07/15/2004 Env Bd Packet - Laserfiche WebLink

Home Search

`? is STS Laboratory Index Test Procedures Water Content (Wc) (ASTM 2216) The water content of a soil is the ratio of the weight of water in a given soil mass to the weight of the dry soil. Generally, the soil is dried in a conventional or microwave oven. Water content is commonly expressed as a percentage. Hand Penetrometer (Qp) In the hand penetrometer test, the unconfined compressive strength of a soil is estimated, to a maximum value of 4.5 tons per square foot (tsf), by measuring the resistance of a representative portion of a cohesive soil sample to penetration by a 1/4 -inch diameter, spring - calibrated cylinder. Results from penetrating into a stone or obviously disturbed portions of the sample are generally disregarded. Hand penetrometer testing has been carefully correlated with unconfined compressive strength tests, and when performed correctly provides a useful and a relatively simple testing procedure in which soil strength can be quickly and reliably estimated. Unconfined Compression Test (Qu) (ASTM D 2166) In the unconfined compression strength test, a undisturbed cylinder of cohesive soil 2 to 3 inches in diameter with a height of 4 to 6 inches is loaded axially until failure or until a 20% stain has been reached, whichever occurs first. It provides an indication of the samples undrained shear strength. Atterberg Limits (ASTM D 318) Atterberg Limits tests provide a measure of a cohesive soils plasticity. The liquid limit is the water content at which a 1/2 -inch wide groove that is cut into a shallow cup of remolded soil closes with 25 10mm drops of the cup. The plastic limit is the water content below which the soil . no longer behaves as a plastic material based on behavior of rolled soil ribbons. The Plasticity Index is the difference between the liquid and plastic limits. Grain Size Analysis (ASTM D 422) Grain size analyses are performed to determine the distribution of particles by weight for a soil sample. The distribution of particles larger than 0.075 mm (retained on a No. 200 sieve) is determined by sifting a dried and broken soil sample through a series of generally smaller sieves, then weighing the retained portions. If specified, the distribution of particles smaller than 0.075 mm is also determined using a hydrometer to determine particle dispersion and settlement within water. Classification of Samples In conjunction with the sample testing program, retained soil samples are examined in our laboratory and are classified on the basis of their texture and plasticity in accordance with the United Soil Classification System (USCS). The soil descriptions on the boring logs are in conformance with this system and the estimated group symbols according to this system are included in parentheses following the soil descriptions on the boring logs. A separate sheet entitled "STS Soil Classification System" provides a brief explanation of this system of soil classification and is also included in the Appendix.