Red mud filler for bituminous road coatings - where alkali materials in red mud are neutralised so filler contains aluminium hydroxide gel

摘要

The filler contains an aluminium hydroxide gel, which is formed by at least partial neutralisation of the alkalies in the red mud. The alkalies pref. consist of soluble sodium aluminate and insol. sodium alumium silicate. The red mud pref. also contains SiO2 gel, and a frost-inhibitor, esp. NaCl. The filler pref. has a grain size below 1 mm; and the grains are pref. coated with higher hydrocarbons, esp. diesel oil. The red mud is pref. neutralised by being stirred with an agent, possibly after the addn. of NaCl. The agent is pref. AlCl3 and/or Al2(SO4)3, and/or HCl or H2SO4. The mixed is then pref. dried and milled. Useful as a filler added to bitumen to make road coatings, where the filler may also inhibit frost, esp. when it contains HCl. The filler is simple and inexpensive to make, and does not create dust.