Isaac Galobardes
Deparment: Department of Civil Engineering

Items: 15

Views: 461

1. Sustainability analysis of functionally graded concrete produced with fibres and recycled aggregates

Author:Chan, R;Hu, T;Liu, X;Galobardes, I;Moy, CKS;Hao, JL;Krabbenhoft, K


Abstract:Fibre reinforced concrete is widely used in the pavement construction despite presenting some economic and environmental issues. To address these matters, the concept of functionally graded material (FGM) concept with materials that present changeable properties over its volume is adopted on concrete, generating functionally graded concrete (FGC). To understand these new composite materials more studies are needed. In this study, eight mixes of FGC concretes were produced to assess the effect of the recycled aggregate and different depths of the fibre reinforced layer on the flexural performance. Besides, a simplified sustainability analysis was performed to assess the goodness of these special concretes. The experimental results indicate that the FGC studied could be used in structural applications requiring lower loading capacity. The sustainability analysis indicates that a cut in the total volume of steel fibres and the use of recycled aggregates would enhance the benefits of the FGC.
2. Adaptation of the standard EN 196-1 for mortar with accelerator

Author:Galobardes, I;Salvador, RP;Cavalaro, SHP;Figueiredo, A;Goodier, CI


Abstract:In certain applications, accelerators are added to favour a rapid evolution of mechanical properties in mortar and compatibility. concrete. In order to assure adequate performance, it is necessary to test the between the accelerator and other components of the mixture. The EN 934-5 establishes that such evaluation of accelerators should be performed according with the procedure established in the EN 196-1. However, this standard does not take into account the inclusion of the accelerators or the particularities of the mortar produced with these admixtures. The objective of this paper is to adapt the EN 196-1 in order to characterize the strength of mortars with accelerator. First, an experimental parametric study to evaluate the influence of the production procedure on the results was conducted. Based on the results obtained, a modified production process was proposed. Then, a wide experimental program including a total of 40 mixes of mortars with different formulations and contents of accelerators was performed. Based on a statistical analysis, a new admissible variation used to calculate the compressive strength was proposed. (C) 2016 Elsevier Ltd. All rights reserved.
3. Magnetic probe to test spatial distribution of steel fibres in UHPFRC prisms

Author:Li, Lufan ; Xia, Jun ; Galobardes, Isaac

Source:FIB 2018 - Proceedings for the 2018 fib Congress Better, Smarter, Stronger,2019,Vol.

Abstract:The mechanical properties of ultra-high performance fibre reinforce concrete (UHPFRC) vary owing to the different distribution of fibres within the mix. By taking advantage of the magnetic properties of steel fibres, a non-destructive method (NDT) based on a magnetic probe was investigated. The probe was built to measure not only a 2D but also a 3D spatial distribution. The experimental program was mainly carried on vibrated and non-vibrated prisms. In that sense, the effective depth of the probe was determined first. The inductance data revealed the distribution of fibres in different prism sections. The results showed how vibrated prisms presented a better performance in flexural strength test. To validate the method, slices were cut from the concrete prisms and an image analysis was conducted based on photos taken of the cross sections. The sedimentation of fibres inside concrete due to external vibration was verified and related to the mechanical performance. Due to the convenience of this method, it is highly expected it could be applied in field for material quality control or in lab for material characterization. © 2019 by the fib. All rights reserved.
4. Control of the ultra-high performance fibre reiforced concrete (UHPFRC) concerning to postcracking performance

Author:Galobardes, Isaac ; Wang, Kaiyang ; Li, Lufan ; Xia, Jun

Source:FIB 2018 - Proceedings for the 2018 fib Congress Better, Smarter, Stronger,2019,Vol.

Abstract:UHPFRC presents great advantages. However, there are some drawbacks concerning to quality control process non-uniform fibre distribution (content/orientation) and variation of post-cracking performance. Regarding the first, the high number of fibres complicates the homogenization of the mix. On the other hand, the toughness control, which depends on the content of fibres incorporated, as the conventional process described by the ASTM standard (beam test), is labour demanding and requires large specimens to be tested. Besides, this test is not suitable to be performed using specimens prepared with cores extracted from the structure and the variability of the result is high. In order to minimize drawbacks, an experimental study is presented analysing the suitability of using the inductive method and the Barcelona test to control UHPFRC. In that sense, six UHPFRC are analysed. The results of the inductive method are used to know the real fibre contents in the mixes and how this parameter is related to the residual strength of the material. The experimental results are statistically analysed and a correlation equation is obtained to determine the UHPFRC residual strength class using only the results from the Barcelona test. The last proves to be a feasible alternative to the beam test. © 2019 by the fib. All rights reserved.

Author:Lu, X;Dounas, T;Spaeth, B;Bissoonauth, C;Galobardes, I


Abstract:New possibilities of concrete constructions in architecture, the traditional formwork can be gradually replaced by the use of flexible textile. At the same time textile reinforcement combined with fabric formwork, introduces an innovative integrated solution in the fabrication of concrete. Based on a simple understanding of the textile weaving and knitting techniques, this project concentrates on the architectural production and the structural optimization of the textile as both concrete reinforcement and formwork. Furthermore, we present a robotic simulation of the process that develops using a series of computational experiments to research the sequence of weaving and/or knitting. Through the computational process and the design simulations, the research is firmly rooted in analog and digital exploration of material and its implementation in architecture, with particular emphasis on the convergence of robotics and computation. Note that the paper deals mainly with the software and weaving simulation as part of a larger research project, without dealing with the production of physical artefacts.
6. Feasibility study on further utilization of timber in China

Author:Sikora, K;Hao, JL;Galobardes, I;Xing, WQ;Wei, SB;Chen, ZT


Abstract:The use of timber in building industry has expanded in many countries over last 20 years due mainly to its lightweight, little adverse impact to the environment, and strong anti-seismic properties. Despite the fast development of the construction industry in China in recent years, timber products utilization is still very limited. Therefore, the purpose of this study was to investigate the feasibility to further utilize timber based products in the building industry in China. A review of engineered wood products utilization in China, and oversees was conducted first. The general properties of timber products were followed. Based on this, a survey focusing on the current situation and suitability of localised grown timber products was carried out to study the feasibility. This paper concludes that timber based products have a great future in China. It recommends that it is imperative to further research how to promote timber's utilization in China to be in line with the sustainable development.
7. Comparison between the falling head and the constant head permeability tests to assess the permeability coefficient of sustainable Pervious Concretes

Author:Sandoval, Gersson F.B. ; Galobardes, Isaac ; Teixeira, Raquel S. ; Toralles, Berenice M.

Source:Case Studies in Construction Materials,2017,Vol.7

Abstract:The use of Pervious Concrete (PC) increased in the last years as an alternative to solve the run-off problem. PC shows a high percentage of empty spaces/gaps, which vary from 10 to 35%%, facilitating the flow of rain and water through its structure. PC presents higher k permeability coefficient compared to conventional concrete. Permeability is the main property of PC, although there is no standardized method that guarantees the correct and precise measurement of such property in laboratory conditions. Currently, two main methodologies are used to assess the permeability coefficient the falling head and the constant head permeability tests. In that regard, the American Concrete Institute recommends the use of the first method, although no comparison was done between them. Furthermore, the recommendations do not consider the use of sustainable aggregates during the production of the PC. In this study, the permeability tests were explained and used to assess the permeability coefficient of different mixes of PC produced with sustainable aggregates. The experimental results were used to analyze the relationship between the porosity and the permeability of concrete and compare the performance of the falling head and constant head permeability tests. The study presents the advantages of performing the constant head permeability test to assess the permeability of the PC. © 2017 The Authors
8. Engineered Bamboo's Further Application: An Empirical Study in China

Author:Xing, WQ;Hao, JL;Galobardes, I;Wei, SB;Chen, ZT;Sikora, KS


Abstract:The trend of sustainable development has been followed more globally nowadays. There is an urgent need for ecological friendly construction materials in China since the use of concrete produces pollution and leads to inefficient use of energy. Bamboo can effectively address the sustainability trends due to: lightweight construction, little adverse impact on the environment, and anti-seismic properties. However, bamboo products utilization has been very limited. Therefore, the purpose of this study was to investigate the feasibility to further utilize bamboo products in the construction industry in China. A review of engineered bamboo products utilization in China, and oversees was conducted. Based on this, a survey focusing on the current situation and suitability of bamboo products was carried out to study their feasibility, and preliminary testing on bonding shear strength for different configurations are presented. The results are promising, in particular the relatively low clamping pressure of 0.6 MPa seems to be sufficient for bonding, and it is clear that engineered bamboo products have a great potential in China. However, further more comprehensive studies on the performance of the laminated bamboo are needed.
9. Alternative quality control of steel fibre reinforced sprayed concrete (SFRSC)

Author:Galobardes, I;Silva, CL;Figueiredo, A;Cavalaro, SHP;Goodier, CI


Abstract:Steel fibre reinforced sprayed concrete (SFRSC) is used in applications with high structural capacity requirements. The quality control of SFRSC typically includes the assessment of toughness-related properties and measurement of the fibre content. The toughness may be measured with the beam test to EN 14488-3:2006, whereas the fibre content is generally measured by manual methods, such as collecting and weighing the fibres. Both procedures are time-consuming, difficult to perform and challenging to conduct with specimens extracted from the in-situ structure. These difficulties can therefore limit the frequency of characterization and hence potentially compromise the reliability of the information obtained, thus hindering the capacity of engineers to either detect potential problems or to optimize the material. The objective of this work therefore is to explore a simpler SFRSC quality control system that includes the inductive method for the assessment of fibre content and the Barcelona test for the assessment of toughness. Dry-mix SFRSC with five fibre contents were sprayed and tested with beam, Barcelona and inductive tests. Results confirm the greater sensitivity of the Barcelona test and the advantages of combining it with the inductive method for an enhanced quality control. Furthermore, equations are proposed to predict the beam test results using the Barcelona test results. These equations provide a good fit (R-2 = 0.97) regardless of the fibre content in the mix, thus confirming the robustness of the approach both for the classification and for the quality control of SFRSC. (C) 2019 Elsevier Ltd. All rights reserved.
10. Parametric design of sculptural fibre reinforced concrete facade components

Author:Herr, Christiane M. ; Lombardi, Davide ; Galobardes, Isaac

Source:CAADRIA 2018 - 23rd International Conference on Computer-Aided Architectural Design Research in Asia Learning, Prototyping and Adapting,2018,Vol.2

Abstract:This paper presents the first stage of a study examining the digital design and fabrication of a parametrically defined sculptural concrete façade element employing fibre reinforced concrete. On the background of a literature review of related precedent studies, the paper extends the scope of previous studies by offering a detailed insight into the process of integrating architectural considerations with material properties of fibre reinforced concrete, detailed structural analysis and construction constraints. The paper offers technical details with a focus on material to similar on-going studies. © 2018 and published by the Association for Computer-Aided Architectural Design Research in Asia (CAADRIA) in Hong Kong.
11. Correlation between permeability and porosity for pervious concrete (PC)

Author:Sandoval,Gersson F.B.;Galobardes,Isaac;Schwantes-Cezario,Nicole;Campos,André;Toralles,Berenice M.

Source:DYNA (Colombia),2019,Vol.86

Abstract:The aim of this study was to propose a correlation for the hydraulic parameters of pervious concrete (PC). Thus, three aggregates from civil construction waste and one basalt aggregate (reference) were used to produce PC. The ratio c/a (cement: aggregate) 1:3.26 and a w/c ratio of 0.34 were used in all mixtures. Compressive and flexure tensile strength tests were performed to mechanically characterize the mixtures produced, whereas porosity and constant head permeability tests were also carried out to assess the material hydraulic properties. Firstly, the experimental results were compared with the requirements established in international guidelines (ACI 522R-10, NBR 16416 (2015) and VTT-R-080225-13). The results complied with the guidelines indicating it is feasible to produce pervious concretes with the sustainable aggregates used in the study in low structural applications such as walkways. On the other hand, a correlation between permeability and porosity was proposed based on Darcy’s and Bernoulli’s laws. The proposed equation, obtained by means of a non-linear regression, is an exponential equation that characterizes the hydraulic efficiency of the internal channels of the material considering the pores interconnection. The correlation between porosity and permeability was finally validated using results from the literature showing the same trend found in laboratory, and therefore it was demonstrated that the proposed correlation in an efficient tool to predict the hydraulic efficiency of pervious concrete.
12. Assessing the potential of functionally graded concrete using fibre reinforced and recycled aggregate concrete

Author:Liu, XZ;Yan, MP;Galobardes, I;Sikora, K


Abstract:Despite ordinary Portland cement concrete presenting low performance in tension and a negative impact on the natural environment, it is the most used construction material. Researchers have noted that the usage of fibres as reinforcement and recycled aggregates, instead of natural ones, may minimize these issues. The concept of functionally graded material for new composite materials is proposed to address these problems. In this paper, five different concrete mixes were produced to analyse the potential of using functionally graded concretes (FGC) for sustainable structures. Their mechanical performance, a sustainable quality control method for these materials and their costs and embodied CO2 were analyzed. The results show that FGC, even though showing a post-cracking flexural performance lower than conventional FRC, possesses high potential in terms of structural design based on Model Code 2010 specifications. The equations provided to use the Barcelona test to control the material, which is more environmentally friendly than the standardized beam test, may facilitate the introduction of FCC in the construction market. Finally, considering costs and embodied CO2, FCC presents a good prospect to be used as structural material for future sustainable concrete elements. (C) 2018 Elsevier Ltd. All rights reserved.
13. Parametric study of functionally graded concretes incorporating steel fibres and recycled aggregates

Author:Chan, R;Liu, XZ;Galobardes, I


Abstract:Even presenting several drawbacks, especially regarding environmental impact, concrete is the most consumed human-made material worldwide. In this sense, incorporating steel fibres and recycled aggregates, and applying the functionally graded material concept may help in the sustainability of concrete. In this paper, relationships between mechanical properties, embodied CO2, cost, among other parameters of functionally graded concretes (FGC) incorporating steel fibres and recycled aggregates were studied. The test results show that the FGC mechanical performance is inferior to fibre reinforced concrete but superior to fibre reinforced recycled aggregate concrete. Therefore, the FGC studied could be used in lower loading capacity applications, such as car parks and cycling lanes. In terms of embodied CO2 and cost, the FGC studied are more affected by the content of fibre than the content of recycled aggregates. Also, equations correlating design and sustainability parameters with reinforced thickness and content of fibre were proposed. (C) 2020 Elsevier Ltd. All rights reserved.
14. Analysis of potential use of fibre reinforced recycled aggregate concrete for sustainable pavements

Author:Chan, R;Santana, MA;Oda, AM;Paniguel, RC;Vieira, LB;Figueiredo, AD;Galobardes, I


Abstract:Fibre reinforced concrete (FRC) has advantages, such as minimizing cracking, increasing the composite absorption of energy and enhancing the residual strength. At the same time, the demand for sustainability led to the development of using construction and demolition waste as recycled aggregates in structural and non-structural components. The aim of this study is to analyse the technical and environmental feasibility of using fibre reinforced recycled aggregate concrete (FRRAC) in pavements. An experimental program was carried out to assess the mechanical behaviour of the FRC and FRRAC. Then, a case of study was performed to evaluate the feasibility of using FRRAC in pavements design, in which the fibre content and CO2 emissions (CE) were estimated for different slab thicknesses. It was observed that, to support the same design loads, slabs thicker than 0.22 m require similar fibre contents, independently of the concrete mix. Besides, it was confirmed that the CE are lower for the alternative with recycled aggregate for slab thicknesses higher than 0.20 m. In conclusion, these results open up the possibility of using FRRAC to produce more sustainable rigid pavements. (C) 2019 Elsevier Ltd. All rights reserved.
15. Comparison between Analytical Equation and Numerical Methods for Determining Shear Stress in a Cantilever Beam

Author:Al-Qasem, I;Hasan, AR;Abdulwahid, MY;Galobardes, I


Abstract:A three meter-length cantilever beam loaded with a concentrated load at its free end is studied to determine shear stresses. In the present study, three cross sections are considered: rectangle (R); I, and T. The study presents a comparison of maximum shear stresses obtained by means of two methods: classical analytical equation derived by Collingnon, and finite element method (FEM) software. Software programs ANSYS and SAP2000 were used. The results show difference between the maximum shear stresses obtained by the analytical equation and the software, being the last is always higher. The average differences for ANSYS and SAP2000, independently of the cross section, were 12.76%% and 11.96%%, respectively. Considering these differences, correction factors were proposed to the classical analytical formula for each cross section case to obtain more realistic results. After the correction, the average differences decrease to 1.48%% and 4.86%%, regardless of the cross section shape.
Total 15 results found
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