Building Materials Building Materials

Measuring the Thermal Conductivity of Building Materials

Energy demands continue to rise as a result of increasing population and urbanization. Maintaining a comfortable indoor temperature accounts for a significant portion of energy use worldwide, and innovative new insulative and efficient materials for building structures are at the forefront of energy conservation.

Cement and concrete play major roles in the construction industry and researchers are seeking ways of creating better materials that provide high levels of insulation without sacrificing structural strength. Thermal conductivity is critical in the development of these materials as lower thermal conductivity values correlate to better insulative systems. With Trident, testing thermal conductivity of concrete is easy, as sample sizes do not need to be adjusted and can be tested in a matter of seconds.  Both MTPS and TPS transient sensor can be used, depending on the objectives of the testing.

  • Trident with MTPS and FLEX TPS sensors

    Trident with MTPS and FLEX TPS sensors

  • Thermal Conductivity Testing of Aerogel Concrete with MTPS

    Thermal Conductivity Testing of Aerogel Concrete with MTPS

  • Thermal Conductivity Testing of Concrete with TPS

    Thermal Conductivity Testing of Concrete with TPS

  • Thermally Insulated Concrete

    Thermally Insulated Concrete

  • PMIC Lab

    The main benefit of the TCi to our testing lab is its ease of use and short test times. It allows us to get accurate results as quickly as possible and with excellent repeatability. Our test times are only a fraction of what they are using steady state methods. Equally important, the service level has exceeded our expectations.”

    Dr. Ernest Wolff, CEO,
    PMIC Lab (Sector: Contract Lab)

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Case Highlights

Basalt fiber-reinforced foam concrete containing silica fume: An experimental study

Abstract from original publication: Foam concrete refers to a type of low-density concrete that is commonly known to have favorable insulation and thermal performance due to its intentionally increased porosity. However, foam concrete is known to generally have a very low physico-mechanical and durability performance mainly due to its high porosity and the con- nectivity of the pores that can allow the entrance of unfavorable substances into the concrete medium. As a result, most often, foam concrete is considered inapplicable to major load bearing structural elements. To counter this tendency, this study adopted the use of basalt fibers with silica fume to increase the structural integrity of foam concrete. In that respect, 18 mixes with varying content of foaming agent, basalt fiber and silica fume have been prepared. Apparent porosity, water absorption, compressive, flexural and splitting tensile strength, sorp- tivity, ultrasonic pulse velocity (UPV), drying shrinkage, freeze–thaw, thermal conductivity, and thermal resis- tance tests were performed to evaluate the physico-mechanical, durability, and insulation properties of the produced foam concretes. Based on the results, a highly durable foam concrete with a maximum compressive, flexural and splitting tensile strength of ~ 46, 6.9 and 3.07 MPa, respectively, has been developed. Furthermore, it is observed that the inclusion of silica fume can significantly influence the pore network and enhance fiber- paste matrix. The effect of basalt fiber, however, is found to be more dependent on the use of silica fume, potentially due to its low integration with cementitious paste. The results of this study are significant and point out to the great potential for producing a highly durable and lightweight insulating foam concrete through the use of basalt fiber and silica fume. [1]

For thermal conductivity test, a C-therm, TCi Thermal Conductivity Analyzer with a thermal conductivity range of 0 to 500 W/mK, conforming to ASTM D7984 was used. In this test, a constant momentary heat pulse is applied on the surface of the test sample, thermal effusivity is determined as the temperature increases at the surface of the material with elapsed time. [1]

tci results publication 3

a) Thermal conductivity and b) thermal conductivity versus dry unit weight of different foam concretes. [1]

[1] Osman Gencel, Mehrab Nodehi, Oguzhan Yavuz Bayraktar, Gokhan Kaplan, Ahmet Benli, Aliakbar Gholampour, Togay Ozbakkaloglu, Basalt fiber-reinforced foam concrete containing silica fume: An experimental study, Construction and Building Materials, Volume 326, 2022, 126861, ISSN 0950-0618, https://doi.org/10.1016/j.conbuildmat.2022.126861. (https://www.sciencedirect.com/science/article/pii/S0950061822005475)

Chemical Retreating for Gel-Typed Aerogel and Insulation Performance of Cement Containing Aerogel

This case highlights research into more insulative building materials by mixing aerogels with cement for better thermal performance. Aerogel is an extremely insulative material with a stated value of less than 0.03 W/mK in pure form.

Thermal conductivity results of the mixed samples tested with the TCi are shown in the graph below. Increasing weight % of aerogel content directly related to a reduction in thermal conductivity of the cured cement composite. Treating of 2.0 weight % aerogel saw a thermal conductivity decrease of over 75%.

Thermal Conductivity Testing of Lightweight Concrete with Transient Plane Source Method

thermal conductivity testing of concrete

The thermal conductivity of a light-weight concrete was measured utilizing the C-Therm Transient Plane Source (TPS) FLEX sensor.

The flexible, 13mm Kapton-based sensor was placed between a sliced lightweight concrete cylinder. 

Referencing ISO standard documents and an approximation of the thermal conductivity, the power applied was chosen to be 0.5W and the measured test time to be 40s. Experiments were carried out in 10 trial segments.

thermal conductivity data of lightweight concrete

Following ten measurements with removal of the sensor between tests, the thermal conductivity of the lightweight concrete was determined to be 0.52 W/mK with a reproducibility better than 5%. 

Figure 1. illustrates the reproducibility results, with the average thermal conductivity of the 10 trials represented by the solid line. Above and below the average line are +/- 5% error lines. The observed variation between tests can be partially attributed to the sample’s inhomogeneity.

The precision was also examined via an additional 10 measurements without the removal of the sensor between measurements. A 3 minute wait time between measurements ensured the heat completely dissipated prior to the next measurement. The precision was determined to have a better than 2% relative standard deviation.


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