Concrete & Cementitious Materials:
ASTM D7984, ASTM D5334 & ISO 22007-2
Why Thermal Conductivity Measurement Matters for Concrete and Cement
Thermal conductivity is a critical performance parameter for concrete and cement used in building envelopes, structural elements, pavements, and energy-efficient construction. Lower thermal conductivity improves insulation performance and reduces building energy demand, while thermal conductivity and specific heat together determine the thermal mass behavior that moderates indoor temperature swings — an increasingly important consideration in low-carbon concrete design.
Accurate characterization of cementitious materials requires measurement techniques capable of handling hard, heterogeneous, and moisture-sensitive samples, including hardened concrete, cement paste, mortar, foam and lightweight concrete, and aerogel- or fiber-modified mixes. The C-Therm Trident enables rapid, reliable thermal conductivity and diffusivity testing with the TPS (ISO 22007-2, ASTM E3088), MTPS (ASTM D7984) and TLS (ASTM D5334) methods — delivering results in seconds without sample machining — to support mix design, low-carbon concrete development, and quality control in modern construction materials research.
The Modified Transient Plane Source (MTPS) method — ASTM D7984, exclusive to the C-Therm Trident — measures a cast face, a saw-cut core, or a cube directly. No machining, no guard ring, no thermal grease, no waiting hours for steady state. A result takes seconds. In peer-reviewed correlation work on cementitious specimens, MTPS tracked heat flow meter results at R² > 0.9 and laser flash at R² = 0.978.
Why C-Therm Trident is Ideal for Concrete and Cementitious Materials
The C-Therm Trident Thermal Conductivity Instrument is engineered to rapidly characterize concrete and cementitious materials under representative application conditions. It delivers fast, reliable, and standards-ready data on thermal conductivity, thermal diffusivity, and related thermal properties with minimal sample preparation—supporting high-throughput testing of concrete, cement formulations, aggregates, admixtures, hempcrete, and other sustainable building materials for energy-efficient and low-carbon construction.
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No Sample PreparationNo drilling. No planning. Minimal volume of sample required.
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Representative Test Conditions Test concrete under application-relevant conditions, including wet and dry states, varying moisture content, temperature exposure, hot box environments, and other factors that influence thermal transport. |
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High Volume Throughput Accelerate large scale concrete projects with fastest test times. Rapidly testing cement formulations, aggregates, and admixtures without creating laboratory bottlenecks. Generate results in seconds, not hours |
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Standards-Ready Data Generate reliable data and validate technical data sheets conforming to industry standards ASTM E3088, ISO 22007-2, ASTM D7984, and ASTM D5334. |
Thermal Testing for Low-Carbon Concrete
Explore how thermal testing of low-carbon concrete can inform its use as thermal mass in energy-efficient buildings. This webinar demonstrates the journey from bench-scale material characterization to building-scale energy modeling and analysis.
Which Cementitious Material Are You Characterizing?
Low-Carbon Concrete & Thermal Mass
low-carbon concrete · thermal mass · concrete mix optimization · biochar admixture · recycled waste aggregates
Cutting embodied carbon means cutting clinker — but every substitution that lowers the carbon number also changes how the finished structure stores and releases heat. Supplementary cementitious materials, biomineral additives, biochar, and recycled aggregates such as crushed concrete, glass, and steel slag each shift conductivity, density, and specific heat together, and not in the same direction: glass and rubber lower conductivity, metallic slags raise it, recycled concrete aggregate raises porosity and moisture sensitivity at once. The response is non-linear with replacement ratio, so a measured series beats a predicted value.
C-Therm supports the U.S. Department of Energy-funded program with the Thermal Architecture Lab and Shu Yang Group at the University of Pennsylvania, characterising low-carbon concrete formulations with biomineral additives — measuring both thermal conductivity and specific heat to evaluate thermal-mass performance at building scale.
Measuring thermal conductivity and specific heat to evaluate thermal-mass performance at building scale
High-Voltage Duct Banks & Thermal Backfill
fluidized thermal backfill · thermal dryout curves · concrete encased duct bank
Underground cable ampacity is governed by how fast heat leaves the duct bank, which is set by the thermal resistivity (rho, °C·cm/W) of the encasement and surrounding backfill. Fluidized thermal backfill is engineered specifically to hold a low, stable rho, and utility specifications typically require testing to IEEE 442 and ASTM D5334.
The critical measurement isn’t a single value but the thermal dryout curve — rho as a function of moisture content. Cable heat drives moisture out of the backfill; past the knee of the curve, resistivity climbs sharply, the cable runs hotter, and the drying accelerates. That runaway is what pushes a circuit past its temperature rating, and ampacity design under Neher-McGrath and NEC Annex B depends on knowing where the knee sits. A well-designed FTB keeps it outside the expected service moisture range — which can only be demonstrated by measuring the same material across a controlled moisture series.
Power cables emerging from a backfilled trench — backfill thermal resistivity governs cable ampacity
Hempcrete, Bio-Based & Lightweight Concrete
hempcrete · bio-based concrete · sustainable construction materials · foamed and aerated concrete · lightweight aggregate concrete
Hemp-lime entered the 2024 International Residential Code as Appendix BL as non-structural wall infill and insulation. But the code’s values are density-indexed and permit interpolation, not extrapolation, so any mix outside the table needs measured data. Published hemp-lime conductivity runs about 0.06–0.11 W/m·K at 200–400 kg/m3, rising to 0.12–0.18 W/m·K at 450–800 kg/m3 — a narrow band across a wide density range, which makes measurement precision the limiting factor in formulation work.
Foamed concrete, autoclaved aerated concrete, lightweight aggregate mixes and aerogel-cement composites share the same problem: conductivity is set by pore structure and moisture rather than binder chemistry. They share a measurement problem too — rough, porous, irregular faces, where a conformable sensor earns its place.
0.52 W/m·K, reproducibility better than 5%. C-Therm measured a sliced lightweight concrete cylinder with the 13 mm Kapton FLEX TPS sensor at 0.5 W over a 40-second test. Ten measurements with sensor removal returned reproducibility better than 5%; ten consecutive without removal returned precision better than 2% RSD — the residual scatter tracking specimen inhomogeneity, not instrument performance.
Testing of lightweight concrete with TPS
Nuclear, Shielding & High-Temperature Concrete
radiation shielding concrete · reactor containment wall · nuclear civil/structural engineering · irradiated concrete · elevated temperature spalling · mass concrete
Magnetite, barite, serpentine, hematite and steel-slag heavyweight mixes are specified for attenuation — but their thermal behaviour governs the temperature gradient through a containment or biological shielding wall, and therefore the thermal stresses the structure carries. ACI 349 places temperature limits on safety-related concrete structures for exactly this reason. Heavyweight aggregates also push conductivity well above ordinary concrete, into a range where needle-probe methods run out of headroom; MTPS covers 0.01–500 W/m·K and handles dense mixes without difficulty.
Temperature and ageing raise further problems. In mass pours, heat of hydration must escape faster than it builds or the thermal gradient cracks the section, with thermal diffusivity (k / ρ·Cp) the governing input to the thermal control plan. In fire and accident scenarios, explosive spalling is driven by pore-pressure build-up from bound-water release, and both conductivity and heat capacity shift substantially as the material dehydrates. Neutron and gamma exposure add radiation-induced volumetric expansion and aggregate microcracking — altering thermal transport in ways that matter for subsequent-licence-renewal ageing-management cases, and for which measured data on irradiated specimens remains scarce.
Reactor hall interior — the surrounding containment and biological shielding concrete carry the thermal gradient
See It in Action
Request a demo to see how the C-Therm Trident delivers fast, accurate, and repeatable thermal conductivity measurements for concrete and cementitious materials.
Customer Success Stories
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University of Pennsylvania
… with the help of the C-Therm instrument we were able to robustly test the thermal properties of these samples with a high degree of precision.
Zherui WangBuilding Technology Researcher
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Toronto Metropolitan University
The thermal conductivity measuring device …is easy to operate. A new user would not face difficulty in using it. …it is suitable for testing cement-based composites and geopolymer which is very important for our research group. …equipment is a great addition to our research lab and will allow us to open a new area of research.
Khandaker M. Anwar Hossain, Ph.D., P.Eng.Professor
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Northeastern University, Boston
… I received a rare chance to see how their instrument works on my sample and hits the performance expectations I have. The sales team is professional and knowledgeable as they understand what their customer truly needs and the weight of purchase decision the customer faces on such instrument.
Melissa ChenResearch Scientist
Concrete & Cementitious Materials Webinars, Research & Application Videos
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Webinar: Thermal Conductivity Testing for Building Thermal Mass Performance in Cement
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Measuring Thermal Conductivity of Concrete | ASTM E3088, ISO 22007-2, ASTM D5334
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Webinar: Measuring the Thermal Conductivity of Novel Building Materials
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Webinar: Building a Sustainable Future with Efficient Materials
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Webinar: The Importance of Thermal Conductivity in Bio-Based Building Materials
Application Resources
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Trident™ Application Highlight: Thermal Conductivity of Concrete and Cementitious Materials
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Trident™ Application Highlight: Thermal Conductivity of Concrete Using the 60 mm TPS Sensor
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Printability, Thermal and Compressive Strength Properties of Cementitious Materials: A Comparative Study with Silica Fume and Limestone
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Theoretical Calculation Modeling of Thermal Conductivity of Geopolymer Foam Concrete in Building Structures Based on Image Recognition
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Structure–property relationships in mycelium biocomposites: Particle size and orientation as design parameters for hygrothermal and mechanical performance
Thermal Conductivity Instrument & Sensors for Concrete Testing
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Trident Thermal Conductivity Instrument
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MTPS Sensor
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TPS Sensors
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TLS Sensor
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TPS Setup on Trident
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TPS Clamp with Samples
Technical Specifications
C-Therm Trident – Comparison of Methods
| Specification | MTPS (cured concrete, cores, cut slabs, cube faces) |
TPS (aggregates, powders, anisotropic composites) |
TLS (fresh mixes, grouts, thermal backfill) |
|---|---|---|---|
| Thermal Conductivity Range | 0.01–500 W/m·K | 0.005–2000 W/m·K | 0.1–6 W/m·K |
| Volumetric Heat Capacity | Up to 5 MJ/m³·K* | Up to 5 MJ/m³·K | – |
| Temperature Range | –50 to 200°C | –200 to 600°C | –55 to 300°C |
| Precision | Better than 1% | Better than 2% | Better than 3% |
| Accuracy | Better than 5% | Better than 3% | ± (3% + 0.02) W/m·K at 20 °C |
| Test Time | 0.8–3 s | 10–180 s | Less than 4 min |
| Sensor Dimensions | Ø18 mm | Ø6, Ø13, Ø30 mm sensors | 150 mm length |
| International Standards | ASTM D7984 | ISO 22007-2 ASTM E3088 |
ASTM D5334 |
*Calculated parameter
Frequently Asked Questions
Several, depending on specimen state. ASTM D7984 covers the Modified Transient Plane Source (MTPS) method, used for cured concrete, cores, and cut faces. ASTM D5334 covers the transient line source needle probe, used for fresh mixes, grouts, and thermal backfills, and is referenced alongside IEEE 442 in utility specifications. ASTM C518 (heat flow meter) and ASTM C177 (guarded hot plate) are the steady-state standards used for assembly-level R-value declarations. ISO 22007-2 covers the transient plane source method. It is a common misconception that no dedicated standard exists for concrete — the correct answer is that the applicable standard depends on whether the specimen is fresh, cured, or an assembly.
To discuss which standard applies to your specimens, contact us or book a demo with one of our experts.
For cured specimens, the fastest route is MTPS to ASTM D7984: place the single-sided sensor against a flat cast face, saw-cut core, or cube face and read a result in under three seconds. No machining, guard ring, or thermal grease is required. Condition specimens to a defined moisture state first — oven-dry, saturated surface-dry, or equilibrated to a target RH — and report that state with every value, because concrete conductivity is strongly moisture-dependent. For fresh or flowable mixes, cast a TLS needle probe into the specimen and measure to ASTM D5334.
To discuss your specific sample, contact us or book a demo with one of our experts.
An MTPS measurement takes 0.8 to 3 seconds on the C-Therm Trident; a TPS measurement takes 10 to 180 seconds depending on sensor and sample. Allowing for repeat positions and repositioning, a specimen is typically characterised in under a minute, and a mix-design matrix of a dozen formulations can be screened in a single session. Steady-state methods such as the guarded hot plate or heat flow meter need hours per specimen to reach equilibrium, which is why they suit final assembly-level verification rather than formulation screening.
Use MTPS (ASTM D7984) for cured specimens where speed and non-destructive testing matter: mix screening, QC, cores, and dense or heavyweight mixes up to 500 W/m·K. Use TPS (ISO 22007-2) where the specimen is porous, irregular, or better suited to a double-sided configuration — hempcrete, foamed and aerated concrete, and sliced cylinders — and for aggregates and powders, or where anisotropic data is needed. Use the TLS needle probe (ASTM D5334) where the material is fresh, flowable, or granular: plastic-state mixes, grouts, and fluidized thermal backfill. Use a steady-state heat flow meter (ASTM C518) where you need an assembly-level R-value for a code submission. They are complementary rather than competing, and C-Therm supplies all four.
To discuss your specific sample and the most suitable method, contact us or book a demo with one of our experts.
Thermal mass is volumetric heat capacity — density multiplied by specific heat — not thermal conductivity. A complete characterisation therefore needs three measurements: thermal conductivity (MTPS to ASTM D7984), specific heat (differential scanning calorimetry), and bulk density. Together these give thermal diffusivity, which is the input building-energy models actually consume. Measuring conductivity alone describes a mix’s insulating behaviour but not its ability to store and release heat over a daily cycle — which is the property that moderates indoor temperature swings and reduces HVAC load.
To discuss further, contact us or book a demo with one of our experts.
Published hemp-lime values fall roughly between 0.06 and 0.11 W/m·K at dry densities of 200–400 kg/m³, rising to about 0.12–0.18 W/m·K between 450 and 800 kg/m³. The 2024 International Residential Code, Appendix BL, provides code-permitted values indexed by density and allows interpolation but not extrapolation, so mixes outside the tabulated range require measured data. Because hemp-lime is highly hygroscopic, conductivity should be measured at a controlled, reported moisture state — a dry-state value alone understates in-service conductivity. MTPS measures a cast or cut hempcrete face directly with no specimen preparation.
Yes. For plastic-state and early-age material, the transient line source needle probe (ASTM D5334) is cast directly into the specimen, placing the heat source in intimate contact with the mix, and allowing the same specimen to be tracked through curing. Once the specimen has hardened enough to present a flat face, MTPS can be used for non-destructive repeat measurements on that same specimen over time.
Substantially — water conducts heat far better than the air it displaces in the pore network, so a saturated specimen can measure well above the same specimen oven-dry. The effect is largest in porous, lightweight, and bio-aggregate systems. A conductivity value is therefore only meaningful when reported with its moisture state, and comparisons between mixes must be made at matched conditioning. Where moisture varies in service — thermal backfills, external renders, hempcrete walls — measure across a moisture series rather than at a single point.
For MTPS, a flat face is sufficient — a cast face, saw-cut core, or cube face. No lapping, polishing, parallel-facing, or thermal grease, and the measurement is non-destructive, so the specimen can be tested repeatedly or subsequently used for mechanical testing. For TLS, the probe is cast into fresh material or inserted into a drilled hole in a cured specimen. For steady-state heat flow meter testing, specimens must be cut to apparatus dimensions with parallel faces — the main reason steady-state methods are slower.
Yes, by two routes. Residual properties are measured on cooled specimens after a heating regime using MTPS, which suits pre- and post-exposure comparison on the same specimen. In-situ elevated-temperature behaviour is measured with C-Therm’s High-Temperature Heat Flow Meter, rated to 850 °C. Because explosive spalling is driven by pore-pressure build-up during bound-water release, simultaneous thermal analysis (STA/TGA) is usually run alongside to characterise the dehydration steps.
To discuss Trident and the High-Temperature Heat Flow Meter, contact us or book a demo with one of our experts.
Thermal resistivity (rho, °C·cm/W) is the reciprocal of thermal conductivity, and utility specifications for fluidized thermal backfill typically call for testing to IEEE 442 and ASTM D5334 using a thermal needle probe. The probe is cast into the FTB specimen so the line source is in intimate contact with the material. For cured duct-bank encasement, MTPS can be used on cored specimens for hardened-state verification. Ampacity calculations under Neher-McGrath and NEC Annex B take rho as a direct input, so measurement accuracy translates into cable sizing.
You may contact us or book a demo with one of our experts to discuss the details.
A thermal dryout curve plots thermal resistivity against moisture content for a soil or backfill material. It matters because cable heat drives moisture out of the surrounding material: as moisture drops past the knee of the curve, resistivity rises sharply, the cable runs hotter, and the drying accelerates — a runaway condition that can push a circuit past its temperature rating. Fluidized thermal backfill is engineered to keep that knee well outside the expected service moisture range. Building the curve requires measuring the same material across a controlled moisture series, which the TLS needle probe method supports directly.