Determination of the thermophysical properties of evolutive porous media: application to Civil Engineering materials

Abstract

Abstract. The purpose of this paper is to describe the development and the use of two measurement techniques especially adapted to the rapid determination of the thermophysical properties of evolutive porous media. The first technique exploits the method of the "heated and non-heated wires" and is validated on wet clay by comparison with previous works [Mounanga et al., Eur. Phys. J. Appl. Phys. 26, 65 (2004)]. It is then used to quantify the evolution of both thermal conductivity and volumetric heat capacity of hardening cement pastes maintained at 294 ± 1 K. The second technique is based on the classical method of the "heating film" and a data treatment using forward calculation. This technique is first used to measure the properties of wellknown materials (hardened mortars, wet sand [Mounanga et al., Eur. Phys. J. Appl. Phys. 26, 65 (2004); Delacre, Ph.D. thesis, University of Artois, 2000] and glass [Bastian, Rev. Phys. Appl. 22, 431 (1987)] and then applied to media whose properties evolve both over time and through space (drying sand).

Fabrication, microstructure, and properties of fired clay bricks using construction and demolition waste sludge as the main additive

“…Linear shrinkage was determined through the difference between the diameter of the dry and fired specimens divided by the diameter of the dried sample (Ukwatta et al, 2017).The loss of ignition (LOI) of the RA-S and earth material was determined by calcination at 1000°C for 2 h (Eliche-Quesada et al, 2018). Weight loss data of fired bricks were obtained by the difference between the weight after drying and firing processes (Eliche-Quesada et al, 2018).The thermal conductivity of raw materials and fired bricks were measured by the hot plate method, according to Poullain et al (2006).…”

Transient Thermal Response of Lightweight Cementitious Composites Made with Polyurethane Foam Waste

“…The main principles of the two methods are described in the following paragraphs. The theoretical background of these methods can be found in detail in recent studies (see, for example, [28,29] for the heating-film method and [30,31] for the hot-disk method).…”

“…3 requires that the condition for long time is fulfilled: t > 3l 2 κπ 2 where l is the specimen thickness (m) and κ is the thermal diffusivity of the material (m 2 · s −1 ). For cement mortars (with thermal diffusivity values lying between 0.6 × 10 −6 m 2 · s −1 and 0.8 × 10 −6 m 2 · s −1 [29]) the long-time condition is fulfilled for t > 1000 s. This condition was respected when computing the thermal conductivity of the specimens using the heating-film method. Figure 2 shows the specimens' size and shape and also the casting direction of the mortars.…”

Proportioning and characterization of lightweight concrete mixtures made with rigid polyurethane foam wastes

“…In our case, this heater is a paper coated with a semi-conducting graphited material (TELEDELTOS paper) subjected to an electrical potential difference [16,17]. The rise in temperature of the concrete prism is recorded by two thermocouples fixed on the heated face (T h , h for ''heated") and on the opposite face (T nh , nh for ''non heated") (Fig.…”

“…The test time is 10 min for each specimen. The temperature-time evolutions are post-processed using an inverse method [17] in order to determine the thermal conductivity and the heat capacity of the material.…”