Hi guys I need some help in my pavement design class for thi

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Drainage Provisions :

Drainage problems are frequently a major cause of parking area pavement failures.This is especially the case with irrigation sprinkler systems located in parking lot islands and medians.As a general guideline, parking area surfaces should have a minimum slope of 2 percent (2%) or 1/4 inch per foot. In saturated areas,the use of HMA base (compared to use of untreated aggregate base) will greatly reduce the potential for strength and stability problems.

Subgrade Preparations :

All underground utilities should be protected or relocated before grading. All topsoil should be removed. Low quality soil may be improved by adding granular materials, lime, asphalt, or other mixtures to stabilize the existing soils.Laboratory tests are recommended to evaluate the load­supporting characteristics of the subgrade soil.The subgrade should be compacted to a uniform density of 95 percent of the maximum density.If the subgrade is a finegrained silt or clay, a separation fabric should be considered for use to prevent the finer material in the subgrade from inundating the more open­graded layers to be placed as a part of the pavement section.

Untreated Aggregate Base Construction:

The untreated aggregate base course section based on the pavement design, should consist of one or more layers placed directly on the prepared subgrade, with or without a separation fabric, depending on soil type. It should be spread and compacted with moisture control to the uniform thickness, density and finished grade as required on the plans. The minimum thickness of untreated aggregate base course is four inches for Class 6 (3/4”) material. The minimum thickness should be increased for larger (1½” or 3”) material. The aggregate material should be of a type approved and suitable for this kind of application.

Prime Coat:

An application of low viscosity liquid asphalt may be required over untreated aggregate base before placing the HMA surface course. A prime coat and its benefits differ with each application, and its use often can be eliminated. Discuss requirements with the paving contractor.If a prime coat is used, AEP(asphalt emulsified prime) should be specified as it is designed to penetrate the base material. The use of a tack coat is not recommended for use as prime coat.

Hot Mix Asphalt (HMA) Base Construction:

The asphalt base course material should be placed directly on the prepared subgrade in one or more lifts. It should be spread and compacted to the thickness indicated on the plans.Compaction of this asphalt base is one of the most important construction operations contributing to the proper performance of the completed pavement. This is why it is so important to have a properly prepared and unyielding subgrade against which to compact. The HMA base material should meet the specifications for the mix type specified.

Tack Coat:

Before placing successive pavement layers, the previous course should be cleaned and a tack coat of diluted emulsified asphalt should be applied if needed. The tack coat may be eliminated if the previous coat is freshly placed and thoroughly clean.

Hot Mix Asphalt (HMA) Surface Course:

Material for the surface course should be an HMA mix placed in one or more lifts to the finished lines and grade as shown on the plans. The plant mix material should conform to specifications for Superpave hot mix asphalt.