| It's well known that a small amount of water-soluble polymer modified cement admixtures could significantly improve the processing properties of fresh mixed concrete, double and redouble the strength and durability of hardened concrete thus extend the lifespan of buildings. Therefore, the applications of different admixtures in concrete have long been hot topics and are intensively studied in this paper. The design, synthesis and characterization of two new-type waterbonre polymers, namely, superplasticizer of polycarboxylic acid (SPC) and polyurethane modified by polyacrylate emulsion or dispersion (PUA), were carried out in this work with the support of the Guangdong Science and Technology Project of"Research on New-Generation Polymer Water-Reducing Admixture". What's studied in this paper include effects of synthesizing acrylate-methyl poly(ethylene oxide) macro-monomer (AMPEO), structure design and optimization, relationship between structures and properties of SPC; controllable technologies for particles and particle distributions of PUA and its film forming performance; microstructure and mechanical strength of concrete with SPC and PUA. It is also in this paper that wavelet analysis was used for the first time to work over the effects of waterborne polymeric admixture on cement hydration process, which was a complicated multiple-dimentional system. At present, the industrialization of SPC was achieved and high-performance concrete with SPC could be easily prepared. Main contents are as follows.A new comb-like polycarboxylate superplasticizer was synthesized which contains polyether, carboxylic acid and sulfonic acid. An AMPEO was first prepared from acryl derivants and methyl poly(ethylene oxide) using the method of bulk polymerization and direct-etherification with the existence of 2-hydroxyl-1-methoxyl-anthraquinone. Comb-like polycarboxylate superplasticizer (SPC) were then synthesized in water from AMPEO, acryl acid, and unsaturated monomers containing varied sulfonic groups, based on radical ternary copolymerization. Structures of the products were confirmed using FTIR, 1H-NMR, 13C-NMR, and GPC.Results from orthogonal design show that the type of unsaturated sulfonic monomer and its contents are the main affecting factors and those such as, initiator contents (X3, mg), chain transfer contents (X4, mg), acrylic acid contents (X1, mmol), unsaturated sulfonic monomer contents (X2, mmol) are also affecting factors. A linear equation based on regression using SPSS is obtained to describe the relationship among those affecting factors and the fluidity of cement grout (FCG, mm): FCG =5.44×10-3 X1 + 3.21×10-2 X2 + 4.49×10-2 X3 - 5.34×10-2 X4+ 246.39 The molecular structure and the distribution of molecular weights of SPC are important factors which affect the properties of water reducing admixture. Results showed that SPC containing 28 ethylene oxide chains in the side chain (28SPC) showed superior properties than those with other numbers. The water-reducing rate order for varied SPC with different side chain length is: 28SPC > 20SPC > 12SPC > 8SPC > 36SPC > 56SPC. With the dosages of 0.30% and 0.35%, the water-reducing rates of 28SPC were 35.6% and 40.0% respectively. The performances of these SPCs are better than those similar foreign products. Compared to naphthalene sulfonate formaldehyde condensate (NSF), SPC shows higher FCG, lower slump loss and higher water-reducing rate. For example, with the same dosage of 0.10%, the slump loss of mixed concrete after 120 min is 15.0% for SPC compared to 66.7% for NSF water reducer. Synthesized SPC showed high water-reducing rate when the difference of weight-average molecular weights and peak molecular weight (Mw-Mp) is above zero and in interval of 6600 and 18000. SPC also showed higher water-reducing rate when it had the same side chains, yet lower PDI and smaller (Mw-Mp).The polyurethane aqueous dispersion modified by polyacrylate (PUA) with controlled particle size, fine filming and water-resisting properties were prepared. The effects of CNO/OH ratio (R), contents of -COOH in water soluble PU chain, feeding methods, molecular weight of polyether, chain-extending agents, cross-linking agents, and stirring speed on the preparation of polyurethane aqueous dispersion (PU) were studied. And stable PUA with small particle, narrow particle size distribution, fine filming and desirable water-resisting properties were prepared.Joint application of organic polymer materials and concrete is an important and effective way to improve the durability of concrete based materials. PUA modified concrete (PMC) with good comprehensive properties was prepared. It is a new application field of PU material, although traditional water-borne PU dispersion cannot be homogeneously added into a fresh mixed cement paste. It was found that the diffusion coefficient of Cl- ranges from(25 to 50)×10-14 cm2·s-1 with the presence of PUA, and the durability of this kind of concrete in sea water should be more than 70 years, according to CCES 01-2004. Mechanical test results show that the bending strength and axial compressive strength were improved by 45% and 49% respectively. The analysis based on IR, TGA and XRD had confirmed the formation of chemical bond between polymer and cement particles. A compact film is formed on the surface of cement particles, as observed in SEM, which discloses that the addition of PUA can fill the space of concrete, decrease the connectivity of pore and improve the durability of PMC. Wavelet analysis was applied for the first time to analyze the changing rule in the process of cement hydration. Since cement is polymineralic aggregation, the process of cement hydration is a complex and multiple scale problem. It was observed that the peak time of cement hydration heat was delayed from 345 min to 581 min from the results of TAM-AIR equipment. Results of non-contacting resistivity meter showed that hydration resistivity during the process of cement hydration were significantly increased because of PUA. The curves for effects of SPC and PUA on hydration heat and hydration resistivity during the process of cement hydration, which were related to multiple factors and were of multiple scales, were analyzed through wavelet analysis in this paper. The changing rule of the power of hydration signal was also analyzed in both time-domain and frequency-domain. The addition of water-soluble additives could effectively delay the peak time of cement hydration. It was also noticed that the influence would be different for varied additives. In order to exactly obtain the message during the hydration process of cement, wavelet analysis was introduced for its special time-frequency properties. In this way, the distribution of hydration heat and resistivity in both time-domain and frequency-domain could be obtained by analyzing the regularity of varied signals at different times. Results showed that the incorporation of SPC and PUA could effectively inhibit the noise interference of hydration heating and proved that hydration process of cement was more stable with SPC. As the quality of buildings is profoundly influenced by the hydration process of cement, it has many guiding meanings for using wavelet analysis to study this complex and multiple scale system.Based on the above theoretical and experimental studies, SPC had been successfully industrialized and identified the achievements in scientific research by Science and Technology Department of People's Government of Guangdong Province. The product could meet and was actually far better than the requirements of first class products in national standard (GB8076-1997), and was at the advanced level of similar foreign products. With the dosage of 0.25%, the water-reducing rate is more than 35% and the rate of growth of compressive on 3, 7, 28 days are 150%, 176%, 159% respectively. Application tests showed that the product was highly adaptable to varied cement, and was suitable for the preparation of pumping concrete, self-leveling concrete, high-performance concrete(HPC) and a variety of precast concrete.
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