Mechanical properties of braided reinforced composites

This work presents the study that is being done at University of Minho concerning the development of braided reinforced composites for civil engineering purposes. A research study has been undertaken to understand the mechanical behaviour of core reinforced braided fabrics. Various samples have been produced using polyester fibers, for the production of the braided fabric, and glass, carbon, polyethylene and sisal fibers, for the core reinforcement. The results of tensile and bending tests carried out in the correspondent core reinforced braided fabrics obtained are presented and discussed. Moreover, the influence of the testing conditions and the braiding angle is also presented and discussed. In order to produce braided reinforced composite rods to be used as concrete reinforcement, a special technique has been developed using a standard vertical braiding machine. The tensile and bending properties of braided reinforced composite rods have been evaluated and the results obtained are presented, discussed and compared with those of conventional materials, such as steel

The mechanical properties of braided reinforced composites for application in concrete structures

The current work is concerned with the development of braided reinforced composites for civil engineering applications. The research study aims at understanding the mechanical behaviour of core reinforced braided fabrics. Various samples have been produced using polyester fibres, for the production of the braided fabrics, and glass, carbon, polyethylene and sisal fibres, for the core reinforcement. The results of the tensile tests carried out in the various samples of reinforced braided fabrics obtained are presented and discussed. Moreover, the influence of the testing conditions and of the braiding angle are also studied. In order to produce braided reinforced composite rods to be used as concrete reinforcement, a special technique has been developed using a standard vertical braiding machine. The tensile and bending properties of braided reinforced composite rods have been evaluated and the results obtained are presented, discussed and compared with those of conventional materials, such as steel

Composite rods as a steel substitute in concrete reinforcement

The current work is concerning with the development of braided reinforced composites rods for concrete reinforcement, as a steel substitute. The research study aims to understand the mechanical behaviour of composite rods reinforced by a fibrous structure – core reinforced braided fabric. Several samples of braided reinforced composite rods were produced. Polyester fibres were used to produce the braided fabric; several types of fibres, and several combinations of fibres, were used as braided fabric core reinforcement; and polyester resin was used as polymeric matrix. The mechanical properties of braided reinforced composite rods have been evaluated under tensile. The objective was to identify the type of fibre, or combination of fibres, to be used as braided fabric core reinforcement, in order to produce composite rods with mechanical properties similar to those of steel rebars.Fundação para a Ciência e a Tecnologia (FCT) - POCI/CTM/6086/2004

Processing of near-net-shape dental crowns by conventional alumina slip casting in gypsum mould

Trabalho apresentado em Microscopy in Research - An SPMicros Congress, 9-10 December 2013, Monte da Caparica, PortugalN/

Halogen ligth thermogravimetric technique for determining the retained water in fine aggregates used for concrete mixing design

[EN] Measuring the rate of water retention of the aggregates used in mortars and concrete is required to achieve a good mix design. The water retention, specifically absorption, is used to keep constant the water/cement ratio. This paper focuses on the study of a new technique for measuring retained water in fine aggregates. In order to obtain results, the procedure described in the existing standards takes more than 24 h. Additionally, it involves high consumption of heat energy due to the use of drying ovens. Furthermore, the results obtained remain highly variable and therefore discussed by the scientific community.In this research, a novel technique based on a halogen moisture analyzer was implemented. The technique was assessed using an experiment design with a surface response model. The most important factors and levels were identified together with the interactions between them. Finally, the model was validated and the results obtained with this technique were compared with those obtained by conventional techniques in order to verify that they were equivalent.Arias Jaramillo, Y.; Paya Bernabeu, JJ.; Ochoa Botero, JC. (2015). Halogen ligth thermogravimetric technique for determining the retained water in fine aggregates used for concrete mixing design. Journal of Thermal Analysis and Calorimetry: an international forum for thermal studies. 123:127-134. doi:10.1007/s10973-015-4902-8S127134123Djerbi Tegguer A. Determining the water absorption of recycled aggregates utilizing hydrostatic weighing approach. Constr Build Mater. 2012;27:112–6.Kasemchaisiri R, Tangtermsirikul S. A method to determine water retainability of porous fine aggregate for design and quality control of fresh concrete. Constr Build Mater. 2007;21:1322–34.Gonilho Pereira C, Castro-Gomes J, Pereira de Oliveira L. Influence of natural coarse aggregate size, mineralogy and water content on the permeability of structural concrete. Constr Build Mater. 2009;23:602–8.Cortas R, Roiziére E, Staquet S, Hamami A, Delplancke-Ogletree M. Effect of the water saturation of aggregates on the shrinkage induced cracking risk of concrete at early age. Cem Concr Compos. 2014;50:1–9.Black R. The determination of specific gravity using Siphon-Can method. Cem Concr Aggreg. 1986;8:46–50.Saxer E. A direct method of determining absorption and specific gravity of aggregates. 1956;2.Hughes B, Famili H., Part 1—Absorption of concrete aggregates, Part 2—saturated air techniques for determining the absorption of aggregates. In: Absorptions of concrete aggregates. Birmingham University; 1971.Tam VWY, Gao XF, Tam CM, Chan CH. New approach in measuring water absorption of recycled aggregates. Constr Build Mater. 2008;22:364–9.Balcedowiak W. Phase analysis of high-calcium line by TG. J Therm Anal Calorim. 2000;60:70–7.Mendoza O, Tobón JI. An alternative thermal method for identification of pozzolanic activity in Ca(OH)2/pozzolan pastes. J Therm Anal Calorim. 2013;114:589–96.Kosmatka SH, Kerkhoff B, Panarese W, MacLeod NF, McGrath RJ, Design and control of concrete mixtures. 7rd ed. Cement association of Canada. 2002. pp. 88.Cárdenas JI, Restrepo C. Patrimonio geológico y patrimonio minero de la cuenca carbonífera del suroeste antioqueño, Colombia. Boletín de ciencias de la tierra. 2006;18:91–102 ISSN 0120-3630 .Klein NS, Aguado A, Tollares-Carbonari BM, Real LV. Prediction of the water absorption by aggregates over time: modelling through the use of value function and experimental validation. Constr Build Mater. 2014;69:213–20

Directionally oriented fibrous structures for llghtweight concrete elements reinforcement

This paper reports on the work that is being undertaken at the University of Minho concerning the development of directionally oriented fibrous structures (DOFS) to be used as a concrete reinforcement material. Several glass fibre wovenlike DOFS were produced varying two parameters: roving linear density (tex) and reinforcement structural density (rovings/ cm). Self-compacting concrete slabs were reinforced by DOFS structures and their bending behaviour was evaluated. The results were compared with those of steel reinforced slabs and plain (non reinforced) concrete slabs. They show that DOFS improve the mechanical behaviour of self-compacting concrete, however, their mechanical behaviour is different from steel

Core reilforced braided composite armour as a substitute to steel in concrete reinforcement

This paper presents the work that is being done at the University of Minho concerning the development of brainded rods concrete reinforcement. Several samples of core reinforced braided fabrics have been produced varying the type of braided fabric (core reinforced and hybrid), the linear density of the core reinforcing yarns and the type of braiding structure (with or without ribs). The tensile properties of braided fabrics has also been analysed. Core reinforced braided composites rods were produced and tested to evaluate tensile and bending properties. The results obtained are presented and discussed. Reinforced concrete beams, with composite armour and steel armour, were produced and were subjected to bending test and the test results are presented. The adherence between composite rods and concrete was analysed as well