You can have the most powerful diesel earth compactor on the market, but if your soil is too dry or too wet, you will never hit your 95% Modified Proctor density. In geotechnical engineering, every soil type has an Optimum Moisture Content (OMC). If the soil is bone dry, the particles have too much friction to slide together; if it’s saturated, the water is incompressible and pushes the particles apart (a phenomenon called "pumping"). The "hand-squeeze test" is the veteran's way to check: if the soil holds its shape but doesn't stain your glove with water, it's usually ready. For professional jobs, we use a Nuclear Density Gauge to verify that the impact rammer or plate has achieved the required stiffness. Compaction is a science of balance between mechanical force and soil chemistry.
