From Bending to Torsion to Tension: Multi-Fixture DMA Characterization of Asphalt Shingles

Dynamic mechanical analyzers (DMA) can precisely quantify the viscoelastic properties of materials as a function of temperature, time, frequency and amplitude.  It offers a wide range of well-established testing and analysis methods, including tension, bending, compression, torsion and combined axial-torsional loading modes. Different fixtures such as three-point bending (TPB), single cantilever (S-CTL) and solid rectangular fixtures (SRF) were used to characterize the mechanical performance of individual asphalt shingles. These methods coupled with fixtures enable evaluation of properties such as force–displacement behavior, creep and recovery, relaxation and thermal expansion effectively. Additionally, by choosing   same fixture but different sizes, shingle behavior under varying mechanical constraints can be assessed to simulate real world service conditions.

Different deformation modes on the DMA device can represent different practical service conditions for asphalt shingles. Bending motion can simulate the natural sagging that occurs during storage or handling. Folding deformation can mimic wind-induced uplift that may cause shingles to bend upward and potentially fracture. Torsional deformation can reflect the material’s resistance to twisting or tearing forces.

Two major challenges will be discussed in this study: ensuring consistency in shingle sample preparation to achieve reproducible results and selecting appropriate geometries to represent specific mechanical conditions. Experimental results demonstrate that reliable and repeatable DMA measurements can be obtained for asphalt shingles when proper sample preparation and geometry selection are implemented.

Key takeaways:

• Features and Applications of Different DMA Fixture Types
• Using DMA to Evaluate the Mechanical Performance of Asphalt Shingles
• Converting Real-World Performance Questions into DMA Test Methods