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From this, the dry density could be determined by simply measuring the weight of the soil before and after compaction, calculating the moisture content, and furthermore calculating the dry density. Ralph R. Proctor went on to teach at the University of Arkansas. In 1958, the modified Proctor compaction test was developed as an ASTM standard.
The unit weight of a soil when all void spaces of the soil are completely filled with air, with no water. The formula for dry unit weight is: = + = + where γ is the moist unit weight of the material; γ d is the dry unit weight of the material; γ w is the unit weight of water; w is the moisture content of the material; G s is the specific ...
Water content or moisture content is the quantity of water contained in a material, such as soil (called soil moisture), rock, ceramics, crops, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed as a ratio, which can range from 0 (completely dry) to the value of the materials' porosity at saturation.
Changes of pore water content due to drying or wetting processes cause significant volume changes of concrete in load-free specimens. They are called the shrinkage (typically causing strains between 0.0002 and 0.0005, and in low strength concretes even 0.0012) or swelling (< 0.00005 in normal concretes, < 0.00020 in high strength concretes).
Saturated surface dry (SSD) is defined as the condition of an aggregate in which the surfaces of the particles are "dry" (i.e., surface adsorption would no longer take place), but the inter-particle voids are saturated with water. In this condition aggregates will not affect the free water content of a composite material. [1] [2]
The test hammer hits the concrete at a defined energy. Its rebound is dependent on the hardness of the concrete and is measured by the test equipment. By reference to a conversion chart, the rebound value can be used to determine the concrete's compressive strength. When conducting the test, the hammer should be held at right angles to the ...
Traditional concrete has a water:cement ratio of about 0.5, which refers to the weight of the water divided by the weight of the cement. A water:cement ratio of 0.5 provides good workability while keeping the amount of excess water in the mix fairly low. Without at least this much extra water, the concrete would be too dry to place.
If the water table is at depth d w in fine-grained soils, then the pore pressure at the ground surface is: [4] =, where: p g is the unsaturated pore water pressure (Pa) at ground level, g w is the unit weight of water (kN/m 3), = / d w is the depth of the water table (m),