Fly Ash Soil Stabilization for Non-uniform Subgrade Soils: Engineering properties and construction guidelines

Fly Ash Soil Stabilization for Non-uniform Subgrade Soils: Engineering properties and construction guidelines
Author:
Publisher:
Total Pages: 182
Release: 2005
Genre: Fly ash
ISBN:

Soil treated with self-cementing fly ash is increasingly being used in Iowa to stabilize pavement subgrades, but without a complete understanding of the short- and long-term behavior. To develop a broader understanding of fly ash engineering properties, mixtures of five different soil types, ranging from ML to CH, and several different fly ash sources (including hydrated and conditioned fly ashes) were evaluated.

Fly Ash Soil Stabilization for Non-uniform Subgrade Soils

Fly Ash Soil Stabilization for Non-uniform Subgrade Soils
Author: David J. White (Ph. D.)
Publisher:
Total Pages: 171
Release: 2005
Genre: Fly ash
ISBN:

Soil treated with self-cementing fly ash is increasingly being used in Iowa to stabilize fine-grained pavement subgrades, but without a complete understanding of the short- and long-term behavior. To develop a broader understanding of fly ash engineering properties, mixtures of five different soil types, ranging from ML to CH, and several different fly ash sources (including hydrated and conditioned fly ashes) were evaluated. Results show that soil compaction characteristics, compressive strength, wet/dry durability, freeze/thaw durability, hydration characteristics, rate of strength gain, and plasticity characteristics are all affected by the addition of fly ash. Specifically, Iowa self-cementing fly ashes are effective at stabilizing fine-grained Iowa soils for earthwork and paving operations; fly ash increases compacted dry density and reduces the optimum moisture content; strength gain in soil-fly ash mixtures depends on cure time and temperature, compaction energy, and compaction delay; sulfur contents can form expansive minerals in soil-fly ash mixtures, which severely reduces the long-term strength and durability; fly ash increases the California bearing ratio of fine-grained soil-fly ash effectively dries wet soils and provides an initial rapid strength gain; fly ash decreases swell potential of expansive soils; soil-fly ash mixtures cured below freezing temperatures and then soaked in water are highly susceptible to slaking and strength loss; soil stabilized with fly ash exhibits increased freeze-thaw durability; soil strength can be increased with the addition of hydrated fly ash and conditioned fly ash, but at higher rates and not as effectively as self-cementing fly ash. Based on the results of this study, three proposed specifications were developed for the use of self-cementing fly ash, hydrated fly ash, and conditioned fly ash. The specifications describe laboratory evaluation, field placement, moisture conditioning, compaction, quality control testing procedures, and basis of payment.

Fly Ash Soil Stabilization for Non-uniform Subgrade Soils

Fly Ash Soil Stabilization for Non-uniform Subgrade Soils
Author: David J. White (Ph. D.)
Publisher:
Total Pages: 76
Release: 2005
Genre: Fly ash
ISBN:

To provide insight into subgrade non-uniformity and its effects on pavement performance, this study investigated the influence of non-uniform subgrade support on pavement responses (stress and deflection) that affect pavement performance. Several reconstructed PCC pavement projects in Iowa were studied to document and evaluate the influence of subgrade/subbase non-uniformity on pavement performance. In situ field tests were performed at 12 sites to determine the subgrade/subbase engineering properties and develop a database of engineering parameter values for statistical and numerical analysis. Results of stiffness, moisture and density, strength, and soil classification were used to determine the spatial variability of a given property. Natural subgrade soils, fly ash-stabilized subgrade, reclaimed hydrated fly ash subbase, and granular subbase were studied. The influence of the spatial variability of subgrade/subbase on pavement performance was then evaluated by modeling the elastic properties of the pavement and subgrade using the ISLAB2000 finite element analysis program. A major conclusion from this study is that non-uniform subgrade/subbase stiffness increases localized deflections and causes principal stress concentrations in the pavement, which can lead to fatigue cracking and other types of pavement distresses. Field data show that hydrated fly ash, self-cementing fly ash-stabilized subgrade, and granular subbases exhibit lower variability than natural subgrade soils. Pavement life should be increased through the use of more uniform subgrade support. Subgrade/subbase construction in the future should consider uniformity as a key to long-term pavement performance.

Fly Ash Soil Stabilization for Non-Uniform Subgrade Soils, Volume II

Fly Ash Soil Stabilization for Non-Uniform Subgrade Soils, Volume II
Author: David J. White
Publisher:
Total Pages: 75
Release: 2005
Genre: Fly ash
ISBN:

To provide insight into subgrade non-uniformity and its effects on pavement performance, this study investigated the influence of non-uniform subgrade support on pavement responses (stress and deflection) that affect pavement performance. Several reconstructed PCC pavement projects in Iowa were studied to document and evaluate the influence of subgrade/subbase non-uniformity on pavement performance. In situ field tests were performed at 12 sites to determine the subgrade/subbase engineering properties and develop a database of engineering parameter values for statistical and numerical analysis. Results of stiffness, moisture and density, strength, and soil classification were used to determine the spatial variability of a given property. Natural subgrade soils, fly ash-stabilized subgrade, reclaimed hydrated fly ash subbase, and granular subbase were studied. The influence of the spatial variability of subgrade/subbase on pavement performance was then evaluated by modeling the elastic properties of the pavement and subgrade using the ISLAB2000 finite element analysis program. A major conclusion from this study is that non-uniform subgrade/subbase stiffness increases localized deflections and causes principal stress concentrations in the pavement, which can lead to fatigue cracking and other types of pavement distresses. Field data show that hydrated fly ash, self-cementing fly ash-stabilized subgrade, and granular subbases exhibit lower variability than natural subgrade soils. Pavement life should be increased through the use of more uniform subgrade support. Subgrade/subbase construction in the future should consider uniformity as a key to long-term pavement performance.

Fly Ash Soil Stabilization for Non-uniform Subgrade Soils: Influence of subgrade non-uniformity on PCC pavement performance

Fly Ash Soil Stabilization for Non-uniform Subgrade Soils: Influence of subgrade non-uniformity on PCC pavement performance
Author:
Publisher:
Total Pages: 82
Release: 2005
Genre: Fly ash
ISBN:

Soil treated with self-cementing fly ash is increasingly being used in Iowa to stabilize pavement subgrades, but without a complete understanding of the short- and long-term behavior. To develop a broader understanding of fly ash engineering properties, mixtures of five different soil types, ranging from ML to CH, and several different fly ash sources (including hydrated and conditioned fly ashes) were evaluated.

Engineering Properties and Construction Guidelines for Soil Stabilized with Self-cementing Fly Ash

Engineering Properties and Construction Guidelines for Soil Stabilized with Self-cementing Fly Ash
Author: Zachary Guy Thomas
Publisher:
Total Pages: 444
Release: 2003
Genre:
ISBN:

Research was initiated to evaluate the engineering properties and to observe the short and long-term behavior of soil stabilized with self-cementing fly ash. Typically Iowa soils have low strength due to high fines content. Five Iowa soils ranging from ML to CH were used in this study as well as self-cementing fly ash from eight Iowa power plants. Fly ash addition had a profound effect on the compaction characteristics of the soils. The influences of fly ash content, moisture content, and compaction delay on compressive strength were observed for samples molded with ISU 2-in x 2-in apparatus as well as standard 4-inch diameter Proctor equipment. Long-term strength gain was evaluated for samples that were over 2.5 years old. California Bearing Ration (CBR) of fine-grained soils was also increased substantially with the addition of fly ash. Strength gain was also tested for samples cured in various environments. Freeze-thaw and wet-dry durability of soils were increased and reductions in plasticity characteristics were observed with fly ash addition. The morphology of soil-fly ash mixtures was studied as well as the clay mineralogy of the soils used in the study. In addition to the study of soil-fly ash mixtures, previous ISU research involving hydrated and conditioned fly ash was continued. The research utilized four sources of hydrated fly ash (HFA) and two sources of conditioned fly ash (CFA) from Iowa. Moisture content, curing temperature and time all had an impact on the strength gain of HFA and CFA. Shear strength parameter values for these materials were also determined. In addition to evaluating the strength of HFA and CFA alone, these two types of materials were also tested as soil stabilizers. The final part of research was to use the information determined in the previous tests to develop construction guidelines. Three construction guidelines were developed for use in Iowa. Two of these guidelines described the procedures for using HFA and CFA as select fill under pavement structures, while the third set of guidelines was developed for constructing sections of self-cementing fly ash stabilized soil.

Fly Ash for Soil Improvement

Fly Ash for Soil Improvement
Author: Kevan D. Sharp
Publisher:
Total Pages: 136
Release: 1993
Genre: Science
ISBN:

"Fly Ash for Soil Improvement provides civil and geotechnical engineers with a contemporary review of the beneficial uses of fly ash for both general construction purposes and for waste containment/soil stabilization. Peer-reviewed papers describe the use of self-cementing fly ashes as a soil stabilization agent; fly ash stabilization of tropical Hawaiian soils, south Texas soils, and industrial wastes; enzyme-enhanced stabilization; lime sludge amended fly ash; calcareous expansive clays; and engineering properties of a clay modified by fly ash and slag."--BOOK JACKET.Title Summary field provided by Blackwell North America, Inc. All Rights Reserved

Proceedings of 5th International Conference on Civil Engineering and Architecture

Proceedings of 5th International Conference on Civil Engineering and Architecture
Author: Thomas Kang
Publisher: Springer Nature
Total Pages: 1118
Release: 2023-11-05
Genre: Technology & Engineering
ISBN: 9819940494

This book states that the proceedings gathers selected papers from 2022 5th International Conference on Civil Engineering and Architecture (ICCEA 2022), which was held in Hanoi, Vietnam on December 16-18, 2022. The conference is the premier forum for the presentation of new advances and research results in the fields of theoretical, experimental, and practical civil engineering and architecture. And this proceedings from the conference mainly discusses architectural design and project management, environmental protection and spatial planning, design and analysis of building materials, and structural engineering and safety. And these materials can be useful and valuable sources for researchers and professionals working in the field of civil engineering and architecture.