c-made

PARAMETERS FOR SELF-COMPACTING CONCRETE

2008-11-19T11:21:00.000Z

This is an experimental study on the mortar phase for self-compacting concrete. A series of mortars were produced with similar flow properties, measured by spread and v-funnel tests, adequate to produce self-compacting concrete. The water content and the modified carboxylic superplasticizer dosage were determined experimentally for each mortar. Different percentages of cement replacement materials were used in binary blends, each one combining one of the two types of cement with one of the three mineral additions selected: limestone powder, granite filler and fly ash. Each of the binary blends of powders was combined in five different proportions in volume with the fine aggregate (Vp/Vs). Mortars were tested for compressive strength at 28 days age and this value was related to the water/cement ratio, the percentage of replacement materials, and Vp/Vs parameter. The analysis revealed the possibility of establishing adequate mortar parameters to obtain simultaneously the self-compactability and the required compressive strength of self-compacting concrete.

Project of Scientific Re-equipments (Projecto de Re-equipamentos científicos )

2008-11-18T11:27:00.001Z

The project of Scientific Re-equipment was elaborated in 2001. The project started during 2005 under the frame of C-MADE Centre of Materials and Building Technologies of University of Beira Interior (http://www.cmade.ubi.pt/). The acquisition of new equipments and improvement of laboratory infra-structures has contributed to centralize research objectives on the development of new solutions, durability and improvement of mechanical behaviour of new building products, environmentally sustainable and energy efficient. The actions to achieve project objectives, which began in 2004 until present date, result in several Msc and PhD thesis. Special relevance was given to self-compacting concrete methodology; self-compacting concrete reinforced with steel fibbers; Structural masonry behaviour with self-compacting concrete infill; influence of natural aggregates on structural concrete; Development of alkaline binders obtained from mine waste mud; Reuse of waste materials in low cost bituminous mixes; Valorisation of industrial and urban solid waste in cement based materials.

Development of an integrated unit for free cooling of buildings

2008-05-05T14:44:00.016+01:00

In this project (http://www.c-made.ubi.pt/resarch-projects.html) we are developing a new type of integrated construction element to be included in the building envelope and destined to be used for its cooling.

The study about evaporative cooling alone it’s finished and the evaporative cooling capabilities of different ceramic and textile materials were experimentally tested.

The major propose of the study was to select an evaporative cooling material to be used in a more complex passive cooling unit being developed. A test tunnel was constructed for this particular work and the behaviour of several ceramic and textile samples where analyzed.

A spacer fabrics consisting of two distinctive layers of polyester fabric joined together by a third layer sandwiched in between, also polyester made, proved to be the material with best evaporative cooling behaviour.

EVAWET project – Application of geopolymers in water management structures

2008-03-19T03:09:00.024Z

In the scope of the EVAWET project (http://www.c-made.ubi.pt/resarch-projects.html ) new materials are being tested for wastewater treatment processes (e.g. packed bed, percolating filters, moving/mobile bed and constructed wetlands). These materials, called geopolymeric mine waste mud (GMWM) binders, are made from the alkali activation of waste materials (especially those coming from mining activities) and have been developed by researchers of C-Made as alternative materials to the traditional Portland cement in the scope of the VALREMIN project.

The properties of the GMWM binders, such as very high strength at early ages and very high tensile strength, may be advantageous for wastewater treatment processes, namely the ones which used attached growth biofilm. However, there are other properties which should be better studied in order to make the geopolymers suitable for that purpose such as the porosity, specific surface, water absorption and release of chemical compounds to water.

Several types of geopolymers have already been produced, using tungsten mine waste mud after calcination at 800 °C, with differents aggregate/binder ratios and contents of calcium hydroxide, alkaline silicate and water, which are presently being tested to evaluate the leachate potential of chemical compounds to water. As the tensile strength seems to decrease after 14 days of curing more time is need to better understand the solubility potential of the material in permanent contact with wastewater. The results should come soon.

AGREDUR lastest results

2008-03-13T12:58:00.024Z

In this research project http://www.c-made.ubi.pt/prototypes-project1.html concretes using different coarse aggregates of different geological sources, granite, basalt, calcareous and marble, were produced in specific mix proportions and laboratory controlled conditions. Aggregates used were of good quality, having low particle water absorption and relevant mechanical properties. The influence of coarse aggregate type, size, as well dry or water saturated conditions, on the concrete mechanical and durability parameters were determined.

It was found that aggregates type, size or water content during mixing does not influence significantly concrete mechanical behaviour for a C30/37 concrete strength class.

Regardless of aggregate type, concrete mixtures produced using larger size aggregates presented higher vacuum water absorption and oxygen permeability, than mixtures using smaller size aggregates. This might be explained by the fact that larger coarse aggregates in concrete contribute not only to the increase of path length of capillary pores and its interconnectivity, but also to the increase of cement-aggregate interface zone.

Also regardless of aggregate type, concrete mixtures using saturated aggregates before mixing presented lower vacuum water absorption and oxygen permeability than mixtures were aggregates were introduced in a relatively dry state. It is likely that when aggregates are water saturated before mixing it does not absorbs water from the cement mortar fraction, and thus contributes to a dense cement aggregate interface. Consequently, if aggregate is dry it will absorb water contributing to a porous cement aggregate interface zone.

Thus, it is beleived that concrete durability properties are not affected by aggregates mineralogy, but in turn are significantly affected by the aggregate size and its water content.