No abstract

No abstract

Influence of glycol, which is the main composition of the most frequently used aircraft dicer, on the freeze-thaw durability of Portland cement concrete were investigated. Freeze-thaw durability of Portland cement concrete was tested by accelerated freeze-thaw test. Four kinds of solutions, namely tap water, 3.5% NaCl solution, glycol solutions and a LBR-A type commercial aircraft deicer were employed to be the freezing-thawing mediums. Results show that freeze-thaw durability of concrete exposed to glycol solutions is closely related to the solution concentrations. Failure of concretes exposed to 3.5% glycol solution is similar to that of those exposed 3.5% NaCl solution, which are attributed to serious surface scaling. While damage of concrete exposed to 12.5% and 25% glycol solutions are postponed, and the durability of concrete are increased. Compared with glycol solution, the commercial aircraft deicer demonstrated much more negative effect to concrete freeze-thaw durability, and the degree even exceeds 3.5% NaCl solution. Consequently, the commercial aircraft deicer is not a kind of environmental friendly deicer as usually considered.

PPS and PA6were blended to improve the mechanical properties of the large diameter PPS monofilaments. The influence of the structure of the blends on the blending monofilaments, the comparative analysis with relevant polymer monofilaments and the acid and alkali resistance were studied in this article. The results demonstrated that: the mechanical properties of the PPS monofilaments were improved. The tensile strength and the collaboration strength of the monofilaments increased. The toughness of the PPS monofilaments increased. Simultaneously, the acid resistance and the alkali resistance of the PPS monofilaments were retained in the PPS/PA6blending monofilaments.

The concept of powder volume equivalent coefficient is presented to study the reasonable powder volume and solve the problem that the cohesiveness and bleeding of low strength manufactured sand concrete is poor. With the way of laboratory experiment, water requirement of normal consistency of different powder is tested to determine the powder volume. The impact of powder volume on the low strength manufactured sand concrete workability under same sand ratio is analyzed with improved Mehta method. The experimental result shows that freshly mixed low strength manufactured sand concrete workability can be evaluated with powder volume equivalent coefficient and the reasonable powder equivalent volume is 156~160L/m3.