Fundamental characterisation of impregnation on concrete structures

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Balakrishna, MN, 2017. Fundamental characterisation of impregnation on concrete structures. PhD, Nottingham Trent University.

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Abstract

The corrosion of reinforcing steel arising from contamination by chlorides from de-icing salt is the major cause of deterioration of concrete bridges in the UK and many parts of the world. In fact, the main long-term deterioration mechanism involves moisture movement and the transport of chlorides within the concrete. In order to build durable and reliable structures, it is necessary to predict the movement of moisture and chloride within the concrete. Thus, an objective of this present research are fourfold. First, this research will examine an influence of conditioning such as drying condition, on the results of Schmidt hammer test and Ultrasonic pulse velocity test. Secondly, this research will examine an influence of conditioning such as wetting and drying condition on the results of ISAT. Third, this research will examine an influence of pre-conditioning in turn wetting/drying process on the results of Sorption tests. Fourth, the primary focus of this study is to examine effects of cyclic wetting (Fully and partially saturated) as well as drying on Chloride absorption for long-term duration with/without hydrophobic impregnation. In fact, chloride profiles of samples exposed to various pre-determined cycles of wetting, and drying were determined as well as assess chloride diffusion coefficient in pre-conditioned concrete cubes/slabs for a designed six mixtures type of concrete. Actually all tests were conducted under two different conditions such as slump, and w/c ratio value was varied with constant compressive strength as in the first case. Compressive strength, and w/c ratio value was varied with constant slump as in the second case.

The concrete hardness value could be increase with higher compressive strength and varied slump. Whereas the concrete hardness value was decrease slightly with lower, compressive strength and constant slump value and goes on increases with increased compressive strength. The ultrasonic pulse velocity could be increased or slightly deceased with higher compressive strength and varied slump. An ultrasonic pulse velocity was decrease with, lower compressive strength and constant slump value and goes on increases with increased compressive strength. The sorptivity coefficient (rate of absorption) was very lesser with higher compressive strength and varied slump value in designed mixtures type. However, average sorptivity coefficient was higher for lower compressive strength and constant slump and reduced with higher compressive strength value. In addition to that, it is possible to established power type of equation between sorptivity coefficient and square root of time for designed different mixtures type. The water diffusion coefficient was correlate with square root of time, in turn, the average variation of water diffusion coefficient was more for in case of higher compressive strength and varied slump. However, in the case of lower compressive strength and constant slump, the water diffusion coefficient was slightly higher in varied compressive strength and slump. In fact from this research work that, it is possible to establish logarithmic relationship between water diffusion coefficient and square root of time. From this research work, it is possible to establish a power type of equation relationship between water diffusion coefficient and sorptivity coefficient. Moisture content can have negative influence on measured results of various types of concrete. The ISAT value in DCC concrete cubes was more as when compared to PSC and FSC concrete cubes. Similarly, the ISAT value was more in PSC as when compared to FSC concrete cubes.

For higher compressive strength and varied slump value, an average chloride concentration at drill depths in control concrete cubes was slightly higher in magnitude as when compared to impregnation concrete cubes. It is observe that, for lower compressive strength and constant slump value, the average chloride concentration at drill depths in control concrete cubes was to be slightly more as when compared to higher compressive strength. For higher/lower compressive strength and varied/constant slump value, the average chloride concentration at drill depths in control/solvent/water based impregnation pre-partially/fully saturated concrete cubes was found to be slightly lower in magnitude as when compared to dry conditioned control/solvent/water based impregnation concrete cubes. It’s also clear that, for higher/lower compressive strength and varied/constant slump value, the average chloride concentration at drill depths in pre-partially saturated control/solvent/water based impregnation concrete cubes was slightly higher in magnitude as when compared to fully saturated conditioned control/solvent/water based impregnation concrete cubes. The chloride concentration could be increase in DCC control slabs as when compare to control as impregnation PSC/FSC slabs. Similarly, the chloride concentration in control concrete slabs could be increase for in case of PSC concrete slabs as when compared to FSC slabs. Similarly, the chloride concentration in PSC control concrete slabs could be increase as when compared to FSC solvent/water based impregnation concrete slabs. An average chloride concentration from different drill depths could be increase in DCC control concrete slabs with higher compressive strength and varied slump value as when compare to control PSC, and FSC concrete cubes. Chloride concentration (average) from drill depths in DCC (SB)/(WB) based impregnation concrete slabs with higher compressive strength, and varied slump value could be increased as when compared to (SB) impregnation DCC/PSC/FSC concrete slabs and goes on reduces with higher compressive strength and constant slump value.

Item Type:	Thesis
Creators:	Balakrishna, M.N.
Date:	June 2017
Divisions:	Schools > School of Architecture, Design and the Built Environment
Record created by:	Linda Sullivan
Date Added:	10 Apr 2018 10:20
Last Modified:	10 Apr 2018 10:20
URI:	https://irep.ntu.ac.uk/id/eprint/33238