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Laureano R. Hoyos

Bio: Laureano R. Hoyos is an academic researcher from University of Texas at Arlington. The author has contributed to research in topics: Expansive clay & Suction. The author has an hindex of 24, co-authored 136 publications receiving 1997 citations. Previous affiliations of Laureano R. Hoyos include University of Guam & University of Washington.


Papers
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Journal ArticleDOI
TL;DR: In this article, the effects of three different cement dosages and various confining and deviatoric stress levels on the resilient modulus (MR) response of treated RAP materials were studied.
Abstract: The use of reclaimed asphalt pavement (RAP) aggregate materials in road construction reduces natural resource depletion and promotes the recycling of RAP materials for other applications. However, product variability and low resilient moduli characteristics often limit RAP applications in road bases. Stabilization of RAP materials with cement was hence attempted in a research study to evaluate the effectiveness of cement treatments in enhancing resilient characteristics of RAP aggregates. The present paper describes the results from a series of resilient modulus tests that were conducted in a laboratory environment using a repeated load triaxial test setup. The effects of three different cement dosages and various confining and deviatoric stress levels on the resilient modulus (MR) response of treated RAP materials were studied. MR values of untreated and cement-treated RAP aggregates ranged from 180 to 340 MPa and 200 to 515 MPa, respectively, which reveal the enhancements with cement treatment. Regressi...

241 citations

Journal ArticleDOI
TL;DR: In this article, a series of tests were performed on RAP aggregate materials treated with different dosages of portland type I/II cement and with alkali-resistant glass fibers, and the results confirmed the potential of cement-fiber-treated RAP material as an environmentally and structurally sound alternative to nonbonded materials for base and subbase applications in pavement engineering.
Abstract: The use of reclaimed asphalt pavement (RAP) materials in road construction has been proven to reduce both the amount of construction debris disposed of in urban landfills and the rate of depletion of natural resources. However, source-dependent product variability, federal and local environmental regulation, and deficient strength-stiffness characteristics often limit RAP applications in road bases. These limitations have led to new research efforts aimed at exploring novel, cost-effective, chemical and/or mechanical stabilization methods to treat RAP materials before their reuse in pavement construction. In this work, a series of tests were performed on RAP aggregate materials treated with different dosages of portland type I/II cement and with alkali-resistant glass fibers. Tests include permeability, leachate, unconfined compression, and small-strain shear moduli through resonant column testing. Leachate tests include pH, total and volatile dissolved solids, total and volatile suspended solids, and turbidity. Test results confirm the potential of cement-fiber-treated RAP material as an environmentally and structurally sound alternative to nonbonded materials for base and subbase applications in pavement engineering. A companion paper presents the results from a comprehensive repeated-load triaxial test program to investigate the resilient modulus characteristics of cement-treated RAP.

150 citations

Journal ArticleDOI
TL;DR: In this paper, a research study was conducted to address the effectiveness of sulfate resistant cement stabilizers Types I/II and V, for providing better treatment of the sulfate rich soils.
Abstract: Performance of pavements has been affected by heave distress problems caused by sulfate rich soils treated with calcium-based stabilizers. A research study was conducted to address the effectiveness of sulfate resistant cement stabilizers Types I/II and V, for providing better treatment of sulfate rich soils. Experiments were designed and conducted on both control and cement treated sulfate soils to investigate compaction relationships, Atterberg limits, linear shrinkage and free swell strain potentials, unconfined compressive strength, and low strain shear moduli properties. This paper presents a comprehensive summary and analysis of these test results. Test results were statistically analyzed to study the potentials of sulfate resistant cement stabilization methods for significant enhancements to the strength and stiffness properties as well as reductions in swell and shrinkage strain potentials of natural sulfate rich soils. Mineralogical studies were used to verify research findings observed from the macro test results.

122 citations

Journal ArticleDOI
TL;DR: In this paper, a novel methodology to conduct volumetric shrinkage strain test on cylindrical soil specimens and a digital imaging technique to analyze and determine volumality shrinkage strains of the test are described.
Abstract: Expansive soils undergo large volumetric shrinkage strains, which eventually lead to high heave movements upon hydration of these soils. Current test methods to determine shrinkage strain potentials of soils are restricted by several limitations including small specimen sizes, molds with rigid walls that restrain shrinkage strains in lateral directions, and manual measurement errors. In this paper, a novel methodology to conduct volumetric shrinkage strain test on cylindrical soil specimens and a digital imaging technique to analyze and determine volumetric shrinkage strains of the test are described. As part of the evaluations of this methodology, volumetric shrinkage strains of four types of medium to high expansive soils were researched. Shrinkage tests were conducted on all four soils at three different moisture contents. Volumetric shrinkage strains were then measured using both digital and conventional manual approaches. Test results showed that the test and the developed measurement methodology provided repeatable and realistic shrinkage strain measurements. Digital measurements provided more accurate results than manual measurements by accounting for even minor shrinkage cracks in the soils. The significance of the digital measurements in relation to the current shrinkage strain characterizations is discussed. Potential geotechnical application areas where these test results could be used are also described.

79 citations

Journal ArticleDOI
TL;DR: In this article, a proximitor-based resonant column and self-contained bender elements were used for soil testing under controlled suction states, as compared to more reliable and fully-standardized procedures such as resonant columns or simple shear test methods.

77 citations


Cited by
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01 Jan 1987
TL;DR: Eisma et al. as mentioned in this paper showed that the CEC can vary over 2 orders of magnitude for various types of, minerals and can vary one order of magnitude within one soil type.
Abstract: Positive ions that are available in soils absorb on grain surfaces. The total sum of cations that can be absorbed bij a soil/sediment at a certain PH is defined by the cation-exchange capacity (CEC, in meq g-1: mol equivalents per gram). The uptake of cations is an important parameter in agriculture and the larger the CEC, the more cations can be absorbed to the soil. The CEC depends highly on the pH of soil and sediments, where the CEC decreases with decreasing PH (increasing acidity). The exchange of ions on sediments occurs commonly fast on geological time scales, but the kinetics of adsorption in natural environments is still poorly understood. The strength of the bonding between the cations and the sediments varies from weak Van der Waals bondings (physical adsorption) to strong chemical bonds. The CEC is widely used for agricultural assessment because it is a measure of general soil fertility as well as an indicator of structural stability because CED is capabel of enhancing development of shrinkage cracks. The list below shows the CEC for different types of minerals. The data indicate that the CEC can vary over 2 orders of magnitude for various types of , minerals and can vary one order of magnitude within one soil type. Cation exchange capacity for different types of sediment (Eisma, 1992; Locher and de Bakker, 1990):

1,169 citations

Journal ArticleDOI
TL;DR: A comprehensive laboratory evaluation of the geotechnical and geoenvironmental properties of five predominant types of construction and demolition (C&D) waste materials was undertaken in this article, and the results showed that these materials are suitable for reuse.
Abstract: A comprehensive laboratory evaluation of the geotechnical and geoenvironmental properties of five predominant types of construction and demolition (C&D) waste materials was undertaken in th...

336 citations

Journal ArticleDOI
TL;DR: In this article, a modified hyperbolic model and a statistical analysis of existing Resonant Column and Torsional Shear test results for 122 specimens obtained from South Carolina, North Carolina, and Alabama are presented.
Abstract: Predictive equations for estimating normalized shear modulus and material damping ratio of Quaternary, Tertiary and older, and residual/saprolite soils are presented in this paper. The equations are based on a modified hyperbolic model and a statistical analysis of existing Resonant Column and Torsional Shear test results for 122 specimens obtained from South Carolina, North Carolina, and Alabama. Variables used in the equations for normalized shear modulus are: shear-strain amplitude, confining stress, and plasticity index (PI). The equations for damping ratio are expressed in terms of a polynomial function of normalized shear modulus plus a minimum damping ratio. It is found that the Quaternary soils exhibit more linearity than soils of the other two groups. Also, it is found that the effect of PI on dynamic soil behavior is not as significant as previously thought. Data from all three groups exhibit significant variations with confining stress, similar to the variations determined by Stokoe et al. The uncertainties associated with the equations for PI of 0 and mean effective confining stress of 100 kPa are quantified using the point estimate method. A case study from Charleston, S.C. is provided to illustrate an application of the equations to seismic response analysis and the importance of considering confining stress and geologic age.

322 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present details of a study that deals with determination of engineering properties, identification of phases of major hydration products, and microstructural characteristics of a zinc-c...
Abstract: This paper presents details of a study that deals with determination of engineering properties, identification of phases of major hydration products, and microstructural characteristics of a zinc-c...

273 citations

BookDOI
TL;DR: In this article, the characterization of cementitiously stabilized layers and the properties that influence pavement performance are discussed, as well as performance-related procedures for characterizing these layers and performance-prediction models for incorporation into the mechanistic-empirical pavement analysis methods.
Abstract: This report presents information on the characterization of cementitiously stabilized layers and the properties that influence pavement performance. It also contains recommended performance-related procedures for characterizing these layers and performance-prediction models for incorporation into the mechanistic–empirical pavement analysis methods. Individual chapters highlight pavement distresses of hot-mix asphalt pavements and concrete pavements, laboratory tests and model development, and model calibration. The material contained in the report will be of immediate interest to state materials, pavement, and construction engineers and others involved in the different aspects of pavement design and construction.

270 citations