DEVELOPMENT AND RESEARCH OF A COMPOSITE MATERIAL FOR THE LAYER OF A BALLAST-FREE BRIDGE FLOOR

Abstract

To connect the reinforced concrete slabs of the ballastless bridge deck with the metal girders of the railway bridges, a rubber-wood lining layer, which is convenient for laying and has favorable physical and mechanical characteristics, is traditionally applied, which has insufficient durability due to wood rot. An analysis of the stress-strain state of a reinforced concrete slab of a ballastless bridge deck was performed, and it was established that the strength of the material of the lining layer between the slabs and the bridge girders after 6–8 hours after laying should be at least 1 MPa, at the age of 2 days or more – at least 5 MPa, the modulus of deformation should not be more than 10,000 MPa. The value of the modulus of deformation and compressive strength of the rubber-wood lining layer was determined. Such a lining layer undergoes significant deformations due to the rubber and suddenly breaks down. The modulus of deformation is 58.3 MPa for pine and 144 MPa for oak. A structural and technological solution of the laying layer made of rolled composite material, consisting of a non-woven material of a volumetric structure of NWMVS from anisometrically oriented polyester fibers, cement, fine sand aggregate and hardening accelerator additives, was developed and patented. The dependences of the modulus of deformation and compressive strength of the paving layer made of rolled composite material on the ratio of the amount of sand to the amount of cement in the mineral mixture S/C, the consumption of the mineral mixture per unit of volume of NWMVS M/NM, and the thickness of NWMVS were investigated. Such a lining layer also undergoes significant deformations, however, destruction with a violation of structural integrity is not observed. It was established that the modulus of deformation and conditional compressive strength of the composite material decrease with an increase in the content of S/C sand in the mineral mixture and a decrease in the consumption of the mineral mixture per unit area and volume of NWMVS M/NM. The laying layer made of rolled composite material has a modulus of deformation of 144 MPa for S/C no more than 0.11, M/NM 1000 kg/m3 . Such compositions are recommended to be inserted for the lining layer, the method of which is patented.