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Prof. Ruben Paul Borg
University of Malta

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0 Cement
0 Civil Engineering
0 Concrete
0 geopolymer concrete
0 concrete durability

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Concrete
Cement
supplementary cementitious materials
Civil Engineering

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Short Biography

Professor Ruben Paul Borg is a Structural & Materials Engineer and Academic at the University of Malta. He was appointed Principal Investigator on various International Research Projects including the Horizon 2020 ReSHEALience in Ultra High Durability Concrete, the Interreg Med CESBA Med Project in Sustainable Building and Materials, CABARET in Resilience in the Built Environment, ANDROID in Disaster Resilience and the Deconstruction and Recycling of Construction Waste Project. He served on the Management Committee of various European Research projects in Sustainability of Construction and Resilience. He is a member of the Board of Directors of iiSBE (International Initiative for a Sustainable Built Environment) and founded SBE Malta (Sustainable Built Environment Malta) as national chapter. He was appointed Chairman of ECCE (European Council of Civil Engineers) for Knowledge and Technology and Representative of the Institution of Civil Engineers (UK). Prof. Borg is active in fib (International Federation for Structural Concrete) and RILEM (International Union of Laboratories and Experts in Construction Materials, Systems and Structures) scientific committees. Prof. Borg is on the Editorial Board of the Scopus Indexed Q2 International Journal on Advanced Science, Engineering and Information Technology and the Scopus Indexed Journal of Sustainable Architecture and Civil Engineering.

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Project

Project Goal: Ultra High Durability Concrete

Starting Date:01 January 2018

Current Stage: www.uhdc.eu

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Original research article
Published: 28 May 2021 in Frontiers in Built Environment
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The purpose of the work reported in this paper is to assess the performance of recycled ultra-high durability concrete (R-UHDC), produced using different fractions of recycled aggregate obtained from crushed ultra-high durability concrete (UHDC), as a substitute for the natural aggregate. Four different recycled ultra-high durability concrete (R-UHDC) mixes were designed and manufactured with a reference mix based on the natural aggregate and three mixes with the natural aggregate replaced using recycled UHDC according to two percentage replacement values (50 and 100%). The effect of environmental degradation of the recycled parent concrete was also addressed, using recycled aggregates subjected to accelerated carbonation (replacement percentage equal to 50%). The work has been conducted in the framework of the activities of the Horizon 2020 ReSHEALience Project in ultra-high durability concrete. One key objective of the project was to formulate the concept and experimentally validate the performance of ultra-high durability concrete for structures and infrastructures exposed to extremely aggressive scenarios. The ReSHEALience consortium has defined UHDC as a “strain-hardening (fiber-reinforced) cementitious material with functionalizing micro- and nano-scale constituents especially added to deliver high durability in the cracked state under extremely aggressive exposure conditions.” In this context, the research was conducted to investigate the potential of recycling the UHDC mixes, developed and validated in previous research and employing them as a partial or even total replacement of the natural fine aggregate in the production of new UHDC. This supports the cradle-to-cradle approach in life cycle engineering applications. The research confirmed the effective regeneration of new UHDC based on the recycled aggregate obtained from crushed UHDC, attaining the required rheological characteristics, mechanical properties (compressive strength, flexural strength, and toughness), and durability performance (chloride penetration resistance, chloride migration, water capillary suction, and resistivity). This work is intended as the first step toward the sustainability assessment of the end of life of UHDC materials and structures and the potential of recycled UHDC for new structures and retrofit structural applications.

ACS Style

Ruben Paul Borg; Estefania Cuenca; Roberto Garofalo; Fabrizio Schillani; Milena Lozano Nasner; Liberato Ferrara. Performance Assessment of Ultra-High Durability Concrete Produced From Recycled Ultra-High Durability Concrete. Frontiers in Built Environment 2021, 7, 1 .

AMA Style

Ruben Paul Borg, Estefania Cuenca, Roberto Garofalo, Fabrizio Schillani, Milena Lozano Nasner, Liberato Ferrara. Performance Assessment of Ultra-High Durability Concrete Produced From Recycled Ultra-High Durability Concrete. Frontiers in Built Environment. 2021; 7 ():1.

Chicago/Turabian Style

Ruben Paul Borg; Estefania Cuenca; Roberto Garofalo; Fabrizio Schillani; Milena Lozano Nasner; Liberato Ferrara. 2021. "Performance Assessment of Ultra-High Durability Concrete Produced From Recycled Ultra-High Durability Concrete." Frontiers in Built Environment 7, no. : 1.

Journal article
Published: 22 December 2020 in Buildings
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The interaction between concrete and steel occurs during concrete mixing and finishing processes, during filling of concrete moulds, formwork, composite columns and during pumping of concrete mixtures. More experimental investigation is required to predict variations in interface friction, as a result of the composition of the lubrication layer which depends on the composition of concrete. This study provides experimental results to allow for a better understanding of friction at concrete-steel interface, with changes in the coarse aggregate (CA) content in the aggregate mixture (AM). Friction tests on fresh concrete have been carried out using the BTRHEOM tribometer (Nantes, France) and the interface parameters were calculated on the basis of the interface friction between the concrete and the steel wall, through the ADRHEO software. The roughness parameters were measured along the length of the rotary steel cylinder of the tribometer. In addition, the roughness of new and modified metal form-lining in steel composite columns was also measured. Variations in the CA content in the AM in the 42 to 52% range had minimal effects on the yield stress of the interface. The viscous constant of the interface as measured with a tribometer decreased, when the roughness parameter Rt values of the rotary cylinder wall, which refer to the absolute vertical distance between the maximum profile peak height and the maximum profile valley depth along the sampling length, were in the 17.10 to 28.73 μm range. The roughness profile peaks’ asperity recorded, was higher for the worn metal form-lining and for the steel composite columns with the inner surface covered in rust, when compared to the rotary cylinder roughness profile. The hypothesis is based on the principle that a sufficient lubrication layer, with the required thickness of fine mortar is created at the interface between the concrete and the metal form-lining or steel composite column wall, when the CA content in the AM varies in the range from 42 to 52% and the wall roughness parameters (Rt) of these elements varies in the 15.00 to 30.00 μm range.

ACS Style

Audrė Rugytė; Mindaugas Daukšys; Svajūnas Juočiūnas; Ruben Paul Borg. The Behaviour of Fresh Concrete with Varying Coarse Aggregate Content at the Concrete-Steel Wall Interface. Buildings 2020, 11, 2 .

AMA Style

Audrė Rugytė, Mindaugas Daukšys, Svajūnas Juočiūnas, Ruben Paul Borg. The Behaviour of Fresh Concrete with Varying Coarse Aggregate Content at the Concrete-Steel Wall Interface. Buildings. 2020; 11 (1):2.

Chicago/Turabian Style

Audrė Rugytė; Mindaugas Daukšys; Svajūnas Juočiūnas; Ruben Paul Borg. 2020. "The Behaviour of Fresh Concrete with Varying Coarse Aggregate Content at the Concrete-Steel Wall Interface." Buildings 11, no. 1: 2.

Journal article
Published: 21 August 2020 in Buildings
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Crystalline admixtures and industrial by-products can be used in cement-based materials in order to improve their mechanical properties. The research examined long-term curing and the exposure to environmental actions of polymer–cement mortars with crystalline admixture (CA) and different by-products, including Bengħisa fly ash and Globigerina limestone waste filler. The by-products were introduced as a percentage replacement of the cement. A crystallization additive was also added to the mixtures in order to monitor the improvement in durability properties. The mechanical properties of the mortar were assessed, with 20% replacement of cement with fly ash resulting in the highest compressive strength after 540 days. The performance was analyzed with respect to various properties including permeable porosity, capillary suction, rapid chloride ion penetration and chloride migration coefficient. It was noted that the addition of fly ash and crystalline admixture significantly reduced the chloride ion penetration into the structure of the polymer cement mortar, resulting in improved durability. A microstructure investigation was conducted on the samples through Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS). Crystals forming through the crystalline admixture in the porous structure of the material were clearly observed, contributing to the improved properties of the cement-based polymer mortar.

ACS Style

Jakub Hodul; Nikol Žižková; Ruben Paul Borg. The Influence of Crystalline Admixtures on the Properties and Microstructure of Mortar-Containing By-Products. Buildings 2020, 10, 146 .

AMA Style

Jakub Hodul, Nikol Žižková, Ruben Paul Borg. The Influence of Crystalline Admixtures on the Properties and Microstructure of Mortar-Containing By-Products. Buildings. 2020; 10 (9):146.

Chicago/Turabian Style

Jakub Hodul; Nikol Žižková; Ruben Paul Borg. 2020. "The Influence of Crystalline Admixtures on the Properties and Microstructure of Mortar-Containing By-Products." Buildings 10, no. 9: 146.

Journal article
Published: 01 January 2020 in Journal of Cultural Heritage
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ACS Style

Siphesihle Mpho Motsa; Georgios A. Drosopoulos; Maria Stavroulaki; Emmanuel Maravelakis; Ruben Paul Borg; Pauline Galea; Sebastiano D’Amico; Georgios E. Stavroulakis. Structural investigation of Mnajdra megalithic monument in Malta. Journal of Cultural Heritage 2020, 41, 96 -105.

AMA Style

Siphesihle Mpho Motsa, Georgios A. Drosopoulos, Maria Stavroulaki, Emmanuel Maravelakis, Ruben Paul Borg, Pauline Galea, Sebastiano D’Amico, Georgios E. Stavroulakis. Structural investigation of Mnajdra megalithic monument in Malta. Journal of Cultural Heritage. 2020; 41 ():96-105.

Chicago/Turabian Style

Siphesihle Mpho Motsa; Georgios A. Drosopoulos; Maria Stavroulaki; Emmanuel Maravelakis; Ruben Paul Borg; Pauline Galea; Sebastiano D’Amico; Georgios E. Stavroulakis. 2020. "Structural investigation of Mnajdra megalithic monument in Malta." Journal of Cultural Heritage 41, no. : 96-105.

Website
Published: 21 August 2019 in Advances in Engineering Materials, Structures and Systems: Innovations, Mechanics and Applications
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The Maltese Megalithic Temples, are among the oldest free-standing structures of such complexity in the world. The Mnajdra megalithic structures, date to the 4th millennium BCE, are of international significance as a UNESCO World Heritage site. The appraisal of structural performance is necessary to safeguard these monuments. Towards this direction, assessment of the material properties of Mnajdra megalithic monument in Malta is considered by means of finite element analysis and comparison with experimental research. First, the geometry of the monument has been imported from laser-scanner data provided by the local authorities. Then, experimental microtremor measurements are compared with parametric eigenvalue finite element analysis, for the determination of the proper material properties.

ACS Style

Siphesihle M. Motsa; Georgios A. Drosopoulos; Maria Stavroulaki; Georgios Stavroulakis; Ruben Paul Borg; Pauline Galea; Sebastiano D’Amico. Large-scale contact analysis for the stability estimation of the Mnajdra monuments. Advances in Engineering Materials, Structures and Systems: Innovations, Mechanics and Applications 2019, 2160 -2164.

AMA Style

Siphesihle M. Motsa, Georgios A. Drosopoulos, Maria Stavroulaki, Georgios Stavroulakis, Ruben Paul Borg, Pauline Galea, Sebastiano D’Amico. Large-scale contact analysis for the stability estimation of the Mnajdra monuments. Advances in Engineering Materials, Structures and Systems: Innovations, Mechanics and Applications. 2019; ():2160-2164.

Chicago/Turabian Style

Siphesihle M. Motsa; Georgios A. Drosopoulos; Maria Stavroulaki; Georgios Stavroulakis; Ruben Paul Borg; Pauline Galea; Sebastiano D’Amico. 2019. "Large-scale contact analysis for the stability estimation of the Mnajdra monuments." Advances in Engineering Materials, Structures and Systems: Innovations, Mechanics and Applications , no. : 2160-2164.

Journal article
Published: 01 August 2019 in Solid State Phenomena
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Many years of experience in practice not only in the Czech Republic but also around the world have shown that crystallising waterproofing technology (mortars, coatings) improves the water and water-vapor impermeability of the treated structures and thus positively affects the durability of concrete. The sealing of pores, capillaries and cracks also prevents degradation due to physical and mechanical structural actions (e.g. the effects of ice and salts in pores, etc.). In the presented research, the influence of different crystallization admixture (CA) contents on the mechanical properties of polymer-cement mortar with 24% cement substitution by waste limestone was investigated. The crystallization admixture (CA) was added in different amounts at 0.8, 1.6 and 2.4% of the cement content in the mix. It was determined that the mechanical properties, namely the compressive and flexural strengths were not significantly influenced by the CA addition, with the highest difference recorded in the compressive strength (7%). The cohesion with the base concrete containing different amounts of limestone was sufficient, and the bond of the mortar to concrete was also closely examined using scanning electron microscopy (SEM). Through the SEM investigation it was determined that the presence of waste limestone of particle size below 250 μm did not affect the formation of crystals during the proper hydration process, in a climatic chamber at a high relative humidity (99%).

ACS Style

Jakub Hodul; Nikol Žižková; Rostislav Drochytka; Ruben Paul Borg. Influence of Crystallization Admixture on Mechanical Parameters and Microstructure of Polymer-Cement Mortars with Waste Limestone. Solid State Phenomena 2019, 296, 27 -34.

AMA Style

Jakub Hodul, Nikol Žižková, Rostislav Drochytka, Ruben Paul Borg. Influence of Crystallization Admixture on Mechanical Parameters and Microstructure of Polymer-Cement Mortars with Waste Limestone. Solid State Phenomena. 2019; 296 ():27-34.

Chicago/Turabian Style

Jakub Hodul; Nikol Žižková; Rostislav Drochytka; Ruben Paul Borg. 2019. "Influence of Crystallization Admixture on Mechanical Parameters and Microstructure of Polymer-Cement Mortars with Waste Limestone." Solid State Phenomena 296, no. : 27-34.

Original research article
Published: 14 May 2019 in Frontiers in Built Environment
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Micro-cracks, which develop during the service life of reinforced concrete structures, reduce the durability of concrete through the penetration of fluids. Microbially-induced calcium carbonate precipitation (MICP) occurs naturally in the presence of ureolytic bacteria which precipitate calcium carbonate (CaCO3) through urea hydrolysis. This deposition leads to the filling of micro-cracks and sealing of pores, reducing ingress of fluids into the concrete. The research aims were to assess the potential of Lysinibacillus sphaericus for healing cracks in concrete and to study the effects of this treatment on the absorption properties of treated concrete. Lysinibacillus sphaericus was cultivated in vitro and induction of MICP through urea hydrolysis was tested on cement paste with two different calcium sources. The calcium precipitates where characterized by light microscopy, Scanning Electron Microscopy, Energy Dispersive Spectroscopy and Fourier Transform Infrared Spectroscopy. The final phase of the study involved testing of the crack healing capacity and the effect on absorption of the MICP process on mortar samples. These parameters were measured by means of visual examinations, light and digital microscopy, Ultrasonic Pulse Velocity (UPV), and absorption tests. The study confirmed that MICP is induced successfully on concrete using Lysinibacillus sphaericus. Samples exposed to repeated treatment cycles of Lysinibacillus sphaericus in the presence of a calcium source, exhibited a more extensive and even coating of CaCO3 crystals on the surface confirming that repeated cycles of treatment are more effective in increasing the amount of CaCO3 deposition and therefore increasing crack healing capacity. Digital microscopy and UPV analysis proved that this precipitate was successful in partially healing cracks in samples. Sorptivity tests confirmed this and showed that it was also successful as a surface treatment to reduce absorption.

ACS Style

Christine Farrugia; Ruben Paul Borg; Liberato Ferrara; Joseph Buhagiar. The Application of Lysinibacillus sphaericus for Surface Treatment and Crack Healing in Mortar. Frontiers in Built Environment 2019, 5, 1 .

AMA Style

Christine Farrugia, Ruben Paul Borg, Liberato Ferrara, Joseph Buhagiar. The Application of Lysinibacillus sphaericus for Surface Treatment and Crack Healing in Mortar. Frontiers in Built Environment. 2019; 5 ():1.

Chicago/Turabian Style

Christine Farrugia; Ruben Paul Borg; Liberato Ferrara; Joseph Buhagiar. 2019. "The Application of Lysinibacillus sphaericus for Surface Treatment and Crack Healing in Mortar." Frontiers in Built Environment 5, no. : 1.

Review
Published: 02 January 2019 in Waste and Biomass Valorization
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Industrial by-products such as silica gel waste and red clay based on natural illite, have been used as precursors for the preparation of alkali activated materials (AAM). Raw materials, precursors and the alkali-activated materials were examined using X-ray diffraction, XRFA and SEM analysis. The reactive concentrations of Si and Al were determined using the colorimetric method. The compressive strength of alkali-activated samples was also evaluated. The precursors were made from Lithuanian red clay (Ukmergė deposit) and silica gel waste. The clay and silica gel waste were first mixed together and then calcined at 900 °C or 600 °C to obtain the precursors. The results show that during the calcination process, new phase CaF2 formed in the precursors. It is possible that fluoride compound which forms during the calcination process, acts as a flux (at a temperature of 900 °C), and for this reason, the reactive amorphous phase is transformed into mullite and cristobalite (crystalline phases), which are not reactive. According to the XRD diffractogram, calcination at a temperature of 600 °C was sufficient to convert the crystalline structure of kaolinite into an amorphous phase. In this case, at a calcination temperature of 600 °C, it was recommended to use up to 25% of silica gel waste. The maximal compressive strength (7 MPa) was achieved by using 5% of silicagel waste. It was concluded that red clay–silica gel waste AAM can be considered for the production of green composite materials.

ACS Style

Ruben Paul Borg; Danute Vaičiukynienė; Vincas Gurskis; Dalia Nizevičienė; Rytis Skominas; Dainius Ramukevičius; Raimondas Sadzevičius. Alkali-Activated Material Based on Red Clay and Silica Gel Waste. Waste and Biomass Valorization 2019, 11, 2973 -2982.

AMA Style

Ruben Paul Borg, Danute Vaičiukynienė, Vincas Gurskis, Dalia Nizevičienė, Rytis Skominas, Dainius Ramukevičius, Raimondas Sadzevičius. Alkali-Activated Material Based on Red Clay and Silica Gel Waste. Waste and Biomass Valorization. 2019; 11 (6):2973-2982.

Chicago/Turabian Style

Ruben Paul Borg; Danute Vaičiukynienė; Vincas Gurskis; Dalia Nizevičienė; Rytis Skominas; Dainius Ramukevičius; Raimondas Sadzevičius. 2019. "Alkali-Activated Material Based on Red Clay and Silica Gel Waste." Waste and Biomass Valorization 11, no. 6: 2973-2982.

Conference paper
Published: 01 January 2019 in IABSE Symposium, Guimarães 2019: Towards a Resilient Built Environment Risk and Asset Management
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In the framework of H2020, the European Commission recently funded the project ReSHEALience (www.uhdc.eu). The main idea behind the project is that the long-term behaviour of structures under extremely aggressive exposure conditions can highly benefit from the use of high performance materials, in the framework of durability-based design approaches. The project consortium, coordinated by Politecnico di Milano, features 14 partners from 8 different countries, including 6 academic/research institutions and 8 industrial partners, covering the whole value chain from producers of concrete constituents to construction companies to stake-holders and end-users. The main goals of the project are the development (a) of an Ultra High Durability Concrete (UHDC) and (b) a Durability Assessment-based Design (DAD) methodology to improve structure durability and predict long-term performance under Extremely Aggressive Exposures (EAE). The project will tailor the composition of UHDC, by upgrading the UHPC/UHPFRC concept through the incorporation of tailored nanoscale constituents.

ACS Style

Liberato Ferrara; Patrick Bamonte; Cristina Suesta Falcó; Francesco Animato; Carmine Pascale; Aleksej Tretjakov; Esteban Camacho Torregrosa; Peter Deegan; Stamatina Sideri; Enrico Maria Gastaldo Brac; Pedro Serna; Viktor Mechtcherine; Maria Cruz Alonso; Alva Peled; Ruben Paul Borg. An Overview on H2020 Project “ReSHEALience”. IABSE Symposium, Guimarães 2019: Towards a Resilient Built Environment Risk and Asset Management 2019, 184 -191.

AMA Style

Liberato Ferrara, Patrick Bamonte, Cristina Suesta Falcó, Francesco Animato, Carmine Pascale, Aleksej Tretjakov, Esteban Camacho Torregrosa, Peter Deegan, Stamatina Sideri, Enrico Maria Gastaldo Brac, Pedro Serna, Viktor Mechtcherine, Maria Cruz Alonso, Alva Peled, Ruben Paul Borg. An Overview on H2020 Project “ReSHEALience”. IABSE Symposium, Guimarães 2019: Towards a Resilient Built Environment Risk and Asset Management. 2019; ():184-191.

Chicago/Turabian Style

Liberato Ferrara; Patrick Bamonte; Cristina Suesta Falcó; Francesco Animato; Carmine Pascale; Aleksej Tretjakov; Esteban Camacho Torregrosa; Peter Deegan; Stamatina Sideri; Enrico Maria Gastaldo Brac; Pedro Serna; Viktor Mechtcherine; Maria Cruz Alonso; Alva Peled; Ruben Paul Borg. 2019. "An Overview on H2020 Project “ReSHEALience”." IABSE Symposium, Guimarães 2019: Towards a Resilient Built Environment Risk and Asset Management , no. : 184-191.

Conference paper
Published: 27 November 2018 in IOP Conference Series: Materials Science and Engineering
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Concrete chemical admixtures are used to improve the fresh and hardened properties of mortar or concrete in different applications. Their addition can allow for the reduction of the water to cement ratio (w/c), without affecting the workability of the mixture. By reducing the amount of water, the cement paste will have higher density. However, the reduction of the water content in a concrete mixture should be done in such a way that complete cement hydration take place and sufficient workability is achieved. In order to maintain the workability of the concrete mix, the dosage of the admixture must be carefully calculated and must be taken into account in the calculation of the w/c ratio. In the present study, three types of chemical admixtures; Type A water-reducing, Type D water-reducing and retarding and Type F high range, water-reducing admixtures conforming to ASTM C 494/C 494M – 04 standards, were used to optimize the percentage of the admixture with respect to the w/c ratio. The suitable time for the addition of the admixture is also investigated. Results show that using 1.5 % of Type A admixture with 0.45 w/c gives 45.6 MPa, 28 day compressive strength with an associated slump of 110 mm, compared to zero slump without admixture. 1.0 % Type A admixture with 0.52 w/c gives 33 MPa, 28 day compressive strength with an associated slump of 95 mm, compared to 35 mm slump achieved without admixture. For Type D admixture, using 1.5 % with 0.5 w/c the slump was 190 mm with 47 MPa, 28 day compressive strength, compared to 15 mm slump achieved without admixture. 1.0% of Type F admixture with 0.35 w/c and 0.45 w/c gave slumps of 25 mm, 225 mm and strength of 63.5MPa and 55.3MPa respectively. For all mixes, the best slump results were achieved when the admixtures were added during the initial mixing process, while maximum compressive strengths were achieved for different times of inclusion of the admixtures.

ACS Style

Ali M Mansor; Ruben Paul Borg; Ahmed M M Hamed; Mohammed M Gadeem; Mansour M Saeed. The effects of water-cement ratio and chemical admixtures on the workability of concrete. IOP Conference Series: Materials Science and Engineering 2018, 442, 012017 .

AMA Style

Ali M Mansor, Ruben Paul Borg, Ahmed M M Hamed, Mohammed M Gadeem, Mansour M Saeed. The effects of water-cement ratio and chemical admixtures on the workability of concrete. IOP Conference Series: Materials Science and Engineering. 2018; 442 (1):012017.

Chicago/Turabian Style

Ali M Mansor; Ruben Paul Borg; Ahmed M M Hamed; Mohammed M Gadeem; Mansour M Saeed. 2018. "The effects of water-cement ratio and chemical admixtures on the workability of concrete." IOP Conference Series: Materials Science and Engineering 442, no. 1: 012017.

Conference paper
Published: 27 November 2018 in IOP Conference Series: Materials Science and Engineering
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Environmental concerns, stemming from high-energy demands and CO2 emission associated with cement manufacture, have brought about pressures to reduce cement consumption through the use of supplementary cementitious materials (SCMs). Besides addressing environmental concerns, the incorporation of SCMs in cement bound materials and concrete can modify and improve specific concrete properties. Metakaolin (MK) in an important SCM which can enhance the performance of cementitious composites through its high pozzolanic reactivity. This study was carried out to characterize the materials and to assess the effect of Libyan metakaolin (LMK) on the mechanical properties including the compressive strength of cement mortar. LMK was produced by calcining kaolinite clay at 700°C for 2 h. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Differential Thermal Analysis / Thermo-Gravimetric analysis (DTA/TG) and Fourier Transform Infrared Spectroscopy (FTIR) s were performed on the raw and calcined kaolinite powders. Seven mixes were prepared with different LMK replacement percentages (0.0 to 30%), by weight of cement, and a constant water binder ratio (w/b) of 0.5. The specimens were cured for 3, 7, 28, 56 and 90 days. At the end of each curing period, the specimens were tested for compressive strength. The results confirm the transformation of kaolinite clay into metakaolin and the pozzolanic reactivity of the produced LMK and conforms to ASTM requirements in this respect. The study confirms that LMK could be effectively used in reducing cement content up to 30% by weight without compromising compressive strength of the cement mortar.

ACS Style

Ruben Paul Borg; Ahmed M M Hamed; Ramadan Edreis; Ali M Mansor. Characterization of Libyan metakaolin and its effects on the mechanical properties of mortar. IOP Conference Series: Materials Science and Engineering 2018, 442, 012005 .

AMA Style

Ruben Paul Borg, Ahmed M M Hamed, Ramadan Edreis, Ali M Mansor. Characterization of Libyan metakaolin and its effects on the mechanical properties of mortar. IOP Conference Series: Materials Science and Engineering. 2018; 442 (1):012005.

Chicago/Turabian Style

Ruben Paul Borg; Ahmed M M Hamed; Ramadan Edreis; Ali M Mansor. 2018. "Characterization of Libyan metakaolin and its effects on the mechanical properties of mortar." IOP Conference Series: Materials Science and Engineering 442, no. 1: 012005.

Conference paper
Published: 27 November 2018 in IOP Conference Series: Materials Science and Engineering
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Alkali-activated materials are potential alternatives for Portland cement. Their use leads to reductions in CO2 emissions and recycling of various industry by-products. These new alternative binders have a wide range of uses and high technological properties. In the research presented in this paper, the influence of additional sulphur slime powder (as accelerator) was investigated. The biomass bottom ash (BBA) was used as raw material and sodium hydroxide was used as the alkaline activator. The sulphur slime is a by-product in a fertilizer production plant. The samples were prepared with different amounts of sulphur slime; the levels of sulphur slime additive were 0%, 0.5%, 1.0%, 3.0% and 5.0% by weight in the raw material mixtures. Alkali-activated binders were mixed and conditioned at a temperature of 60 °C for 48 h, followed by curing at room temperature for 26 days. The microstructure of the material was analyzed through scanning electron microscopy (SEM) and the composition of the materials was analyzed using X-ray diffraction (XRD) and X-ray fluorescence (XRF) spectroscopy. The compressive strength of hardened alkali activated paste was measured after 28 days. In all the cases investigated, the compressive strength of hardened cement paste samples increases with the presence of Sulphur slime powder. It was found that during the hardening process sulphur reacts with sodium hydroxide forming Na2SO4, which acts as an accelerator. According to some researchers, Na2SO4 shows a significant accelerating influence in alkali-activated binder systems. The optimal amount of sulphur slime in raw materials mixtures was also evaluated.

ACS Style

Danutė Vaičiukynienė; Ruben Paul Borg; A Kantautas; V Bocullo; V Vaičiukynas. The influence of sulphur slime on the properties of alkali binding material from biomass bottom ashes. IOP Conference Series: Materials Science and Engineering 2018, 442, 012015 .

AMA Style

Danutė Vaičiukynienė, Ruben Paul Borg, A Kantautas, V Bocullo, V Vaičiukynas. The influence of sulphur slime on the properties of alkali binding material from biomass bottom ashes. IOP Conference Series: Materials Science and Engineering. 2018; 442 (1):012015.

Chicago/Turabian Style

Danutė Vaičiukynienė; Ruben Paul Borg; A Kantautas; V Bocullo; V Vaičiukynas. 2018. "The influence of sulphur slime on the properties of alkali binding material from biomass bottom ashes." IOP Conference Series: Materials Science and Engineering 442, no. 1: 012015.

Conference paper
Published: 27 November 2018 in IOP Conference Series: Materials Science and Engineering
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The use of synthetic additives as setting retarders and plasticisers has over the past years become a standard practice in mortar mixtures, despite their potential adverse environmental effects. Since antiquity, man has used organic additives ranging from plant and animal-derived extracts, to improve the setting properties of mortars. These practices are slowly being revived and investigated scientifically to promote the use of materials with lower impacts on the environment. Amongst the many different types of plant-derived extracts that have been used as mortar and concrete additives, the prickly pear (Opuntia ficus-indica) mucilage extract, is popular in Meso- and South-America. The scientific basis of these additives lies in the hydrating properties of the mucilage polysaccharide complex. The purpose of this research was to prepare Opuntia ficus-indica (OFI) extracts in different forms and incorporate them in cement pastes and mortar mixtures by either replacing the water in the mixture with OFI mucilage or by replacing the cement in the mixture with OFI lyophilised powder. The inclusion of Opuntia ficus-indica additives in cement-based mortars increased their performance in terms of strength for both water and powder replacements. Conversely results in cement pastes showed that Opuntia ficus-indica additives weakened the cement paste samples in terms of strength in both water and power replacements. Results for both cement-based mortars and cement pastes showed an increase in setting time for both water and powder replacements, indicating that Opuntia ficus-indica additives could be potentially used as retarding agents.

ACS Style

Anne Aquilina; Ruben Paul Borg; Joseph Buhagiar. The application of Natural Organic Additives in Concrete: Opuntia ficus-indica. IOP Conference Series: Materials Science and Engineering 2018, 442, 012016 .

AMA Style

Anne Aquilina, Ruben Paul Borg, Joseph Buhagiar. The application of Natural Organic Additives in Concrete: Opuntia ficus-indica. IOP Conference Series: Materials Science and Engineering. 2018; 442 (1):012016.

Chicago/Turabian Style

Anne Aquilina; Ruben Paul Borg; Joseph Buhagiar. 2018. "The application of Natural Organic Additives in Concrete: Opuntia ficus-indica." IOP Conference Series: Materials Science and Engineering 442, no. 1: 012016.

Conference paper
Published: 27 November 2018 in IOP Conference Series: Materials Science and Engineering
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The various elements that are affecting the Earth's climate have brought climate change to the top of the priority list amongst scientists and policy-makers. Expected changes to local climatic conditions impact directly on the surrounding environment and potentially lead to changes in the degradation processes of building materials, affecting the durability and service life of infrastructures. The aim of this paper is to investigate the effects of future climate projections on concrete structures in Malta, in particular on carbonation-induced corrosion resulting from increasing temperatures and CO2 concentrations. Thirteen reinforced concrete structures in Malta were chosen for a retrospective analysis in order to validate two carbonation depth prediction models. The validated prediction models were subsequently used to evaluate the varying climate change scenarios in order to determine the effects on concrete carbonation depth for several concrete grades. The age of the structures used for the retrospective analysis ranged from 10 to 60 years. The field data verified the validity of both prediction models for structures with carbonation depths less than 50mm. Although both models proved valid for the retrospective analysis, a difference was noted between the models with regards to the predicted carbonation depth in relation to different climatic scenarios. An increase in carbonation depth of up to 40% is being predicted, by 2070, when considering the worst case climatic scenario. The findings prove that climate change plays a major role on the carbonation depth of concrete, which in turn reduces the service life of concrete structures.

ACS Style

Bernice Mizzi; Ying Wang; Ruben Paul Borg. Effects of climate change on structures; analysis of carbonation-induced corrosion in Reinforced Concrete Structures in Malta. IOP Conference Series: Materials Science and Engineering 2018, 442, 012023 .

AMA Style

Bernice Mizzi, Ying Wang, Ruben Paul Borg. Effects of climate change on structures; analysis of carbonation-induced corrosion in Reinforced Concrete Structures in Malta. IOP Conference Series: Materials Science and Engineering. 2018; 442 (1):012023.

Chicago/Turabian Style

Bernice Mizzi; Ying Wang; Ruben Paul Borg. 2018. "Effects of climate change on structures; analysis of carbonation-induced corrosion in Reinforced Concrete Structures in Malta." IOP Conference Series: Materials Science and Engineering 442, no. 1: 012023.

Conference paper
Published: 27 November 2018 in IOP Conference Series: Materials Science and Engineering
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Chloride ion ingress into reinforced concrete structures is one of the primary causes of concrete degradation. Real-time monitoring of concrete structures for the ingress of chloride ions is therefore of paramount importance towards the achievement of durable and sustainable structures. It is therefore important that the chloride ion detection method used must be accurate and reliable. This paper will endeavour to show how embedded 316L stainless steel and EN3b mild steel galvanic electrode pairs will react to chloride ions present in the concrete pore solution. Through practical experimentation the correlation between the chloride ion concentration in the pore solution and galvanic voltage measurements between the electrode pairs was explored. An experimental setup was proposed, based on concrete samples with in-built fluid containment vessels holding sodium chloride solution, which was allowed to permeate through the pore structure of the concrete over a defined period of time. At particular time intervals core samples were taken at different depths in concrete samples, and the chloride ion content was determined with depth of penetration through titration on the extracted material. The chloride ion content results from titration tests were compared to the measured galvanic voltages. Within certain limits there was good correlation between the chloride ion concentration and the measured voltage readings across the galvanic electrode pair. Galvanic voltage measurements provide a relevant technique for the detection of chloride ions in concrete and in the design of a chloride ion sensory system. Validation testing was also carried out, where samples with known salt concentrations were prepared against which the results obtained could be compared.

ACS Style

Stephen Sammut; Edward Gatt; Ruben Paul Borg. Chloride ion detection through the voltage response of a galvanic pair. IOP Conference Series: Materials Science and Engineering 2018, 442, 012020 .

AMA Style

Stephen Sammut, Edward Gatt, Ruben Paul Borg. Chloride ion detection through the voltage response of a galvanic pair. IOP Conference Series: Materials Science and Engineering. 2018; 442 (1):012020.

Chicago/Turabian Style

Stephen Sammut; Edward Gatt; Ruben Paul Borg. 2018. "Chloride ion detection through the voltage response of a galvanic pair." IOP Conference Series: Materials Science and Engineering 442, no. 1: 012020.

Conference paper
Published: 27 November 2018 in IOP Conference Series: Materials Science and Engineering
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ACS Style

Liborio Cavaleri; Ruben Paul Borg; F. P. La Mantia; Vincenzo Liguori. Quarry limestone dust as fine aggregate for concrete. IOP Conference Series: Materials Science and Engineering 2018, 442, 1 .

AMA Style

Liborio Cavaleri, Ruben Paul Borg, F. P. La Mantia, Vincenzo Liguori. Quarry limestone dust as fine aggregate for concrete. IOP Conference Series: Materials Science and Engineering. 2018; 442 ():1.

Chicago/Turabian Style

Liborio Cavaleri; Ruben Paul Borg; F. P. La Mantia; Vincenzo Liguori. 2018. "Quarry limestone dust as fine aggregate for concrete." IOP Conference Series: Materials Science and Engineering 442, no. : 1.

Journal article
Published: 01 August 2018 in Ceramics International
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ACS Style

Danutė Vaičiukynienė; Ruben Paul Borg; Andrius Kielė; Aras Kantautas. Alkali-activated blends of calcined AlF3 production waste and clay. Ceramics International 2018, 44, 12573 -12579.

AMA Style

Danutė Vaičiukynienė, Ruben Paul Borg, Andrius Kielė, Aras Kantautas. Alkali-activated blends of calcined AlF3 production waste and clay. Ceramics International. 2018; 44 (11):12573-12579.

Chicago/Turabian Style

Danutė Vaičiukynienė; Ruben Paul Borg; Andrius Kielė; Aras Kantautas. 2018. "Alkali-activated blends of calcined AlF3 production waste and clay." Ceramics International 44, no. 11: 12573-12579.

Journal article
Published: 01 April 2018 in Construction and Building Materials
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Heuristically known at least since the first half of XIX century, the self-healing capacity of cement-based materials has been receiving keen attention from the civil engineering community worldwide in the last decade. As a matter of fact, stimulating and/or engineering the aforementioned functionality via tailored addition and technologies, in order to make it more reliable in an engineering perspective, has been regarded as a viable pathway to enhance the durability of reinforced concrete structures and contribute to increase their service life. Research activities have provided enlightening contributions to understanding the mechanisms of crack self-sealing and healing and have led to the blooming of a number of self-healing stimulating and engineering technologies, whose effectiveness has been soundly proved in the laboratory and, in a few cases, also scaled up to field applications, with ongoing performance monitoring. Nonetheless, the large variety of methodologies employed to assess the effectiveness of the developed self-healing technologies makes it necessary to provide a unified, if not standardized, framework for the validation and comparative evaluation of the same self-healing technologies as above. This is also instrumental to pave the way towards a consistent incorporation of self-healing concepts into structural design and life cycles analysis codified approaches, which can only promote the diffusion of feasible and reliable self-healing technologies into the construction market. In this framework the Working Group 2 of the COST Action CA 15202 “Self-healing as preventive repair of concrete structures – SARCOS” has undertaken the ambitious task reported in this paper. As a matter of fact this state of the art provides a comprehensive and critical review of the experimental methods and techniques, which have been employed to characterize and quantify the self-sealing and/or self-healing capacity of cement-based materials, as well as the effectiveness of the different self-sealing and/or self-healing engineering techniques, together with the methods for the analysis of the chemical composition and intrinsic nature of the self-healing products. The review will also address the correlation, which can be established between crack closure and the recovery of physical/mechanical properties, as measured by means of the different reviewed tests.

ACS Style

Liberato Ferrara; Tim Van Mullem; Maria Cruz Alonso; Paola Antonaci; Ruben Paul Borg; Estefanía Cuenca; Anthony Jefferson; P.L. Ng; Alva Peled; Marta Roig-Flores; Mercedes Sánchez; Christof Schroefl; Pedro Serna; Didier Snoeck; Jean Marc Tulliani; Nele De Belie. Experimental characterization of the self-healing capacity of cement based materials and its effects on the material performance: A state of the art report by COST Action SARCOS WG2. Construction and Building Materials 2018, 167, 115 -142.

AMA Style

Liberato Ferrara, Tim Van Mullem, Maria Cruz Alonso, Paola Antonaci, Ruben Paul Borg, Estefanía Cuenca, Anthony Jefferson, P.L. Ng, Alva Peled, Marta Roig-Flores, Mercedes Sánchez, Christof Schroefl, Pedro Serna, Didier Snoeck, Jean Marc Tulliani, Nele De Belie. Experimental characterization of the self-healing capacity of cement based materials and its effects on the material performance: A state of the art report by COST Action SARCOS WG2. Construction and Building Materials. 2018; 167 ():115-142.

Chicago/Turabian Style

Liberato Ferrara; Tim Van Mullem; Maria Cruz Alonso; Paola Antonaci; Ruben Paul Borg; Estefanía Cuenca; Anthony Jefferson; P.L. Ng; Alva Peled; Marta Roig-Flores; Mercedes Sánchez; Christof Schroefl; Pedro Serna; Didier Snoeck; Jean Marc Tulliani; Nele De Belie. 2018. "Experimental characterization of the self-healing capacity of cement based materials and its effects on the material performance: A state of the art report by COST Action SARCOS WG2." Construction and Building Materials 167, no. : 115-142.

Journal article
Published: 07 December 2017 in Journal of Sustainable Cement-Based Materials
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This paper presents the results of a preliminary study aimed at assessing the crack sealing capacity in chloride environments of different concrete mixtures, incorporating supplementary cementitious materials as well as self-healing enhancing crystalline admixtures. For each addition, also including pulverized fuel ash and silica fume, different contents were taken into consideration. Cylinder specimens were pre-cracked in splitting up to three different crack-opening ranges, simulating different service conditions, and then exposed to different conditioning environments, also containing different concentrations of sodium chloride and including both permanent immersion and wet/dry cycles. Healing conditioning was performed up to three months and crack sealing was visually inspected and quantified via image analysis procedures, monthly. Optimum dosages of each cement substitute/addition were quantified, also considering, besides the healing capacity, also the fresh state performance and compressive strength development. The good performance of mixes with crystalline admixture even under open-air exposure, as well as of other investigated mixes with reference to crack openings and exposure conditions, paves the way to revise the significance of a serviceability design parameter such as the maximum allowable crack width as a function of the exposure with the concept of a sealable crack width.

ACS Style

Ruben P. Borg; Estefania Cuenca; Enrico Maria Gastaldo Brac; Liberato Ferrara. Crack sealing capacity in chloride-rich environments of mortars containing different cement substitutes and crystalline admixtures. Journal of Sustainable Cement-Based Materials 2017, 7, 141 -159.

AMA Style

Ruben P. Borg, Estefania Cuenca, Enrico Maria Gastaldo Brac, Liberato Ferrara. Crack sealing capacity in chloride-rich environments of mortars containing different cement substitutes and crystalline admixtures. Journal of Sustainable Cement-Based Materials. 2017; 7 (3):141-159.

Chicago/Turabian Style

Ruben P. Borg; Estefania Cuenca; Enrico Maria Gastaldo Brac; Liberato Ferrara. 2017. "Crack sealing capacity in chloride-rich environments of mortars containing different cement substitutes and crystalline admixtures." Journal of Sustainable Cement-Based Materials 7, no. 3: 141-159.