GB507731A - Improvements in or relating to expansion joints - Google Patents

Abstract

507,731. Rubber compositions. INTERNATIONAL LATEX PROCESSES, Ltd. Nov. 4, 1938, No. 31962. Convention date, Nov. 6, 1937. Drawings to Specification. [Class 70] [Also in Group X] A method of forming an expansion joint in an expansion joint space between two constructional members, such as paving slabs, consists in inserting a compressible and expansible material in the space and anchoring it to the constructional members by forming in situ between the material and the constructional members a deposit of solids from an uncoagulated latex composition. The term " latex " is used to designate coagulablo aqueous dispersions of elastic materials, including artificial dispersions of rubber as well as natural latex. Two suitable latex compositions comprise (I) centrifuged latex, Potassium hydroxide solution, sulphur paste, diamyl ammonium diamyl dithiocarbamate emulsion, sodium silicate, whiting, and zinc oxide paste, and (2) rubber reclaimed from tyres, whiting, rosin, zinc oxide, sulphur, sodium hydroxide and tetramethyl thiuram monosulphide. In these compositions, the diamyl ammonium diamyl dithiocarbamate and the tetramethyl thiuram monosulphide act as low-temperature accelerators. A further composition, which is stated to adhere readily to the constructional members, comprises centrifuged latex, potassium hydroxide solution, sulphur paste, diamyl ammonium diamyl dithiocarbamate emulsion, casein solution, sodium silicate, a china clay aqueous dispersion, aluminous cement, and zinc oxide paste. Before pouring this composition into the joint, a 33<1>/3 per cent dispersion of sodium silico fluoride may be added to act as a delayed coagulant. Other delayed coagulants, which may be added instead of the sodium silico fluoride, are a watery emulsion of pine tar or a polyvalent metal salt. The latex compound may be made heat-sensitive by the addition of polyvalent metal salts, disubstituted guanidines, or an ammonium salt of a strong acid and zinc oxide. In the case of a heat-sensitive latex which is not coagulable at normal temperatures, the compound may be heated in situ, as by playing live steam on the joint, to produce more or less immediate gelling.