In order to solve the problem of poor adhesion of organic coatings on the surface of hot-dip galvanizing, we conducted a series of experiments to select the suitable pre-treatment method and type of the coatings. We adopted temperature shock & alternating damp heat combined test and waterproof test to simulate the service conditions, and investigated the adhesion of organic coating on the surface of hot-dip galvanizing in the wet environment. With the XPS analysis, we discussed the avoidance of formation of weak boundary layer on the hot-dip galvanizing surface by pre-treatment, and the improvement on adhesion of the organic coatings. We also proposed the pre-treatment method of coupling treatment with silane or combined alkali washing & grinding procedures, by which the organic coating on the hot-dip galvanizing surface performed excellent adhesion and water proof ability against wet conditions.

In this paper both the NaCl immersion and the co-action of load and NaCl solution immersion were employed to analyze the wet adhesive property and resistance of chlorion diffusivity of two types of linear polyaspartic ester (PAE) polyureas coated concrete: B2（PAE-b-H12MDI prepolymerH66）coated concrete and F2（PAE-f-H12MDI prepolymerH62） coated concrete. The research on the adhesion of B2 and F2 coated concrete showed that the adhesion were about 2N/mm and 1.5N/mm respectively before exposure, and the adhesion reduced about 6.8% and 11.8% respectively after 10% NaCl immersion for 300 days and made 8% and 5% further decrease under the co-action of load and NaCl solution immersion, double-factor exposure for 300 days. Compared with single NaCl solution immersion, the co-action of load and NaCl solution immersion also had more influence on the chlorion diffusivity of the coated concrete. The average chlorion content of B2 and F2 coated concrete increased about 19-21%, and the diffusion coefficient of chlorion of B2 and F2 coated concrete was 10－13-10－14m2/s, due to the micro-crack of concrete in tensile area increased under bending load, accelerating chlorion diffusion and permeation. The research showed that chlorion diffusion behaviour of B2 and F2 coated concrete under the NaCl immersion and the co-action of load and NaCl solution immersion satisfied second Fick’s law.

In this paper the effect of curing temperature on the morphology and properties of PAE based polyureas were evaluated using FTIR, AFM and electrochemical impedance spectroscopy (EIS). The PAE based polyureas were prepared from synthesized PAE chain extenders and hexamethylene diisocyanate（HDI）trimer/polytetramethylene ether glycol (PTMG) prepolymer. The morphology and properties were investigated through FTIR, EIS and atomic force microscope(AFM). The results indicated that curing temperature has a great influence on morphology and properties of the polyureas. FTIR studies showed that hydrogen-bonded urea carbonyl are increased from 74.3% to 82.1%, and the length of hydrogen bonding were decreased from 0.307 nm to 0.303 nm while curing temperature were increased from 20°C to 80°C. FTIR experimental studies indicated that the degree of hydrogen-bonded –NH groups and urea carbonyl groups increased while curing temperature increased, as a consequence, intermolecular force enhanced. The AFM was applied to study the topography of PAE based polyureas for the first time,and the microphase separation phenomenon of the PAE based polyureas were observed directly through AFM topography studies. AFM studies confirmed that the compatibility of soft and hard segment decreased and microphase separation degree increased while the curing temperature increased. The EIS studies indicated that during 90 days immersion, the resistance of 20°C cured samples changed obviously higher than 80°C cured ones. The results showed that much corrosion medium permeated into the coatings, and the corrosion resistance of 80°C cured PAE based polyureas exhibited a higher EIS features and a better corrosion resistance than the 20°C cured ones. The effect of curing temperature on EIS properties of PAE based polyureas could be confirmed by FTIR and AFM morphology studies.

One of the negative factors of thermal is the effect on the adhesion of polymer coating. The high difference of thermal expansion coefficient between epoxy system and substrate is far, so put forward a new substrate system base on polyurethane (QTECH-112 system). To study the thermal change situation, the static strain testing and the substrate system microstrain change situation on low temperature and common temperature were tested respectively, and the mircostrain at the corners of the structure had also been tested. Results showed that both substrate systems had little microstrain in common temperature. But the epoxy system had high shrink strain under the low temperature, and caused the thermal stress, wihch could not be neglected during the concrete ; As a polyurethane elastomer, QTECH-112 system’s, thermal stress reduced by stress relaxation. The boundary of structure had limited on strain, so it should considered on structure design.

No abstract