Method and apparatus for determining stiffness of a roadway

Abstract

An apparatus for the compaction of roadway materials includes a compaction analyzer for calculating stiffness during construction of the roadway. The apparatus generates a dynamic modulus for each layer of a roadway which can be used to calculate the overall effective modulus. A method for determining stiffness includes generating a dynamic modulus for each layer and calculating the overall effective modulus using the modulus of each layer.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]Priority is claimed from U.S. Provisional Application Ser. No. 61 / 621,259, entitled “Method of Determining Stiffness” filed Apr. 6, 2012.BACKGROUND OF THE INVENTION[0002]The current disclosure is directed to methods and apparatus for the compaction of roadway materials, and more particularly, to methods and apparatus for calibrating a compaction analyzer, and determining stiffness during construction.[0003]Asphalt is often used as pavement. In the asphalt paving process, various grades of aggregate are used. The aggregate is mixed with asphalt cement (tar) and sand, and heated to approximately 150° C. to 169° C., and a paver lays down the hot asphalt mix and levels the asphalt mix with a series of augers and scrapers. The material as laid is not dense enough due to air voids in the asphalt mix. Therefore, a roller makes a number of passes over the layer of asphalt material, referred to herein as the asphalt mat, driving back and forth, or...

AI Technical Summary

Benefits of technology

The present invention is an apparatus and method that can easily achieve its goals. It has certain advantages and options for improvement. The skilled person can modify certain parts and steps of the invention, while still staying within the scope of the present invention.

Problems solved by technology

The material as laid is not dense enough due to air voids in the asphalt mix.

The process of measuring density of the asphalt mat during the compaction process is cumbersome, time-consuming, and is not indicative of the overall compaction achieved unless measurements are taken at a large number of points distributed in a grid fashion, which is difficult to achieve in the field due to cost considerations alone.

Failure to meet the target density is unacceptable and remedial measures may result in significant cost overruns.

Early deterioration of pavements due to rutting, fatigue cracking, and other types of distresses may be attributed to inadequate stiffness achieved during the compaction process.

Remedial measures to rectify inadequate compaction after pavement has cooled down are costly and time consuming.

While density of an asphalt mix is a measure of its quality it does not directly provide information of the performance of the pavement under loading conditions.

Stiffness on the other hand directly impacts the performance of a pavement under traffic loads.

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