Challenges in Translating Rubberized Mortar Properties to Concrete: Segregation and Shear Slump

Abstract:

Rubberized cementitious composites are gaining focus in sustainable construction. Crumb rubber, sourced from waste tires, is used as a partial replacement for sand in concrete. However, rubber's low density, elasticity, and hydrophobic nature reduce workability and mechanical strength, owing to voids and poor compaction. To address these issues, supplementary cementitious materials (SCMs) like silica fume and fly ash, along with polypropylene (PP) fibres, were incorporated in this study. A control mortar mix with a 1:4 cement-to-sand ratio was established, and 10% of the sand was replaced by crumb rubber. SCMs were added at 5% by mass of cement, PP fibres at 0.1% by volume, and a water-reducing agent at 2% by mass. The results demonstrated that the flow-ability was reduced by 50%, reflecting the stiffening effect of rubber, but the compressive strength remained comparable to that of the control specimens due to the beneficial impact of silica fume, fly ash, and fibres. Density decreased by 19% due to the rubber's low density. However, when this mix was applied to concrete, it resulted in shear slump and segregation, as the rubberized mortar was insufficient to cover the coarse aggregates. This suggests that sand replacement in concrete should be done by volume rather than mass to prevent these issues and ensure proper aggregate coverage.

• Periodical: Construction Technologies and Architecture (Volume 17)
• Pages: 43-50
• DOI: https://doi.org/10.4028/p-1m7IXC
• Online since: April 2025
• Authors: Sheikh Zakria Ejaz, Chaudhary Tabarak Shafqat, Usama Jameel, Hurraira Choudary, Anwar Khitab*
• Keywords: Fly Ash, Performance Enhancement, Polypropylene Fibres, Rubberized Cementitious Composites, Silica Fumes

References

[1] A. Khitab, M. Alam, H. Riaz, S. Rauf, Smart Concretes: Review, Int. J. Adv. Life Sci. Technol. 1 (2014) 47–53.

DOI: 10.18488/journal.72/2014.1.2/72.2.47.53

[2] A. Khitab, W. Anwar, Classical Building Materials, in: 2016: p.1–27.

DOI: 10.4018/978-1-5225-0344-6.ch001

[3] A. Al-Fakih, B.S. Mohammed, M.S. Liew, On rubberized engineered cementitious composites (R-ECC): A review of the constituent material, Case Stud. Constr. Mater. 14 (2021) e00536.

DOI: 10.1016/j.cscm.2021.e00536

[4] N.M. Saeed, H.Z. Hassan, An overview of fresh and mechanical properties of rubberized concrete, Discov. Civ. Eng. 1 (2024) 14.

DOI: 10.1007/s44290-024-00016-8

[5] A.M. Mhaya, S. Baharom, G. Fahim Huseien, Improved strength performance of rubberized Concrete: Role of ground blast furnace slag and waste glass bottle nanoparticles amalgamation, Constr. Build. Mater. 342 (2022) 128073.

DOI: 10.1016/j.conbuildmat.2022.128073

[6] A.A.M. Fadiel, T. Abu-Lebdeh, I.S. Munteanu, E. Niculae, F.I.T. Petrescu, Mechanical Properties of Rubberized Concrete at Elevated Temperatures, J. Compos. Sci. 7 (2023) 283.

DOI: 10.3390/jcs7070283

[7] S. Sun, X. Han, A. Chen, Q. Zhang, Z. Wang, K. Li, Experimental Analysis and Evaluation of the Compressive Strength of Rubberized Concrete During Freeze–Thaw Cycles, Int. J. Concr. Struct. Mater. 17 (2023) 28.

DOI: 10.1186/s40069-023-00592-6

[8] L.-Y. Feng, A.-J. Chen, H.-D. Liu, Effect of Waste Tire Rubber Particles on Concrete Abrasion Resistance Under High-Speed Water Flow, Int. J. Concr. Struct. Mater. 15 (2021) 37.

DOI: 10.1186/s40069-021-00475-8

[9] E. Eltayeb, X. Ma, Y. Zhuge, J. Xiao, O. Youssf, Dynamic performance of rubberised concrete and its structural applications – An overview, Eng. Struct. 234 (2021) 111990.

DOI: 10.1016/j.engstruct.2021.111990

[10] R.B.N. Khan, A. Khitab, Enhancing Physical, Mechanical and Thermal Properties of Rubberized Concrete, Eng. Technol. Q. Rev. 3 (2020) 33–45.

[11] A. Khitab, R.B.N. Khan, Suitability of concrete incorporated with scrubbed rubber tire particles: Assessment based on destructive and non-destructive testing, Pakistan J. Eng. 1 (2022) 6–22.

[12] M. Sattar, R.B.N. Khan, A. Khitab, Performance Evaluation of Ordinary Concrete having Crumb Rubber Treated with Alkaline Solution, Tech. Journal, UET Taxila. 3 (2024) 8–13.

[13] ASTM C305, Standard Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency, West Conshohocken, PA, 19428-2959 USA, 2022.

DOI: 10.1520/c0305-99

[14] ASTM C188-17, Standard Test Method for Density of Hydraulic Cement, West Conshohocken, PA, 19428-2959 USA, 2023.

[15] ASTM C1437-20, Standard Test Method for Flow of Hydraulic Cement Mortar, West Conshohocken, PA, 19428-2959 USA, 2020.

[16] ASTM C1314-21, Standard Test Method for Compressive Strength of Masonry Prisms, West Conshohocken, PA, 19428-2959 USA, 2021.

[17] ASTM C143/C143M-20, Standard Test Method for Slump of Hydraulic-Cement Concrete, West Conshohocken, PA, 19428-2959 USA, 2020.

[18] ASTM C642-21, Standard Test Method for Density, Absorption, and Voids in Hardened Concrete, West Conshohocken, PA, 19428-2959 USA, 2021.

DOI: 10.1520/C0642-21

[19] M. Al-Gburi, S.A. Yusuf, Investigation of the effect of mineral additives on concrete strength using ANN, Asian J. Civ. Eng. 23 (2022) 405–414.

DOI: 10.1007/s42107-022-00431-1

[20] M.T. Arshad, S. Ahmad, A. Khitab, A. Hanif, Synergistic Use of Fly Ash and Silica Fume to Produce High-Strength Self-Compacting Cementitious Composites, Crystals. 11 (2021) 915.

DOI: 10.3390/cryst11080915

[21] A. Khitab, S. Ahmad, R.A. Khan, M.T. Arshad, W. Anwar, J. Tariq, A.S.R. Khan, R.B.N. Khan, A. Jalil, Z. Tariq, Production of Biochar and Its Potential Application in Cementitious Composites, Crystals. 11 (2021) 527.

DOI: 10.3390/cryst11050527