ASTM Test Method for Classification of Soils for Engineering Purposes (D 2487) was significantly revised in 1983. The revisions require that soil is to be classified by using both a symbol and a name, and the group names were standardized. Organic silts and clays were redefined to recognize that organic soils occur that plot above the “A” line on the plasticity chart. More precise guidelines were established, particularly with regard to plasticity, so that only one particular classification will result. If boarderline classifications are used, the classification symbols are separated with a slash with the classification symbol indicated using the standard appearing first. Appendixes give example written descriptions, preparation of soil for testing, and guidelines for using the system for materials such as shale, mudstone, crushed rock, and slag

The USA and USSR jointly constructed a special test section of 915-mm diameter Reinforced Plastic Mortar (RPM) fiberglass pipe in June 1979 near Riga, Latvia. This experiment was part of the working agreement of the US-USSR team “Investigations of Effectiveness of Plastic Pipe in Drainage and Irrigation.” Measurements were made of pipe deflections, soil properties, and in-place densities. Six different embedment conditions were used. The pipe deflections were measured during each state of construction and over a 4-year period. Data of particular interest is the increase in the vertical diameters caused during soil compaction at the sides of the pipe and the frequent deflection measurements in the few weeks following the final placement of the 3 m of backfill over the pipe. The ratio of the vertical deflection after 4 years to the vertical deflection on the day the backfilling was completed ranges from 1.6 to 1.7 for the dumped side support, 4.5 for a side support with a moderate degree of compaction, and 2.2 to 2.9 for the side support placed to a high degree of compaction.

Soil-cement slurry used in buried pipe installations has become an increasing popular choice for contractors. Flexible pipe, including PVC and RPM, as well as rigid pipe are being installed using this technique. The ingredients of the soil-cement can vary, but typically is a combination of soil, portland cement, and water. In most cases, the pipe trench is trimmed to a semicircular shape that is only slightly larger than the pipe diameter. The soil-cement is used to fill the gap between the pipe and the in situ soil. Accordingly, the native trench material must be able to provide adequate supporting strength to the pipe. The consistency of the soil-cement can vary from a fluid (slurry) to a mixture with a 25 cm slump depending on the placement requirements. The consistency, ingredients, and placement dimensions can all vary as long as two basic requirements are met: 1. The material must be placed so that there is complete contact between the pipe and the in situ soil. 2. The unconfined compressive strength of the hardened material is at least 700 kN/m2 (100 1b/in2) at 7 days. The most suitable soil to use is a silty sand with the fines content not exceeding about 30 percent. This allows native soils from the trench excavation or from nearby the construction site to be used. Cementitious fly ash has been used in place of cement and bentonite has been added to improve pumping characteristics.

ASTM Practice for Description and Identification of Soils (Visual-Manual Procedure) (D 2488) was significantly revised in 1984. Revisions were made to parallel the recent changes in ASTM Classification of Soils for Engineering Purposes (D 2487) and to reflect more of current practices used for visual-manual description and identification. Where possible, the number of terms for descriptive information (dry strength, moisture condition, and so forth) was reduced, and the criteria for deciding which term to use were made less subjective. Criteria for describing particle shape and for describing cementation of coarse-grained soils were added. Appendixes give example written descriptions, procedures for estimating particle size distribution, and guidelines for using the system for materials such as shale, mudstone, crushed rock, and slag.

Minimum test specimen masses are recommended for determining the moisture content of soils. The specimen mass is dependent on the accuracy required, the maximum particle size present in the soil being tested, and the estimated moisture content of the soil. Equations are presented to calculate the minimum specimen mass required and nominal values are shown in a table.