Soil Materials Testing

Soil Material Testing

Abstract

In the past, material classification for soils has been heavily based on plasticity. Soil material classification is important in the construction of roads, as the longevity of a road is partially dependent on the structure of the soil beneath it. In order to improve these characteristics in soil, various stabilizing agents are used, which come in three different forms: mechanical, chemical, and bituminous. Being able to correctly identify what stabilizing agent is best suited to improve the mechanical properties is quintessential to effectively repairing roads. Although the material classification for soils is typically determined through plasticity, the soils around upstate New York have plasticity levels that make this classification extremely difficult to do. Thus, a new design chart, based on tests such as sand equivalent and sieve analysis, is being developed in order to improve the precision of soil material classification.

Summary

In March 2021, an inventory was compiled of over 32+ samples of soil from different parts of upstate New York. Each of these materials is currently in the process of being tested through 3 different test compliant with the ASTN standards. Each of these methods, linked with their official ASTN document, test different physical properties of the soil samples

1. Sand Equivalent Testing Method to test the proportion of fines + dusts in a sample

2. Hydrometer and Sieve Analysis Testing Method to test the percentages of sizes of soil particles

3. Liquid Limit, Plastic Limit, and Plasticity Index to test the cohesion of a soil sample

Example image of the layers of the construction of a road. This research project focuses on the sub base and sub-grade of a flexible pavement.

Chart of the gradation of soil, determined by silt percentage, sand percentage, and clay percentage. Red circle is the ideal ratio for road construction.

In-Progress Developments

Working on finishing the basic tests for every sample. This involves the initial sample which uses a splitter and various drying methods, followed by the implementation of the 3 ASTN tests listed above. (Currently: 1/3 of the way through!)
Analyzing the recorded data by creating Excel graphs.
Graphing the resulting percentage on the gradation of soil graph, this will create a visual chart of the soil samples and where they stand on the chart. From there, mechanical tests on how to improve the soil samples for road construction use. Examples include: altering the ratio of size particles, adding cement, or adding asphalt.