Predicting Deterioration for Design and Maintenance: AAR and Chlorides

2018 ◽  
Author(s):  
Jonathan G. M. Wood
Keyword(s):  
Cementitious Materials ◽  
Rapid Testing ◽  
Concrete Deterioration ◽  
Migration Data ◽  
Durability Design ◽  
Alkali Aggregate Reaction ◽  
Chloride Migration ◽  
Testing Data ◽  
Physical And Chemical ◽  
Research Centres

In the 1980s engineers faced major challenges from severe concrete deterioration from AAR (Alkali Aggregate Reaction) and from corrosion. The construction of the Channel and Storebaelt Tunnels required major improvements in specifying concrete to combat both these problems. Anglo-Danish cooperation of consultants and research centres led to innovations in cementitious materials, assessment of aggregates, the testing of materials and predicting deterioration. Since then RILEM has provided an international framework to guide developments on AAR diagnosis, appraisal, testing and specification. Quantitative durability design remains in its infancy. Rapid testing data do not predict migration over many decades. Fick’s law models neglect the physical and chemical processes of chloride migration. Data from old structures is needed for calibrating models and validating theories.

Effect of w/cm and Composition on Correlations of Concrete Electrical Resistivity and Chloride Migration Coefficients

2016 ◽  
Vol 711 ◽  
pp. 21-28
Author(s):  
Francisco J. Presuel-Moreno
Keyword(s):  
Electrical Resistivity ◽  
Steady State ◽  
Fly Ash ◽  
Laboratory Experiments ◽  
Chloride Ion ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Ion Migration ◽  
Resistivity Measurements ◽  
Chloride Migration

The performance with regard to chloride penetration of specimens made with three base compositions (supplementary cementitious materials: 20% fly ash, 20% fly ash + 8% silica fume, and 50% slag replacement by weight of cement), and water-to-cementitious ratios of 0.35, 0.41, or 0.47 were investigated here. In this investigation, laboratory experiments were carried out to study the correlation between electrical resistivity and non-steady state chloride ion migration coefficients (Dnssm) of concrete. NT Build 492 was used to determine chloride migration coefficients. Rapid migration tests and resistivity measurements were performed several times over two years, and the non-steady state migration coefficient (Dnssm) vs. resistivity values were correlated. Experimental results show that a good correlation was found between electrical resistivity and Dnssm. Based on the relationships developed from this investigation, it appears that the correlations are age and composition dependent.

Screening of Different Encapsulated Polymer-Based Healing Agents for Chloride Exposed Self-Healing Concrete Using Chloride Migration Tests

2018 ◽  
Vol 761 ◽  
pp. 152-158 ◽  
Author(s):  
Philip van den Heede ◽  
Bjorn van Belleghem ◽  
Maria Adelaide Araújo ◽  
João Feiteira ◽  
Nele de Belie
Keyword(s):  
Service Life ◽  
High Viscosity ◽  
Cementitious Materials ◽  
Self Healing ◽  
Polymer Precursor ◽  
Marine Environments ◽  
Steel Reinforced Concrete ◽  
Low Viscosity ◽  
Chloride Migration ◽  
The One

The service life of steel reinforced concrete in aggressive marine environments could be increased substantially by embedding a self-healing mechanism that ensures autonomous healing of cracks upon their occurrence. Previous proof-of-concept experiments have shown that the incorporation of encapsulated polymer-based healing agents (HAs) counts as a very appropriate way to achieve this goal. Over the years, several polymer-precursor-capsule systems have been developed in that perspective at our laboratory. Cementitious materials containing either commercial or in-house developed encapsulated HAs have been subjected to preliminary feasibility tests (water absorption, permeability tests, etc.). However, these experiments did not yet allow for a fast and straightforward assessment of the self-healing efficiency (SHE) in relation to the expected durability and service life performance of the material. This approach would have many advantages when having to select the most suitable polymer-precursor-capsule system for a particular concrete application. In this paper, a modified chloride migration test based on the one prescribed in NT Build 492 has been proposed to support the development of self-healing concrete for marine environments. Four polymer-based HAs have been screened that way, i.e. an in-house developed high-viscosity polyurethane (PU) precursor, a commercial low-viscosity PU precursor, the same commercial PU precursor with addition of accelerator and benzoyl peroxide (BPO), and an in-house developed 2-component acrylate-endcapped precursor + cross-linker. For now, a highly repeatable SHE value of 100% could only be obtained for the second option.

Addition of Ornamental Rock Residues on Ceramic Blocks: Physical and Chemical Analysis

2020 ◽  
Vol 1012 ◽  
pp. 262-267
Author(s):  
Michelle Souza Oliveira ◽  
Fabio da Costa Garcia Filho ◽  
Fernanda Santos da Luz ◽  
Euzébio Bernabé Zanelato ◽  
Jonas Alexandre ◽  
...  
Keyword(s):  
Chemical Analysis ◽  
Industrial Waste ◽  
Chemical Characterization ◽  
Cementitious Materials ◽  
Physical And Chemical Characterization ◽  
Ceramic Blocks ◽  
Physical And Chemical

The incorporation of industrial waste in cementitious materials is an alternative for its adequate disposal. Among the residues that do not yet have adequate disposal are the residues created by the ornamental rock industries. In this context, this work aims to identify and characterize clays of the region where the ornamental rock industry is dominant and to verify the performance of the ceramic masses with the incorporation of the marble and granite residue. Physical and chemical characterization tests were performed on both clay and residues. After the identification of the two best clays, ceramic masses were prepared where it was possible to evaluate the performance of the clays with each of the residues in incorporations up to 20 wt.%. The results indicated that CI-A with 15 wt.% marble incorporation obtained the best performance.

scholarly journals Sustainable low-carbon binders and concretes

2020 ◽  
Vol 166 ◽  
pp. 06007
Author(s):  
Myroslav Sanytsky ◽  
Tetiana Kropyvnytska ◽  
Stanislav Fic ◽  
Hanna Ivashchyshyn
Keyword(s):  
Activity Index ◽  
Chemical Properties ◽  
High Volume ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Cement Matrix ◽  
Low Carbon ◽  
Blended Cements ◽  
Physical And Chemical

Sustainable development depends on a consistency of interests, social, ecological and economic, and that the interests are evaluated in a balanced manner. In order to reduce CO2 emissions, the conception of decreasing clinker factor and increasing the role of supplementary cementitious materials (SCMs) in the cementitious materials has high economical and environmental efficiency. The performance of clinkerefficient blended cements with supplementary cementitious materials were examined. The influence of superfine zeolite with increased surface energy on the physical and chemical properties of low-carbon blended cements is shown. Increasing the dispersion of cementitious materials contributes to the growth of their strength activity index due to compaction of cement matrix and pozzolanic reactions in unclincker part. In consequence of the early structure formation and the directed formation of the microstructure of the cement matrix is solving the problem of obtaining clinker-efficient concretes. Shown that low-carbon blended cements with high volume of SCMs are suitable, in principle, for producing structural concretes.

scholarly journals A low-order coupled chemistry meteorology model for testing online and offline data assimilation schemes: L95-GRS (v1.0)

2016 ◽  
Vol 9 (1) ◽  
pp. 393-412 ◽  
Author(s):  
J.-M. Haussaire ◽  
M. Bocquet
Keyword(s):  
Data Assimilation ◽  
Wind Field ◽  
Chemical Species ◽  
Highly Nonlinear ◽  
Testing Data ◽  
Latitude Circle ◽  
Physical And Chemical ◽  
The Impact ◽  
Field Estimate ◽  
Low Order

Abstract. Bocquet and Sakov (2013) introduced a low-order model based on the coupling of the chaotic Lorenz-95 (L95) model, which simulates winds along a mid-latitude circle, with the transport of a tracer species advected by this zonal wind field. This model, named L95-T, can serve as a playground for testing data assimilation schemes with an online model. Here, the tracer part of the model is extended to a reduced photochemistry module. This coupled chemistry meteorology model (CCMM), the L95-GRS (generic reaction set) model, mimics continental and transcontinental transport and the photochemistry of ozone, volatile organic compounds and nitrogen oxides. Its numerical implementation is described. The model is shown to reproduce the major physical and chemical processes being considered. L95-T and L95-GRS are specifically designed and useful for testing advanced data assimilation schemes, such as the iterative ensemble Kalman smoother (IEnKS), which combines the best of ensemble and variational methods. These models provide useful insights prior to the implementation of data assimilation methods into larger models. We illustrate their use with data assimilation schemes on preliminary yet instructive numerical experiments. In particular, online and offline data assimilation strategies can be conveniently tested and discussed with this low-order CCMM. The impact of observed chemical species concentrations on the wind field estimate can be quantitatively assessed. The impacts of the wind chaotic dynamics and of the chemical species non-chaotic but highly nonlinear dynamics on the data assimilation strategies are illustrated.

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