The Expansion Index test is a simple and effective method for predicting swelling potential of compacted soils. A soil specimen is moisture conditioned to 50% saturation, and compacted into a 4in (102mm) diameter mold. After a confining load is applied, the specimen is immersed in water, and volumetric swell is recorded for up to 24 hours. The expansion index, or EI, is calculated from these measurements. A high EI value indicates a need to design structures and pavements for expansive soils.
The unique, self-contained design does not require a separate consolidometer loading device to mount, load, and saturate the specimen for testing. After compaction into the 4x1in (101.6x25.4mm) IDxH stainless steel ring, the specimen is placed in the HM-562 Consolidometer with a closely fitting, air-dry porous stone at each end and loaded with the stainless steel weight. After consolidating for ten minutes, the assembly is immersed in distilled water to initiate the test.
All immersed parts are either stainless steel or anodized aluminum for durability and corrosion resistance. Included are an anodized aluminum base and collar with stainless steel hold-down rods, stainless steel specimen ring, 12.6lb (5.7kg) loading weight, and porous stones. MA-333 0.5in range x 0.0001in resolution dial indicator is required for the test (purchased separately). Additional Porous Stones, Stainless Steel Specimen Rings, and Loading Weights are purchased for more efficient sample preparation.