Assessment of Physical Properties of Ambo and Jema Sand and Evaluation of Their Performance as Fine Aggregate in High Strength Concrete
No Thumbnail Available
Date
2023-06
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
In Ethiopia, the construction of high-rise buildings, long span bridges and complex concrete structures which make use of high strength concrete is becoming common in recent times. In order to meet the ever increasing demand for fine aggregate in concrete construction, an alternative to the river sand is inevitable as river sand is quickly depleting and its quality from time to time is becoming questionable.
The use of sand stone as a replacement to the fine aggregate for the production of High strength concrete in Ethiopia is an important study area since sufficient research on detail engineering characteristics and performance is not yet fully investigated. In this research, the performance and rate of strength development of high strength concrete made from sand stone sampled from Ambo and Jema river basin is studied. In addition, a comparison of strength development of High Strength Concrete was made between the sandstone fine aggregates and river sand (control sand). The experimental concrete is prepared and mixed in two separate sizes of coarse aggregate, 19 mm and 12.5 mm nominal maximum. The corresponding water cement ratio for 19 mm coarse aggregate was 0.27 and for the 12.5 mm coarse aggregate it was 0.29. Chemical admixture was used for all the concrete mixes in proportion to the cement content.
The control concrete mix has attained the target strength for C70, C80 and C90 when 520 kg, 550 kg and 580 kg of cement per metric cube of concrete used and when 19 mm coarse aggregate used whereas it has not attained the C90 strength when 12.5 mm aggregate used. Concrete made with Ambo sand has attained the target strength of C70, C80 but failed for C90 for both types of coarse aggregate when used in the mix. Concrete made with Jema sands has not attained the target strength of C70, C80 and C90 for same amount of cement and coarse aggregate sizes that was used for the control mix.
For Ambo sand concrete, when 19 mm aggregate is used, the percent of the compressive strength against the control concrete is 96.4%, 96.6%, 96.1% for C70, C80, C90 and it is in order of 97.1%, 97.7%, 94.4% when 12.5 mm aggregate used. The percent of the compressive strength of Jema sand concrete against the control concrete when 19 mm aggregate is used is 90.8%, 87.6%, 85% for C70, C80, C90 and it is in order of 89.5%, 87.5%, 87.3% when 12.5 mm aggregate used.
The flexural test values, the modulus of elasticity values and mortar strength test results of concrete made from Ambo and Jema sands have met the requirement while Ambo sand produces a concrete with marginal increment than Jema sand. From the cost computation, to produce a unit volume of high strength concrete, the cost of concrete made from Ambo sand is 3.26% cheaper than Jema sand and it is 1.16% cheaper than the control sand.