Abstract A method of producing artificial roadstones for use in bituminous surfacing compositions for roads, airfield runways and the like. The artificial road-stones are produced by a method which comprises the steps of (a) extruding a mixture comprising water, a bonding material, at least 50 percent by weight of which is composed of materials capable of forming on reaction with water stable, substantially insoluble, hydrated calcium silicates and/or calcium aluminates, and a granular aggregate, and (b) hardening the extruded composition to form the desired artificial roadstones. The bonding material constitutes from 5 to 100 percent by weight of the solids in the mixture to be extruded and has a particle size distribution such that substantially all thereof passes a No.100 mesh British Standard sieve and the granular aggregate constitutes from 0 percent to 95 percent by weight of the solids in the mixture and is composed wholly or substantially wholly of material passing a 3/8 inch mesh British Standard sieve and retained on a No.100 mesh British Standard sieve.
A method according to claim 1, wherein the mixture of water, bonding material and granular aggregate is extruded through holes of substantially circular, rectangular, triangular or diamond section and of a size such that the width of the holes at the widest part is in the range of from 3/8 inch to 2 inches.
Claim 2
Dependent Claim
29 words
A method according to claim 2 wherein the extruded material is divided into lengths of not more than 2 inches and not less than 3/8 inch before being hardened.
Claim 3
Dependent Claim
12 words
A method according to claim 1, wherein the bituminous material is bitumen.
Claim 4
Dependent Claim
27 words
The method of claim 1 wherein said mixture of water, bonding material and granular aggregate is extruded through holes of substantially circular, rectangular, triangular or diamond section.
Claim 5
Dependent Claim
32 words
The method of claim 1 wherein said bonding material has a composition such that the molar ratio of Ca0 to Si02 is in the range 1 : 1.5 to 1 : 2.5.
Claim 6
Dependent Claim
46 words
The method of claim 1 wherein said bonding material is composed of material at least 50 percent by weight of which is capable of forming on reaction with water stable, substantially insoluble hydrated calcium silicates and wherein the extruded material is hardened by treatment with steam.
Claim 7
Dependent Claim
27 words
The method of claim 7 wherein said extruded material is hardened by treatment with steam at a pressure in the range of from 220 to 240 p.s.i.g.
Claim 8
Dependent Claim
11 words
The method of claim 1 wherein said bituminous material is bitumen.