GB758624A - Prestressed pavements - Google Patents

Abstract

758,624. Pre-stressed concrete; floors. PRELOAD CO., Inc. Nov. 26, 1954 [Dec. 3, 1953], No. 34335/54. Class 20(4). The method of pre-stressing a continuous slab such as a concrete roadway, an aircraft runway, or industrial floor comprises forming an abutment 10, Fig. 2, and a series of sections of slab 13 extending away from the abutment 10, with a joint between each section 13 and compressing the sections extending away from the abutment with compressive forces of decreasing amplitude at several successive joints. As shown each section 13 is provided at its ends with haunches 24 on which jacks 14 act, the sections 13 resting on a sub-base (not shown) constructed in any normal manner. The jack 14 between abutment 10 and the first section 13 applies a force of 900 pounds per square inch, the next jack applies 600 and the third 300. The joint between abutment 10 and the first section 13 is filled with mortar and when the latter has set the jack is released. Now the jack 14 between the first and second sections 13 is increased in force to 900 pounds per square inch and the following two jacks to 600 and 300 respectively. The second joint is then filled with mortar and the procedure repeated. When the last section is reached a fixed abutment similar to that 10 may be used in applying the full prestress. In a modification, Fig. 6, the first three sections 13J, 13K and 13L are used as the abutment, jacks between the sections applying forces of 300 and 600 pounds per square inch respectively. The three jacks applying forces of 900, 600 and 300 pounds per square inch are employed as before, that of 900 being between sections 13L and 13M. The joints between sections 13L, 13M, 13L 13K, and 13J 13K, are mortared and the procedure continued as before. High tensile rods 57, 58 unbonded to the concrete are prestressed and anchored to provide the extra compression to bring all three slabs 13J, 13K, 13L up to the same compression despite variations in the forces exerted by the jacks 14. The reinforcing rods may be placed obliquely to the longitudinal edges of the slabs. On curved sections, Fig. 5, more reinforcing steel 56 is provided than on straight sections, to prevent the section 13a from moving out of alignment, the steel 56 being prestressed and anchored by known means. In modifications the concrete is replaced by plastic material and glass fibres are substituted for steel.