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Non-Destructive Testing of Early Age Concrete Made With Alternative Aggregate.

Al-Mufti, Rafal Latif. (2012) Non-Destructive Testing of Early Age Concrete Made With Alternative Aggregate. Doctoral thesis, University of Surrey (United Kingdom)..

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Abstract

The increasing demand for concrete in construction places pressure on its constituent materials including aggregate. Attention has turned to alternative aggregates, such as recycled concrete (RCA), recycled asphalt (RA), and manufactured Lytag (lightweight) aggregates, to reduce the impact of quarrying. The aims in this research were to investigate the very early age behaviour and properties of RCA, RA, and Lytag concretes in relation to normal (gravel) concrete using non-destructive testing (NDT). This would lead to the use of NDT in the assessment of early age strength and setting of concrete. Early age was taken as the period from immediately after concrete mixing and up to 28 days. It was also the aim to investigate the early age concrete creep properties using UPV measurements. Finally, possible improvements in RA concrete strength were also investigated. A computerised data acquisition system was set up for continuous early age measurement of UPV. Strengths, during the first 24 hours, are higher for Lytag than normal and RCA concretes, and all are higher than RA concrete. Beyond 24 hours, similar strengths are produced by Lytag and gravel concretes, which are higher than RCA concrete, and all higher than RA concrete. During early hours after concrete mixing, higher UPV values are obtained for concretes containing Lytag and RCA aggregates, which have higher acoustic absorption. This recedes with maturity, producing higher UPV for concrete containing gravel than RA, which is higher than RCA, and all significantly higher than Lytag. Rebound number deviates from strength in its behaviour with aggregate type, with higher surface hardness produced by the concrete with the higher pore content. Strength and UPV relationships obtained for the period up to 1 day and 28 days enables the estimation of strength from UPV. UPV can also be used to determine concrete setting. Early age specific creep is higher for RA than Lytag and RCA concretes, which are higher than gravel concrete. Measurements of UPV can reflect the presence of creep and the determination of its value. Concrete containing recycled asphalt, roughened for 3 hours, can produce similar strengths to gravel concrete.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors : Al-Mufti, Rafal Latif.
Date : 2012
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 2012.
Depositing User : EPrints Services
Date Deposited : 24 Apr 2020 15:26
Last Modified : 24 Apr 2020 15:26
URI: http://epubs.surrey.ac.uk/id/eprint/855078

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