UAF Soils Stabilization Study-Final Draft_020606-1

8/12/2019 UAF Soils Stabilization Study-Final Draft_020606-1

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DRAFT FINAL REPORT, TESTS OF SOIL STABILIZATIONPRODUCTS, PHASE I

UAF PROJECT NO. 331555CONOCOPHILLIPS PROJECT NO. 8174.0-LOA-AKR

ATTENTION: MANDY POGANY AND JAY HERMANSON

DRAFT FINAL REPORT

Prepared forConocoPhillips

Author(s)Lauren Little, Undergraduate Student, Department of Civil Engineering,

University of Alaska FairbanksBilly Connor, PE, Director, Alaska University Transportation Center

Dr. Robert F. Carlson, Adjunct Professor, Department of Civil Engineering,University of Alaska Fairbanks


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Table of Contents

Acknowledgements .................................................................................................................. iiiSummary of Findings ................................................................................................................ 1

Problem Statement and Research Objective ......................................................................... 2

Scope of Study ...................................................................................................................... 2Research Approach ............................................................................................................... 2CHAPTER 2 - FINDINGS ....................................................................................................... 3

State-of-the-Art Summary .................................................................................................... 3Literature Review............................................................................................................. 3Professional Knowledge Review ..................................................................................... 7

Phase 1A Results................................................................................................................... 9Phase 1B Results ................................................................................................................. 11

CHAPTER 3 - INTERPRETATION, APPRAISAL, AND APPLICATIONS ...................... 20Discussion ........................................................................................................................... 20General Recommendations ................................................................................................. 20

CHAPTER 4 - CONCLUSIONS AND SUGGESTED RESEARCH .................................... 22Conclusions ......................................................................................................................... 22Suggested Research ............................................................................................................ 22

REFERENCES ....................................................................................................................... 23APPENDIX A FREEZE THAW PICTURES ......................Error! Bookmark not defined.APPENDIX B FREEZE THAW OBSERVATION TABLES ............................................. B


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Acknowledgements

The research reported herein was performed by the University of Alaska, FairbanksDepartment of Civil Engineering and made possible through funding from ConocoPhillipsgrant number G00002414. In addition, NANA Pacific monitored all work performed.


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Summary of Findings

The literature and professional knowledge review indicated that asphalt emulsions andPortland cement have been the most commonly used stabilization agents in Alaska, and areproven to work on silty sand material. However, Portland cement is not cost effective for

sand stabilization, and is not as easily transported or placed, requiring special equipment. Inaddition, asphalt emulsions also require special equipment to place and typically require ahigher fines content than that which was found in the material used in this study. There arealternatives, however, as polymer emulsions have shown themselves to be a more effectivestabilization agent, and have begun being used in Alaska, in particular the product EK35,which has been used on rural airports in the state (Little, 2005). According to United StatesArmy Corp of Engineers (USACE) testing, polymer emulsions are the most effectivestabilization agents for silty sand material (Santoni, et. al., 2002). Also successful in Alaskawas the liquid stabilizer EMC2, which was used on the Elliott and Alaska Highways as a dustcontrol agent (Randolph, 1997).

The two materials used, Eolian and Fluvial soils from the NPRA, were classified as poorlygraded sands per the Unified Soil Classification System (USCS). Moisture-densityrelationships indicated an optimum moisture content of 13% for the Fluvial, with a drydensity of 104.8 lb/ft3, and 11.5% for the Eolian, with a dry density of 104.1 lb/ft3.

Based on the literature and professional knowledge review, the polymer emulsionsEnviroseal M10+50, Soil-Sement Engineered Formula (hereafter known as Soil Sement), andSoiltac, as well as the liquid stabilizer EMC2were tested in the lab for strength using CBR,and for freeze-thaw resistance using freeze-thaw CBR testing. Overall, Soil Sement showedthe greatest improvements in the two sands used as base material (Eolian and Fluvial). Forthe Eolian sand, the Soil Sement showed a 992% improvement over the unmodified soil CBRvalue when comparing the average dry CBR values, and an 872% improvement over theunmodified soil CBR value when comparing the average freeze-thaw CBR values. For theFluvial sand, the Soil Sement showed a 497% improvement over the unmodified soil CBRvalue when comparing the average dry CBR values, and a 3751% improvement over theunmodified soil CBR value when comparing the average freeze-thaw CBR values. For theEolian sand, all products improved the dry and freeze-thaw CBR values by at least 200%,with the exception of the EMC2, which actually performed worse than the unmodified soil inboth dry and freeze-thaw CBR. For the Fluvial sand, all products except EMC2improved thefreeze-thaw CBR values over the unmodified soil by at least 500%, however only the SoilSement and Soiltac improved the average dry CBR values over the unmodified soil, as theEnviroseal and EMC2actually performed worse than the unmodified soil. What wasinteresting was in some cases the average freeze-thaw CBR values were higher than the dryCBR values, which might be attributable to the fact that the samples were oven driedfollowing the freeze-thaw cycles, which could have strengthened bonds in the modified soilsamples.


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CHAPTER 1 - INTRODUCTION AND RESEARCH APPROACH

Problem Statement and Research Objective

The University of Alaska Fairbanks was contracted by ConocoPhillips to determine the stateof the practice on soil stabilization agents for northern climates, to select stabilization agents

to perform lab tests with based on a literature and professional knowledge review, and toperform tests on these agents when mixed with two soils from the National PetroleumReserve Alaska (NPRA) region of Alaska. The project was split into two phases, 1A and1B. Phase 1A covered the literature and professional knowledge review as well as theclassification of the soils to be used in the testing. Phase 1B covered the laboratory testing ofthe selected soil stabilization agents with the two soils from the NPRA.

Scope of Study

The scope of study included the determination of the state-of-the-practice in northern regionsoil stabilization, as well as the selection of stabilizing agents to perform laboratory testingon. The laboratory testing scope included the performing of CBR and unconfined

compression testing per ASTM standards, as well as freeze-thaw CBR testing.

Research Approach

Laboratory testing was conducted using ASTM standards. The following ASTM standardswere used in this study:ASTM D1557 Test Method for Laboratory Compaction Characteristics of Soil UsingModified Effort (56,000 ft-lbf/ft

2(2,700 kN-m/m

3))

ASTM D560 Standard Test Methods for Freezing and Thawing Compacted Soil-CementMixturesASTM D2166 Standard Test Method for Unconfined Compressive Strength of CohesiveSoil

ASTM D1883 Standard Test Method for CBR (California Bearing Ratio) of Laboratory-Compacted Soils

All CBR and unconfined compression samples were compacted per ASTM D1557, andmoisture-density relationships for the unmodified Eolian and Fluvial soils were determinedper ASTM D1557. A mechanical compactor, manufactured by Soiltest, was used for allcompaction in phase 1B. Hand compaction was used in phase 1A.

Freeze-thaw testing was performed per ASTM D560, however some modifications weremade. Because the samples were in their CBR molds, volume change measurements andresistance to abrasion measurements were not performed. In addition, because the molds

were on their base plates, the felt pad froze to the base plate and the soil sample, makingfrozen weight measurements difficult without disturbing the sample, therefore only thawweight measurements were recorded.

Unconfined compression testing has not been performed yet due to difficulties removingsamples from their molds. An addendum will follow with results of unconfined compressiontesting per ASTM D2166.


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CHAPTER 2 - FINDINGS

State-of-the-Art Summary

Literature Review

The use of soil stabilization products for the stabilization of fine-grained soils is quitewidespread across the United States. The traditional methods of stabilization include the useof cement, lime and coal fly ash, however as technology and the understanding of the soilstabilization mechanisms improve, additional stabilization products have been developed.These products, typically called nontraditional stabilizers, are compiled into five groups afterScholen (1992): electrolytes, enzymes, mineral pitches, clay fillers and acrylic polymers.

The State of Alaska Northern Region Department of Transportation & Public Facilities(ADOT) has used several traditional and nontraditional stabilizers for airport and highwayprojects:

In 1966, Peyton et al. investigated the use of soil stabilizers for ADOT. They found thattetrasodium polyphosphate decreased the frost susceptibility (likelihood of frost heaving) ofthe silt and that low concentrations of cement actually increased frost susceptibility.

In 1982, Kaminski, et al. performed laboratory tests using Type I and Type III cements forstabilizing Barrow soils. Then in September of 1982 they laid a 100 x 24 foot test section inBarrow, Alaska. In June of 1983 they evaluated the test strip by measuring Benkelman Beamdeflections under the design loading condition (a fully loaded "DJB" dump truck). The testsection performed satisfactorily. It was evaluated again in October of 1983 and again wasfound to perform satisfactorily, however there were minor failures at the extreme edges ofthe shoulders.

In 1985, Esch and Gentry performed a study on soil stabilizers on sands and silty sands fromthe Bethel, Hooper Bay and St. Michael areas of the Yukon-Kuskokwim river delta region ofAlaska. They concluded that emulsified asphalt mixed with Type III Portland cement couldstabilize the soils enough so that they could be used for wearing course or sub grade materialfor highway and airport construction. They found that CSS-1 asphalt emulsions worked thebest, followed by SS-1 emulsions.

Also in 1985, R&M Consultants (Kozisek and Rooney) were commissioned by ADOT toplace test strips of soil in Bethel stabilized with asphalt cement (AC) Portland cement (PC)and CTG. The AC was a CSS-1 emulsion and the cement was Type III. They found that bothstabilizers worked very well, and the AC-PC stabilizer not only stabilized the soil strengthwise, but also provided erosion and water resistance. The CTG was found to provide morestrength improvement, however.

In 1986, ADOT commissioned Pacific Northwest Laboratories to investigate soilstabilization techniques for remote airfields (Koehmstedt). The soil samples were taken fromthe Bethel, Alaska airport and were tested in the laboratory with CSS-1 emulsions todetermine if they could be sufficiently stabilized to use as a sub base and base course


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material for airport and roadway applications. The soils used were a poorly graded sand and asilty sand per the Unified Soil Classification System. The study found that the asphaltemulsions and Type I Portland cement mixtures significantly improved the soils CBR valuesand cohesive strengths, however it was noted that a thorough testing of the soils propertiesand zeta potential were crucial in deciding upon the most effective asphalt/cement

combination.

Also in 1986, the U.S. Army Cold Regions Research Laboratory (CRREL) prepared a reportfor ADOT regarding stabilization techniques of fine-grained soil for road and airfieldconstruction (Danyluk). The soil used in this study was organic silt intended for use as a subbase or base course material for low-volume roads and airfields in Alaska. The stabilizersused were cement, cement with additives (calcium chloride, hydrogen peroxide, sodiumsulfate and lime), lime/fly ash, asphalt emulsion, tetrasodium polyphosphate and calciumacrylate. It was found that lime and lime/fly ash did not provide any improvement for the soilin question, and the tetrasodium polyphosphate did not improve strength but did reduce frostsusceptibility and permeability. Cement was also shown to have very little effect on the soil

in regards to strength improvements and actually worsened the frost susceptibility. Cementwith calcium chloride and cement with sodium sulfate showed slightly better improvement,with significant improvement in the unconfined compressive strength as well asimprovements in the permeability, frost-heave ratio and after-thaw CBR values. However,the cement with hydrogen peroxide did not show as much improvement. The asphaltemulsion proved to be the most cost effective method of improving the soil and showedimprovement in all categories tested. The calcium acrylate showed the most improvement,but is not readily available and therefore not economical.

In 1991, ADOT in cooperation with the Federal Highways Administration (FHWA)performed a study on the effectiveness of the concentrated liquid stabilizer EMC

2

(Randolph). Two 2 km segments of the Elliott Highway were stabilized with EMC2, oneusing premixed aggregate, and the second using mixed in place aggregate. The strips werecompared with an adjacent segment of road treated with calcium chloride. It was found thatboth EMC2treated segments required little maintenance (maintenance was only necessary onthe superelevated curves) for the three year study period, whereas the calcium chloride had tobe reapplied every year and had pothole damage. Following the three year study period,asphalt was laid down on top of the EMC2treated segment and also produced excellentresults, especially when compared to an adjacent asphalted section that continually potholed.Shannon & Wilson, Inc. performed unconfined compression tests on samples and found avalue of 1850 kPa for untreated aggregate and 2900 kPa for the EMC

2treated aggregate. The

material used for this entire project was a well-graded maximum aggregate, with thepercentage passing the No. 200 sieve averaging 12% and a PI of about 6. Shannon & Wilson,Inc. also found that the untreated material required less compactive effort in the modifiedProctor test.

In 1996, EMC2was applied on the Alaska Highway between mileposts 1222 and 1270

(Hicks). After the EMC2stabilization, 4 inches of an emulsified stabilized base and a high-float surface treatment was applied over top. This was applied to the control section as well.At the end of the first year, the pavement conditions were reported as being similar for the


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control and EMC2stabilized section, however the deflection analysis indicated lower strengthfor the EMC

2section.

In 2002, professor Gary Hicks prepared a soil stabilization design guide for ADOT. Prior toproducing this document extensive research was done on the history of soil stabilizers in

Alaska (Hicks). According to Hicks stabilization guide, cement and cementitious blends,bitumens and bitumen/cement blends are most suitable for soils with a PI less than 6 andhaving less than 25% passing the No. 200 sieve. For bituminous stabilization, bitumenemulsion was deemed most appropriate for clean sandy or gravelly soils with a PI less than 6.The guide also indicated that lime was not an appropriate stabilizing agent in cohesion less orlow cohesion soil without the addition of pozzolanic additives. For cementitiously stabilizedpoorly graded sand (A-3 per AASHTO), 7-11% cement by weight is typically adequate forstabilization.

The United States Army Corp of Engineers (USACE) has performed multiple studies on thestabilization of soils using nontraditional stabilizers. According to Santoni et al. (2005) the

goal of many of these stabilizer studies was to find a soil-stabilizer mixture that could curewithin 1 to 7 days, weigh approximately 50% less than traditional stabilization mixtures (i.e.Portland cement) and provide strength improvements (a UCS value of 50 psi greater than theunstabilized soil) to marginal soil for use in airstrips. The general conclusions drawn fromthe USACE studies was that polymers provided the most consistent engineering propertyimprovements for a variety of soil types, especially sands, of the nontraditional stabilizergroups. However, not all polymers were successful at improving UCS strength over thecontrol, stressing that the stabilizers should be tested in the laboratory before being used inthe field.

Santoni et al. (2005) evaluated the effect of two products designed to accelerate the strengthimprovement of a silty-sand material previously stabilized by nontraditional stabilizers. Thenontraditional stabilizers used were labeled as lignosulfonate 1, polymer 1, polymer 2,polymer 3, polymer 4, polymer 5, polymer 6, silicate 1 and tree resin 1. For comparison, twotraditional stabilizers, Type 1 Portland cement and emulsified asphalt, were used. Theaccelerators used were a Type 1 Portland cement and polymer 4. Wet and dry UCS strengthof the soil-stabilizer mixtures was evaluated, with a strength improvement of 50 psi being theminimum increase to be considered significant. It was found that Silicate 1, Polymer 1,Polymer 2 and Polymer 3 stabilized samples provided significant UCS increase as comparedto the untreated soil and the soil stabilized with traditional additives. It was also found thatPolymers 2, 3 and 4 provided significant UCS improvement relative to control samples andother nontraditional stabilized samples under dry and wet conditions (up to 65% of UCSwhen compared to control samples). Emulsified asphalt with 3% cement accelerator providedexcellent resistance to moisture deterioration.

Prior to testing the accelerated strength improvements of silty-sand stabilized withnontraditional additives, Santoni et al. (2002) performed tests on the same silty-sand materialwith the nontraditional stabilizers. The stabilizers tested were a Type I Portland cement,hydrated lime, cationic asphalt emulsion, 1 acid, 4 enzymes, 2 lignosulfonates, 1 petroleumemulsion, 3 polymers and 1 tree resin. UCS was used for comparison of performance. It was


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found that of the traditional stabilizers (cement, lime, asphalt emulsion) only the cementincreased the UCS by more than 100% over the control for both wet and dry tests. Polymers1-3 showed good potential for stabilization as the UCS was increased by an average of 57%over the control in the dry test and 221% in the wet test. The petroleum emulsion, tree resinand lignosulfonate 1 showed good waterproofing potential, but no significant dry UCS

improvement. Overall it was determined that the nontraditional stabilizers gained strengthquicker than the traditional stabilizers.

Newman and Tingle (2004) performed a study on the use of emulsion polymers for soilstabilization of airfields following the earlier USACE studies after determining that polymersshowed the most potential to stabilize the most soils. It was noted that polymer emulsions arealso very useful as they do not require a solvent carrier, are easily cleaned up using water anddetergent and often do not pose an environmental risk when used in bulk. The soil tested forthis study was a silty-sand (SM) and 6 polymer emulsions (called P1-6 respectively) and 3concentrations of Portland cement were tested as stabilizers. They found that all of thepolymers used increased the UCS over the unmodified soil after 28 days of cure time for both

the wet and dry testing. The P1 polymer modified soil produced significantly highertoughness values after 28 days of cure compared to the other polymer modified soils. The P1,P2 and P4 modified soils had significantly higher toughness values than the 9% cementmodified soil. All of the additives improved retained wet strength and toughness, and thepolymer additives had slightly higher wet retained toughness than the cement stabilized soilafter 28 days of cure. Interestingly enough, the polymers basic chemical makeup did notproduce any consistency in results (i.e. both P1 and P5 were both acrylic vinyl acetatecopolymers, but P1 significantly outperformed P5).

Milburn and Parsons (2004) performed a study on multiple soil types with four stabilizers,cement, lime, fly ash and Permazyme. They tested a CH, CL, ML, SM and SP soil, with theSM being labeled as Stevens, the SP being labeled as Lakin and ML being labeled asAtwood. The cement provided the greatest UCS increase of 1580% and 1310% for theAtwood and Stevens soils used in the test. All of the stabilizers increased the UCS of theunstabilized Atwood and Stevens soil by at least 100%, with the Permazyme being the leasteffective, followed by the fly ash. During freeze thaw testing, the cement stabilized samplesyet again outperformed the others, losing only 3% of the soil mass for the Atwood silty soil,and just 2% for the Stevens silty soil. The cement treated silty soils also maintained thehighest strength values compared to the native soils following freeze-thaw cycles. Thecement treated silty soils also outperformed the other stabilizers in wet-dry UCS testing,indicating that it was the most effective stabilizer used for the soils tested in the study.

In 2003, Lgre and Tremblay performed a study on a clayey-silt soil (CL-ML) stabilized

with cement kiln dust (CKD), quicklime, Portland cement and CKD-lime combinations.They found that 6% Portland cement provided the greatest UCS increase at 7 and 28 days ofcuring, while the 6% CKD-lime at 1:3 stabilizer provided the greatest UCS improvement at100 days of curing. In field testing, the 3% lime-3% CKD mixture provided significantstrength increases in both laboratory testing and in the field as measured by a dynamic conepenetrometer (DCP). It was also found that while CKD performed well in the laboratory, itdid not perform well in the field.


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In 1991, Ajayi-Majebi et al. performed a study on a clayey-silt soil (CL-ML) stabilized witha combination of the epoxy-resin bisephenol A/apichlorohydrin with a polyamide hardener.The intent of their study was to determine if the epoxy-resin based stabilizer would create asuitable sub grade material for small airports (not exceeding 30,000 lbs. load). They foundthat the stabilizer improved the unsoaked CBR values for all of the clay-silt ratios used to

create a suitable sub grade material per the FAA. It was also noted that CBR values for thestabilized soils increased with increasing temperature and that the lower the clay to silt ratiowas, the better the CBR value.

Das and Singh (1999) performed a study on three different soil mixtures stabilized withsodium chloride. Their mixtures were labeled A, B and C respectively. Mixture A wascomposed of 20% commercial clay and 80% River Aire soil (River Aire soil is a local soil inthe United Kingdom that is largely a silty-sand), Mixture B was composed of 6% commercialclay, 24% River Aire soil and 70% sand, and Mixture C was composed of 4% commercialclay, 16% River Aire soil, 50% sand and 30% gravel. They found that CBR values, UCSvalues and indirect tensile strength values were greatly improved with the inclusion of

sodium chloride as a stabilizing agent and that sodium chloride as a stabilizing agentproduces a marked increase in the resilient modulus. They also noted that a higher claycontent yielded more substantial strength improvements with the sodium chloride stabilizer.

Tolleson et al. (2003) studied the effect of the enzyme stabilizer PZ-22X with several soiltypes, ranging from poorly graded sand (SP) to cohesive clay (CL). They found that theenzyme stabilizer improved the CBR values and SSG values for all but one type of soil anddetermined that the effectiveness of this particular enzymatic stabilizer did not depend on theproperties of the fines in the soil, but of the quantity, as performance decreased withincreasing fines over 30% fines.

Professional Knowledge Review

In email responses, June 9, 2005, Northern Region ADOTs materials engineer, Leo Woster,said that they have primarily used calcium chloride for soil stabilization, but it is used moreas a surface treatment for dust control on the Dalton Highway and likely some other roads.He said that does create a more stable surface, but it typically lasts only 3 years and thenmust be reapplied (2005). It was also mentioned that several types of stabilizers (tree sap,enzymes, etc) were used about 15 years ago, but did not perform any better than calciumchloride and were significantly more expensive and therefore never caught on.

In phone conversations, June, 2005, Northern Region ADOTs aviation engineering manager,Cindie Little, said that soil stabilizing products have been used on rural airports (2005). Atthe Ft. Yukon airport, the clay filler sodium montmorillonite was used to control dust anderosion. They have also used the dust palliative EK35 on three airports, Kiana, Birch Creekand Russian Mission. At the Kiana airport, the EK35 has produced satisfactory results, but isin need of a reapplication after five years. These products have all been used solely for dustand erosion control, and are not expected to produce any significant structural strengthimprovements for the soil according to Mrs. Little. At the Shishmaref airport, a 4 inchgeoweb was filled with local sand and then covered with an emulsified asphalt/sand wearing


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coarse. This project was done in 1985 or 1986. In 1990 or 1991 it was resurfaced with hotmix asphalt and is currently in design to be resurfaced again. The only problem with thegeoweb has been that the seam where the grids come together is beginning to separate.

In a phone conversation, June 14, 2005, Northern Region ADOTs former geotechnical

engineer, Robert McHattie, said that Northern Region has primarily used asphalt to stabilizesilty, sandy soils when strength was needed (2005). They have used calcium chloride for dustsuppression, but it was not noted to improve trafficability. He said that the calcium chlorideadds apparent cohesion to the soil by attracting moisture to the soil. He noted that asphaltstabilized silty sandy soils might be strong enough to withstand traffic, but not necessarilyparked vehicles or other stationary loads, especially in warmer temperatures. He said thatstabilized sand in a containment grid with a gravel wearing course has worked well on thecoastal region of Alaska. He also noted that many of the stabilization techniques found inmanuals are largely for a stabilized base course, not for a wearing course. He suggestedcomposite systems, such as the one used in Shishmaref and mentioned a new product calledDura-Base that is essentially a heavy duty polyethylene mat. He suggested that the Dura-

Base mat might work well for stabilizing parking areas and other areas where heavystationary loads might exist, and regular stabilization products such as asphalt for the roadleading to these Dura-Base stabilized areas. He also noted that many of the stabilizers onthe market require some amount of organics or clays to work properly.

University of Kansas civil engineering department associate professor Dr. Robert L. Parsonshas done many studies on soil stabilizers for the Kansas Department of Transportation. In anemail response June 15, 2005, he said that for his region, the rule of thumb was lime forclays, class C fly ash for silts, and cement for sands and that this rule of thumb hassuccessfully guided their research (2005). He recommends class C fly ash if it is available forsilty sands, as well as cement. He said that in his work cement worked best in freeze-thawtesting (ASTM D560). He also warns not to place too much emphasis on high CBR values inthe lab, as once you get past a respectable CBR value, comparisons between high values forhighly stabilized soils don't mean a whole lot. He also recommends finding a suitable way totest for frost heave as he thinks it would likely be a big issue for our region.

In a phone conversation and subsequent email communication, Jeb S. Tingle of the UnitedStates Army Corp of Engineers said that polymer/cement combinations work very well forstabilizing sandy material as the polymer reduces the shrinkage potential and the cementgives the soil higher early strength (2005). He also sent coding for the products used in hisand Santonis testing (Santoni, et. al, 2005, 2002) which has been used to help determinewhich stabilizers to test for phase 1B of this project. In his and Santonis studies, he used theproducts EK35, EnviroKleen, Soil-Sement and Soil-Sement Engineered Formula amongothers. Soil-Sement and Soil-Sement Engineered Formula both performed well (Santoni et.al, 2005). EnviroKleen and EK35, however, did not perform well, showing little or noimprovement in UCS values both dry and wet (Santoni, et. al, 2005).

Cost Analysis

Table 1 - Cost Comparison of Potential Products


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Product

Unit

Cost

($/yd2) Comments

EK35 $6.24 assumed 6" lift with 1.7% product

EMC2 $0.36

Emulsified Asphalt $4.88 assumed 5.5" thick layer with 5% asphalt content

EnviroKleen $6.77 assumed 6" lift with 1.7% product

Enviroseal M10+50 $1.73

Gravel $30.00

Soil-Sement EngineeredFormula $9.53 assumed 6" lift with 1.7% product

Soiltac $1.31

Type I Portland Cement $3.83 assumed 4" thick layer with 7% cement



Phase 1A Results

Eolian Sand

Maximum Particle Size: 2.00 mm (No. 10)

Chart 1 Gradation Curves

Eolian 1 Gradation Curve

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%

110.0%

0.0100.1001.00010.000

Particle size, mm

%F

iner

6/15/05 Analysis

6/17/05 Analysis

Table 2 Gradation Values

Date Cu Cz6/15/05 1.82 1.31

6/17/05 1.82 1.31


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6/17/05 2.00 1.19

Chart 4 Modified Proctor Compaction Curve

Compaction Curve

98.50

99.00

99.50

100.00

100.50

101.00

101.50

102.00

102.50

103.00

103.50

0.00% 5.00% 10.00% 15.00% 20.00% 25.00%

Moisture Content, %

DryUnitWeight,lb/ft^3

Table 4 Soil Test Results Summary

Fluvial 1 Eolian 1

SG 2.72 2.72

LL None None

PL N/A N/API Non-plastic Non-plastic

Average Cu 2.22 1.82

Average Cz 1.24 1.31

USCS Classification SP SP

dmaximum (lb/ft3) 103.0 103.0

wopt(%)117% 117%

1Although the compaction curve did not display a definite peak, 17% was used for optimummoisture content as the soil began to bleed (leach water from the base of the mold) at the19% moisture content.

Phase 1B Results

Modified Proctor Results Unmodified Soil

Chart 5 - Eolian Compaction Curves


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Eolian Phase 1B Compaction Curves

102.00

102.50

103.00

103.50

104.00

104.50

105.00105.50

106.00

0.00% 5.00% 10.00% 15.00% 20.00%

Moisture Content (%)

DryDensity(

10/6/2005 10/8/2005

Chart 6 Fluvial Compaction Curves

Fluvial Phase 1B Compaction Curves

102.00

102.50

103.00

103.50

104.00

104.50

105.00

105.50

106.00

0.00% 5.00% 10.00% 15.00% 20.00%

Moisture Content (%)

DryDensity(p

10/1/2005 10/13/2005

Table 5 Soil Test Results Summary


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Fluvial 1 Eolian 1

dmaximum (lb/ft 3) 104.8 104.1wopt(%) 13% 11.5%

CBR Results

Table 6 - Dry CBR Results - Eolian

Product ID#

CBR

Value

EMC2

EEMC7 13.49

EEMC8 15.87

EEMC9 13.05

EnvirosealM10+50

EE3 37.53

EE4 55.39

EE5 81.76

Soil Sement

ESS3 82.21

ESS4 243.34

ESS5 302.52

Soiltac

EST1 58.67

EST2 100.60

EST3 77.11

Unmodified

UME1 17.25

UME2 20.25

UME3 20.00

Chart 7 - Dry CBR Results Eolian


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Dry CBR values - Eolian

81.76

13.05

82.21

14.14

209.36

19.17

100.60

302.52

15.87 20.25

58.67

17.25

37.53

78.7958.23

-40.00

0.00

40.00

80.00

120.00

160.00

200.00

240.00

280.00

320.00

High CBR Low CBR Avg CBR

High CBR 15.87 81.76 302.52 100.60 20.25

Low CBR 13.05 37.53 82.21 58.67 17.25

Avg CBR 14.14 58.23 209.36 78.79 19.17

EMC2 Enviroseal Soil Sement Soiltac Unmodified

Table 7 - Dry CBR Results Fluvial

Product ID#

CBR

Value

EMC2

FEMC7 14.16

FEMC8 12.00

FEMC9 15.80

EnvirosealM10+50

FE3 4.53

FE4 16.60

FE5 14.05

Soil Sement

FSS2 160.22

FSS4 74.10

FSS5 68.67

Soiltac

FST1 64.92

FST2 51.33

FST3 38.98

Unmodified

UMF1 14.59

UMF2 18.37

UMF3 17.81

Chart 8 - Dry CBR Results Fluvial


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Dry CBR values - Fluvial

12.00 4.53

38.9813.99 11.73

101.00

51.74

16.92

15.80 16.60 18.37

160.22

64.92

68.67

14.59

-40.00

0.00

40.00

80.00

120.00

160.00

200.00

240.00

280.00

320.00

High CBR Low CBR Avg CBR

High CBR 15.80 16.60 160.22 64.92 18.37

Low CBR 12.00 4.53 68.67 38.98 14.59

Avg CBR 13.99 11.73 101.00 51.74 16.92


Freeze-Thaw CBR Results

Table 8 - Eolian Freeze-Thaw CBR Results

Product Name ID #

F-T CBR

Value

EMC2 EEMC4 N/A*EEMC5 9.50

EnvirosealM10+50

EE1 111.33

EE2 90.00

Soil SementESS1 152.24

ESS2 110.01

SoiltacEST4 57.00

EST6 49.13

UnmodifiedUME4 N/A*

UME5 13.49*A value of N/A means that the soil sample fell apart before the CBR test could be performed.

Table 9 - Eolian Freeze-Thaw CBR Comparison

Product Avg F-TCBR

Avg Dry

CBR

% Strength

Reduction

% Change

from UM

(Dry)

% Change from

UM (F-T)

EMC2 9.50 14.14 33% -26% -30%


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Enviroseal 100.67 58.23 -73% 204% 646%

SoilSement 131.12 209.36 37% 992% 872%

Soiltac 53.07 78.79 33% 311% 293%

Unmodified 13.49 19.17 30% 0% 0%

Chart 9 - Eolian Freeze-Thaw CBR Comparison

Average CBR values - Eolian

13.499.50

100.67

131.12

53.07

14.14

58.23

209.36

78.79

19.17

0.00

50.00

100.00

150.00

200.00

250.00


Product Name

CBRvalue(

Avg F-TCBR Avg Dry CBR

Table 10 - Fluvial Freeze-Thaw CBR Results

Product Name ID #

F-T CBR

Value

EMC2 FEMC4 N/A*

FEMC5 N/A*

Enviroseal

M10+50

FE1 72.00

FE2 106.67

Soil SementFSS1 156.56

FSS3 160.22

SoiltacFST4 28.79

FST5 24.35

UnmodifiedUMF4 N/A*

UMF5 4.11


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*A value of N/A means that the soil sample fell apart before the CBR test could be performed.

Table 11 - Fluvial Freeze-Thaw CBR Comparison

Product

Avg F-T

CBR

Avg Dry

CBR

% Strength

Reduction

% Change

from UM

(Dry)

% Change

from UM (F-

T)EMC2 0.00 13.99 100% -17% -100%

Enviroseal 89.33 11.73 -662% -31% 2072%

SoilSement 158.39 101.00 -57% 497% 3751%

Soiltac 26.57 51.74 49% 206% 546%

Unmodified 4.11 16.92 76% 0% 0%

Chart 10 - Fluvial Freeze-Thaw CBR Comparison

Average CBR values - Fluvial

4.11

26.57

158.39

89.33

0.0016.92

51.74

101.00

11.7313.99

0.00

50.00

100.00

150.00

200.00

250.00


Product Name

CBRvalue(

Avg F-T CBR Avg Dry CBR

Unconfined Compression Results

Unconfined compression results will be reported at a later date due to difficulty removingsamples from their molds for testing.


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Dry Density Comparison

Chart 11 - Eolian Dry Density Comparison

Average Dry Density - Eolian

101.34

98.7499.64

100.19

102.97

90.00

92.00

94.00

96.00

98.00

100.00

102.00

104.00

Unmodified EMC2 Enviroseal

M10+50

Soil-Sement Soiltac

Product Name

AverageDryDensit


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Chart 12 - Fluvial Dry Density Comparison

Average Dry Density - Fluvial

103.16

99.72

95.31

102.67

99.86

90.00

92.00

94.00

96.00

98.00

100.00

102.00

104.00

Unmodified EMC2 Enviroseal

M10+50

Soil-Sement Soiltac

Product Name

AverageDryDensit


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CHAPTER 3 - INTERPRETATION, APPRAISAL, AND APPLICATIONS

Discussion

Both soils exhibit typical compaction curves for poorly graded sand material. Looking atcharts 5 and 6, there are two humps, the second hump is used for determination of the

optimum moisture content. The decrease following the first hump can be attributed to thecapillary tension effect, where the capillary tension in the pore water limits the ability of thesoil particles to move around and be densely compacted..The CBR test was used for this project because it has been successfully correlated withstrength potential of the subgrade, subbase, and base course material for use in road andairfield construction. In addition, the CBR values were recorded following twelve freezethaw cycles, to determine strength losses due to extreme temperature and moisture variations.All of the polymer products performed adequately, improving the CBR values over theunmodified soils as shown in charts 7-10, with the exception of the Enviroseal modified dryFluvial specimens, which interestingly enough performed very poorly. The EMC2modified

specimens did not perform adequately, however, as all samples performed worse than theunmodified soil. It did, however, have a very firm surface layer, indicating promise for dustcontrol.

Dry densities were compared in charts 11 & 12, and there appears to be no correlationbetween dry density and CBR value. Most samples had similar dry densities to theunmodified soil, especially the Eolian samples, however the samples with higher drydensities did not necessarily produce the best CBR results. The Fluvial dry densities varygreater than the Eolian samples largely because of inconsistencies in compacting due to thehigher moisture content.

General Recommendations

Overall, the Soil Sement and Soiltac provided the most consistent and reliable performance,with the Soil Sement greatly outperforming all other products used in the test. The Envirosealalso showed significant improvement over the Eolian sand, however it was less reliable withthe Fluvial sand. It should be noted that overall, the Fluvial sand did not perform as well asthe Eolian. This can likely be attributed to the higher moisture content required; because ofthe high moisture content, most of the samples slightly leeched water, and did not compact assmoothly as the Eolian samples, however the Soil Sement and Soiltac both proved that theycould provide adequate CBR values with either soil. The EMC

2did not perform sufficiently

in any of the tests and it would not be recommended for further use as a stabilization agentbased on this research. Based on the results of the lab tests, further testing should be

performed on the Soil Sement and Soiltac, with the Enviroseal also to be considered if timeand funding permits. In addition, EK35 would be a good candidate for further field testingbased on its results in the state of Alaska already. It was not suitable for lab testing, however,because it is compaction activated and therefore requires regular loading to performadequately. Based on the cost comparison, the Soiltac is the most economical alternative, andit did provide a suitable improvement over the unmodified soil, however the Soil Sementprovided the strongest, most moisture resistant material. What was very interesting wasduring the freeze-thaw testing, the Soil Sement remained dry throughout, as evidenced by a


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lack of discoloration except where the base was directly in contact with water, while theother products all darkened in color, indicating moisture was dispersed throughout thesample.


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CHAPTER 4 - CONCLUSIONS AND SUGGESTED RESEARCH

Conclusions

The polymer emulsions appear to be the stabilization agents for the future. All three polymeremulsions used in this testing program performed superbly, creating strong specimens that all

provided suitable CBR values for roads.

Suggested Research

While lab testing provides an indication of the strength of the soil as well as the compatibilityof the products with the soils used, it does not provide a true indication of the trafficability(the ability of the materials to hold up to traffic loads and abrasion) of the materials. To beable to truly test how these products will perform in the field requires a field test or anaccurate simulation of the field environment. This can be accomplished using a linear testtrack or by placing and monitoring a section (or sections) in the field. A linear test trackwould be ideal for follow-up testing because it would allow control of the environmental andloading factors, allowing a direct comparison of performance between soil types, however a

full scale field test would likely be required at some point.


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REFERENCES

Ajayi-Majebi, A., Jones, E.E., Grissom, W.A., and Smith, L.S. Epoxy-Resin Based ChemicalStabilization of a Fine, Poorly Graded Soil System. In Transportation ResearchRecord 1295, TRB, National Research Council, Washington, D.C., 1991.

Danyluk, L.S. Stabilization of Fine-Grained Soil for Road and Airfield Construction. ReportAK-RD-86-30, Alaska Department of Transportation & Facilities, Juneau, AK, April1986.

Das, B.M and Singh, G. Soil Stabilization with Sodium Chloride. In TransportationResearch Record 1673, TRB, National Research Council, Washington, D.C., 1999.

Gentry, C.W., and Esch, D.C. Soil Stabilization for Remote Area Roads. Report FHWA-AK-RD-86-08, Federal Highway Administration, U.S. Department of Transportation,Washington, D.C., August 1985.

Hicks, R.G.Alaska Soil Stabilization Design Guide. Report FHWA-AK-RD-01-06B, AlaskaDepartment of Transportation & Public Facilities Research & Technology Transfer,Fairbanks, AK, February 2002.

Hicks, R.G.Evaluation ofSoil Stabilization Practices in Alaska Phase I. Report FHWA-AK-RD-01-06A, Alaska Department of Transportation & Public Facilities Research& Technology Transfer, Fairbanks, AK, January 2001.

Koehmstedt, P.L. Soil Stabilization for Remote Airfields. Report AK-RD-86-22, AlaskaDepartment of Transportation & Public Facilities, Juneau, AK, January 1986.

Kozisek, L. and Rooney, J.W. Soil Stabilization Test Strips, Bethel, Alaska. Report AK-RD-86-27, Alaska Department of Transportation & Public Facilities, Juneau, AK, January1986.

Lgre, G. and Tremblay, H. Laboratory and Field Evaluation of Cement Kiln Dust and Limefor Stabilizing Clayey Silt on Low-Volume Unpaved Roads. In TransportationResearch Record 1819 Vol. 2, TRB, National Research Council, Washington, D.C.,2003, pp. 3-10.

Little, C.M. Personal communication June 13, 2005.

McHattie, R. Personal communication June 14, 2005.

Milburn, J.P. and Parsons, R.L. Performance of Soil Stabilization Agents. Report KU-01-8,Kansas Department of Transportation, Topeka, KS, May 2004.

Newman, K. and Tingle, J.S.Emulsion Polymers for Soil Stabilization. Proceedings, 2004FAA Worldwide Airport Technology Transfer Conference, FAA, Atlantic City, NJ.


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Parsons, R.L. Personal communication June 15, 2005.

Peyton, H.R., Kennedy, C.F., and Lund, J.W. Stabilization of Silty Soils in Alaska Phase II.Report Number 3, University of Alaska Arctic Environmental Engineering

Laboratory, University of Alaska Fairbanks, Fairbanks, AK, June 1966.

Randolph, R.B. Earth Materials Catalyst Stabilization for Road Bases, Road Shoulders,Unpaved Roads, and Transportation Earthworks. In Transportation Research Record1589, TRB, National Research Council, Washington, D.C., 1997, pp. 58-63.

Santoni, R.L., Tingle, J.S., and Nieves, M. Accelerated Strength Improvement of Silty SandUsing Nontraditional Additives.https://transportation.wes.army.mil/triservice/soilstab.aspx. Retrieved 6/3/05.

Santoni, R.L., Tingle, J.S., and Webster S.L. Stabilization of Silty-Sand with NontraditionalAdditives. In Transportation Research Record 1787, TRB, National ResearchCouncil, Washington, D.C., 2002, pp. 33-41.

Scholen, D.E. Nonstandard Stabilizers. Report FHWA-FLP-92-011, Federal HighwayAdministration, Washington, D.C., July 1992, 113 pages.

Tingle, J.S. Personal communication June 29, 2005.

Tolleson, A.R, Shatnawi, F.M., Harman, N.E., and Mahdavian, E.An Evlauation of StrengthChange on Subgrade Soils Stabilized with an Enzyme Catalyst Solution Using CBR

and SSG Comparison. Report R-03-UTC-ALTERPAVE-GEO-01, James E. ClyburnUniversity Transportation Center, Orangeburg, S.C., September 2003.

Vinson, T.S., Mahoney, J.P., and Kaminski, M.J. (1984). Cement Stabilization for RoadConstruction in Cold Regions. Proceedings, 3rdInternational Cold RegionsEngineering Specialty Conference, ASCE, Edmonton, Canada.

Woster, L. Personal communication June 9, 2005.


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Documents

UAF Soils Stabilization Study-Final Draft_020606-1