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Miguel Azenha - One of the best experts on this subject based on the ideXlab platform.
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concrEtE with finE and coarsE rEcyclEd aggrEgatEs E Modulus Evolution comprEssivE strEngth and non dEstructivE tEsting at Early agEs
Construction and Building Materials, 2018Co-Authors: Mirian Velaylizancos, Miguel Azenha, Jose Luis Duarte Granja, Isabel Martinezlage, Pablo VazquezburgoAbstract:Abstract ThE combinEd usE of finE and coarsE rEcyclEd aggrEgatEs in thE manufacturE of concrEtE has multiplE advantagEs from thE Economic and EnvironmEntal points of viEw. ThErE is a lack of knowlEdgE about thE bEhavior of concrEtEs containing rEcyclEd aggrEgatEs, manifEstEd by strong limitations (EvEn prohibitions) in intErnational standards for structural purposEs. This papEr aims to study thE influEncE of finE and coarsE rEcyclEd aggrEgatE of concrEtE (jointly), with particular Emphasis on thE Evolution of thE kinEtics of E-Modulus and its rElationship with comprEssivE strEngth and non-dEstructivE tEsting. ConcrEtEs with diffErEnt dEgrEEs of rEplacEmEnt of natural aggrEgatEs by rEcyclEd aggrEgatEs wErE studiEd: 0% (rEfErEncE concrEtE), 8%, 20% and 31% of thE total amount of aggrEgatEs. E-Modulus MEasurEmEnt through AmbiEnt REsponsE MEthod (EMM-ARM) was usEd to monitoring thE E-Modulus Evolution. WE also studiEd thE influEncE of thEsE rEcyclEd aggrEgatEs on thE corrElation bEtwEEn E-Modulus and comprEssivE strEngth, as wEll as with two non-dEstructivE tEsting tEchniquEs: Ultrasonic PulsE VElocity, and ElEctrical conductivity. ThE activation EnErgy of thE studiEd concrEtEs, basEd on data computEd from comprEssivE strEngth mEasurEmEnts at diffErEnt curing tEmpEraturEs was calculatEd. WE obsErvEd a nEgativE influEncE of rEcyclEd aggrEgatE on thE Evolution of E-Modulus from thE first 12 h, comparEd to thE rEfErEncE mixturE. ThE crossovEr EffEct on E-Modulus Evolution producEd by high curing tEmpEraturEs affEcts morE to thE concrEtEs with rEcyclEd aggrEgatE. Our data EvidEncEd that thE maturity corrEction for E-Modulus Evolution, basEd on thE activation EnErgy of comprEssivE strEngth, producEd accuratE supErposition of E-Modulus in thE EquivalEnt agE domain.
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Addition of biomass ash in concrEtE: EffEcts on E-Modulus, ElEctrical conductivity at Early agEs and thEir corrElation
Construction and Building Materials, 2017Co-Authors: Mirian Velay-lizancos, Miguel Azenha, Isabel Martínez-lage, Pablo Vázquez-burgoAbstract:Abstract This rEsEarch aims to study thE influEncE of biomass ashEs in thE Evolution of E-Modulus at an Early agE (0–7 days) in concrEtEs with diffErEnt pErcEntagEs of rEplacEmEnt of cEmEnt by biomass ash (0%, 15% and 30%). Its bEhaviour was EvaluatEd through thE continuous monitoring of thE E-Modulus mEthod as wEll as using a NDT: mEasurEmEnt of intErnal ElEctrical conductivity. WhErEas at 7 days thE influEncE of a rEplacEmEnt of 15% of biomass ash on E-Modulus is nEgligiblE, during thE first day thE nEgativE influEncE is vEry important, with valuEs of loss of E-Modulus highEr than 70%. ThE influEncE of thE biomass ash in thE Evolution of intErnal ElEctrical conductivity suggEsts that thE biomass ash could rEducE thE chloridE ion pEnEtration rEsistancE, EvEn in concrEtE with 15% of biomass ash that did not inducE a dEcrEasE of thE E-Modulus at 7 days. ThE influEncE of thE biomass ash in thE corrElations of E-Modulus and ElEctrical conductivity has bEEn studiEd. Maturity corrEctions wErE madE.
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quality control and monitoring of nsm cfrp systEms E Modulus Evolution of Epoxy adhEsivE and its rElation to thE pull out forcE
Composites Part B-engineering, 2015Co-Authors: Pedro Miguel Gomes Fernandes, Jose Senacruz, Jose Luis Duarte Granja, Andrea Benedetti, Miguel AzenhaAbstract:Abstract Background In FibrE-REinforcEd PolymEr (FRP) applications, thE mEchanical bEhaviour of thE strEngthEning systEm strongly dEpEnds on thE Epoxy adhEsivE, particularly at Early agEs. MEthods ThE prEsEnt papEr dEscribEs thE application of an innovativE tEchniquE (tErmEd EMM-ARM: Elasticity Modulus Monitoring through AmbiEnt REsponsE MEthod) for continuous monitoring of thE stiffEning procEss of an Epoxy adhEsivE usEd in structural rEinforcEmEnts applications. A simultanEous study of dirEct pull-out tEsts with concrEtE spEcimEns strEngthEnEd with nEar-surfacE mountEd (NSM) carbon FRP laminatE strips was carriEd out to comparE thE Evolution of bond pErformancE with thE E-Modulus of Epoxy sincE Early agEs. REsults ThE pEak pull-out forcE and thE Epoxy E-Modulus obtainEd by EMM-ARM Exhibit vEry similar Evolution kinEtics. Conclusions A rElationship bEtwEEn thE Evolution of Epoxy E-Modulus and thE maximum pull-out forcE is assEssEd, highlighting thE potEntial of applying EMM-ARM for quality control and dEcision-making assistancE of NSM systEms.
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Maturity tEsting through continuous mEasurEmEnt of E-Modulus: an intEr-laboratory and intEr-tEchniquE study
2014Co-Authors: Stéphanie Staquet, Miguel Azenha, Jose Luis Duarte Granja, Claude Boulay, Brice Delsaute, Jerome Carette, Keliang Hou, Florent BabyAbstract:Nowadays, many construction companiEs usE maturity-basEd approachEs to support dEcisions that havE strong impact on costs and sustainability of thE construction procEss, such as: agE of prE-strEssing opErations, dEcision of propping/formwork rEmoval; instant of subjEction to load, Etc. CurrEnt approachEs to quality control through maturity consist in Evaluating thE comprEssivE strEngth Evolution of thE concrEtE mix at a rEfErEncE curing tEmpEraturE (usually 20°C), togEthEr with thE dEtErmination of thE apparEnt activation EnErgy (Ea) of thE mix. ThE valuE of Ea is usually obtainEd from onE of thEsE thrEE sourcEs: (i) rEfErEncE rEcommEndations basEd on thE typE of cEmEnt; (ii) calorimEtric tEsting; (iii) tEsting of comprEssivE strEngth Evolution at sEvEral distinct tEmpEraturEs. ThE only tEchniquE of dEtErmining Ea that rEally addrEssEs a mEchanical propErty is thE lattEr onE, dEmanding howEvEr thE dEploymEnt of many spEcimEns and tEsts. FurthErmorE, thE dEstructivE charactEr of this tEchniquE limits thE possibility of maintaining thE samE spEcimEn for thE EntirE Ea tEsting, thus incrEasing thE variability/scattEring of rEsults. ThE prEsEnt study intEndEd to EvaluatE thE possibility of assEssing mEchanical-basEd activation EnErgy for concrEtE through continuous or quasicontinuous assEssmEnts of E-Modulus sincE vEry Early agEs. E-Modulus is a mEchanical propErty dEpEnding on thE advancEmEnt of thE hydration rEaction and thE tEmpEraturE storiEs during thE curing, with thE intErEsting charactEristic of allowing non-dEstructivE tEsting to bE carriEd out. This papEr prEsEnts an intEr-laboratory and intEr-tEchniquE comparativE study of E-Modulus Evolution at sEvEral tEmpEraturEs. ThrEE laboratoriEs wErE involvEd, contributing with spEcific tEsting tEchniquEs appliEd to a singlE mix of normal strEngth concrEtE: 1) BTJASPE (BETon au JEunE AgE, Suivi dE la PrisE Et du modulE d'ElasticitE), availablE at IFSTTAR in FrancE; 2) EMM-ARM (Elasticity Modulus MEasurEmEnt through AmbiEnt REsponsE MEthod) availablE at thE UnivErsity of Minho in Portugal; 3) TSTM (TEmpEraturE StrEss TEsting MachinE), availablE at UnivErsitE LibrE dE BruxEllEs in BElgium.
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Comparison BEtwEEn DiffErEnt ExpErimEntal TEchniquEs for StiffnEss Monitoring of CEmEnt PastEs
Journal of Advanced Concrete Technology, 2014Co-Authors: Jose Luis Duarte Granja, Miguel Azenha, Christoph Fernandes Sousa, Cristiana FerreiraAbstract:In 2009, a nEw mEthodology for thE continuous monitoring of E-Modulus of cEmEnt-basEd matErials sincE casting was proposEd, undEr thE dEsignation EMM-ARM (E-Modulus MEasurEmEnt through AmbiEnt REsponsE MEthod). This mEthodology is a variant to classic rEsonant frEquEncy mEthods that allows continuous stiffnEss monitoring from thE instant of casting. AftEr thE Encouraging rEsults obtainEd in thE first applications of EMM-ARM to cEmEnt pastEs, thE prEsEnt papEr givEs continuity to prEvious dEvElopmEnts, through validations with additional ExpErimEntal mEthodologiEs and ExtEnsion to thErmal activation tEsting. At first, a comparison is pErformEd bEtwEEn thE rEsults of EMM-ARM and thosE obtainEd through: pulsE vElocity mEthods (both ultrasonic contact probEs and bEndEr-ExtEndEr ElEmEnts), pEnEtration rEsistancE (Vicat nEEdlE) and cyclic comprEssion on cylindrical spEcimEns. AftErwards, thE possibility of studying thE activation EnErgy of thE stiffnEss Evolution on tEsts conductEd at 20oC and 40oC is ExplorEd.
Joaquim Figueiras - One of the best experts on this subject based on the ideXlab platform.
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E-Modulus Evolution and its rElation to solids formation of pastEs from commErcial cEmEnts
Cement and Concrete Research, 2012Co-Authors: Lino Maia, Miguel Azenha, Mette Rica Geiker, Joaquim FigueirasAbstract:Abstract ModEls for Early agE E-Modulus Evolution of cEmEnt pastEs arE availablE in thE litEraturE, but thEir validation is limitEd. This papEr providEs corrElatEd mEasurEmEnts of Early agE Evolution of E-Modulus and hydration of pastEs from fivE commErcial cEmEnts diffEring in limEstonE contEnt. A rEcEntly dEvElopEd mEthodology allowEd continuous monitoring of E-Modulus from thE timE of casting. ThE mEthodology is a variant of classic rEsonant frEquEncy mEthods, which arE basEd on dEtErmination of thE first rEsonant frEquEncy of a compositE bEam containing thE matErial. ThE hydration kinEtics — and thus thE ratE of formation of solids — was dEtErminEd using chEmical shrinkagE mEasurEmEnts. For thE cEmEnts studiEd similar rElationships bEtwEEn E-Modulus and chEmical shrinkagE wErE obsErvEd for comparablE watEr-to-bindEr ratio. For commErcial cEmEnts it is suggEstEd to modEl thE E-Modulus Evolution basEd on thE amount of bindEr rEactEd, instEad of thE dEgrEE of hydration.
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IdEntification of thE pErcolation thrEshold in cEmEntitious pastEs by monitoring thE E-Modulus Evolution
Cement and Concrete Composites, 2012Co-Authors: Lino Maia, Miguel Azenha, Rui Faria, Joaquim FigueirasAbstract:Abstract ThE dEtErmination of thE fluid-to-solid transition in cEmEnt-basEd matErials is fundamEntal to undErstanding thE Evolution of Early-agE mEchanical propErtiEs and to dEtEct thE timE aftEr which thE matErial may withstand strEssEs. ThE transition is gradual, and non-dEstructivE mEthods arE nEEdEd for clEar idEntification. This papEr prEsEnts a study using a rEcEnt mEthod for continuously monitoring thE E -Modulus of cEmEnt-basEd matErials sincE casting, basEd on Evaluating thE first rEsonant frEquEncy of a compositE bEam containing thE matErial undEr tEst. It is intEndEd to dEmonstratE thE capability of this mEthod to dEtEct thE pErcolation thrEshold and to chEck EvEntual corrElations with thE rElEasEd hEat of hydration. FivE sEts of mix compositions arE tEstEd, with w/c ratios ranging from 0.30 to 0.50, with thE addition of limEstonE fillEr, or with partial rEplacEmEnt of cEmEnt by fly ash, silica fumE or mEtakaolin.
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Elasticity Modulus Monitoring Through an AmbiEnt Vibration REsponsE MEthod – Application to CEmEnt BasEd PastEs
Nondestructive Testing of Materials and Structures, 2011Co-Authors: Lino Maia, Miguel Azenha, Rui Faria, Joaquim FigueirasAbstract:ThE E-Modulus of cEmEnt-basEd matErials is a propErty that ExpEriEncEs a high ratE of changE at Early agEs, and its continuous monitoring sincE casting is fundamEntal to idEntify thE phasE transition from fluid to solid. This papEr prEsEnts a study with a rEcEntly dEvElopEd non-dEstructivE mEthod for continuous monitoring thE E-Modulus of cEmEnt-basEd matErials sincE casting. BasEd on thE Evaluation of thE first rEsonant frEquEncy of a compositE cantilEvEr containing thE matErial undEr tEsting, it is possiblE to dEtEct thE E-Modulus growth, and also to idEntify thE changEs on its Evolution duE to modifications on thE mix composition. TwEnty onE compositions arE tEstEd, Encompassing cEmEntitious pastEs with fivE typEs of cEmEnt and fivE w/c ratios, as wEll as thrEE diffErEnt contEnts of limEstonE fillEr, fly ash, silica fumE and mEtakaolin.
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InfluEncE of thE cEmEntitious pastE composition on thE E-Modulus and hEat of hydration Evolutions
Cement and Concrete Research, 2011Co-Authors: Lino Maia, Miguel Azenha, Rui Faria, Joaquim FigueirasAbstract:E-Modulus and hEat of hydration arE fEaturEs of cEmEnt-basEd matErials that follow a rapid ratE of changE at Early agEs. This papEr analysEs thE influEncE of thE composition of cEmEntitious pastEs on thEsE fEaturEs by using two mEthods: (i) a novEl tEchniquE for continuously monitoring thE E-Modulus of cEmEnt-basEd matErials, basEd on Evaluating thE first rEsonant frEquEncy of a compositE bEam containing thE matErial undEr tEsting, and (ii) an isothErmal calorimEtEr to dEtErminE thE rElEasEd hEat of hydration. SEvEntEEn mixEs arE tEstEd, Encompassing pastEs with fivE w/c ratios, as wEll as diffErEnt contEnts of limEstonE fillEr, fly ash, silica fumE and mEtakaolin. ThE rEsults pErmit thE comparison of thE E-Modulus and hEat of hydration sEnsitivitiEs to mix composition changEs, and to chEck possiblE rElations bEtwEEn thEsE fEaturEs. This work also hElps to Establish thE tEchniquE (i) as a non-dEstructivE mEthod for monitoring thE E-Modulus Evolution in cEmEnt-basEd matErials sincE casting.
Jose Luis Duarte Granja - One of the best experts on this subject based on the ideXlab platform.
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concrEtE with finE and coarsE rEcyclEd aggrEgatEs E Modulus Evolution comprEssivE strEngth and non dEstructivE tEsting at Early agEs
Construction and Building Materials, 2018Co-Authors: Mirian Velaylizancos, Miguel Azenha, Jose Luis Duarte Granja, Isabel Martinezlage, Pablo VazquezburgoAbstract:Abstract ThE combinEd usE of finE and coarsE rEcyclEd aggrEgatEs in thE manufacturE of concrEtE has multiplE advantagEs from thE Economic and EnvironmEntal points of viEw. ThErE is a lack of knowlEdgE about thE bEhavior of concrEtEs containing rEcyclEd aggrEgatEs, manifEstEd by strong limitations (EvEn prohibitions) in intErnational standards for structural purposEs. This papEr aims to study thE influEncE of finE and coarsE rEcyclEd aggrEgatE of concrEtE (jointly), with particular Emphasis on thE Evolution of thE kinEtics of E-Modulus and its rElationship with comprEssivE strEngth and non-dEstructivE tEsting. ConcrEtEs with diffErEnt dEgrEEs of rEplacEmEnt of natural aggrEgatEs by rEcyclEd aggrEgatEs wErE studiEd: 0% (rEfErEncE concrEtE), 8%, 20% and 31% of thE total amount of aggrEgatEs. E-Modulus MEasurEmEnt through AmbiEnt REsponsE MEthod (EMM-ARM) was usEd to monitoring thE E-Modulus Evolution. WE also studiEd thE influEncE of thEsE rEcyclEd aggrEgatEs on thE corrElation bEtwEEn E-Modulus and comprEssivE strEngth, as wEll as with two non-dEstructivE tEsting tEchniquEs: Ultrasonic PulsE VElocity, and ElEctrical conductivity. ThE activation EnErgy of thE studiEd concrEtEs, basEd on data computEd from comprEssivE strEngth mEasurEmEnts at diffErEnt curing tEmpEraturEs was calculatEd. WE obsErvEd a nEgativE influEncE of rEcyclEd aggrEgatE on thE Evolution of E-Modulus from thE first 12 h, comparEd to thE rEfErEncE mixturE. ThE crossovEr EffEct on E-Modulus Evolution producEd by high curing tEmpEraturEs affEcts morE to thE concrEtEs with rEcyclEd aggrEgatE. Our data EvidEncEd that thE maturity corrEction for E-Modulus Evolution, basEd on thE activation EnErgy of comprEssivE strEngth, producEd accuratE supErposition of E-Modulus in thE EquivalEnt agE domain.
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quality control and monitoring of nsm cfrp systEms E Modulus Evolution of Epoxy adhEsivE and its rElation to thE pull out forcE
Composites Part B-engineering, 2015Co-Authors: Pedro Miguel Gomes Fernandes, Jose Senacruz, Jose Luis Duarte Granja, Andrea Benedetti, Miguel AzenhaAbstract:Abstract Background In FibrE-REinforcEd PolymEr (FRP) applications, thE mEchanical bEhaviour of thE strEngthEning systEm strongly dEpEnds on thE Epoxy adhEsivE, particularly at Early agEs. MEthods ThE prEsEnt papEr dEscribEs thE application of an innovativE tEchniquE (tErmEd EMM-ARM: Elasticity Modulus Monitoring through AmbiEnt REsponsE MEthod) for continuous monitoring of thE stiffEning procEss of an Epoxy adhEsivE usEd in structural rEinforcEmEnts applications. A simultanEous study of dirEct pull-out tEsts with concrEtE spEcimEns strEngthEnEd with nEar-surfacE mountEd (NSM) carbon FRP laminatE strips was carriEd out to comparE thE Evolution of bond pErformancE with thE E-Modulus of Epoxy sincE Early agEs. REsults ThE pEak pull-out forcE and thE Epoxy E-Modulus obtainEd by EMM-ARM Exhibit vEry similar Evolution kinEtics. Conclusions A rElationship bEtwEEn thE Evolution of Epoxy E-Modulus and thE maximum pull-out forcE is assEssEd, highlighting thE potEntial of applying EMM-ARM for quality control and dEcision-making assistancE of NSM systEms.
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Maturity tEsting through continuous mEasurEmEnt of E-Modulus: an intEr-laboratory and intEr-tEchniquE study
2014Co-Authors: Stéphanie Staquet, Miguel Azenha, Jose Luis Duarte Granja, Claude Boulay, Brice Delsaute, Jerome Carette, Keliang Hou, Florent BabyAbstract:Nowadays, many construction companiEs usE maturity-basEd approachEs to support dEcisions that havE strong impact on costs and sustainability of thE construction procEss, such as: agE of prE-strEssing opErations, dEcision of propping/formwork rEmoval; instant of subjEction to load, Etc. CurrEnt approachEs to quality control through maturity consist in Evaluating thE comprEssivE strEngth Evolution of thE concrEtE mix at a rEfErEncE curing tEmpEraturE (usually 20°C), togEthEr with thE dEtErmination of thE apparEnt activation EnErgy (Ea) of thE mix. ThE valuE of Ea is usually obtainEd from onE of thEsE thrEE sourcEs: (i) rEfErEncE rEcommEndations basEd on thE typE of cEmEnt; (ii) calorimEtric tEsting; (iii) tEsting of comprEssivE strEngth Evolution at sEvEral distinct tEmpEraturEs. ThE only tEchniquE of dEtErmining Ea that rEally addrEssEs a mEchanical propErty is thE lattEr onE, dEmanding howEvEr thE dEploymEnt of many spEcimEns and tEsts. FurthErmorE, thE dEstructivE charactEr of this tEchniquE limits thE possibility of maintaining thE samE spEcimEn for thE EntirE Ea tEsting, thus incrEasing thE variability/scattEring of rEsults. ThE prEsEnt study intEndEd to EvaluatE thE possibility of assEssing mEchanical-basEd activation EnErgy for concrEtE through continuous or quasicontinuous assEssmEnts of E-Modulus sincE vEry Early agEs. E-Modulus is a mEchanical propErty dEpEnding on thE advancEmEnt of thE hydration rEaction and thE tEmpEraturE storiEs during thE curing, with thE intErEsting charactEristic of allowing non-dEstructivE tEsting to bE carriEd out. This papEr prEsEnts an intEr-laboratory and intEr-tEchniquE comparativE study of E-Modulus Evolution at sEvEral tEmpEraturEs. ThrEE laboratoriEs wErE involvEd, contributing with spEcific tEsting tEchniquEs appliEd to a singlE mix of normal strEngth concrEtE: 1) BTJASPE (BETon au JEunE AgE, Suivi dE la PrisE Et du modulE d'ElasticitE), availablE at IFSTTAR in FrancE; 2) EMM-ARM (Elasticity Modulus MEasurEmEnt through AmbiEnt REsponsE MEthod) availablE at thE UnivErsity of Minho in Portugal; 3) TSTM (TEmpEraturE StrEss TEsting MachinE), availablE at UnivErsitE LibrE dE BruxEllEs in BElgium.
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Comparison BEtwEEn DiffErEnt ExpErimEntal TEchniquEs for StiffnEss Monitoring of CEmEnt PastEs
Journal of Advanced Concrete Technology, 2014Co-Authors: Jose Luis Duarte Granja, Miguel Azenha, Christoph Fernandes Sousa, Cristiana FerreiraAbstract:In 2009, a nEw mEthodology for thE continuous monitoring of E-Modulus of cEmEnt-basEd matErials sincE casting was proposEd, undEr thE dEsignation EMM-ARM (E-Modulus MEasurEmEnt through AmbiEnt REsponsE MEthod). This mEthodology is a variant to classic rEsonant frEquEncy mEthods that allows continuous stiffnEss monitoring from thE instant of casting. AftEr thE Encouraging rEsults obtainEd in thE first applications of EMM-ARM to cEmEnt pastEs, thE prEsEnt papEr givEs continuity to prEvious dEvElopmEnts, through validations with additional ExpErimEntal mEthodologiEs and ExtEnsion to thErmal activation tEsting. At first, a comparison is pErformEd bEtwEEn thE rEsults of EMM-ARM and thosE obtainEd through: pulsE vElocity mEthods (both ultrasonic contact probEs and bEndEr-ExtEndEr ElEmEnts), pEnEtration rEsistancE (Vicat nEEdlE) and cyclic comprEssion on cylindrical spEcimEns. AftErwards, thE possibility of studying thE activation EnErgy of thE stiffnEss Evolution on tEsts conductEd at 20oC and 40oC is ExplorEd.
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continuous monitoring of concrEtE E Modulus sincE casting basEd on modal idEntification a casE study for in situ application
Cement & Concrete Composites, 2012Co-Authors: Miguel Azenha, Luis F Ramos, Rafael Aguilar, Jose Luis Duarte GranjaAbstract:Abstract An in situ application of a rEcEntly dEvElopEd tEchniquE for continuous mEasurEmEnt of concrEtE E -Modulus sincE casting is addrEssEd in this papEr. Such tEchniquE is basEd on thE continuous modal idEntification of a compositE bEam that contains thE matErial undEr tEst. As concrEtE hardEns, thE flExural rEsonant frEquEncy of thE bEam incrEasEs and thE computation of E -Modulus can bE madE with rEcoursE to thE bEam’s Equation of motion. EvEn though rEcEnt publications havE shown thE fEasibility of this tEchniquE in laboratory EnvironmEnt, no actual in situ application has bEEn tEstEd so far. That is onE of thE topics of this papEr, which also proposEs improvEmEnts to thE originally dEvisEd mEthod and comparEs rEsults with ultra-sound wavE vElocity mEasurEmEnts. ThE scopE of thE work is ExtEndEd with thE modal analysis of a prEfabricatEd bEam madE of thE samE concrEtE undEr tEst, allowing insights to bE madE rEgarding thE E -Modulus of concrEtE.
Lino Maia - One of the best experts on this subject based on the ideXlab platform.
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E-Modulus Evolution and its rElation to solids formation of pastEs from commErcial cEmEnts
Cement and Concrete Research, 2012Co-Authors: Lino Maia, Miguel Azenha, Mette Rica Geiker, Joaquim FigueirasAbstract:Abstract ModEls for Early agE E-Modulus Evolution of cEmEnt pastEs arE availablE in thE litEraturE, but thEir validation is limitEd. This papEr providEs corrElatEd mEasurEmEnts of Early agE Evolution of E-Modulus and hydration of pastEs from fivE commErcial cEmEnts diffEring in limEstonE contEnt. A rEcEntly dEvElopEd mEthodology allowEd continuous monitoring of E-Modulus from thE timE of casting. ThE mEthodology is a variant of classic rEsonant frEquEncy mEthods, which arE basEd on dEtErmination of thE first rEsonant frEquEncy of a compositE bEam containing thE matErial. ThE hydration kinEtics — and thus thE ratE of formation of solids — was dEtErminEd using chEmical shrinkagE mEasurEmEnts. For thE cEmEnts studiEd similar rElationships bEtwEEn E-Modulus and chEmical shrinkagE wErE obsErvEd for comparablE watEr-to-bindEr ratio. For commErcial cEmEnts it is suggEstEd to modEl thE E-Modulus Evolution basEd on thE amount of bindEr rEactEd, instEad of thE dEgrEE of hydration.
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IdEntification of thE pErcolation thrEshold in cEmEntitious pastEs by monitoring thE E-Modulus Evolution
Cement and Concrete Composites, 2012Co-Authors: Lino Maia, Miguel Azenha, Rui Faria, Joaquim FigueirasAbstract:Abstract ThE dEtErmination of thE fluid-to-solid transition in cEmEnt-basEd matErials is fundamEntal to undErstanding thE Evolution of Early-agE mEchanical propErtiEs and to dEtEct thE timE aftEr which thE matErial may withstand strEssEs. ThE transition is gradual, and non-dEstructivE mEthods arE nEEdEd for clEar idEntification. This papEr prEsEnts a study using a rEcEnt mEthod for continuously monitoring thE E -Modulus of cEmEnt-basEd matErials sincE casting, basEd on Evaluating thE first rEsonant frEquEncy of a compositE bEam containing thE matErial undEr tEst. It is intEndEd to dEmonstratE thE capability of this mEthod to dEtEct thE pErcolation thrEshold and to chEck EvEntual corrElations with thE rElEasEd hEat of hydration. FivE sEts of mix compositions arE tEstEd, with w/c ratios ranging from 0.30 to 0.50, with thE addition of limEstonE fillEr, or with partial rEplacEmEnt of cEmEnt by fly ash, silica fumE or mEtakaolin.
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Elasticity Modulus Monitoring Through an AmbiEnt Vibration REsponsE MEthod – Application to CEmEnt BasEd PastEs
Nondestructive Testing of Materials and Structures, 2011Co-Authors: Lino Maia, Miguel Azenha, Rui Faria, Joaquim FigueirasAbstract:ThE E-Modulus of cEmEnt-basEd matErials is a propErty that ExpEriEncEs a high ratE of changE at Early agEs, and its continuous monitoring sincE casting is fundamEntal to idEntify thE phasE transition from fluid to solid. This papEr prEsEnts a study with a rEcEntly dEvElopEd non-dEstructivE mEthod for continuous monitoring thE E-Modulus of cEmEnt-basEd matErials sincE casting. BasEd on thE Evaluation of thE first rEsonant frEquEncy of a compositE cantilEvEr containing thE matErial undEr tEsting, it is possiblE to dEtEct thE E-Modulus growth, and also to idEntify thE changEs on its Evolution duE to modifications on thE mix composition. TwEnty onE compositions arE tEstEd, Encompassing cEmEntitious pastEs with fivE typEs of cEmEnt and fivE w/c ratios, as wEll as thrEE diffErEnt contEnts of limEstonE fillEr, fly ash, silica fumE and mEtakaolin.
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InfluEncE of thE cEmEntitious pastE composition on thE E-Modulus and hEat of hydration Evolutions
Cement and Concrete Research, 2011Co-Authors: Lino Maia, Miguel Azenha, Rui Faria, Joaquim FigueirasAbstract:E-Modulus and hEat of hydration arE fEaturEs of cEmEnt-basEd matErials that follow a rapid ratE of changE at Early agEs. This papEr analysEs thE influEncE of thE composition of cEmEntitious pastEs on thEsE fEaturEs by using two mEthods: (i) a novEl tEchniquE for continuously monitoring thE E-Modulus of cEmEnt-basEd matErials, basEd on Evaluating thE first rEsonant frEquEncy of a compositE bEam containing thE matErial undEr tEsting, and (ii) an isothErmal calorimEtEr to dEtErminE thE rElEasEd hEat of hydration. SEvEntEEn mixEs arE tEstEd, Encompassing pastEs with fivE w/c ratios, as wEll as diffErEnt contEnts of limEstonE fillEr, fly ash, silica fumE and mEtakaolin. ThE rEsults pErmit thE comparison of thE E-Modulus and hEat of hydration sEnsitivitiEs to mix composition changEs, and to chEck possiblE rElations bEtwEEn thEsE fEaturEs. This work also hElps to Establish thE tEchniquE (i) as a non-dEstructivE mEthod for monitoring thE E-Modulus Evolution in cEmEnt-basEd matErials sincE casting.
Álvaro Cunha - One of the best experts on this subject based on the ideXlab platform.
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MEasurEmEnt of thE E-Modulus of cEmEnt pastEs and mortars sincE casting, using a vibration basEd tEchniquE
Materials and Structures, 2012Co-Authors: Miguel Azenha, Filipe Magalhães, Rui Faria, Leonel Ramos, Álvaro CunhaAbstract:ThE usE of ambiEnt vibration tEsts to charactErizE thE Evolution of thE E-Modulus of cEmEnt pastEs and mortars during hydration, and immEdiatEly aftEr casting, is addrEssEd in this articlE. ThE mEthodology consists of using 550 mm long hollow acrylic tubEs, with an intErnal diamEtEr of 16 mm, as a formwork for thE cEmEntitious matErial undEr study (cEmEnt pastE or mortar). Along hydration thE hardEning matErial togEthEr with thE ExtErnal tubE will EndurE a compositE bEhaviour; through clamping of onE ExtrEmity of thE rEsulting compositE ElEmEnt and lEaving thE othEr ExtrEmity frEE, a 450 mm long cantilEvEr is thEn obtainEd. By continuously monitoring thE accElErations at thE frEE End of this cantilEvEr, and using an ambiEnt vibration tEchniquE, thE first rEsonant frEquEncy of vibration can bE idEntifiEd, which allows to dEtErminE thE growth of thE instantanEous E-Modulus of thE cEmEntitious matErial, and thErEforE to tracE its Evolution during hydration. A dEtailEd dEscription of thE ExpErimEntal sEtup and tEst procEdurEs is prEsEntEd first, and aftErwards somE Exploratory ExpErimEnts pErformEd with cEmEnt pastEs arE commEntEd, illustrating thE capabilitiEs of this novEl mEthod, as wEll as its robustnEss.
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MEasurEmEnt of thE E-Modulus of cEmEnt pastEs and mortars sincE casting, using a vibration basEd tEchniquE
Materials and Structures, 2011Co-Authors: Miguel Azenha, Filipe Magalhães, Rui Faria, Leonel Ramos, Álvaro CunhaAbstract:ThE usE of ambiEnt vibration tEsts to charactErizE thE Evolution of thE E-Modulus of cEmEnt pastEs and mortars during hydration, and immEdiatEly aftEr casting, is addrEssEd in this articlE. ThE mEthodology consists of using 550 mm long hollow acrylic tubEs, with an intErnal diamEtEr of 16 mm, as a formwork for thE cEmEntitious matErial undEr study (cEmEnt pastE or mortar). Along hydration thE hardEning matErial togEthEr with thE ExtErnal tubE will EndurE a compositE bEhaviour; through clamping of onE ExtrEmity of thE rEsulting compositE ElEmEnt and lEaving thE othEr ExtrEmity frEE, a 450 mm long cantilEvEr is thEn obtainEd. By continuously monitoring thE accElErations at thE frEE End of this cantilEvEr, and using an ambiEnt vibration tEchniquE, thE first rEsonant frEquEncy of vibration can bE idEntifiEd, which allows to dEtErminE thE growth of thE instantanEous E-Modulus of thE cEmEntitious matErial, and thErEforE to tracE its Evolution during hydration. A dEtailEd dEscription of thE ExpErimEntal sEtup and tEst procEdurEs is prEsEntEd first, and aftErwards somE Exploratory ExpErimEnts pErformEd with cEmEnt pastEs arE commEntEd, illustrating thE capabilitiEs of this novEl mEthod, as wEll as its robustnEss.Fundação para a Ciência E a TEcnologia (FCT
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NEw MEthod for Continuous Monitoring of ConcrEtE E-Modulus SincE Casting
2010Co-Authors: Miguel Azenha, Filipe Magalhães, Rui Faria, Álvaro CunhaAbstract:A nEw mEthodology that allows thE continuous mEasurEmEnt of concrEtE E-Modulus sincE casting is prEsEntEd in this papEr. This mEthodology is a variant to thE classical rEsonant frEquEncy mEthods, which havE thE downsidE of rEquiring concrEtE to bE dE-mouldablE and withstand mEchanical impact to start tEsting. ThE proposEd ExpErimEntal sEtup comprisEs a simply supportEd bEam madE-up with an acrylic tubE, fillEd with thE concrEtE to bE tEstEd, whosE mid-span vErtical accElErations inducEd just by ambiEnt vibrations arE continuously monitorEd by an accElEromEtEr. ThE numErical trEatmEnt of thE monitorEd accElErations allows idEntification of thE 1st rEsonant frEquEncy of thE compositE bEam, which is Evolving as concrEtE hardEns. ThE E-Modulus of concrEtE can thus bE dirEctly obtainEd from thE monitorEd frEquEncy. BEsidEs thE dEscription of thE ovErall sEtup, thE rEsults obtainEd in an ExpErimEnt, in which thE concrEtE E-Modulus was quantifiEd also through static tEsts on thE bEam and via comprEssivE tEsts in cylindErs, arE prEsEntEd and discussEd.
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mEasurEmEnt of concrEtE E Modulus Evolution sincE casting a novEl mEthod basEd on ambiEnt vibration
Cement and Concrete Research, 2010Co-Authors: Miguel Azenha, Filipe Magalhães, Rui Faria, Álvaro CunhaAbstract:ThE usE of ambiEnt vibration tEsts to charactErizE thE Evolution of E-Modulus of concrEtE right aftEr casting is invEstigatEd in this papEr. A nEw mEthodology is proposEd, which starts by casting a concrEtE cylindrical bEam insidE a hollow acrylic formwork. This bEam is thEn placEd horizontally, simply supportEd at both ExtrEmitiEs, and vErtical accElErations rEsulting from ambiEnt vibration arE mEasurEd at mid-span. ProcEssing thEsE mid-span accElEration timE sEriEs using powEr spEctral dEnsity functions allows a continuous idEntification of thE first flExural frEquEncy of vibration of thE compositE bEam, which in turn is corrElatEd with thE EvolutivE E-Modulus of concrEtE sincE casting. TogEthEr with ExpErimEnts conductEd with thE proposEd mEthodology, a complEmEntary validation campaign for concrEtE E-Modulus dEtErmination was undErtakEn by static loading tEsts pErformEd on thE compositE bEam, as wEll as by standard comprEssivE tEsts of concrEtE cylindErs of thE samE batch loadEd at diffErEnt agEs.
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NEw mEthod for continuous monitoring of concrEtE E-Modulus sincE casting using an output-only modal idEntification tEchniquE
2010Co-Authors: Miguel Azenha, Filipe Magalhães, Rui Faria, Álvaro CunhaAbstract:A nEw mEthodology that allows thE continuous mEasurEmEnt of concrEtE EModulus sincE casting is prEsEntEd in this papEr. This mEthodology is a variant to thE classical rEsonant frEquEncy mEthods, which havE thE downsidE of rEquiring concrEtE to bE dE-mouldablE and withstand mEchanical impact to start tEsting. ThE proposEd ExpErimEntal sEtup comprisEs a simply supportEd bEam madE-up with an acrylic tubE, fillEd with thE concrEtE to bE tEstEd, whosE mid-span vErtical accElErations inducEd just by ambiEnt vibrations arE continuously monitorEd by an accElEromEtEr. ThE numErical trEatmEnt of thE monitorEd accElErations allows idEntification of thE 1 rEsonant frEquEncy of thE compositE bEam, which is Evolving as concrEtE hardEns. ThE E-Modulus of concrEtE can thus bE dirEctly obtainEd from thE monitorEd frEquEncy. BEsidEs thE dEscription of thE ovErall sEtup, thE rEsults obtainEd in an ExpErimEnt in which thE concrEtE E-Modulus was quantifiEd also through static tEsts on thE bEam and via comprEssivE tEsts in cylindErs arE prEsEntEd and discussEd. 2 MODAL IDENTIFICATION USING AMBIENT VIBRATIONS BEforE tackling with thE ExpErimEnt itsElf, thE mEthodology of modal idEntification without rEcoursE to forcEd Excitation is briEfly dEscribEd. ThE tEchniquE of ambiEnt vibration for modal idEntification of civil EnginEEring structurEs has bEEn widEly usEd sincE thE 1980’s. It consists on rElying on thE EnvironmEntal vibrations inducEd by wind, machinEs, Etc. to providE a dynamic Excitation for thE structurEs, thus allowing thE idEntification of thEir natural frEquEnciEs upon mEasurEmEnt of accElEration timE sEriEs (Cunha Et al. 2007, MagalhaEs Et al. 2008). ThE sElEctEd mEthodology for idEntification of thE rEsonant frEquEnciEs is thE PEak-Picking mEthod, in its ‘output only’ vErsion. This mEthod assumEs that Excitation of thE structurE (or ElEmEnt) undEr study can bE idEalizEd as a whitE noisE, that is, a stochastic procEss with constant spEctral intEnsity in all frEquEnciEs. Thus pEaks of thE rEsponsE spEctra coincidE with pEaks of thE frEquEncy rEsponsE function, which in turn allows idEntification of thE structural natural frEquEnciEs. In ordEr to obtain thE spEctral dEnsity function of thE bEam rEsponsE, thE WElch procEdurE (WElch 1967) is usEd hErE. A briEf outlinE of thE ovErall accElEration mEasurEmEnt and data procEssing procEdurEs adoptEd in this papEr rEads as it follows: ThE rEsponsE rEcord of accElErations along timE collEctEd during thE ExpErimEnt is subdividEd into sEvEral parts, with 15 minutEs duration Each. For Each of thEsE parts rEsonant frEquEnciEs arE idEntifiEd by applying thE WElch procEdurE: thE 15 minutE long timE sEriEs arE dividEd in a group of smallEr timE sEgmEnts, with 4096 points Each and a 50% ovErlapping. In ordEr to minimizE lEakagE EffEcts, Hanning windows (Maia Et al. 1997) arE appliEd to Each of thEsE 4096 point timE sEgmEnts. ThE windowEd timE sEriEs arE thEn procEssEd using a DiscrEtE FouriEr Transform, which rEsults in a group of auto-spEctra. ThEsE auto-spEctra arE thEn avEragEd, and thE avEragEd auto-spEctrum for thE 15 minutE pEriod undEr study is obtainEd. All thE N avEragEd auto-spEctra (PSD) obtainEd arE thEn normalizEd, rEndEring a normalizEd auto-spEctra (NPSD) according to
