PDH Engineer     PE PDH
PDH Online

Soil Stabilizations for Pavements


Quiz Questions

1.The definition of soils would be naturally occurring materials that are used for the construction of all except the surface layers of pavements (i.e., concrete and asphalt) and that are subject to classification tests ( ASTM D 2487) to provide a general concept of their engineering characteristics.
True
False
2. The definitions of additive would be manufactured commercial products that, when added to the soil in the proper quantities, improve some engineering characteristics of the soil such as strength, texture, workability, and plasticity. Additives addressed in this manual are limited to Portland cement, flyash, and bitumen.
True
False
3.Pavement design is based on the premise that minimum specified structural quality will be achieved for each layer of material in the pavement system. Each layer must resist shearing, avoid excessive deflections that cause fatigue cracking within the layer or in overlying layers, and prevent excessive permanent deformation through densification. As the quality of a soil layer is increased, the ability of that layer to distribute the load over a greater area is generally increased so that a reduction in the required thickness of the soil and surface layers may be permitted.
True
False
4.Stabilization is the process of blending and mixing materials with a soil to improve certain properties of the soil. The process may include the blending of soils to achieve a desired gradation or the mixing of commercially available additives that may alter the gradation, texture or plasticity, or act as a binder for cementation of the soil.
Ture
False
5.The most common improvements achieved through stabilization include better soil gradation, reduction of plasticity index or swelling potential, and increases in durability and strength. In wet weather, stabilization may also be used to provide a working platform for construction operations. This type of soils quality improvement is referred to as soil modification.
True
False
6.The strength and stiffness of soil layer can be improved through the use of additives to permit a reduction in design thickness of the stabilized material compared with an unstabilized or unbound material.
True
False
7.A typical slurry mix proportion is 1 ton of lime and 500 gallons of water, which yields about 600 gallons of slurry containing 31 percent lime solids. At higher concentrations there is difficulty in pumping and spraying the slurry.
Ture
False
8.In some areas where extremely plastic, gumbo clay (PI 50+) abounds, it may prove advantageous to add the requisite amount of lime in two increments to facilitate adequate pulverization and obtain complete stabilization. For example, 2 or 3 percent lime is added first, partially mixed, and then the layer is sealed and allowed to cure for up to a week. The remaining lime is then added preparatory to final mixing. The first application mellows the clay and helps in achieving final pulverization, and the second application completes the lime-treatment process.
Ture
False
9.The most important factors for cement stabilization are:
Pulverization
Cement content
Moisture content
Uniformity of mixing
Time sequence of operations
Compaction and curing
True
False
10.The most important factors in lime stabilizations are:
Pulverization and scarification
Lime content
Uniformity mixing
Time sequence of operations
Compacting and curing
Ture
False
11.The most important factors in bituminous stabilization are:
Surface moisture content
Asphalt content
Uniformity of mixing
Aeration
Compaction
Curing
Viscosity of asphalt
True
False