Seasonal Instrumentation of SHRP Pavements

Seasonal Instrumentation of SHRP Pavements
Author: William Edward Wolfe
Publisher:
Total Pages: 199
Release: 2004
Genre: Pavements
ISBN:

Test pavements constructed by the Ohio Department of Transportation (ODOT) on U.S. 23 in Delaware, OH were studied. Environmental data collected from 1997 to 2003 at five test locations are presented. Also, porewater pressures in the near surface soils beneath select pavement sections were measured. These measurements showed that pore pressures in the soil under the pavement have continued to increase over time strongly suggesting that the subsurface soils quickly became saturated as water was drawn up into the profile. Models used to predict the resilient modulus of cohesive subgrade soils typical of those found in Ohio were evaluated. The current study consisted of performing a series of static laboratory tests to determine the soil's engineering properties. These tests were followed by the direct measurement of the resilient modulus. Tests were performed on both unsaturated and saturated soil samples. The moduli as predicted by these existing methods were compared with the measured values. An improved and more accurate resilient modulus prediction model has been developed and validated in this study. Results obtained from M[subscribt r] laboratory testing show that for cohesive soils, the water content, the applied deviator stress, the confining stress and the unconfined compressive strength all affected the resilient modulus of the sample. The resilient modulus values of the saturated soil samples were, in most cases, less than half that of the modulus at optimum moisture content.

Engineering Properties Affecting the Resilient Modulus of Fine-grained Soils as Subgrade

Engineering Properties Affecting the Resilient Modulus of Fine-grained Soils as Subgrade
Author: Dong-Gyou Kim
Publisher:
Total Pages: 338
Release: 1999
Genre:
ISBN:

Ohio soils used as subgrade soils for a road were studied to evaluate parameters affecting resilient modulus. The dominant Ohio soils could be classified in one of three AASHTO Soil Classification system groups, A-4, A-6, and A-7. Laboratory tests were performed on the cohesive soils to measure Atterberg Limits, particle size, optimum moisture content, maximum dry density, and unconfined compressive strength. The resilient modulus tests were conducted on each sample compacted at the dry of optimum, optimum, or wet of optimum moisture content. The measured resilient modulus for each soil sample was analyzed to evaluate the effect of stresses and engineering indexes. Three different models to predict the resilient modulus using engineering indexes were used to compare the measured resilient modulus. The confining stress affected the resilient modulus. The resilient modulus decreased with an increase in the deviator stress, and linearly increased with an increase in the percent of silt and clay and maximum unconfined compressive strength. The increase in moisture content considerably affected the decrease in the resilient modulus. The resilient modulus predicted using the three models showed a large variation with the resilient modulus measured.

Development of a Constitutive Model for Resilient Modulus of Cohesive Soils

Development of a Constitutive Model for Resilient Modulus of Cohesive Soils
Author: Dong Gyou Kim
Publisher:
Total Pages:
Release: 2004
Genre: Soil mechanics
ISBN:

Abstract: The objective of this study was to evaluate existing constitutive models currently used by State Department of Transportations (DOTs) and to develop an improved model for predicting resilient modulus (Mr) of cohesive soils from simple soil properties typically measured in DOT laboratories in preference to expensive and complex Mr laboratory testing. The data set used consisted of cohesive soils typical of those used for subgrades in Ohio. Thirteen representative cohesive soils representing A-4, A-6, and A-7-6 soil types collected from road construction sites across Ohio, were tested in the laboratory to determine their basic engineering properties. Mr tests were conducted at three different moisture contents (dry of optimum moisture content, optimum moisture content, and wet of optimum moisture content). Additional tests were performed on samples compacted to optimum conditions but allowed to fully saturate. Mr predicted from six existing models studied showed wide scatter and poor correlation with the measured Mr. An improved constitutive model was developed to account for the effects on Mr of the stress state of the soil and its engineering properties obtained from simple laboratory tests. While most of the existing models investigated in this study significantly overestimated the Mr of a cohesive soil, the proposed model predictions are close to the experimental values and are in most cases a slight underestimation. This implies that Mr values predicted by the proposed model are generally slightly conservative, and can be safely used in the design of flexible pavements to be built on cohesive soils. The proposed model can be a useful and reliable tool for estimating Mr of cohesive subgrade soils using basic soil properties and the stress state of the soil.

Resilient Modulus Prediction Employing Soil Index Properties

Resilient Modulus Prediction Employing Soil Index Properties
Author:
Publisher:
Total Pages: 64
Release: 2004
Genre:
ISBN:

Subgrade soil characterization in terms of Resilient Modulus (MR) has become crucial for pavement design. For a new design, MR values are generally obtained by conducting repeated load triaxial tests on reconstituted/undisturbed cylindrical specimens. Because the test is complex and time-consuming, in-situ tests would be desirable if reliable correlation equations could be established. Alternately, MR can be obtained from correlation equations involving stress state and soil physical properties. Several empirical equations have been suggested to estimate the resilient modulus. The main focus of this study is to substantiate the predictability of the existing equations and evaluate the feasibility of using one or more of those equations in predicting resilient modulus of Mississippi soils. This study also documents different soil index properties that influence resilient modulus. Correlation equations developed by the Long Term Pavement Performance (LTPP), Minnesota Road Research Project, Georgia DOT, Carmichael and Stuart, Drumm et al., Wyoming DOT, and Mississippi DOT are studied/analyzed in detail. Eight road (subgrade) sections from different districts were selected, and soils tested (TP 46 Protocol) for MR in the laboratory. Other routine laboratory tests were conducted to determine physical properties of the soil. Validity of the correlation equations are addressed by comparing measured MR to predicted MR. In addition, variations expected in the predicted MR due to inherent variability in soil properties is studied by the method of point estimates. The results suggest that LTPP equations are suited for purposes of predicting resilient modulus of Mississippi subgrade soils. For fine grain soils, even better predictions are realized with the Mississippi equation. A sensitivity study of those equations suggests that the top five soil index properties influencing MR include moisture content, degree of saturation, material passing #200 sieve, plasticity index and density.

Determination of Resilient Modulus Values for Typical Plastic Soils in Wisconsin

Determination of Resilient Modulus Values for Typical Plastic Soils in Wisconsin
Author: Hani Hasan Titi
Publisher:
Total Pages: 316
Release: 2011
Genre: Pavements
ISBN:

The objectives of this research are to establish a resilient modulus test results database and to develop correlations for estimating the resilient modulus of Wisconsin fine-grained soils from basic soil properties. A laboratory testing program was conducted on representative Wisconsin fine-grained soils to evaluate their physical and compaction properties. The resilient modulus of the investigated soils was determined from the repeated load triaxial (RLT) test following the AASHTO T307 procedure. The laboratory testing program produced a high-quality and consistent test results database.