Materials Performance

MAR 2018

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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56 MARCH 2018 W W W.MATERIALSPERFORMANCE.COM CHEMICAL TREATMENT the compressive strength (MPa) of the con trol concrete specimen after n cycles. Scanning Electron Microscopy Examination Microscopic examination of the con crete specimens S0, S1, S3, S5, S7, and S9 was performed with SEM after 28 days of curing. The preparation of concrete blocks followed normal microscopy practice. A small piece of the concrete block obtained from the middle of the prism was immersed in acetone for 4 h, dried at 55 °C for four days, cast in epoxy, and polished with sand papers using ethanol as a lubricant. 12 The exteriors of these specimens were dried, and sputter coated with a thin layer of gold to avoid charging when the SEM images were obtained. Results and Discussion Freeze-Thaw Cycles Variations of the weight loss ratios of the concrete samples with SAPs vs. the number of freeze thaw cycles are shown in Fi gure 1. In crea sed am ount s of S APs decreased the relative weight loss of the test concrete specimens when compared with the control concrete specimen. The difference in weight loss ratio between the ordinary concrete specimens with different additions of SAPs tended to increase as the number of freeze thaw cycles increased. After 50 freeze thaw cycles, the weight loss of SAPs modified concrete specimens S1, S3, S5, S7, and S9 decreased by 9.52, 20.95, 28.57, 44.76, and 67.62%, respectively, compared with the control concrete speci men S0. After 150 freeze thaw cycles, the corresponding results were 16.29, 27.27, 36.74, 51.14, and 62.88%. These results show that increasing the SAPs content enhanced the freeze thaw resistance of concrete. The reason may be that the cement pore structure became filled due to the SAPs absorbing water, and the permeability of the concrete declined d u r i n g f r e e z e t h a w t e s t i n g , w h i c h decreased the concrete's free water. Fur thermore, the positive influence of SAPs on concrete may be explained by the forma tion of a p o lym er gel af t er th e S APs absorbed water, which led to the creation of an excellent "reservoir" for ice expansion FIGURE 2 Variations of the concrete's shrinkage ratio after aging. FIGURE 3 The variations of sulfate attack resistance coefficient of compressive strength for concrete specimens after sulfate wet-dry testing. attack resistance coefficient of compres sive strength was calculated according to Equation (3): K f = f cn /f co × 100% (3) where K f equals the corrosion resistance coefficient of compressive strength (%), f cn equals the compressive strength (MPa) of the concrete specimen for sulfate wet dry cycle testing after n cycles, and f co equals

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