Evaluation Of Nuclear Gauge As A Prospective Quality Control Tool In Pavement Construction

Author : Robert L. Parsons
Publisher :
ISBN 13 :
Total Pages : 100 pages
Book Rating : 4.3/5 (555 download)

DOWNLOAD NOW!

Download or read book Evaluation of Soil Modification Mixing Procedures written by Robert L. Parsons and published by . This book was released on 2001 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lime is routinely used as a soil modification agent in Kansas to improve the performance of subgrade soils with the primary goal of reducing volume change. Effective mixing of lime and soil is critical to ensuring that the expected improvements occur throughout the soil mass. The results are presented herein on the effectiveness of current soil-lime mixing and construction procedures for five soils treated with powdered quicklime or lime slurry. A series of tests was performed on each soil as part of the evaluation process. Test procedures included field density determination, dynamic cone penetrometer, unconfined compression, lime content, pH, Atterberg limits, swell testing, and determination of the maximum unit weights and optimum moisture contents for the native soil and lime treated soil. The effect of significantly reducing the mellowing period for ease of construction was evaluated and determined to negatively affect subgrade compaction and strength due to high water contents remaining from the mixing process. Additionally, the results of the testing showed that two passes with a rotary mixer were sufficient to effectively pulverize and mix the soil and lime to achieve modification. However, the results also suggested that there was the potential for additional strength gains with additional mixing. The consistency of lime distribution on a larger scale was also evaluated and determined to be adequate at the locations observed, although there was some evidence that the mixing of soil with lime in a slurry form appeared to yield a more consistent final product than mixing with powdered quicklime. Several recommendations were proposed for consideration by the Kansas Department of Transportation for soil modification procedures. These included moving from a specified percentage of lime for all projects to a lime percentage based on soil testing. Recommendations also included the introduction of a mellowing period after preliminary mixing to allow the lime more time to react with the soil to break down clay lumps and to give the soil time to dry to a water content closer to optimum. Also proposed for consideration was the adoption of National Lime Association specifications for final mixing, which include the use of AASHTO T-180 as the compaction standard and requiring rotary mixing during the final stage of mixing. Further evaluation of the performance of soils mixed with lime slurry compared with soils mixed with quicklime was recommended to determine if lime slurry yields a significantly better product. Other recommendations proposed for consideration included an evaluation of the benefits of making soil stabilization a goal of soil treatment and taking advantage of the benefits of including the stabilized layer as a component in the pavement design. Construction costs beyond those already incurred for modification should be relatively small and the additional structural benefits could yield significant savings.