A Model for the Prediction of Subgrade Soil Resilient Modulus for Flexible-pavement Design

A Model for the Prediction of Subgrade Soil Resilient Modulus for Flexible-pavement Design
Author: Beresford O. A. Davies
Publisher:
Total Pages: 182
Release: 2004
Genre: Pavements
ISBN:

Subgrade soil plays a very important role in the construction of roadways. Before the use of asphalt in the construction of roadway, roads were being constructed based on experience. The introduction of paving asphalt in road construction has led to the development of engineering procedures and designs for the methods of construction. The resilient modulus of the underlying material supporting the pavement is now considered as a key material property in the AASHTO mechanistic-empirical design procedure. Attempts have been made by researchers to predict the Subgrade resilient modulus from laboratory/field experimental methods based on the soil properties. This research seeks to develop a model for predicting the subgrade resilient modulus due to environmental conditions by considering the seasonal variation of temperature and moisture content which affects the soil. The limitation of this research model is that it cannot be used universally since environmental conditions vary from place to place, however, it can be modified to suit other local environmental conditions. The detrimental effect of low resilient modulus of subgrade soil is observed in the damaged analysis.

Evaluation of Procedure to Estimate Subgrade Resilient Modulus for Use in Pavement Structural Design

Evaluation of Procedure to Estimate Subgrade Resilient Modulus for Use in Pavement Structural Design
Author: Harold L. Von Quintus
Publisher:
Total Pages: 54
Release: 2007
Genre: Pavements, Asphalt
ISBN:

The Kansas Department of Transportation (DOT) uses the 1993 DARWin version of the 1986 AASHTO Guide to design rigid and flexible pavements. One of the inputs needed for the flexible pavement design procedure is the modulus of the subgrade soils, which has an effect on the total pavement thickness. Different procedures can be used to estimate the effective roadbed resilient modulus for flexible pavement design and effective modulus of subgrade reaction for rigid pavement design. As part of the study entitled Determination of the Appropriate Use of Pavement Surface History in the KDOT Life-Cycle Cost Analysis Process, an evaluation of the procedure that Kansas DOT uses to estimate the effective subgrade resilient modulus was completed. This report provides the results of that evaluation.

Field and Laboratory Determination of Subgrade Resilient Modulus and Its Application in Pavement Design

Field and Laboratory Determination of Subgrade Resilient Modulus and Its Application in Pavement Design
Author: Richard Ji
Publisher:
Total Pages: 11
Release: 2014
Genre: Flexible pavement design
ISBN:

This paper presents a comparison study of the experimental results from the falling weight deflectometer (FWD) test and laboratory resilient modulus test on granular subgrade materials and its application in flexible pavement design. Field and laboratory testing programs were conducted to develop a practical methodology for estimating resilient modulus (Mr) values of subgrade soils for use in the design of pavement structures. Soil characterization database was established for lab testing. A multiple regression model can be used to predict Mr value using several factors including soil properties, soil type and state of stresses for three popular American Association of State Highway and Transportation Officials (AASHTO) soil types (A-4, A-6, and A-7-6) in Indiana, and these prediction models developed were verified compared with laboratory Mr tests with high R2 value. In situ Mr seasonal variation based on abundant FWD test data in five field testing sites spread in Indiana was conducted in order to find the correlation between resilient modulus, temperature, and precipitation for the period from 2006 to 2012. The proposed method can accurately predict subgrade Mr of lab testing. However results from lab testing are significantly lower than recommended range by mechanistic-empirical pavement design guide (MEPDG) and backcalculation one using an adjust factor of 3. The design examples showed that the seasonal variation of temperature and precipitation as well as traffic can affect the design thickness by as much as 15 to 20 % in general. The findings of this study are expected to be helpful in the implementation of the pavement design in Indiana and elsewhere.

AASHTO Guide for Design of Pavement Structures, 1993

AASHTO Guide for Design of Pavement Structures, 1993
Author: American Association of State Highway and Transportation Officials
Publisher: AASHTO
Total Pages: 622
Release: 1993
Genre: Pavements
ISBN: 1560510552

Design related project level pavement management - Economic evaluation of alternative pavement design strategies - Reliability / - Pavement design procedures for new construction or reconstruction : Design requirements - Highway pavement structural design - Low-volume road design / - Pavement design procedures for rehabilitation of existing pavements : Rehabilitation concepts - Guides for field data collection - Rehabilitation methods other than overlay - Rehabilitation methods with overlays / - Mechanistic-empirical design procedures.

Resilient Moduli Properties of Compacted Unsaturated Subgrade Materials

Resilient Moduli Properties of Compacted Unsaturated Subgrade Materials
Author: Pinit Ruttanaporamakul
Publisher:
Total Pages:
Release: 2012
Genre:
ISBN:

According to the new Mechanistic Empirical Pavement Design Guide (MEPDG) and 1993 AASHTO flexible pavement design guide, Resilient Modulus (MR) has been used extensively as an important material property in structure design of pavement. The modulus is used as the primary input parameter to determine the stiffness parameters and constitutive behavior of pavement components. The system of pavement basically consists of the layers of surface, base, subbase (optional), and subgrade. The compacted subgrade soils supporting pavement structure are typically unsaturated with degrees of saturation varying from 75% to 90%. The effect of unsaturated soil behavior on the mechanical properties of compacted pavement materials become an important variable and need to be considered. The main purpose of this study is to study the resilient moduli properties of compacted and unsaturated subgrade materials and to determine the effect of compaction moisture content, which is related to matric suction of the soils, on the resilient moduli properties. The second objective is to study the use of MEPDG models to calibrate resilient moduli properties either as a function of moisture content or soil suction variables. To accomplish these objectives, soil specimens were prepared at five different moisture content and dry density conditions and tested using conventional resilient modulus testing as per AASHTO T-307 procedure. The basic soil tests such as grain size distribution, Atterberg's limits, and standard proctor compaction were initially performed. Then, the advanced soil tests consisting of soil water characteristic curve (SWCCs), unconfined compressive strength (UCS) test, and conventional resilient modulus test were conducted. The soil suction conditions of the prepared specimens were determined based on the SWCCs information and the compaction moisture content. The test results indicate that compaction moisture content affected the values of resilient modulus of the subgrade soils. The specimens compacted at dry side of optimum moisture content (OMC) showed higher values of resilient modulus compared with the specimens compacted at OMC and wet side of OMC. The testing data were also analyzed with the models provided in MEPDG program. The level 2 input for predicting SWCCs provided in MEPDG gave the predicted SWCCs in similar trend to the measured SWCCs. However, the curves were not quite well matched. Lastly, the modified universal model and the model proposed by Cary and Zapata (2010) were studied and analyzed in detail. The results showed that the universal model is well suited for predicting the resilient modulus of the subgrade soils. However, the resilient modulus values predicted by the model of Cary and Zapata, sometime, showed the higher values than measured results especially, the specimens compacted at 0.8OMC.