Proceedings of the International rilem conference Materials, Systems and Structures in Civil Engineering 2016

384

International RILEM Conference on Materials, Systems and Structures in Civil Engineering 

Conference segment on Service Life of Cement-Based Materials and Structures

22-24 August 2016, Technical University of Denmark, Lyngby, Denmark 

 

[10] Carette J., Staquet S. Monitoring the setting process of mortars by ultrasonic P and S-

wave transmission velocity measurement, Construction and Building Materials, 2015, 94, 

196-208 

[11] Delsaute, B., Boulay, C., Granja, J., Carette, J., Azenha, M., Dumoulin, C., Karaiskos, 

G., Deraemaeker, A., & Staquet, S. Testing Concrete E-modulus at Very Early Ages Through 

Several Techniques: An Inter-laboratory Comparison,  Strain, 2016,  52, 91-109 

[12] C. Boulay, J.-L. Andre, J.-M. Torrenti, Draft operating protocol to determine the level of 

heat released during cement hydration on a concrete specimen placed in a quasi-adiabatic 

calorimeter designed for concretes (QAB), BLCPC, 278 (2010), pp. 37–42 

[13] Broda, M.; Wirquin, E. & Duthoit, B. Conception of an isothermal calorimeter for 

concrete: Determination of the apparent activation energy, Materials and Structures, 

2002, 35, 389-394 

---

385

International RILEM Conference on Materials, Systems and Structures in Civil Engineering 

Conference segment on Service Life of Cement-Based Materials and Structures

22-24 August 2016, Technical University of Denmark, Lyngby, Denmark 

 

CONCRETE DRYING: EFFECTS OF BOUNDARY CONDITIONS AND 

SPECIMEN SHAPE 

 

Jérôme Carette

(1,2)

, Farid Benboudjema

(1)

, Georges Nahas

(2)

, Kamilia Abahri

(1)

, Aveline 

Darquennes

(1)

, Rachid Bennacer

(1)

 

 

(1) LMT-Cachan / ENS Cachan / CNRS / Université Paris Saclay, Cachan, France 

(2) IRSN, Fontenay-aux-Roses, FRANCE 

 

 

 

 

Abstract 

In the framework of the ODOBA project, representative structures in reinforced concrete are 

submitted to various types of durability distress, in order to have elements of knowledge on 

pathologies which could develop in the course of time. Among studied issues are the alkali-

aggregate reaction (AAR) and the delayed ettringite formation (DEF), which appear after a 

large induction period, but develop then quickly, inducing irreversible structure damage. 

These issues are closely related to the water distribution and to the surrounding humidity. 

Controlling the processes of drying and wetting of concrete is of major importance in this 

regard. However, the mechanisms at their origin are currently not well established and 

modelled. This work is a preliminary study aiming at identifying the main mechanisms in 

play during drying-wetting cycles through a coupled experimental-numerical study of the 

humidity gradient inside concrete. In this paper, the drying of various concrete samples is 

cautiously studied through refined measurement of the mass loss and internal relative 

humidity distribution. Various sample sizes and shapes are tested. A simulation strategy is 

described, including the modelling of water vapour diffusion and liquid water permeation. 

The introduction of a boundary layer at the drying interface improves the mass variation 

prediction. 

 

 

1. Introduction 

 

In the framework of the pre-ODOBA ENSC/IRSN and ODOBA project of the IRSN (French 

Institut de Radioprotection et de Sûreté Nucléaire), representative structures of reinforced 

concrete will be built on the IRSN Cadarache nuclear research centre. In these structures will 

be developed pathologies of concrete such as swelling reactions (internal sulphate attack 

(ISA) and alkali-aggregate reaction (AAR)). The concrete used in the construction of these 

structures are chosen by equivalence to the concrete used in the studied nuclear facilities. 

These issues usually develop after a very long induction period (10 to 30 years). 

Unfortunately, after the onset of signs of swelling, development is very rapid with 

---

386

International RILEM Conference on Materials, Systems and Structures in Civil Engineering 

Conference segment on Service Life of Cement-Based Materials and Structures

22-24 August 2016, Technical University of Denmark, Lyngby, Denmark 

 

consequences for the safety functions of these structures. These issues are highly dependent 

on the presence of water in the pore system of concrete. Therefore, control of the process of 

drying-wetting becomes an important parameter, which remains the object of scarce results in 

the literature. Indeed, there remain questions regarding the mechanisms involved. Thus, it is 

difficult to simulate the distribution of the water content in concrete models, which leads to 

difficulties in quantifying the deformation gradients due to the swelling reactions (ISA, 

AAR). 

This work aims at identifying the main mechanisms in play during drying-wetting cycles 

through a coupled experimental-numerical study of the humidity gradient inside concrete. In 

this paper, the drying of various concrete samples is cautiously studied through refined 

measurement of the mass loss and internal relative humidity distribution. Various sample 

sizes and shapes are tested. A simulation strategy is described, including the modelling of 

water vapour diffusion and liquid water permeation [1, 2]. A limited amount of samples were 

tested in this study. In addition, many parameters of the model were determined by other 

authors on the same concrete. Therefore, this study must be considered as a preliminary 

methodology for the monitoring and simulating the drying of concrete rather. Additional 

ongoing tests will provide more information regarding further validation of the suggested 

model. 

 

 

2. Experimental 

setup 

 

2.1. Mix design 

The tested concrete composition is referred to as B11 concrete. This concrete, which 

composition and major properties are shown in Table 1, is used because it is equivalent to the 

concrete actually used in French internal nuclear power plant vessels. In addition, it has been 

widely studied in previous studies [1] and its properties are therefore mostly known.  

 

Table 1: (left) B11 mix design (right) B11 concrete main properties 

 

 

[t/m

3

] 

B11 

[kg/m³] 

 

w/c 

[-] 0.573 

Cement 

(CEM II Airvault Calcia)

 

3.1 336 

  

[t/m

3

] 2.324 

Sand (0/4) 

2.572 

740 

 

Slump 

[cm] 8-11 

Aggregates (4/12,5) 

2.57 

303 

 

Porosity 

[-] 

13.2-

13.8 

Aggregates (10/20) 

2.57 

752 

 

f

c

 (28 days) 

[MPa]  46.5 

Water 

1 193 

 

f

t

 (28 days) 

[MPa]  3.29 

Superplasticizer 

(Plastiment 

HP)

 

1.185 10

-

3

 

1.174   E (28 days) 

[GPa]  31.34 

 

2.2. Curing conditions 

In order to submit all the concrete specimens to the same curing conditions (temperature T 

and relative humidity RH), à large storage bin was developed. The climatic chamber was 

---