Process for the preparation of an incorporable bituminous cold-miscible material based on a bitumen emulsion, and a mixture of minerals with graded grain sizes

摘要

In the prepn. of a cold bituminous mix based on a bitumen emulsion (55% bitumen content) and a mineral mixt. of graded granulometry, the novelty is that (i) the bitumen emulsion is prepd. in an unit integrated into the mixing plant used to produce the bituminous mix, by supplying a pre-acidified road-building bitumen, with the required bitumen penetration temp., and an amount of alkaline water dependent on the bitumen acid value to a first colloid mill and forming an anionic emulsion simultaneously with discharge of the bitumen; (ii) the anionic emulsion is cooled, without intermediate storage, by passage through a heat exchanger and reacted with 0.5-3% water-soluble or swellable, stabilising and cation-activating protein; (iii) the heated water from the heat exchanger is made alkaline and supplied continuously to the emulsion prepn. process in the first colloid mill; (iv) the emulsion assumes, on further passage through the heat exchanger, highly stable cationic properties in the alkaline medium due to the protein addn.; (v) the emulsion is treated, during passage through a second colloid mill, with neutral materials or acidic or sterilising materials or adhesion promoting additives by metering in amounts dependent on the surface properties of the graded mineral mixt. until sufficiently cooled, acidic or alkaline, mixed with the graded mineral mixt. and then transferred, control of the desired emulsion breaking time (i.e. start of phase sepn.) being achieved by choice and metered amount of additives or by incorporation of retarders or accelerators in the emulsion or the mix, while taking account of the pH of the emulsion or mix.