Loading...
2 results
Search Results
Now showing 1 - 2 of 2
- Propriedades do betão auto-compactável com incorporação de agregados finos recicladosPublication . Pinto, Hugo; Oliveira, Luiz Pereira de; Nepomuceno, MiguelEste estudo teve como objectivo analisar o impacto nas propriedades do betão auto-compactável (BAC) resultante da incorporação de agregados finos reciclados em substituição parcial dos agregados finos naturais. O programa experimental realizado envolveu, numa primeira fase, a produção e ensaio de 11 misturas binárias com percentagens sucessivamente crescentes de agregados finos reciclados. Posteriormente, foram ainda produzidas e ensaiadas 6 misturas ternárias para o mesmo efeito. Nas misturas binárias, a percentagem de substituição do agregado fino natural por agregado fino reciclado variou desde os 0% (mistura de referência) até aos 50% em incrementos de 5%, enquanto nas misturas ternárias a percentagem de substituição do agregado fino natural por agregado fino reciclado variou desde os 0% (mistura de referência) até aos 50% em incrementos de 10%. O estudo permitiu concluir que as argamassas com incorporação de agregados finos reciclados constituem um material viável e com potencialidades de utilização na indústria da construção, desde que sejam ponderados os ajustes necessários ao seu desempenho.
- Experimental evaluation of the potential use of waste recycled concrete fine aggregates to produce self-compacting concretePublication . Pinto, Hugo; Nepomuceno, Miguel; Bernardo, Luís; Oliveira, Luiz Pereira deThe current concern with sustainability in the construction sector has led to the adoption of processes to minimise the impact on the environment. The use of recycled concrete aggregates in self-compacting concrete (SCC), as an alternative to natural aggregates, seems to be a solution with great potential. However, it is common knowledge that the use of recycled aggregates in the production of SCC instead of natural aggregates may causes changes in some of its properties, both in the fresh and hardened state, and that the magnitude of those changes will depend on the percentages of incorporation and the nature of recycled aggregates. When using the mix design methodology proposed by Nepomuceno et al, SCC is assumed to be consisted basically of two phases, namely, the liquid phase (mortar phase) and the solid phase (coarse aggregates), being the main SCC properties controlled by the mortar phase. In this perspective, this research work reports the results obtained when testing mortars with flow properties appropriate to produce SCC, when binary and ternary blends of powder materials were used and natural fine aggregates were partially replaced by recycled concrete fine aggregates. The experimental program carried out involved, in a first stage, the production and testing of 11 binary mortar mixtures suitable for the production of SCC, with replacement percentages of natural fine aggregate by recycled concrete fine aggregate varying from 0% (reference mixture) to 50%, in 5% increments. Subsequently, 6 ternary mortar mixtures were produced and tested for the same purpose, with replacement percentages of natural fine aggregate by recycled concrete fine aggregate varying from 0% (reference mixture) to 50%, in 10% increments. Binary mortars included Portland cement type I 42.5R and limestone powder, while ternary mortars included Portland cement type I 42.5R, limestone powder and fly ash. In both cases, the dosages of superplasticizer and mixing water were determined experimentally to obtain the required fresh properties suitable to produce SCC. The results indicate that the 28 days age compressive strength and density of the mortars decrease with the increase in the percentage of incorporation of recycled concrete fine aggregates, regardless of whether they are mortars with binary or ternary blends of powders. In binary mixtures, the mixing water dosage increases with the percentage of incorporation of recycled aggregates, while in ternary mixtures the opposite occurs, at least up to a percentage of 40% of incorporation of recycled aggregates. The superplasticizer dosages, necessary to obtain the appropriate flow properties, were always higher in the ternary mixtures compared to the binary mixtures, even comparing only the reference mixtures. It can be concluded that mortars with the incorporation of recycled concrete fine aggregates constitute a viable material with potential for use in the construction industry, provided that the necessary adjustments to its performance are considered, thus contributing to the sustainability of construction.