Semi-flexible pavement (SFP) combines the best features of both flexible asphalt and rigid cement concrete pavement. SFP consists of a porous asphalt mixture skeleton with 25 %–35 % voids, filled with selected cement slurry. To better balance the flexible and rigid characteristics between the asphalt mixture skeleton and hardened cement paste in SFP, a further understanding of its cement slurry formulation design is required. Results indicate that the penetrant has a significant effect on the fluidity of cement slurry, improving the flowability of cement slurry. Polycarboxylene-based superplasticizer is a desirable penetrant with the dosage of 1 % by mass of cement. Also, the optimum water–cement ratio of 0.6 for cement slurry is proposed, at which the fresh cement slurry can fully penetrate into asphalt mixture skeleton, and improve the engineering properties of SFP. Additionally, styrene butadiene rubber (SBR) latex is an effective flexible admixture for cement slurry, and its dosage of 2 % by mass of cement is proposed. SBR latex improves the stability of fresh cement slurry and enhances the flexibility of hardened cement paste to reduce the cracks in SFP. At the micro level, the fiber-like hydrated products between SBR latex and cement particles improve the flexibility of hardened cement paste. This reduces the cracks on the interface between asphalt mixture skeleton and hardened cement paste when the ambient temperature changes. It is concluded that chemical admixtures are essential requirements for the production of high performance cement slurry. They allow the fresh cement slurry to fully penetrate the asphalt mixture skeleton with a lower water–cement ratio, improving engineering properties of SFP. The proposed cement slurry formulation can better meet the requirements of mechanical properties and durability characteristics of SFP.
Bio-based elastomers used in industry have attracted much attention. We prepared bio-based engineering polyester elastomer (BEE) nanocomposites by mixing bio-based engineering polyester elastomers with carbon (CB). The CB/BEE nanocomposites were exposed to an artificial weathering environment for different time periods. Both its aging behavior changes and aging mechanism were investigated in this article. The tensile strength retention rates were each above 90% after aging at 100 C and 125 C for 72 h. CB/BEE nanocomposites exhibited good anti-aging properties. Furthermore, the chemical changes were detected by Fourier transform infrared spectroscopy and differential scanning calorimetry. The crosslink density changes during aging of BEE were determined as well. A plausible aging mechanism of BEE was proposed. It can be concluded that the thermal oxidation process gives priority to further crosslinking in the initial period of aging. As the aging time increases, chain scission becomes the dominant element in the subsequent thermal oxidation process.
A series of poly(succinic acid/sebacic acid/itaconic acid/butanediol/propanediol) bio-based and non-crystalline engineering elastomers (BEE) were obtained by changing the molar ratio of succinic acid (SA) to sebacic acid (SeA) from 5:5 (BEE-5) to 8:2 (BEE-8). We prepared bio-based engineering elastomer composites (BEE/CB) by mixing BEE with carbon black N330. The lowtemperature and oil resistance properties of the BEE/CB composites were investigated in terms of low-temperature brittleness, coefficient of cold resistance under compression, oil resistance test at different temperatures, and tensile properties. The results showed that the low-temperature brittleness temperature of the BEE/CB composites ranged from 250 to 2608C and the coefficient of cold resistance under compression was 0.18 high at 2608C for BEE-7/CB and 0.23 high at 2408C for BEE-8/CB. The oil resistance properties of BEE-7/CB were higher than those of nitrile-butadiene rubber N240S (NBR N240S), and the oil resistance properties of BEE-8/CB were even as high as those of nitrile-butadiene rubber N220S (NBR N220S). V C 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42855.
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