Drying Depth and Size Effect on Long-Term Behavior of Concrete

Abstract:

This study aims at improving the analysis of drying tests and taking better advantage of the measurements, by studying the influence of the specimen size. One self-consolidating concrete (SCC) was studied during three years. Drying started 24 hours after casting. The tests were carried on three sizes of cylinders: Φ78mm, Φ113mm and Φ163mm, under the same experimental conditions (20±1°C, 50±5% relative humidity). Total and autogenous shrinkages and mass-loss evolutions were monitored according to RILEM recommendations [1]. Assuming that concrete is a homogeneous and non-aging material, a simple model can be written and used to highlight size effects observed in real concrete. By changing the time variable to the ratio of the square root of the time to the notional size of cross-section, the drying curves of different specimen sizes theoretically follow a master curve [2]. However, experimental curves showed upshifts, thus size effect can be highlighted. Phenomena that occur at early age are actually not taken into account by diffusion equation. This paper introduces a new concept called drying depth as a layer where water loss occurs during the first days without resulting in shrinkage at the specimen level. This depth did not depend of the specimen size. However the relative volume of this layer increases as the size of the specimen decreases, which explains the size effect experimentally observed. The hydric properties of this zone can be assumed to be different from the inner concrete, with a higher porosity and higher permeability. Several phenomena could explain this effect, like the initial particle size distribution with a higher paste proportion near the surface due to the wall effect during casting [3] [4] [5]. Because of early drying hydration stops and this creates a coarser pores in the external layer. Finally, the micro-cracking at the surface induced by the differential shrinkage can also influence the hydric parameters.

• Periodical: Key Engineering Materials (Volume 711)
• Pages: 645-651
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.711.645
• Online since: September 2016
• Authors: Hamza Samouh*, Emmanuel Roziere, Ahmed Loukili
• Keywords: Drying Depth, Drying Effect, Size Effect

References

[1] R. T. 107-CSP, Measurement of time-dependent strains of concrete, Mater. Struct., vol. 31, no. October 1998, p.507–512, (1998).

[2] A. Hilaire, Étude des déformations différées des bétons en compression et en traction, du jeune âge au long terme, PhD thesis, ENS Cachan, France, (2014).

[3] P. C. Kreijger, The skin of concrete Composition and properties, Mater. Constr., vol. 17, p.275–283, (1972).

[4] Y. Wei and W. Hansen, Characterizing Cracking Potential of Cementitious Mixtures Based on Shrinkage and Humidity Drop Rate, ACI Mater. J., no. 110, p.433–440, (2013).

DOI: 10.14359/51685790

[5] C. Andrade, J. M. Dı, and C. Alonso, Mathematical Modeling of a Concrete Surface ' Skin Effect ' on Diffusion in Chloride Contaminated Media, Adv. Cem. BASED Mater., vol. 6, p.39–44, (1997).

DOI: 10.1016/s1065-7355(97)00002-3

[6] P. Turcry, A. Loukili, K. Haidar, G. Pijaudier-cabot, and A. Belarbi, Cracking Tendency of Self-Compacting Concrete Subjected to Restrained Shrinkage : Experimental Study and Modeling, J. Mater. Civ. Eng., (2006).

DOI: 10.1061/(asce)0899-1561(2006)18:1(46)

[7] A. Turatsinze, H. Farhat, and J. Granju, Cracking resistant cement-based material, in 5th International RILEM Conference on Cracking in Pavements: Mitigation, Risk Assessment and Prevention, 2004, no. Lmdc.

[8] H. Samouh, Evaluation de la sensibilité à la fissuration des BAP : Apport de l'analyse du comportement viscoélastique, " in Prix jeune chercheurs "René Houper,. ISABTP/UPPA, Anglet, 27 au 29 Mai 2015, 2015, p.1–8.

[9] H. Samouh, E. Rozière, A. Loukili, and P. Sigwalt, Stress relaxation and cracking sensitivity of self- consolidating concrete: effect of limestone filler content, in 7th RILEM Conference on Self-Compacting Concrete, (2013).

DOI: 10.1016/j.cemconres.2018.08.008

[10] J. R. Keeton, Study of creep in concrete, Technical reports R333-I, R333-II, R333-III. U.S. Naval civil engineering laboratory, Port Hueneme, California, (1965).

[11] C. E. Wallo, E.M., Yuan, R.L., Lott, J.L., Kesler, 'Sixth progress report on prediction of creep in structural concrete from short time tests'. T & AM Report No. 658, Department of Theoretical and Applied Mechanics, University of Illinois at Urbana, (1965).

[12] C. Torben, W. Hansen, and A. H. Mattock, Influence of size and shape of member on the shrinkage and creep of concrete, J. Am. Concr. Inst., vol. 63–10, p.267–290, (1966).

[13] J. Almudaiheem and W. Hansen, Effect of specimen size and shape on drying shrinkage of concrete, ACI Mater. J., vol. 84–M16, p.130–135, (1987).

DOI: 10.14359/1860

[14] J. Almudaiheem and W. Hansen, Prediction of concrete drying shrinkage from short-term measurements, ACI Mater. J., vol. 86–M35, p.401–408, (1989).

DOI: 10.14359/2178

[15] ACI Committee 209, Guide for Modeling and Calculating Shrinkage and Creep in Hardened Concrete, (2008).

[16] European standard, Eurocode 2: Design of concrete structures EN1992-1-1. 2004, p.1–250.

[17] H. Samouh, A. Soive, E. Rozière, and A. Loukili, Size effect on long-term drying behavior of self-consolidating concrete: influence of drying depth, Mater. Struct., p.1–20, (2015).

DOI: 10.1617/s11527-015-0771-7

[18] K. Olivier, D. Aveline, B. Farid, and R. Gagné, Etude de la sensibilite a la fissuration des matériaux cimentaires avec additions minérales au jeune âge, " in 31e Rencontres de l, AUGC, (2013).

[19] D. Niknezhad, Contribution à l'étude du comportement mécanique, du retrait et des propriétés de transport des bétons autoplaçants avec additions minérales: approche expérimentale et numérique, INSA de Rennes, (2015).

DOI: 10.1139/l11-116

[20] H. Samouh, E. Rozière, and A. Loukili, Interprétation des mesures du retrait de dessiccation des bétons autoplaçants (BAP), in XXXe Rencontres AUGC-IBPSA. Chambéry, Savoie, 6au 8 Juin 2012, (2012).

[21] M. D. Nguyen, M. Thiery, and P. Belin, A model for hydration-drying interactions in the concrete cover, " in Thermo-Hydromechanical and Chemical Coupling in Geomaterials and Applications: Proceedings of the 3 International Symposium GeoProc, 2008, (2013).

DOI: 10.1002/9781118623565.ch57

[22] F. Benboudjema, F. Meftah, and J. M. Torrenti, Interaction between drying, shrinkage, creep and cracking phenomena in concrete, Eng. Struct., vol. 27, no. 2, p.239–250, Jan. (2005).

DOI: 10.1016/j.engstruct.2004.09.012

[23] C. de Sa, F. Benboudjema, M. Thiery, and J. Sicard, Analysis of microcracking induced by differential drying shrinkage, Cem. Concr. Compos., vol. 30, no. 10, p.947–956, Nov. (2008).

DOI: 10.1016/j.cemconcomp.2008.06.015

[24] H. Samouh, Nouvelles approches des relations entre formulation et comportement différé des matériaux cimentaires: application aux bétons autoplaçants., PhD thesis, In French, Ecole Centrale de Nantes, (2015).