| dc.description.abstract | The effects of the metakaolin on the mechanical properties of the of compressive
strength and abrasion of concrete interlocking blocks, as well as on the processing steps
were evaluated. The pavers were carried out with 0%, 10%, 15%, 20%, 25% and 30%
metakaolin additions. All these materials were fabricated by employing the following
precursors: 50 kg of Portland cement type II; 50 kg of gravel; 80 kg of stone powder;
140 kg of sand; and 15 L of water, whose water cement ratio was 0.3. In addition, the
mechanical properties revealed that all metakaolin pavers presented larger values of
compressive strength (~ 37 MPa) when compared to the corresponding value of the
blocks with absence of metakaolin (~30 MPa), i.e., the metakaolin addition enhanced
the compressive strength property in 24%. Although the contents with 20%, 25% and
30% of addition, this property did not show significant variation. Further, a chemical
rationalization of the steps associated with the fabrication of the concrete pavers was
carried out. The results indicated that for the metakaolin pavers with 30% addition of
the metakaolin, the water quantity is not capable to transform both calcium oxide and
aluminum oxide in their corresponding hydroxide compounds in an efficient manner.
These experiments by fluorescence microscopy indicated that the metakaolin addition of
10% presented a high yield as regards the hydration reactions of the cement.
Furthermore, for the other cases the anhydrous cement was left over. This is evidenced
by the exacerbated fluorescence in the blue region. On the other hand, it was also
evaluated in this work, the usage of the metakaolin as a partial substitute for the
Portland cement. The results showed that the concrete blocks with absence of the
metakaolin had the largest values of compressive strength when compared to the cases
where the cement was replaced by metakaolin. Finally, when it was evaluated all
different types of concrete studied in this work, the metakaolin addition of 10% in the
precursor mixture leads to the concrete with larger potentiality for applications in civil
constructions. | |
