Papers by ENRIC VAZQUEZ/EC/UPC
Construction and Building Materials, 2014
h i g h l i g h t s Viscometer measures describes better fresh concretes properties than slump va... more h i g h l i g h t s Viscometer measures describes better fresh concretes properties than slump value. Fresh recycled aggregate concrete (RAC) can be modelled as a Bingham fluid. The aggregate proportioning method greatly affects rheological parameters. Plug flow and gravel migration phenomena can influence rheology measurements.
Materiales de Construcción, 2012
A new method for proportioning recycled aggregates concrete (RAC) is used to check its feasibilit... more A new method for proportioning recycled aggregates concrete (RAC) is used to check its feasibility under the Spanish context. First, an extensive experimental campaign has been done, with the purpose of check and analyze the applicability of the EMV method with two Spanish recycled concrete aggregates (RCA). The aim of the second part of the investigation, was to elaborate an adaptation of the EMV method to Bolomey methodology (1), using a 20% weight replacement of coarse natural aggregates (NA) for RCA, and so, with this, comply with the Spanish Instruction for Structural Concrete (EHE 2008). Slump, air content, fresh and hardened densities, compressive strength and modulus of elasticity were determined and analyzed, in order to check the concrete properties. Finally, it was observed that, the EMV method is viable, and its adaptation, results in concrete mixes with similar or better properties than the natural aggregate concrete and RAC conventionally prepared.
Construction and Building Materials, 2014
Recycled aggregates concrete (RAC) becomes an important participant in recycled materials, althou... more Recycled aggregates concrete (RAC) becomes an important participant in recycled materials, although there are still questionable issues about some of its properties. Durability of RAC and its relationship with recycled concrete aggregate (RCA) is often discussed, especially in relation with chloride penetration and diffusion properties. An extensive experimental campaign was performed in order to evaluate the effect of RCA content in the retention and diffusion of chlorides in RAC. The influence of composition and mix design of the concrete was first studied using only a 20% replacement of natural aggregate by recycled aggregate. The 20% replacement was chosen in order to comply with Spanish recommendations for structural concrete. The 20% replacement was chosen in order to comply with Spanish recommendations for structural concrete. In the second part of the study concrete mixes ranging from 0.45 to 0.65 w/c ratios, with 0%, 20%, 50% and 100% coarse aggregates replacement were tested. Cement pastes, recycled aggregates and concretes were submitted to saline attack and the total chloride contents were determined. Chloride penetration profiles were determined by means of the NT BUILD 443 specifications. XRD and SEM aided the chlorides binding determination. A chlorides retention phenomenon is detected by the average diffusion coefficient decrease in RAC, thus compensating the RCA higher permeability. According to chloride binding and diffusion results, high RCA content lead to an improvement of durability in RAC with sufficiently low w/c ratio, in terms of chlorides attack.
Cement and Concrete Composites, 2009
Results of a comprehensive investigation about the durability of structural-grade concrete made w... more Results of a comprehensive investigation about the durability of structural-grade concrete made with recycled concrete aggregate (RCA) are presented. The RCA-concrete mixes were proportioned using a new concrete mix design method, termed the equivalent mortar volume (EMV) ...
Recycled aggregates concrete (RAC) becomes an important participant in recycled materials althoug... more Recycled aggregates concrete (RAC) becomes an important participant in recycled materials although there are still questionable properties of it, like chloride penetration and diffusion. An extensive experimental campaign was performed in order to evaluate the effect of recycled concrete aggregates (RCA) over some properties of concretes. Composition and mix design influence on the concrete were studied in mixes ranging from 0.45 to 0.60 w/c ratios, with 0%, 20%, 50% and 100% coarse aggregates replacement. Concretes were submitted to saline attack and the total chloride contents were determined as well as the chloride penetration profiles. Both new cement paste and RCA from different concrete mixes were analysed by XRD and SEM in order to evaluate the chlorides binding. A chloride binding phenomenon is detected in RAC which may compensate the RCA higher permeability. According to chloride diffusion results, high RCA content lead to an improvement of durability in RAC with sufficiently low w/c ratio, in terms of chlorides presence.
Some durability properties are analyzed in concretes made with a novel method for recycled aggreg... more Some durability properties are analyzed in concretes made with a novel method for recycled aggregates concrete (RAC) proportioning, in order to validate it under the Spanish context. Two types of concrete mixes were elaborated; one following the guidelines of the named method, and other based on an adaptation of the method to Bolomey methodology. Two types of recycled concrete aggregates (RCA) were used. RCA replacement for natural aggregates (NA) ranged from 20% to 100%. The 20% was chosen in order to comply with Spanish recommendations. Water penetration under pressure, water absorption and chlorides attack were the studied properties. It is verified that the new method and the developed adaptation results in concrete mixes of better or similar properties to those of the natural aggregates concrete (NAC) and the conventional RAC, saving important amounts of cement.
A new method for proportioning recycled aggregates concrete (RAC) is used to check its feasibilit... more A new method for proportioning recycled aggregates concrete (RAC) is used to check its feasibility under the Spanish context. First, an extensive experimental campaign has been done, with the purpose of check and analyze the applicability of the EMV method with two Spanish recycled concrete aggregates (RCA). The aim of the second part of the investigation, was to elaborate an adaptation of the EMV method to Bolomey methodology (1), using a 20% weight replacement of coarse natural aggregates (NA) for RCA, and so, with this, comply with the Spanish Instruction for Structural Concrete (EHE 2008). Slump, air content, fresh and hardened densities, compressive strength and modulus of elasticity were determined and analyzed, in order to check the concrete properties. Finally, it was observed that, the EMV method is viable, and its adaptation, results in concrete mixes with similar or better properties than the natural aggregate concrete and RAC conventionally prepared.
The most frequently used measure of rheology is the slump test, which evaluates workability. Sinc... more The most frequently used measure of rheology is the slump test, which evaluates workability. Since this value is often operator-sensitive, a more quantitative estimate can be derived in terms of fundamental physical quantities, such as plastic viscosity and yield stress. The higher heterogeneity in terms of experimental slump measure occurs when recycled aggregate concrete (RAC) is tested. In this work, 16 recycled mixes were analysed with two aggregates proportioning methods and results were compared with four controls: rheological parameters were measured with a ConTec BML Viscometer 3. The results represent a valid tool for better understanding of fresh RAC rheology.
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Papers by ENRIC VAZQUEZ/EC/UPC