Design of a Novel Road Pavement Using Steel and Plastics to Enhance Performance, Durability and Construction Efficiency.

Durability is one important problem that pavement engineers need to address in pavement's long service life. Furthermore, easily recycled pavement materials, and safe and efficient pavement construction are also important areas for development in road engineering. For these reasons, a new asphalt steel plastic (ASP) pavement structure was proposed with an asphalt mixture forming the surface layer, and steel plate and plastic materials functioning as the main load-bearing layers. Based on a comprehensive performance review and cost-benefit analysis, stone mastic asphalt (SMA) is recommended to be used as the surface layer; and A656 steel plate and acrylonitrile butadiene styrene (ABS) plastic materials should be the main load-bearing layer, on top of a foundation layer made with graded crushed stones. A glass fiber reinforced polymer (GFRP) insulation layer is recommended for use between the steel plate and ABS. Mechanical properties of the ASP pavement were analyzed using the finite element method. Laboratory tests were conducted to verify the thermal insulation performance of GFRP, the high-temperature stability and the fatigue resistance of ASP pavement. Results show that some of the mechanical properties of ASP pavement (with a structure of 80 mm SMA asphalt mixture, 8 mm steel plate, 140 mm ABS and 200 mm crushed stones) are comparable with conventional long-life pavement (with 350 mm asphalt layer overlaying 400 mm graded crushed stones). Dynamic stability of the ASP slab specimens can reach 10,000 times/mm, and the fatigue life is about twice that of SMA. Besides, the ASP pavement can be prefabricated and assembled on-site, and thus can greatly improve construction efficiency. From the lifecycle perspective, ASP pavement has many advantages over traditional pavements, such as durability, lower environmental footprint and recyclability, making it is worth further research.

[Spectrophotometry determination of trace selenium(IV) in Chinese herbal medicine by catalytic kinetics. I. RDB and potassium bromate].

Trace Se(IV) can catalyze the discolouring oxidizing reaction of RDB with potassium bromate in nitric acid medium, and the conditions of kinetics has been studied in detail. A new method of kinetics spectrophotometry for determination of trace (IV) is established. The sensitivity of the method is 0.905 microg x L(-1). The range of measurement is 0-9.6 microg x L(-1). The method has been used for determining trace Se(IV) in Chinese herbal medicine with satisfactory results.