Abstract
This paper addresses the feasibility and the efficiency of using Natural Pozzolan and/or Rock flour in Roller Compacted Concrete (RCC) gravity dams. For this purpose, five identical mortar trial mixes were prepared using five different supplementary materials, i.e., fly ash produced in South Africa (proven to be effective in RCC construction), fly ash produced in Turkey, Jordanian natural pozzolan, Saudi natural pozzolan, and rock flour from Mujib Dam basalt quarry. The physical and chemical properties of these pozzolanic materials were determined. The effectiveness of each one of these mineral admixtures used as a cement replacement material in controlling alkali silica reaction are studied and analyzed. Correlations were made between the mechanical properties for the five proposed mixes and a control mix using the Jordanian Portland Cement. The results demonstrate that the performance of Natural Pozzolana and/or rock flour as compared with that of fly ash and other pozzolanic material is very satisfactory and can be effectively used in RCC construction.
Highlights
Roller-compacted concrete (RCC) is defined as "concrete compacted by rolling compaction which, in its unhardened state, will support a roller while being compacted" (American Concrete Institute ACI)
The results indicate that the main types of Jordanian aggregates could be considered as innocuous aggregates, with no expected expansion resulting from alkali aggregate reaction, except some types of minerals such as opal and some types of sands and cherts. [10] states that all good RCC has a paste content of about 19% to 21% by volume, regardless of the cement and pozzolan or fly ash content
Five different supplementary cementitious materials were used in preparing the mortar sample mixes, these are, fly ash produced in South Africa, fly ash produced in Turkey, Jordanian natural pozzolan, Saudi natural pozzolan, and rock flour from Mujib Dam basalt quarry
Summary
Materials used for RCC include cementitious materials (Portland cement and pozzolans such as fly ash), aggregates, water, and admixtures. A wide range of materials have been used successfully to produce RCC mixtures It is common practice in proportioning concrete mixtures for dams to utilize large aggregates in order to decrease cementitious material requirements and lower the costs and heat of hydration. The strength of RCC is primarily dependent upon, the quality of the aggregate, degree of compaction, properties of cement, pozzolanic material, water, and admixtures if used, and grading of aggregate. [8] addressed the possibility and the efficiency of using Jordanian natural pozzolana in RCC gravity dams For this purpose, two identical trial mix properties were proposed and undertaken using two different supplementary cementitious materials, i.e., fly ash brought from South Africa and Jordanian natural pozzolana. Low cementitious content RCC requires aggregate fines in order to provide adequate paste without excessive water, and high cementitious content mixes require cleaner aggregates
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