A macromer, methoxypolyethylene glycol acrylate （MPEGAA）, was synthesized by direct esterification using methoxypolyethylene glycol （MPEG-1200） and acrylic acid （AA） as the main materials. MPEGAA was then used t...A macromer, methoxypolyethylene glycol acrylate （MPEGAA）, was synthesized by direct esterification using methoxypolyethylene glycol （MPEG-1200） and acrylic acid （AA） as the main materials. MPEGAA was then used to prepare a polyacrylic acid superplasticizer modified with 2-acrylamido-2- methylpropane sulfonic acid （AMPS）. A single-factor test was performed to investigate the effects of the molar ratio of acid to alcohol （n（AA）/n（MPEG））, inhibitor amount, catalyst amount, temperature, and time of esterification on the synthesis of MPEGAA. The experimental results showed that the optimal esterification conditions were as follows： n（AA）/n（MPEG）, 3.5：1; amount of hydroquinone （as an inhibitor）, 1.2%; amount of para-toluenesulfonic acid （as a catalyst）, 5.5%; reaction temperature, 95 ~C; and reaction time, 6 h. The AMPS- modified polyacrylic acid superplasticizer prepared under the optimal esterification conditions enabled the achievement and maintenance of high cement dispersibility. At an admixture amount of 0.15%, the cement paste fluidity was initially as high as 300 mm, and then decreased to 315 mm after 1 h and to 290 mm after 2 h.展开更多
A 2-acrylamide-2-methyl propylene sodium sulfonic （AMPS）-modified polyacrylic acid superplasticizer was synthesized using aqueous solution polymerization with the major monomers including the self-made active macrom...A 2-acrylamide-2-methyl propylene sodium sulfonic （AMPS）-modified polyacrylic acid superplasticizer was synthesized using aqueous solution polymerization with the major monomers including the self-made active macromers polyethylene glycol mono-methyl ether acrylate acrylic （MPEGAA）, acrylic acid （AA）, AMPS, and sodium methyl allyl sulfonate （SMAS）. The ratios of the monomers were determined using an orthogonal experiment. This research focused on the effects of the dosages of different macromers, the polymerization conditions, and the length of MPEGAA side chains on the properties of the AMPS-modified polyacrylic acid super-plasticizer. The best polymerization conditions of the AMPS-modified polyacrylic acid superplasticizer are when （n（MPEGAA）：n（SMAS）：n（AMPS）：n（AA） equals 0.1：0.1：0.2：0.65, the molecular weight of monomethoxypolyethylene glycol is 1 200, the initiator ammonium persulfate accounts for 5% of the total mass of the polymerized monomers, the polymerization temperature is 80 ~C, and the reaction time is 4 h. The AMPS-modified polyacrylic acid superplasticizer synthesized in the best conditions exhibited excellent dispersivity and dispersion retainability. When the dosage ratio was 0.24%, the initial fluidity was 400 mm and the fluidity had nearly no loss after 1 h.展开更多
A self-made AMPS-modified polyacrylic acid superplasticizer and two others of the same type but with different molecular structures, which are commercially available, are used in this study to investigate the effect o...A self-made AMPS-modified polyacrylic acid superplasticizer and two others of the same type but with different molecular structures, which are commercially available, are used in this study to investigate the effect of a 2-acrylamide-2-methyl propylene sulfonic （AMPS）-modified polyacrylic acid superplasticizer on the properties of cement-based materials. In the experiments, initial fluidity, 1 and 2 h fluidity over time after admixtion, bleeding rate of the net cement mortar, and adsorption capacity and rate of cement particles are determined by adding different dosages of the three superplasticizers into the cement paste to characterize the dispersivity and the dispersion retention capability of each superplasticizer. Water-reducing rates of three kinds of mortars are simultaneously determined to characterize the water-reducing capacity of each superplasticizer, as well as the 3 and 28 d compressive strengths to characterize the compression resistance. Results show that water-reducing effect and fluidity better maintain the capability of the AMPS-modified polyacrylic acid superplasticizer than the two commercially available polyacrylic acid superplasticizers, and the compressive strengths after 3 and 28 d show significant growth. In conclusion, the effects of water reduction and strengthening of the AMPS-modified polyacrylic acid superplasticizer are evidently better than those of the two commercially available polyacrylic acid superplasticizers.展开更多
A self-made 2-acrylamide-2-methyl propylene sulfonic （AMPS）-modified polyacrylic acid superplasticizer and two other commercially available superplasticizers with different molecular structures are used in this stud...A self-made 2-acrylamide-2-methyl propylene sulfonic （AMPS）-modified polyacrylic acid superplasticizer and two other commercially available superplasticizers with different molecular structures are used in this study to investigate the effect of an AMPS-modified polyacrylic acid superplasticizer on the properties of concrete materials. In the experiments, initial and 1.5 h slumps over time after admixtion are determined by adding different dosages of three superplasticizers into the premixed concrete to characterize the slump loss resistance of the premixed concrete. The water-reducing rates of three different types of concrete are determined to characterize the water-reducing capacity of the concrete with each superplasticizer. The 3, 7 and 28 d compressive strength is determined to characterize the mechanical properties of the concrete with each superplasticizer. In the meanwhile, 1, 1.5 and 2.0 h slump loss rates over time after admixtion are determined by adding different dosages of the three superplasticizers into the high-performance concrete （HPC） to characterize the slump loss resistance of HPC. The 7, 28, 60 and 90 d compressive strength is determined to characterize the compressive properties of HPC with each superplasticizer. The dry shrinkage rates of three different types of HPC are determined with each superplasticizer. Electric flux after standard curing for 56 d and chloride ion diffusion coefficient after curing for 28 d of I-IPC are determined to characterize the impermeability of HPC with each superplasticizer. The cross-section was examined using a scanning electron microscopy （SEM） system. Results demonstrate that the AMPS-modified polyacrylic acid superplasticizer has better water-reducing effect and slump than the two commercially available polyacrylie acid superplasticizers. The AMPS-modified polyacrylic acid superplasticizer also shows significant improvement of the compressive strength, especially in comprehensive performance of HPC. In conclusion, the AMPS-modified polyacryl展开更多
基金Funded by the Fujian Education Department(Nos.JA11329,JA12412)the Quanzhou(Fujian)Technology Research and Development Program(No.2010G7)
文摘A macromer, methoxypolyethylene glycol acrylate （MPEGAA）, was synthesized by direct esterification using methoxypolyethylene glycol （MPEG-1200） and acrylic acid （AA） as the main materials. MPEGAA was then used to prepare a polyacrylic acid superplasticizer modified with 2-acrylamido-2- methylpropane sulfonic acid （AMPS）. A single-factor test was performed to investigate the effects of the molar ratio of acid to alcohol （n（AA）/n（MPEG））, inhibitor amount, catalyst amount, temperature, and time of esterification on the synthesis of MPEGAA. The experimental results showed that the optimal esterification conditions were as follows： n（AA）/n（MPEG）, 3.5：1; amount of hydroquinone （as an inhibitor）, 1.2%; amount of para-toluenesulfonic acid （as a catalyst）, 5.5%; reaction temperature, 95 ~C; and reaction time, 6 h. The AMPS- modified polyacrylic acid superplasticizer prepared under the optimal esterification conditions enabled the achievement and maintenance of high cement dispersibility. At an admixture amount of 0.15%, the cement paste fluidity was initially as high as 300 mm, and then decreased to 315 mm after 1 h and to 290 mm after 2 h.
基金Funded by Fujian Education Department(Nos.JA11329,JA12412)Quanzhou (Fujian) Technology Research and Development Program(No.2010G7)
文摘A 2-acrylamide-2-methyl propylene sodium sulfonic （AMPS）-modified polyacrylic acid superplasticizer was synthesized using aqueous solution polymerization with the major monomers including the self-made active macromers polyethylene glycol mono-methyl ether acrylate acrylic （MPEGAA）, acrylic acid （AA）, AMPS, and sodium methyl allyl sulfonate （SMAS）. The ratios of the monomers were determined using an orthogonal experiment. This research focused on the effects of the dosages of different macromers, the polymerization conditions, and the length of MPEGAA side chains on the properties of the AMPS-modified polyacrylic acid super-plasticizer. The best polymerization conditions of the AMPS-modified polyacrylic acid superplasticizer are when （n（MPEGAA）：n（SMAS）：n（AMPS）：n（AA） equals 0.1：0.1：0.2：0.65, the molecular weight of monomethoxypolyethylene glycol is 1 200, the initiator ammonium persulfate accounts for 5% of the total mass of the polymerized monomers, the polymerization temperature is 80 ~C, and the reaction time is 4 h. The AMPS-modified polyacrylic acid superplasticizer synthesized in the best conditions exhibited excellent dispersivity and dispersion retainability. When the dosage ratio was 0.24%, the initial fluidity was 400 mm and the fluidity had nearly no loss after 1 h.
基金Funded by the Fujian Education Department(Nos.JA11329,JA12412)Quanzhou(Fujian)Technology Research and Development Program(Nos.2013Z158,2013Z47,2010G7)
文摘A self-made AMPS-modified polyacrylic acid superplasticizer and two others of the same type but with different molecular structures, which are commercially available, are used in this study to investigate the effect of a 2-acrylamide-2-methyl propylene sulfonic （AMPS）-modified polyacrylic acid superplasticizer on the properties of cement-based materials. In the experiments, initial fluidity, 1 and 2 h fluidity over time after admixtion, bleeding rate of the net cement mortar, and adsorption capacity and rate of cement particles are determined by adding different dosages of the three superplasticizers into the cement paste to characterize the dispersivity and the dispersion retention capability of each superplasticizer. Water-reducing rates of three kinds of mortars are simultaneously determined to characterize the water-reducing capacity of each superplasticizer, as well as the 3 and 28 d compressive strengths to characterize the compression resistance. Results show that water-reducing effect and fluidity better maintain the capability of the AMPS-modified polyacrylic acid superplasticizer than the two commercially available polyacrylic acid superplasticizers, and the compressive strengths after 3 and 28 d show significant growth. In conclusion, the effects of water reduction and strengthening of the AMPS-modified polyacrylic acid superplasticizer are evidently better than those of the two commercially available polyacrylic acid superplasticizers.
基金Funded by the Fujian Education Department(Nos.JA11329,JA12412)Quanzhou(Fujian)Technology Research and Development Program(Nos.2013Z47,2013Z158,2010G7)
文摘A self-made 2-acrylamide-2-methyl propylene sulfonic （AMPS）-modified polyacrylic acid superplasticizer and two other commercially available superplasticizers with different molecular structures are used in this study to investigate the effect of an AMPS-modified polyacrylic acid superplasticizer on the properties of concrete materials. In the experiments, initial and 1.5 h slumps over time after admixtion are determined by adding different dosages of three superplasticizers into the premixed concrete to characterize the slump loss resistance of the premixed concrete. The water-reducing rates of three different types of concrete are determined to characterize the water-reducing capacity of the concrete with each superplasticizer. The 3, 7 and 28 d compressive strength is determined to characterize the mechanical properties of the concrete with each superplasticizer. In the meanwhile, 1, 1.5 and 2.0 h slump loss rates over time after admixtion are determined by adding different dosages of the three superplasticizers into the high-performance concrete （HPC） to characterize the slump loss resistance of HPC. The 7, 28, 60 and 90 d compressive strength is determined to characterize the compressive properties of HPC with each superplasticizer. The dry shrinkage rates of three different types of HPC are determined with each superplasticizer. Electric flux after standard curing for 56 d and chloride ion diffusion coefficient after curing for 28 d of I-IPC are determined to characterize the impermeability of HPC with each superplasticizer. The cross-section was examined using a scanning electron microscopy （SEM） system. Results demonstrate that the AMPS-modified polyacrylic acid superplasticizer has better water-reducing effect and slump than the two commercially available polyacrylie acid superplasticizers. The AMPS-modified polyacrylic acid superplasticizer also shows significant improvement of the compressive strength, especially in comprehensive performance of HPC. In conclusion, the AMPS-modified polyacryl
