Slow-release anti-frost additive for asphalt-based road surfaces - has crystals of deicing agent, esp. sodium chloride, coated with protective organic layer and outer mineral layer, forming synthetic stone

摘要

An anti-frost additive (I) contains a defrosting agent such as NaCl and/or MgCl2 and/or KCl (II). The novelty is that the crystals of (II) have an inner protective organic-based coating (A) and an outer mineral-based protective coating (B), which forms a synthetic stone contg. 35-70 wt.% (II). Also claimed is the prodn. of (I), by encapsulating (II) with a 45-55% dispersion of styrene/acrylate copolymer, using 35-75 wt.% (II) w.r.t. dispersion, mixing the dispersion obtd. with cement, mineral fillers and water, hardening the mixt. and pulverising the prod. USE/ADVANTAGE - (I) is useful as an antifrost additive in asphalt-based road surfaces, in the form of 8-20 wt.% crushed chips w.r.t. road surface material. The invention provides a slow-release antifrost additive for asphalt-based road surface materials which is effective for a long time and provides improved protection against sudden excessive dissolution in water (w.r.t. prior-art systems); the NaCl is gradually released by erosion due to traffic, and provides a good thawing effect in the range 0 to -5 deg.C.