Articles

November Technical Speaker 1

ADVANCES IN DESIGNING AND MONITORING FIELD COMPACTION: M-D Relations

Professor C. Vipulanandan (VIPU), Ph.D., P.E.

Director of CIGMAT & Director of THC-IT

During the past few decades, use of compacted soils (three phase materials) for embankments, pavement subgrades, earthen dam and levee construction, and retaining wall backfills has seen tremendous growth.  Quality civil infrastructures require better long-term performance and lower maintenance costs. Compaction characteristics of soils depends on several factors such as moisture content, applied compaction energy, air content and soil physical properties which affects the degree of saturation at the optimum compaction. In the case of fine-grained soils that interact with water, the density and other properties achieved by compaction depend not only on the water content and compaction effort but also on the type of soil. Hence there is a need for effectively combining the advances in field compaction and monitoring technologies to meet the loading requirements on compacted soils. Technological advances in the areas of compaction, monitoring, and pre-compaction control information can be effectively combined to meet the specifications in the field productively with full engineering and construction control. Recently, Texas Department of Transportation (TxDOT) adopted a compaction specification for embankments where computer generated field compaction curves can be used.

The presentation will also focus on issues related to the advancements in the compaction of soils using modern Intelligent Compactors (IC). Also the limitation of IC, some of the current practices and advances in knowing compacted soil performance and field moisture-density (M-D) relationships will be discussed. There is a need for better characterizing the properties of field compacted soils during construction because it is important to ensure the quality of construction. Several studies have focused on developing devices to measure the modulus of compacted soils. A new surface penetrometer (SP-CIGMAT) was developed and used to evaluate compacted soil undrained shear strength during the construction. This device can be easily attached to any construction vehicle to perform tests on compacted soils during construction. Based on the limited field data, non-linear relationship between the SP-CIGMAT deflection and compacted soil strength has been developed.

Cumaraswamy Vipulanandan (Vipu) is a professor of civil and environmental engineering at the University of Houston (UH), Houston, Texas and has been with UH since 1984.  He is the Director for the Center for Innovative Grouting Materials and Technology (CIGMAT) and the Texas Hurricane Center of r Innovative Technology. He received his MS and PhD in Civil Engineering from Northwestern University, Evanston, Illinois. He has worked on 75 funded research projects totaling over $12 million and has resulted in more than 200 refereed journal and conference papers and over 150 presentations at national and international conferences.