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Aminopropyl-terminated polydimethylsiloxane (APDMS) with different molecular weights ( M-n) were synthesized by 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (BADS) and dimethylcyclosiloxane (Dn). Fourier-transform infrared shows the increase in APDMS Mn and the decrease in -NH2 content in the products with the increasing ratio of Dn/BADS. 1H NMR further confirmed the conclusion obtained by Fourier-transform infrared spectra, and the APDMS Mn resulted from 1H NMR were 1,106 (APDMS1), 1,987 (APDMS2), 2,690 (APDMS3), and 4,313 (APDMS4) g/mol. These APDMS were then blended with the epoxy resin (diglycidyl ether of bisphenol A) system to improve its toughness. Mechanical tests revealed that the impact strength of the epoxy resin was improved by APDMS1 and APDMS2, which has lower Mn. The toughening effect decreased when APDMS4 was used. It was suggested that the APDMS with high Mn was easier to agglomerate, which in turn resulted in lower toughening efficiency. This was also confirmed by scanning electron microscopy results. © 2015 Society of Plastics Engineers. Source

Jiangsu Sobute New Materials Co. | Date: 2011-12-30

Disclosed is a method for testing the setting time of a cement-based material: testing the capillary negative pressure of a non-bleeding cement-based material, with the time at which the capillary negative pressure reaches a threshold value A as the initial setting time, and/or the time at which the capillary negative pressure reaches a threshold value B as the final setting time, wherein threshold value A is 8-10 kPa, and threshold value B is 54-56 kPa. Alternatively, threshold value A and threshold value B are determined by the following method: formulating a cement-based material for the determination of threshold values with the same raw materials at the same formulation ratio; after vibration-compaction, placing a portion into a measuring mold; after vibration-compaction, testing the capillary negative pressure of the non-bleeding cement-based material placed in the measuring mold; under the same conditions, synchronously testing and determining the initial setting time and final setting time of the cement-based material for the determination of threshold values by a penetration resistance method; the capillary negative pressure corresponding to the initial setting time and final setting time of the cement-based material for the determination of threshold values are respectively threshold value A and threshold value B. The method can not only be used in standard tests for a laboratory cement setting time under standard temperature conditions, but can also be used to realize remote, automatic, and continuous in situ monitoring for the setting time of a cast-in-situ concrete structure.

Mu S.,Jiangsu Research Institute of Building Science | Mu S.,Jiangsu Sobute New Materials Co. | Liu J.,Jiangsu Research Institute of Building Science | Liu J.,Jiangsu Sobute New Materials Co.
Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society

This paper reviews the test methods to induce concrete cracking, experimental and characterization methods for chloride transport in cracked concrete and influencing parameters. For these methods of crack preparation, there is a difference between destructive and non-destructive methods to form artificial cracks. The effect of influencing parameters like crack width and depth, ratio of water to cement, cement content, supplementary materials, additive, cover thickness, load, chloride concentration and exposure duration on the chloride transport properties based on some previous work was represented. In addition, some prospects were given to investigate the transport mechanism and the property of cracked concrete in future. For the test methods to induce concrete cracking, the non-destructive method can be used to quantitatively study influence of different cracking parameters on transport properties of concrete. However, it should be established the transport property relationship between artificial and real engineering cracks. As the width is 100 µm below, crack made significant contribution for transport rate of chloride ions. By contrast, crack with a width of higher than 100 µm shown slight effect on the transport rate. In addition, high value of crack depth and ratio of water to binder contributed to the transport rate, while increase of cement amount and addition of mineral admixture can reduce the transport rate. ©, 2015, Chinese Ceramic Society. All right reserved. Source

Qian J.,Jiangsu Research Institute of Building Science | Qian J.,Jiangsu Sobute New Materials Co. | Song M.,Jiangsu Research Institute of Building Science | Song M.,Jiangsu Sobute New Materials Co.
RILEM Bookseries

The objective of this study is to evaluate the effect of limestone powder as a filler material on the fresh and hardened properties of early-age geopolymer. The geopolymer was prepared by alkali activating metakaolin added with limestone filler from 10% to 30% by weight. It was found that the incorporation of limestone powder improved the fluidity and strength. 10% addition of limestone powder increased 17.43% and 14.36% of the 7d compressive and flexural strength respectively, and the sample with 15% addition improved the fluidity of fresh geopolymer distinctly. The mechanism of limestone powder as filler material on the enhancement of properties of geopolymer was investigated by using X-ray diffraction analysis and scanning electron microscopy. The delayed formation of amorphous products with an increased prominence of calcite and a more compacting structure were observed from the XRD and SEM results. Thus the rheology property and the strength development were both promoted due to a better particle size distribution as the extra LS was added. © RILEM 2015. Source

Plank J.,TU Munich | Sakai E.,Tokyo Institute of Technology | Miao C.W.,Nanjing Southeast University | Miao C.W.,Jiangsu Research Institute of Building Science | And 5 more authors.
Cement and Concrete Research

An overview of current PCE compositions and synthesis methods is provided, followed by novel applications for PCEs including C-S-H-PCE nano-composites and a description of still unresolved challenges for PCE technology. In addition, the functionality of chemical admixtures in specific applications for low-carbon cements and concrete systems is discussed. The action mechanisms of retarders and the recycling system of sludge water by using retarder are introduced. Furthermore, the influence of fluoride ion and the effectiveness of PCE polymers in blended cements and the effect of non-adsorbed polymer are presented. And the impact of special interface modifying materials, of a refined pore structure and of chemical admixtures, particularly shrinkage-reducing agents, is described. The article concludes that more accurate quantitative micro-analytical methods and modeling tools will be needed to obtain a holistic understanding of factors affecting the microstructure of concrete, with the final goal of achieving a more durable concrete. © 2015 Elsevier Ltd. Source

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