Comparative accuracy of photogrammetry for volume measurements in shrinkage limit tests of soils with varying plasticity

The use of photogrammetry for measuring specimen volume in shrinkage limit tests was evaluated. Photogrammetry (M3) was applied to four soils, from low-plasticity clay (CL) to high-plasticity clay (CH), in rings of approximately 40 mm × 12 mm. The results were compared with shrinkage limits determined with ASTM D4943-08 (Archimedes’ principle, M1), the reference method, and with calipers (M2). Three-dimensional models were generated from digital camera images. For Soils 1 to 3, the shrinkage limits from M3 were within 0.5 to 2.0 percentage points of M1, compared with 1.4 to 2.4 percentage points for M2. Soil 4 was too plastic to test. For a solid object with well-defined dimensions, the volumes were 168.3, 168.9, and 167.8 cm3 with M1, M2, and M3, and the errors of M2 and M3 were 0.39 and 0.26%. Photogrammetry is therefore a promising non-contact method for determining soil volume and the shrinkage limit.