Use of Steel Fibers to Optimize Self-Consolidating Concrete Mixtures Containing Crumb Rubber


  • The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

International Concrete Abstracts Portal


Title: Use of Steel Fibers to Optimize Self-Consolidating Concrete Mixtures Containing Crumb Rubber

Author(s): Mohamed K. Ismail and Assem A. A. Hassan

Publication: Materials Journal

Volume: 114

Issue: 4

Appears on pages(s): 581-594

Keywords: crumb rubber; fresh properties; mechanical properties; self-consolidating concrete; steel fibers

Date: 7/1/2017

This investigation was conducted to optimize the development of self-consolidating rubberized concrete (SCRC) reinforced with steel fibers (SFs). Specifically, the study aimed to use SFs to compensate for the reduction in splitting tensile and flexural strengths that resulted from adding high amounts of crumb rubber (CR) to SCRC mixtures. The study’s variables included different replacement levels of fine aggregate volume by CR (0 to 40%), binder content (550 to 600 kg/m3 [34.34 to 37.46 lb/ft3]), SF volume fractions (0, 0.35, 0.5, 0.75, and 1%), and size of SFs. Fresh properties were evaluated based on slump flow, J-ring, L-box, V-funnel flow time, and sieve segregation tests. Mechanical properties were investigated through compressive strength, splitting tensile strength, and flexural strength tests. The results indicated that it was possible to improve the splitting tensile and flexural strengths of SCRC by using SFs in SCRC mixtures. However, the addition of SFs reduced the fresh properties of SCRC mixtures and limited the maximum percentage of CR to 15% (compared to 30% when no SFs were used). Although using a higher percentage of SFs (0.5% compared to 0.35%) or longer length of SFs (60 mm [2.36 in.] compared to 35 mm [1.38 in.]) had a higher impact on improving the splitting tensile and flexural strengths of SCRC mixtures, increasing the percentage/length of SFs showed a potential problem for the passing ability, indicating low application possibilities for these mixtures. The results also showed that because the challenge of optimizing the fresh properties, especially the passing ability, was not a factor in vibrated rubberized concrete (VRC) mixtures, it was possible to develop VRC mixtures with up to 35% CR and 1% SFs, providing mixtures with reduced self-weight and lower reductions in flexural and tensile strengths.