SUPERPLASTICIZED CONCRETE CURB. FINAL REPORT

The ability of three commercially available concrete Super Water Reducers (SWRs) to improve the as-built surfaces of New Jersey barrier curb, and their effect on basic concrete properties, including workability, air content, compressive strength, the air-void system in the hardened concrete and durability, were evaluated. Study test data represent over one hundred days of concrete production consisting of both precast and cast-in-place (C-I-P) SWR concretes. While the increased workability provided had a positive effect on constructability, particularly on precast elements containing reinforcement steel, C-I-P as-built curb surfaces were only moderately improved. As expected, study admixtures facilitated reductions in w/c ratio. In the case of three C-I-P trial curb installations, the average compressive strength (6255 psi) represented a 21% increase over the strength level attained by the same mix without a SWR admixture. Key bubble system parameters were typically inferior -- spacing factors were about twice the desired value of 0.008 in. -- to that commonly considered needed to provide freeze-thaw resistance in conventional, non-SWR concrete. However, based on information in the literature, progressively larger spacing factors can be tolerated for a given mix and conditions provided that w/c ratios are appropriately reduced. Test data indicate the needed relationship between these two key parameters was achieved on study projects. Trial barrier curb installations continue to exhibit satisfactory durability after three winters exposure to New Jersey conditions. Recommendations pertaining to specification changes to permit use of SWR admixtures for most concrete items, and follow-up performance monitoring efforts are presented.

Media Info

  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 65 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00616312
  • Record Type: Publication
  • Report/Paper Numbers: FHWA/NJ-91-001-7630
  • Contract Numbers: NJHPR Study 7630
  • Files: TRIS, USDOT, STATEDOT
  • Created Date: Oct 31 1992 12:00AM