Loading...
4 results
Search Results
Now showing 1 - 4 of 4
- The influence of self-compacting steel fibre reinforced concrete infill on the flexure strength and ductility of masonry wallsPublication . Oliveira, Luiz Pereira de; Bernardo, LuísThis paper presents an experimental study on the influence of longitudinal reinforcement ratio and steel fibre volume in self-compacting concrete infill on the strength and ductility of reinforced masonry walls subjected to flexure. Flexure tests were performed as four-point bending tests on twelve walls. The analysis of the concrete infill contribution to the walls capacity is made considering recent recommendations for steel fibre reinforced concrete design. A ductility index was defined and applied to study the ductility behaviour of the masonry walls. The analysed variables are the longitudinal reinforcement ratio and the steel fibre volume in the concrete infill.
- Cement-based grouts for masonry consolidation with high content of limestone filler, metakaolin, glass powder and ceramic wastePublication . Nepomuceno, Miguel C. S.; Bernardo, Luís; Oliveira, Luiz Pereira de; Timóteo, Rúben de OliveiraThis article reports an experimental research on the influence of high-volume mineral additions on the rheological, physical and mechanical properties of cement-based grout for stone masonry structures consolidation. Binary grout mixtures were produced by replacing 50% weight of cement by limestone filler, metakaolin, glass powder and ceramic waste. Grout flow properties, rheological parameters, bleeding water, bulk density and injectability were evaluated. Grout physical and mechanical properties were also tested. New methodology previously used in mortars was applied to interpret flow behaviour. Results showed that a high-volume mineral addition in cement-based grout is compatible with the required fresh and hardened properties.
- Use of refurbished shipping containers for the construction of housing buildings: details for the structural projectPublication . Bernardo, Luís; Oliveira, Luiz Pereira de; Nepomuceno, Miguel; Andrade, Jorge Miguel AlmeidaConstruction using refurbished shipping containers is a recent building system, with already many successful examples around the world. This system presents a huge potential in the field of sustainable construction provided by the recycling of used containers. This paper aims to contribute to a better knowledge of this construction system in what concerns to the structural project. The general constitution of two maritime shipping containers is presented as well as some aspects of their structural behavior. For this purpose, numerical analyses were performed using a finite elements analysis program. Normative aspects for the structural project are also presented. This paper also presents the analysis of a case study with the use of refurbished shipping containers to build a single-family house. The evaluation of the strength of the refurbished shipping containers to building actions is carried out. It is shown that such evaluation is not easy because some mechanical parameters of noncommercial steel section of the elements that compose the shipping containers are unknown. Nevertheless, this study shows the feasibility of this building system.
- 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.