T.C. Nwofor
F.K. Malkani
- Senior Lecturer Department of Civil and Environmental Engineering University of Port Harcourt Rivers State Nigeria
- Student Department of Civil and Environmental Engineering University of Port Harcourt Rivers State Nigeria
Abstract
This research delves into the effect of using various single coarse aggregate sizes and combinations of such by specific proportions. A thorough examination involving control specimens of 12mm, 20mm, and 25mm aggregates sizes, with combining proportions in the ratios – 5/8:3/8, 1/2:1/2, 3/8:5/8 have been conducted, shedding light on critical patterns that dictate concrete performance. The fine aggregate was properly zoned from the preliminary test. The design mix was calculated for a characteristic strength of 15N/mm2. The concrete mixes were in batches, each containing a single coarse aggregate size or a blend of two different coarse aggregate sizes. Crushed aggregate (Granite) was used in this experiment. The study reveals a consistent trend wherein mixes with larger single-sized coarse aggregates demonstrate superior compressive strengths, aligning with established principles of concrete technology. However, improvements were observed upon the use of an optimization ratio to combine different coarse aggregate sizes into a blend. Two standout mixes, E (12mm: 20mm – 5/8:3/8) with compressive strength of 21.4N/mm2 and 26.6N/mm2 and K (20mm: 25mm – 5/8:3/8) with compressive strength of 29.1N/mm2 and 33.3N/mm2, consistently exhibited remarkable strengths at 7 and 28 days respectively. The success of these mixes underscores the pivotal role of specific aggregate sizes and proportions in optimizing concrete performance. The findings offer practical recommendations, emphasizing the importance of carefully tailoring aggregate gradation, exploring effective ratios such as 5/8:3/8, and systematically monitoring strength development over time. This research not only contributes valuable insights for concrete mix design but also provides engineers with a nuanced understanding of how aggregate gradation influences compressive strength.
Keywords: compressive strength, combined gradation, crushed aggregate, preliminary test, aggregate gradation, design mix, optimizing concrete
[This article belongs to Recent Trends in Civil Engineering & Technology(rtcet)]
References
1. Abdel-Jawad YJ, Abdullah WS. Design of maximum density aggregate grading. Constr Build Mater. 2002;16:495–508.
2. Abrams DA. Design of Concrete Mixtures. Bulletin 1, Engineering Experiment Station, Lewis Institute, Chicago Francis. 1918.
3. ACI Committee 211. Standard Practice for Selecting Proportions for Normal, Heavyweight, and Mass Concrete. ACI 211.1-91. 2019.
4. Ashraf WB, Noor MA. Performance evaluation of concrete properties for different combined aggregate gradation approaches. Proc Engr. 2011;14:2627–2634.
5. Nwofor TC, Alabintei DD. Effect of Magnetic Pole Direction on the Properties of Magnetized Water Concrete. Int J Concrete Technol. 2020;6(1):16-22.
6. BS 812-103.1. Testing aggregates – methods for determination of Particle Size distribution. Section 103.1; sieve tests. 1985.
7. BS 5328: part 4. Specification for the procedures to be used in sampling, testing, and assuring compliance of concrete. 1983;68.
8. BS 12. Specification for Portland cement. 1996.
9. BS 882: Part 2: 1973. Coarse and fine aggregate from natural sources. BSI, London, UK.
10. Concrete Mix Design Manual, FIRST EDITION: AUGUST 2017. SPECIAL PUBLICATION NO. COREN/2017/016/RC.
11. EN 12390-3:2009 Testing hardened concrete. Compressive strength of test specimens.
12. Malhotra VM. Effect of Aggregate Size and W/C Ratio on Strength. ACI Materials Journal. 1980;77(6):480-482.
13. Neville AM. Properties of Concrete. 5th Ed. London: ELSB; 2005.
14. Neville AM, Brooks JJ. Concrete Technology. 2nd Ed. Pearson; 2010.
15. Nwofor TC, Sule S. Investigating geometric characteristics of Cement concrete materials. Int J Innovative Res Advance Eng. 2014;1(9):74-82.
16. Popovics S, Wittmann FH. Aggregate Size and Its Effect on Concrete Mechanical Properties. Cement, Concrete and Aggregates. 1990;12(1):29-34.
17. Nwofor TC, Eme DB. Appraisal on The Strength of Concrete Produced with Varying Aggregate Size. Int J Civil Eng Technol. 2015;7(3):233-240.
18. Walker S, Bloem DL. Effects of Aggregate Size on Properties of Concrete. ACI Journal, Proceedings. 1960;57(3):283-298.
Recent Trends in Civil Engineering & Technology
| Volume | 14 |
| Issue | 01 |
| Received | February 1, 2024 |
| Accepted | March 29, 2024 |
| Published | April 30, 2024 |