Bond Performance between Lightweight Concrete with Crumb Rubber and Glass Fibre Reinforced Polymer Bar

• Author / Creator

  Mutsuddy, Rupak

• For any reinforced concrete structure, the bond between concrete and the reinforcement bar is the most important parameter from structural standpoint. Notwithstanding numerous prior studies on describing this interaction for different reinforcing bars, not enough understanding exists for fibre reinforced polymer bars in structural lightweight concrete. In the research reported here, the bond between Glass Fibre Reinforced Polymer (GFRP) bar and a structural lightweight concrete is examined. Crumb rubber derived from recycled tires was used as fine aggregate in the concrete mix. A variety of industrial waste were utilized as supplementary cementing materials to further render the mix sustainable. The experimental aspect focused on the development of the lightweight concrete mixes with potential structural use. Based on their mechanical performance, a particular basic mixture that was prepared with a blend of silica fume and Portland cement, was selected for further examination of bond performance with GFRP. Through their compressive and flexural performance, one notes up to 70% compressive strength loss was observed with the mixes with 100% crumb rubber replacement. An optimal replacement of fine aggregates with 50% crumb rubber was obtained. Two different sizes of GFRP bar were used for the experimental pullout test where the concrete mixes were prepared with the optimal mix, as found earlier. Cylindrical samples with rebar embedded were tested for bond performance as the rebar pulled out from each matrix. This study examined the effect of crumb rubber replacement dosage as well as that of the bar diameter. Results show that the bond strength decreases with an increase in the replacement of conventional fine aggregate with crumb rubber. As expected, in beams, an increase in the bar diameter resulted in a drop in the bond strength. However, when each bar was pulled out of a cylindrical concrete matrix, the bond strength was sensitive to the amount of crumb rubber. An increasing crumb rubber to fine aggregate content resulted in a better performance for larger bar diameter. This was true both in plain concrete and in the presence of steel fibres. In single rebar pullout, the presence of microfibres was seen to benefit the larger bar diameter. This was attributed to the relatively less disturbance created by the fiber at the surface of contact, which promotes better stress transfer through friction. The analytical approach consists of exploring established bond-slip relationships for various concrete compositions and reinforcement types. The results from pullout testing obtained here were used to verify the bond-slip relationship and determine the parameters for the specific mix proportions and bar size in the present case.

• Subjects / Keywords

  • Crumb rubber
  • Fracture toughness
  • Concrete
  • Pullout test
  • Bond beam test
  • Impact loading
  • Stress Rate
  • Bond
  • FRP bar
  • Lightweight

• Graduation date

  Fall 2017

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R35T3GD3F

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.