Effect of a hydrophobic layer on the upward movement of water under freezing conditions

Frost heave is the process in which wet soil with an available water source undergoes freezing, deformation, and upward movement of the soil surface. This deformation can cause damage to engineering structures such as pavements and shallow foundations. Investigating ways to minimize frost heave by reducing water flow in the system is beneficial. A possible way to reduce the water movement is to add a hydrophobic layer of soil between the water source (e.g. water table) and the freezing surface. The objective of this study was to examine the effect of a hydrophobic treated soil layer on water movement and temperature changes in a soil profile under surface freezing conditions. A vertical soil cell set-up including a column-within-a-column design was used to establish one-dimensional vertical heat flow between a surface boundary condition below freezing and an ambient boundary temperature condition at the bottom of the cell. A constant water table was established at the bottom of the column to provide a water source for water uptake due to freezing. Water uptake in soil cells without a hydrophobic layer was found to be greater by one order of magnitude than water uptake in soil cells with a hydrophobic layer. Soil with a hydrophobic layer had less accumulation of ice and froze to greater depths than soil without a hydrophobic layer. A hydrophobic soil layer can reduce water movement in freezing soil

Southeast Michigan Local Road Concrete Pavement Durability Study

Counties and cities in Southeast Michigan have used concrete pavements for nearly 100 years to provide long-lasting, durable streets and roads. Issues of concrete durability have arisen with some of the pavements built after 1990. In order to evaluate the causes of spalling and other deterioration methods, the National Concrete Pavement Technology Center (CP Tech Center) was asked to study the concrete from a number of the pavements, evaluate the causes of the distress, and offer recommendations for improvements. Of particular concern are the roles of coarse aggregate type (limestone or blast furnace slag), alkali-silica reactivity (ASR), and the air entrainment system in the hardened concrete on the joint deterioration distresses that are being observed

Geotechnical Solutions for Soil Improvement, Rapid Embankment Construction, and Stabilization of the Pavement Working Platform, Performance Assessment of Lime and Fly Ash Chemically Treated Subgrade

Chemical treatment and stabilization of subgrades is a long-standing method to construct working platforms and improve the support conditions for pavement systems. Lime, cement, and fly ash are common chemical stabilization agents and are often incorporated with subgrade materials to improve volumetric stability, freeze-thaw performance, and/or subgrade stiffness. Although laboratory test methods and design procedures are relatively well established, the long-term (5+ years) field performance characteristics of treated or stabilized subgrades is poorly documented and was the focus of this study. The main objectives of this project were as follows: Document engineering properties (in situ strength/stiffness) and mineralogical/micro-structural characteristics of chemical stabilized subgrades, in comparison with natural subgrades at the same sites Understand factors that contribute to long-term engineering behavior of stabilized subgrade Nine test sections were selected to assess engineering properties of old stabilized subgrades in Texas, Oklahoma, and Kansas. The selection of the test sites was based on the type of subgrade, availability of old construction records, and age. Subgrades at six of these sites were stabilized with lime and the other three with fly ash. Eight of these test sites were more than 10 years old, and one test site was about 5 years old. Eight sites consisted of flexible pavement supported on base and stabilized subgrade or just stabilized subgrade, and one site consisted of concrete pavement supported on cement treated base and stabilized subgrade Results from this study provide new information that should be of great interest to pavement designers dealing with selection of design parameters for chemically stabilized subgrade layers

Effect of a hydrophobic layer on the upward movement of water under freezing conditions

Frost heave is the process in which wet soil with an available water source undergoes freezing, deformation, and upward movement of the soil surface. This deformation can cause damage to engineering structures such as pavements and shallow foundations. Investigating ways to minimize frost heave by reducing water flow in the system is beneficial. A possible way to reduce the water movement is to add a hydrophobic layer of soil between the water source (e.g. water table) and the freezing surface. The objective of this study was to examine the effect of a hydrophobic treated soil layer on water movement and temperature changes in a soil profile under surface freezing conditions. A vertical soil cell set-up including a column-within-a-column design was used to establish one-dimensional vertical heat flow between a surface boundary condition below freezing and an ambient boundary temperature condition at the bottom of the cell. A constant water table was established at the bottom of the column to provide a water source for water uptake due to freezing. Water uptake in soil cells without a hydrophobic layer was found to be greater by one order of magnitude than water uptake in soil cells with a hydrophobic layer. Soil with a hydrophobic layer had less accumulation of ice and froze to greater depths than soil without a hydrophobic layer. A hydrophobic soil layer can reduce water movement in freezing soil.</p

Southeast Michigan Local Road Concrete Pavement Durability Study

Counties and cities in Southeast Michigan have used concrete pavements for nearly 100 years to provide long-lasting, durable streets and roads. Issues of concrete durability have arisen with some of the pavements built after 1990. In order to evaluate the causes of spalling and other deterioration methods, the National Concrete Pavement Technology Center (CP Tech Center) was asked to study the concrete from a number of the pavements, evaluate the causes of the distress, and offer recommendations for improvements. Of particular concern are the roles of coarse aggregate type (limestone or blast furnace slag), alkali-silica reactivity (ASR), and the air entrainment system in the hardened concrete on the joint deterioration distresses that are being observed.For more on this project and other project reports from InTrans, please visit http://www.intrans.iastate.edu</p

Phase I (Laboratory): Investigation of Soil Stabilization Alternatives—Texas SH 130

Portland cement, hydrated lime, slag, class C and F fly ash, and a few nontraditional chemical stabilizers were evaluated in the laboratory for their effectiveness in improving strength and reducing swell potential of high-plasticity clay materials sampled at the proposed SH 130 project site in Texas. In addition to high plasticity index values, soils in the proposed construction area reportedly contain variable amounts of sulfate content that may lead to deleterious expansion due to secondary mineral growth. Over 900 test specimens from the project site were prepared and tested. The goal of the laboratory phase of this project was to provide recommendations for conducting field test strip evaluations of the select portland cement stabilizers or combinations of Portland cement and other stabilizers. Unconfined compressive strength, volume change, pH, soil classification, X-ray analysis, and scanning electron microscopy methods were used in this analysis. An unconfined compressive strength of 100 psi, a maximum volume change of 2%, and a decrease in the plasticity index were used as evaluation criteria for determining suitable stabilizers for field trials. The following cement-based stabilization mixtures would meet the laboratory-established criteria: 6% Cement Type I/II or Type V, 4% Cement Type I/II + 4% Fly ash Class C, 4% Cement Type I/II + 4% Fly ash Class F, and 3% Cement Type I/II + 3% Fly ash Class C or F. Further evaluation by field testing, with several months of evaluation including in-situ testing, sampling, and in-ground instrumentation monitoring, is recommended for Phase II. A testing plan for evaluation is presented in this report. The outcome of the field investigation would be conclusive performance results for the recommended stabilizers in terms of strength, stiffness, and volume change. It is further recommended that the stabilization construction methods be evaluated as part of the field evaluation. This would specifically include variable mixing rates and use of intelligent compaction technology with GPS mapping capabilities.</p

Field Assessment and Specification Review for Roller-Integrated Compaction Monitoring Technologies

Roller-integrated compaction monitoring (RICM) technologies provide virtually 100-percent coverage of compacted areas with real-time display of the compaction measurement values. Although a few countries have developed quality control (QC) and quality assurance (QA) specifications, broader implementation of these technologies into earthwork construction operations still requires a thorough understanding of relationships between RICM values and traditional in situ point test measurements. The purpose of this paper is to provide: (a) an overview of two technologies, namely, compaction meter value (CMV) and machine drive power (MDP); (b) a comprehensive review of field assessment studies, (c) an overview of factors influencing statistical correlations, (d) modeling for visualization and characterization of spatial nonuniformity; and (e) a brief review of the current specifications.This article is from Advances in Civil Engineering 2011 (2011): 783836, doi:10.1155/2011/783836.</p

Iowa DOT Intelligent Compaction Research and Implementation—Phase I

The Iowa Department of Transportation Intelligent Compaction Research and Implementation was initiated in summer 2009. Three field demonstration projects were conducted in Iowa as part of Phase I of this research program to evaluate three different IC measurement technologies: (1) machine drive power (MDP) measurement technology on Caterpillar CP56 padfoot roller, (2) continuous compaction value (CCV) technology on Sakai SW880 dual vibratory smooth drum asphalt roller, and (3) compaction meter value (CMV) technology on Volvo SD116DX smooth drum vibratory roller. The main objectives of the project include: evaluating the effectiveness of the IC measurement values (IC-MVs) in assessing the compaction quality of cohesive subgrade materials, granular base/subbase materials, and HMA materials, developing project specific correlations between IC-MVs and various conventionally used in-situ point measurements in earthwork quality control (QC) and quality assurance (QA) practice and HMA construction, evaluating the advantages of using the IC technology for production compaction operations, obtaining data to evaluate future IC specifications, and developing content for future educational and training materials for Iowa DOT and contractor personnel for effective implementation of the technology in to earthwork and HMA construction practice. This research report presents results obtained from the three demonstration projects along with an overview of the different IC technologies and various QC/QA test methods. Statistical regression analysis was performed to evaluate correlations between IC-MVs and various in-situ test measurements (e.g., dry unit weight, moisture content, modulus, California bearing ratio, temperature (for HMA)). Comparatively, modulus was better correlated with IC-MVs compared to dry unit weight. Geostatistical analysis methods were used to assess “uniformity” of the spatially referenced IC measurements. Results from this study were used to develop special provision specifications as part of Phase II research program.</p