Full text
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| Author(s): |
Clovis Nita
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Escola Politécnica (EP/BC) |
| Defense date: | 2006-02-23 |
| Examining board members: |
Vanderley Moacyr John;
Maria Alba Cincotto;
Geraldo Cechella Isaia
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| Advisor: | Vanderley Moacyr John |
| Abstract | |
Composites reinforced with natural fibers are a good asbestos fibercomposites replacement material, as a result of the great natural fiber avaibility such as coco nut, sisal and cellulose. Durability aspects need to be improved, like the decrease of fiber resistance in alkaline environment causing the loss of mechanical properties of the composites. An alternative way to solve this problem is using pozzolan. It will react with calcium hydroxide formed by Portland cement hydration and will provide hydration phases as C-S-H and calcium aluminate hydrated, which contributes for the alkaline reduction and in an increase of mechanical performance. The methodology analyzes the effect of wet/dry cycles in composites among the hydration of cement and pozzolanic reaction in composite formulation made with cement, dolomite filler, pozzolan (metakaolin or silica fume) and PVA and cellulose fibers. The pozzolans used in this study consumed almost calcium hydroxide, although low mechanical properties were found. The matrix degradation with expansive brucite formation is explained with two hypotheses: dedolomitization reaction from dolomite filler or periclase hydration from Portland cement observed from 250 cycles. (AU) | |