption properties of SPs on β-C2S were measured and the relationship between the ... The chemical structures of four types of superplasticizers (SPs) and their adsorptive behaviors on β-C2S were investigated. The adsorption properties of SPs on β-C2S were measured and the relationship between the adsorption quantity and the specific surface of β-C2S was analyzed. The experimental results show that the adsorption quantity increases with the surface area increase of β-C2S, but the adsorption quantity per surface area is similar, which means that the main adsorbent is β-C2S itself. Polycarboxylic ester (PCE) showed the highest adsorption amount on β-C2S, followed by β-naphthalene sulfonates (NSF) and formaldehyde-acetone condensates sulfonates (FAS), amino sulphonate (AS) showed the least adsorption amount on β-C2S. PCE affected the surface potential of β-C2S particles in water differently in comparison with other types of SPs. The adsorption capacity of SPs on β-C2S is determined by factors such as molecular structure, functional groups and molecular weight of SPs. 展开更多
关键词 β-dicalcium silicate superplasticizer adsorption ζ-potential PCE
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Adsorption properties of CFBC ash-cement pastes as compared with PCC fly ash-cement pastes 被引量:4
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作者 Zhijuan Wang Yuanming Song 《International Journal of Coal Science & Technology》 EI 2016年第1期62-67,共6页
Circulating fluidized bed combustion (CFBC) ash can be potentially used as supplementary cementitious materials for concrete production due to its desirable pozzolanic activity. The adsorption properties of CFBC ash... Circulating fluidized bed combustion (CFBC) ash can be potentially used as supplementary cementitious materials for concrete production due to its desirable pozzolanic activity. The adsorption properties of CFBC ash-cement pastes were studied, and ordinary pulverized coal combustion (PCC) fly ash-cement pastes were used as control. The water-adsorption and superplasticizer (SP)-adsorption properties of the pastes were evaluated by water demand and UV-visible absorption spectroscopy respectively. The results show that CFBC ash-cement system has greater compressive strength as compared with PCC fly ash-cement system at a given curing age, although the water demand of the former is significantly higher than that of the latter. CFBC ash-cement pastes possess higher adsorption ability of aliphatic SP than PCC fly ash-cement pastes and the adsorption amount increases with an increase in ash replacement ratio. CFBC ash- cement pastes exhibit lower workability with higher slump loss. It is concluded that CFBC ash can be potentially used as supplementary cementitious material in concrete production, but the mix design of CFBC ash concrete needs to be appropriately adjusted. It is suggested that CFBC ash is used for the production of the concrete needing low flowability. 展开更多
关键词 CFBC ash - Coal ash CONCRETE adsorption superplasticizer FLOWABILITY
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