Tools for assessing damage in concrete affected by AAR coming from fine and coarse aggregates

Abstract

Tools for assessing damage in concrete affected by AAR coming from fine and coarse aggregatesTécnicas para a avaliação da deterioração proveniente da reação álcali-agregado (RAA) gerada pela presença de agregados reativos graúdos e miúdos Abstract ResumoOver the last few years, comprehensive management programs for the diagnosis and prognosis of alkali-aggregate reaction (AAR) in aging concrete structures were developed in North America, based on a series of laboratory test procedures. Although promising, these lab-procedures presented several parameters whose impacts were not completely understood, which significantly reduced their applicability for the appraisal of deteriorated concrete structures in service. In this context, it has been suggested that two lab-tools, the Stiff ness Damage Test (SDT) and the Damage Rating Index (DRI) could reliably assess the condition of concrete affected by AAR. This paper presents the condition assessment of 25, 35 and 45 MPa AAR affected concrete specimens incorporating fi ne and coarse reactive aggregates and presenting different distress degrees (i.e. expansion levels from 0.05 to 0.30%) through the use of an innovative multi-level approach. Results show that both SDT and DRI are suitable for assessing damage in AAR affected concrete through their output parameters. Yet, they present a complementary character, which illustrates the need for a multi-level approach.Keywords: stiff ness damage test, damage rating index, condition assessment, multi-level approach, alkali-aggregate reaction (AAR).Nos últimos anos, diversos programas de gestão para o diagnóstico e prognóstico da reação álcali-agregado (RAA) em estruturas de concreto foram desenvolvidos na América do Norte, com base em uma série de procedimentos experimentais em laboratório. Apesar de promissores, esses procedimentos apresentaram uma série de parâmetros cujo impacto não foi amplamente avaliado e discutido, o que reduziu significativamente a utilização destas técnicas na avaliação de estruturas de concreto deterioradas em serviço. Neste contexto, sugere-se que duas técnicas laboratoriais, o ensaio de Deterioração de Rigidez (SDT) assim como a avaliação microscópica do Índice de Deterioração (DRI) destacam-se como ensaios capazes de avaliar de maneira confiável e precisa o estado de deterioração do concreto afetado pela RAA. Este trabalho apresenta a utilização dos métodos descritos acima na avaliação da deterioração de differentes concretos (25, 35 e 45 MPa) afetados pela RAA, incorporando agregados reativos graúdos e miúdos e apresentando diferentes níveis de expansão (0,05 à 0,30%). Os resultados demonstram que tanto o SDT como o DRI são adequados para avaliar o nível de deterioração do concreto afetado pela RAA. Entretanto, estes apresentam um caráter complementar, o que ilustra a necessidade de uma abordagem "multinível" quando da utilização dos mesmos na avaliação de estruturas em serviço.Palavras-chave: Deterioração de Rigidez (SDT), Índice de Deterioração (DRI), avaliação do estado de deterioração, avaliaç...

Investigation of Alkali-Silica Reactivity in Sustainable Ultrahigh Performance Concrete

“…The first ASR damaged structure reported was the Parker Dam in Arizona in 1941 [33]. Later, various structures were diagnosed to be affected by ASR, including for instance the turbine foundation of the Ikata power plant in Japan [34], Bibb Graves Bridge in Albama, USA [35], Seabrook Nuclear Power Plant in New Hampshire, USA [36], Vosnasvej Bridge in Denmark [37], Robert-Bourassa/Charest overpass in Quebec, Canada [38], and the Warsak Dam in Pakistan [39,40]. The deleterious effects of ASR in concrete structures can be minimized by controlling the alkali content, minimizing reactive silica, reducing the exposure to water, and addition of alkali-silica expansion inhibitor admixtures.…”

Effects of alkali-silica reaction on mechanical behavior of four-pile caps

“…The reductions established in the study by Sanchez et al [3], described in Table 3, were applied in order to study the distribution of cracking in the cracking fields along these reductions. Although the analysis of the reductions in the mechanical properties as a result of the expansion due to the AAR is complicated, and there are many contradictory results in the literature, the choice of parameters studied by Sanchez et al [3] was due, from among the authors that related the degradation of concrete mechanical properties to the expansion due to the AAR, described herein, and is experimental study that provided the most complete parameters on the subject.…”

“…The literature includes several experimental studies on the alkali-aggregate reaction, namely Gomes [1], for example, who studied experiments on the structural recovery of foundation caps; Sanchez et al [2] addressed a new method called the accelerated Brazilian concrete prism test (ABCPT), in which the results indicated that that test had great potential to detect aggregate reactivity in current engineering projects; Sanchez et al [3], who presented test results from the Stiffness Damage Test (SDT) and the microscopic evaluation of the Damage Rating Index (DRI) to assess the level of damage to the AAR-affected concrete. However, there are only a few numerical studies on expressions of such reactions on foundation caps.…”

Improving Concrete Infrastructure Projects Conditions by Mitigating Alkali-Silica Reactivity of Fine Aggregates

“…Expedited testing for ASR and relevant standards are developed for early detection of ASR [21][22][23][24]. ASR Laboratory evaluation measures has average reliability due to the difference between lab conditions and the environmental conditions a concrete member is subjected to during its service life [25][26][27][28][29]. Other ASR detection methods includes the development of field exposure site to predict ASR through full scale expansion testing of hardened concrete members [30,31].…”