Bagasse Ash as a Partial Substitute of Cement on Concrete Rigid Pavement
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Date
2017-07
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AAU
Abstract
Sugarcane bagasse ash is an industrial waste from sugar factories. This study aimed to use this materialas a partial substitute of cement in a concrete rigid pavement. The availability of bagasse ash and thevery reasons that the construction of concrete rigid pavements started to be in effect in Ethiopia alongwith the great consideration that the current global situation gave to environmental issues, are the basisfor conducting this study. Past researches have indicated that sugarcane bagasse ash contains high silicawhich is a potential agent for pozzolanic reaction.
In this study, the range of application of using bagasse ash as a partial replacement for Ordinary
Portland cement for concrete pavement has been experimentally investigated from the perspective of
strength, heat of hydration and durability. Strength and thermal assessments were carried out since theearly age of the concrete. Early age measurements were given emphasize so as to see the influence of
this material on early age distresses such as cracking due to the heat from hydration reaction. Systematic
experiments were conducted for replacement ratios of 5%, 10% and 20% by volume of cement. The
percentage of replacement which yielded a relatively better response with respect to the mentionedproperties, was selected as an optimum percentage of replacement.
In the experimental result, a strength enhancement was observed in concrete mixes made with bagasse
ash. This enhancement was seen in concrete mixes that were prepared with bagasse ash amount of 5%and 10% replacement by volume. Moreover, the pozzolanic nature of the bagasse ash was not inhibiting
the early age strength development; the enhancement had started to be seen since the concretes’ earlyage. This was a contributory finding in reducing the risk of early age cracking that will occur in aconcrete due to high initial temperature that is generated from the hydration reaction.
The bagasse ash used in this research did not pass through any treatment or modification except beingsieved with a 300µm sieve. The result of the chemical analysis of bagasse ash taken from Wonji Sugar
factory, Ethiopia had shown that the ash is rich in silica. The mechanical properties in compression
and flexural based tensile strength were investigated from early age up to 56days. The heat of hydration
characteristics at early age was also monitored using embedded thermocouples. Finally, the waterpenetration depth for each mix was tested as an indicator for durability. The findings from the
experimental investigation were analyzed and the application for rigid concrete pavement construction
was discussed. The effects of early age thermal cracking, caused by heat generated due to hydration,for longevity is emphasized. Moreover, a thermo-hygro simulation of a concrete slab panel was madeusing the multi-component heat of hydration model to assess the relative performance of concrete withand without bagasse ash against early age cracking. Finally, the importance of early age thermal analysisusing mutual interlinkage of material aspects and structural mechanics for the durability design of rigidpavements was dealt.
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Keywords
Concrete rigid pavement, Sugarcane bagasse ash, Early age strength assessment, Early age thermal assessment