Influence of Ceramic Recycled Aggregates on the Properties of Prestressed Precast Concrete Elements

This work presents the results of an experimental study performed on the mechanical behavior of concrete manufactured with ceramic recycled aggregates (CRA), from precast ventilation ducts, that once made have been rejected by defective. The ultimate objective is to use these wastes to manufacture prestressed concrete joists used in building floors. The coarse fraction and the fine fraction have been considered. The work has been carried out in three phases: characterization of the material, characterization of concrete with CRA and manufacturing and testing of prestressed joists. With the results obtained it is determined the influence of the ceramic recycled aggregate on the properties analyzed. There are not enough studies about prestressed elements that include the replacement of the aggregate in the fine fraction. In view of the results obtained could both of fine and coarse fraction can be used in these applications

Breast cancer PAM50 signature: Correlation and concordance between RNA-Seq and digital multiplexed gene expression technologies in a triple negative breast cancer series

Background: Full RNA-Seq is a fundamental research tool for whole transcriptome analysis. However, it is too costly and time consuming to be used in routine clinical practice. We evaluated the transcript quantification agreement between RNA-Seq and a digital multiplexed gene expression platform, and the subtype call after running the PAM50 assay in a series of breast cancer patients classified as triple negative by IHC/FISH. The goal of this study is to analyze the concordance between both expression platforms overall, and for calling PAM50 triple negative breast cancer intrinsic subtypes in particular. Results: The analyses were performed in paraffin-embedded tissues from 96 patients recruited in a multicenter, prospective, non-randomized neoadjuvant triple negative breast cancer trial (NCT01560663). Pre-treatment core biopsies were obtained following clinical practice guidelines and conserved as FFPE for further RNA extraction. PAM50 was performed on both digital multiplexed gene expression and RNA-Seq platforms. Subtype assignment was based on the nearest centroid classification following this procedure for both platforms and it was concordant on 96% of the cases (N = 96). In four cases, digital multiplexed gene expression analysis and RNA-Seq were discordant. The Spearman correlation to each of the centroids and the risk of recurrence were above 0.89 in both platforms while the agreement on Proliferation Score reached up to 0.97. In addition, 82% of the individual PAM50 genes showed a correlation coefficient > 0.80. Conclusions: In our analysis, the subtype calling in most of the samples was concordant in both platforms and the potential discordances had reduced clinical implications in terms of prognosis. If speed and cost are the main driving forces then the preferred technique is the digital multiplexed platform, while if whole genome patterns and subtype are the driving forces, then RNA-Seq is the preferred method

Assessment of properties of recycled concrete by means of a highly fractioned factorial design of experiment

The study presented in this paper has been carried out using a highly fractional factorial experimental design. This design allows the analysis of a greater number of factors and levels with a reduced number of mixes. In the state of art of recycled concrete the studies have been carried out varying the level of one factor while the rest remained fixed. However an excessive number of factors or levels are not considered. This highly simplified test program was designed in order to make the number of tests viable whilst guaranteeing the reliability of the conclusions. The concrete has been produced by substituting the natural coarse aggregates for recycled aggregates from construction and demolition waste, which is mainly composed of concrete. In this research some factors that have not been analyzed in previous studies, such as the granular structure of the concrete or the replacement criteria, have been studied. The properties of recycled concrete analyzed were: density, absorption, compressive strength, elastic modulus and penetration of water under pressure. The concrete was made with dry recycled aggregate. The percentage of replacement of the recycled aggregate did not affect the compressive strength since the water/cement rate remained constant. However the elastic modulus is affected by the percentage of replacement when it exceeds 50%. © 2011 Elsevier Ltd. All rights reserved.López-Gayarre, F.; Lopez-Colina, C.; Serrano-Lopez, M.; García Taengua, EJ.; Lopez Martinez, A. (2011). Assessment of properties of recycled concrete by means of a highly fractioned factorial design of experiment. Construction and Building Materials. 25(10):3802-3809. doi:10.1016/j.conbuildmat.2011.04.039S38023809251

Effect of siderurgical aggregates on concrete exposed to saline environments

ABSTRACT: Using recovered waste to obtain high-performance structural concrete is possible and justified by the saving in natural resources and the avoidance of deposit in landfills. The technical justification for these new and ecological concretes must be based on proving their mechanical performance and durability. The former has been widely studied, while the latter has been very vaguely studied, with controversies being found in this regard. This research aims to shed light on the ability of concrete with siderurgical aggregates to resist processes that lead to early deterioration or alteration of its microstructure. To this end, concrete with siderurgical aggregates and limestone reference concrete were subjected to traditional durability tests, as well as novel tests consisting of exposure to saline environments. The results obtained show that the concretes with siderurgical aggregates exhibit a similar behavior in terms of gas and water permeability, accelerated carbonation and resistance to freeze-thaw cycles (except for total replacements) to the limestone reference concrete. Exposure to a salt spray chamber and to seawater show the same effect in terms of chloride profiles, while the steel reinforcements embedded in the concrete did not suffer corrosion for any of the exposure times. These results open the door to using these concretes in maritime work, both onshore and offshore.This research was co-financed by the European Regional Development Fund (ERDF) and the Ministry of Economy, Industry and Competitiveness (MINECO) within the framework of the project RTC-2016-5637-3 and R&D project RES2020PU03 financed by the Department of Universities, Equality, Culture and Sports of the Government of Cantabria, Spain. The research was possible thanks to the collaboration of the company INGECID, the department LADICIM (University of Cantabria) and the companies ROCACERO and SIDENOR, as well as the Department of Universities and Research, Environment and Social Policy of the Government of Cantabria (Spain)

Effect of siderurgical aggregates on concrete exposed to saline environments

Using recovered waste to obtain high-performance structural concrete is possible and justified by the saving in natural resources and the avoidance of deposit in landfills. The technical justification for these new and ecological concretes must be based on proving their mechanical performance and durability. The former has been widely studied, while the latter has been very vaguely studied, with controversies being found in this regard. This research aims to shed light on the ability of concrete with siderurgical aggregates to resist processes that lead to early deterioration or alteration of its microstructure. To this end, concrete with siderurgical aggregates and limestone reference concrete were subjected to traditional durability tests, as well as novel tests consisting of exposure to saline environments. The results obtained show that the concretes with siderurgical aggregates exhibit a similar behavior in terms of gas and water permeability, accelerated carbonation and resistance to freeze-thaw cycles (except for total replacements) to the limestone reference concrete. Exposure to a salt spray chamber and to seawater show the same effect in terms of chloride profiles, while the steel reinforcements embedded in the concrete did not suffer corrosion for any of the exposure times. These results open the door to using these concretes in maritime work, both onshore and offshore. © 202

Long term deformations by creep and shrinkage in recycled aggregate concrete

The main aim of this work was to determine creep and shrinkage variations experienced in recycled concrete, made by replacing the main fraction of the natural aggregate with a recycled aggregate coming from waste concrete and comparing it to a control concrete. It was possible to state that the evolution of deformation by shrinkage and creep was similar to a conventional concrete, although the results after a period of 180 days showed the influence of the substitution percentage in the recycled aggregates present in the mixture. In the case when 100% coarse natural aggregate was replaced by recycled aggregate there was an increase in the deformations by creep of 51% and by shrinkage of 70% as compared to those experienced by the control concrete. The substitution percentages of coarse natural aggregate by coarse recycled aggregate were 20, 50 and 100%. Fine natural aggregate was used in all cases and the amount of cement and water–cement ratio remained constant in the mixture.Domingo Cabo, A.; Lazaro, C.; López Gayarre, F.; Serrano, MA.; López Codina, C. (2009). Long term deformations by creep and shrinkage in recycled aggregate concrete. Materials and Structures. 43(8):1147-1160. doi:10.1617/s11527-009-9573-0S11471160438Alaejos Gutierrez P (2006) Utilización de árido reciclado para la fabricación de hormigón estructural. ACHE (Asociación científico-Técnica del Hormigón Estructural)EHE, Annex 19 (2008) Instrucción de Hormigón Estructural. Ministerio de FomentoSánchez de Juan M (2005) Estudio sobre la utilización de árido reciclado para la fabricación de hormigón estructural. PhD Thesis, Polytechnic University of Madrid, SpainGómez-Soberón JMV (2003) Relationship between gas absorption and the shrinkage and creep of recycled aggregate concrete. Cem Concr Aggreg 25(2):42–48Amnon K (2003) Properties of concrete made with recycled aggregate from partially hydrates old concrete. Cem Concr Resour 33:703–711Kishore R, Bairagi NK (2007) Creep and drying shrinkage of recycled aggregate concrete. In: Proceedings of the first international conference on recent advances in concrete technology, pp 289–298Poon CS, Kou SC, Chan D (2006) Influence of steam curing on hardened properties of recycled aggregate concrete. Mag Concr Res 58:289–299Sato R, Maruyama I, Sogabe T et al (2007) Flexural behavior of reinforced recycled concrete beams. J Adv Concr Technol 5:43–61Zaharieva R (2003) Assessment of the surface permeation properties of recycled aggregate concrete. Cem Concr Compos 25:223–232Torben CH (1986) The second RILEM state of the art report on recycled aggregate and recycled aggregates concrete. Mater Struct 1(111):201–246Barra M (1996) Estudio de la durabilidad del hormigón de arido reciclado en su aplicación como hormigón estructural. PhD Thesis, Polytechnic University of Cataluña, SpainEtxeberria M (2006) Recycled aggregate concrete as structural material. Mater Struct 40:529–541ASTM C512-02 (2002) Standard test method for creep of concrete in compression. American Society for Testing and Materials, PhiladelphiaKakizaki M, Harada M, Soshiroda T, Kubota S, Ikeda T, Kasai Y (1988) Strength and elastic modulus of recycled aggregate concrete. In: Proceedings of the second international RILEM symposium on demolition and reuse of concrete and masonry, vol 2. Reuse of Demolition Waste, pp 565–574CEB-FIP (1990) Model code. Comité Euro-International du Béton–Fédération Internationale de la PrécontrainteRILEM Model B3 (1995) Creep and shrinkage model for analysis and design of concrete structuresGardner NJ, Lockman MJ (2001) Design provisions for drying shrinkage and creep of normal strength concrete. ACI Mater J 98(2):159–16