EFFECT OF AGGREGATE MAXIMUM SIZE UPON COMPRESSIVE STRENGTH OF CONCRETE
Aggregates form 60% to 75% of concrete volume and thus influence its mechanical properties. The strength of normal concrete is affected by the maximum size of a well-graded coarse aggregate by two opposing ways. Concrete mixes containing larger aggregate particles needs less mixing water than those containing smaller aggregates. On the other hand, the smaller size aggregates give larger surface area for bonding with the mortar matrix. This study is a trial to cover these two points with testing three different useable concrete mixes in Kurdistan Region–Iraq which are 1:1.5:3, 1:2:4 and 1:3:6 (Cement: Sand: Gravel). In each mix, five maximum aggregate sizes were used which are 9.5mm, 12.5mm, 19mm, 25mm and 37.5mm , the consistency of the all mixes is fixed for slumps of 25-50mm . According to the test results it is concluded that in general the compressive strength of concrete increases when the maximum size of aggregate decreases and the maximum aggregate size strongly influences the concrete strength. Test results also show that the optimum concrete strength is reached by using aggregates of 9.5mm maximum size. We further concluded that for a specified strength, an economical mix can be produced by decreasing the amount of cement and using an appropriate maximum aggregate size.
2. The maximum aggregate size strongly influences the concrete strength.
3. The optimum compressive strength of concrete is reached by using aggregates of 9.5mm maximum size.
4. For concrete of cement to aggregate ratio below (6), the compressive strength is more affected by the change in the aggregate size than the cement content.
5. For a specified strength, an economical mix can be produced by increasing the cement to aggregate ratio and decreasing the maximum size of aggregate.
6. Lean mixes can be used for structural purposes when using small sized aggregates.
The authors are very grateful to the two technicians Mr. Heja Ahmed and Mr. Khalid Khalil, who are working in concrete Laboratory at Duhok Technical Institute for their assistance in testing the concrete cubes.
1. Rozali kozul and David drawin, “Effects of Aggregate Type, Size and Content on Concrete Strength and Fracture Energy”, the reinforced concrete research council, project 56, June 1997.
2. Yousif A. A., Isaa M. A., others, “Specimen and Aggregate Size Effect on Concrete Compressive Strength”, cement concrete and aggregates journal 22 (3), 2000.
3. Tumidajski P.J. and Gong B., “Effect of Coarse Aggregate Size on Strength and Workability of Concrete”, Canadian Journal of Civil Engineering, 76-78, 2006.
4. Ioannides, A.M. and Mills, J.C. (2006), “Larger Sized Coarse Aggregates in Portland Cement Concrete Pavement and Structures”, Report No. FHWA/OH-2006/10A, Ohio Department of Transportation, Columbus, OH.
5. Jimoha A. A, and Awe S. S., “A Study of the Influence of Aggregate Size and Type on the Compressive Strength of Concrete”, Journal of Research Information in Civil Engineering, 4 (2), 2007.
6. Yaqub M. and Bukhari I., “Effect of Size of Coarse Aggregate on Compressive Strength of High Strength Concretes”, 31st Conference on Our Word in Concrete and Structures: 16-17 August 2006, singapore
7. Kumar R. P.1 and Krishna R. M. V. “A Study on the Effect of Size of Aggregate on the Strength and Sorptivity Characteristics of Cinder Based Light Weight Concrete”, Research Journal of Engineering Sciences, 1 (6), 2012.
8. Krishna A. V., Rao. K. B. and Rajagopal A. “Effect of Different Sizes of Coarse Aggregate on the Properties of NCC and SCC”, International journal of engineering science and technology, 2 (10), 5959-5965, 2010.
9. Ajamu S. O. and Ige J. A., “Effect of Coarse Aggregate Size On Compressive Strength and Flexural Strength of Concrete Beams” journal of Engineering Research and Applications, 5 (4), 67-75, 2015.
10. Woode A. A., Amoh K. D., others,“The Effect of Maximum Coarse Aggregate Size on The Compressive Strength of Concrete Produced in Ghana” journal of Civil and Environmental Research, 7(5), 7-12, 2015.
11. Neville A. M. and Brooks j. j., Concrete Technology, Person Education, England, 2004.
12. BS 1881-108 (1983): “Method for making test cubes from fresh concrete”, British Standards Institution, London.
13. BS1881-116 (1983): “Method for determining compressive strength”, British Standards Institution, London.
14. Shetty M.S., “Concrete technology theory and practice”. Pub. By S. Chand and company Ltd New Delhi. 2000
15. Neville Adam. M. “Aggregate Bond and Modulus of Elasticity of Concrete ACI Materials”, journal V. 94. NO. 1. January – February 1997 PP 71-74.
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