SES Group and Associates LLC

Cape Saint Claire, MD, United States

SES Group and Associates LLC

Cape Saint Claire, MD, United States
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Li X.,SES Group and Associates Inc. | Gibson N.,Turner Fairbank Highway Research Center
Transportation Research Record | Year: 2016

This paper presents the results of laboratory fatigue characterization of recycled and warm-mix asphalt (WMA), which include unaged and long-term oven-aged conditions tested with an asphalt mixture performance tester. Various choices of failure criteria and pavement structural variations were considered. The laboratory results were compared with full-scale performance data. A softer performance grade (PG) was effective at improving the performance for 40% reclaimed asphalt pavement (RAP) recycled binder ratio (RBR) mixes. The softer PG was ineffective at improving the performance of tear-off recycled asphalt shingles, providing 20% RBR. WMA production improved slightly in the 20% RAP RBR mixes, but was less effective in softening the 40% RAP RBR mixes. Long-term aging increased the modulus by about 24% and decreased the fatigue resistance by about 40%. Aged mixes appear to agree better with full-scale accelerated loading facility cracking. Structural differences from ordinary construction variation and the choice of failure criterion can trigger a couple of mixtures to change ranking in predicted fatigue cracking, but the overall rank order of the whole data set is fairly consistent. © 2016, National Research Council. All rights reserved.

Williams A.J.,University of Nevada, Las Vegas | Buck B.J.,University of Nevada, Las Vegas | Beyene M.A.,University of Nevada, Las Vegas | Beyene M.A.,SES Group and Associates LLC
Soil Science Society of America Journal | Year: 2012

Biological soil crusts (BSCs) are bio-sedimentary complexes that play critical ecological roles in arid landscapes; however, the interactions between component biota and sediments are poorly understood. A detailed micromorphological investigation of BSC development and crust microstructure in the Muddy Mountains Wilderness Area, Nevada, examined features in thin section using petrographic microscopy, light microscopy, scanning electron microscopy, and energy dispersive x-ray spectroscopy. The >1800 microscopic observations were linked to crust macroscale features and soil geomorphology. Complex bio-sedimentary structures of BSCs reflect a dynamic genetic history and diverse formative processes, including: (i) stabilization and authigenic mineral precipitation; (ii) wetting-drying and expansion-contraction; (iii) dust capture; (iv) microscale mass wasting; and (v) vesicular (Av) horizon formation. A new conceptual model for hot deserts illustrates how these processes co-develop with BSC succession, during countless wet-dry cycles, to build up pinnacle microtopography while simultaneously forming Av horizons in the bio-rich and bio-poor zones. Complex surficial and internal bio-sedimentary structures, which vary as a function of crust morphology, trap surface water for uptake by crust organisms, while dust influx provides a source of nutrients. These phenomena influence landscape-scale water dynamics and biogeochemical cycling, increasing the availability of soil resources during times of biotic stress. Biological soil crusts uniquely facilitate the accumulation, morphology, and ecosystem function of dust and should, therefore, be considered critical agents in arid pedogenesis and landscape development. © Soil Science Society of America,.

Munoz J.F.,National Research Council Italy | Yao Y.,SES Group and Associates LLC | Youtcheff J.,Turner Fairbank Highway Research Center | Arnold T.,Turner Fairbank Highway Research Center
Cement and Concrete Composites | Year: 2014

This study explored the effect of two combinations of silicon and aluminum oxides, nanosilica-nanoboehmite and nanosilica-gibbsite, on the hydration reaction of cement and the porosity of the interfacial transition zone (ITZ). The influence of sols on the cement hydration reaction was investigated using isothermal calorimetry while their effect on the porosity of the aggregate-paste interface was validated using scanning electron microscopy. The nanosilica-nanoboehmite mixtures were found to accelerate the hydration reaction to a higher degree than the individual components, nanosilica and nanoboehmite. Further, the effect was also found to be dependent on the stoichiometry of the mixture of nanoparticles. The nanosilica-gibbsite combinations not only accelerated the reaction but also increased the cumulative heat of hydration. In this case, the enhancement is attributed to the seeding effect of the gibbsite particles, being more prominent at the smaller particle sizes. Lastly, when these materials were applied as nanoporous thin films on the aggregates, all sol mixtures not only helped to decrease the overall porosity but also contributed to refinement of the porosity in the cement paste adjacent to the aggregate. These effects were observed up to 250 μm away from the surface of the aggregate thus not restricted to the typical length of the interfacial transition zone in concrete (40-50 μm). © 2013 Elsevier Ltd. All rights reserved.

Meininger R.C.,FHWA Office of Infrastructure Research and Development | Stokowski S.J.,SES Group and Associates LLC | Stokowski S.J.,Turner Fairbank Highway Research Center
Public Roads | Year: 2011

Sand, gravel, crushed stone, and, increasingly, industrial byproducts and reclaimed construction materials are the foundation of the Nation's transportation infrastructure. Collectively referred to as aggregates, these materials are essential to constructing, preserving, and rehabilitating roads and bridges. Ensuring a sustainable supply of aggregates requires advance planning and balancing a complex matrix of engineering, geographical, and geological variables and community interests. In general, natural aggregates are mined from stone quarries and from sand and gravel pits. Increasingly, however, agencies are using recycled, reclaimed, and alternative byproduct aggregate materials, such as blast furnace and steel slag, other mining or industrial byproducts, and reclaimed asphalt pavement and recycled concrete aggregate. FHWA estimates the US transportation industry's need for aggregates for pavements at about 700 million tons per year. Other objectives of Alaska's program include development of performance standards that the department can apply to material sites and to facilitate geotechnical asset management to drive long-term decision making concerning these material assets.

Kim H.,SES Group and Associates LLC | Goulias D.G.,University of Maryland University College
Journal of Materials in Civil Engineering | Year: 2015

In the current trend of sustainability, the concrete community has been aggressively looking into adopting green construction material practices and at the same time improving concrete quality and performance for extensive service life and adaptive reuse. Concrete is the construction material most used in the world, with an estimated yearly production of 2.35 billion tons worldwide. In the United States, it is estimated that on average approximately 5% of the ready-mix concrete produced is unused and returned to the plant with only a small portion reused. Such a material when further processed, identified as crushed returned concrete aggregate (CCA), has a significant residual value because among other things it is free of contaminants and has better quality than recycled concrete aggregate (RCA). The objective of this study was to assess the shrinkage behavior of CCA concrete mixtures produced with aggregate from returned concrete. The aggregate was prepared from concrete of different strength. The virgin aggregate (stone) was replaced either partially or at 100% level in the concrete mixtures. The response of the hyperbolic shrinkage prediction model was examined, and based on the experimental results an alternative model is proposed. The proposed model and methodology can be used to estimate the drying shrinkage of CCA mixtures, and eventually can be adopted for assessing the shrinkage behavior of these concrete mixtures in other regions. © 2014 American Society of Civil Engineers.

Balachandran C.,SES Group and Associates LLC | Olek J.,Purdue University | Rangaraju P.R.,Clemson University | Diamond S.,Purdue University
Transportation Research Record | Year: 2011

About 15 years after the introduction of alkali-acetate and alkali-formate deicers, premature deterioration was observed on some airfield pavements that had been exposed to the deicers. A characteristic map cracking pattern was observed on pavement surfaces that had experienced repeated applications of these deicers, and the suspected cause of this cracking pattern was accelerated alkali-silica reaction (ASR). Laboratory-based research indicated that alkali-silica reactive aggregates may undergo active deterioration when intimately exposed to such deicers under conditions promoting accelerated reaction. Investigations were conducted on cores collected from an airport whose deicing operations involved repeated applications of potassium acetate deicer. Detailed microscopic investigation indicated that uniform distress existed throughout the depth of the pavement, although in one, the distress resulted from alkali-carbonate reaction rather than from ASR. However, investigations on the depth of penetration of deicer into these pavement cores showed only limited incursion. A companion laboratory study estimated the extent of deicer penetration under different laboratory exposure conditions. Even in a relatively aggressive wetting and drying exposure regime, ingress of the deicer was limited. Thus, it was concluded that although the potassium acetate deicer can induce severe ASR under aggressive laboratory conditions, penetration into field airport pavements may be so limited in some cases that the potassium acetate deicer does not seem to aggravate the ASR distress should one already exist.

Beyene M.,RJ Lee Group, Inc | Beyene M.,SES Group and Associates LLC | Snyder A.,RJ Lee Group, Inc | Lee R.J.,RJ Lee Group, Inc | Blaszkiewicz M.,RJ Lee Group, Inc
Cement and Concrete Research | Year: 2013

The mechanism of Alkali Carbonate Reaction (ACR) in concrete made from fine-grained, argillaceous dolomitic limestone coarse aggregates remains controversial. ACR distress is described as an increase in volume caused by the crystallization of brucite during the dedolomitization process. However, recent studies by Katayama suggest that ACR is a combination of the "deleteriously expansive Alkali Silica Reaction (ASR) of cryptocrystalline quartz in the matrix of the reactive aggregates and a harmless dedolomitization that produces brucite and a carbonate halo." We investigated ACR susceptible concrete extracted from a wharf structure in Quebec, Canada, and determined that ASR was the cause of damage. Optical and SEM-EDS analyses identified ASR gel extending from reactive aggregates to the paste, and X-ray elemental mapping confirmed the gel composition. Silica (Si) was found in the matrix of the aggregate and is the source of reactive silica. These results support ASR as the mechanism in ACR susceptible concrete. © 2013 Elsevier Ltd.

Tanesi J.,SES Group and Associates LLC | Gudimettla J.,Global Consulting Inc. | Crawford G.,HIPT 20 | Ardani A.,Turner Fairbank Highway Research Center
Transportation Research Record | Year: 2013

A ruggedness study on the AASHTO T 336 coefficient of thermal expansion of concrete test method was performed to evaluate the factors most likely to affect the test results. Seven factors were evaluated: time at temperature extremes, water level, position of the linear variable differential transformer, number of segments, saturation criterion, specimen length, and temperature of the first segment. Two concrete mixtures were used in this study, four laboratories participated, and five commercially made coefficient of thermal expansion devices from two manufacturers were used. On the basis of the results obtained, saturation criterion was found to be the most significant factor. The other factors were found not to have a significant impact on the test results, have already been addressed in the most current version of the test method, or, in the authors' opinion, do not warrant being addressed.

Tanesi J.,SES Group and Associates LLC | Ardani A.,Turner Fairbank Highway Research Center | Leavitt J.,SES Group and Associates LLC
Transportation Research Record | Year: 2013

This study examined the feasibility of using smaller-size concrete beam specimens to conduct flexural strength tests of concrete with a simple beam with third-point loading according to the AASHTO T 97 procedure. Twenty-two mixtures containing four coarse aggregates (limestone, diabase, gravel, and granite) with maximum size varying from .75 to 1.5 in. were prepared. A total of 132 specimens measuring 4 × 4 × 14 in. and 132 standard-size specimens (6 × 6 × 21 in.) were tested. The 4- × 4-in. specimens yielded higher flexural strengths, as expected from the literature review. Analysis of the flexural strength test data revealed a very good correlation (Rsup2/sup 5 .93) between the smaller- and standard-size beams. An equation is proposed to convert the flexural strength of the smaller-size specimen to the flexural strength of the standard-size specimen.

Tanesi J.,SES Group and Associates LLC | Tanesi J.,Turner Fairbank Highway Research Center | Ardani A.,Turner Fairbank Highway Research Center
Transportation Research Record | Year: 2013

This paper documents the use of an isothermal calorimeter as a scanning tool to evaluate early-age behavior of high-volume fly ash mixtures. A series of paste and mortar mixtures containing different fly ashes (one Class C fly ash and two Class F fly ashes) with replacement levels ranging from 20% to 60% and high- and low-alkali cement was evaluated. Materials testing included ASTM C109, compressive strength of mortar cubes at different ages; ASTM C1437, flow; ASTM C403, time of setting; and ASTM C1679, isothermal calorimetry. In most cases, for the same water-binder ratio (0.40) and replacement level, Class C fly ash mixtures exhibited higher strength but delayed setting compared with Class F fly ash mixtures. Isothermal calorimetry proved to be a good scanning tool for predicting setting time and early-age compressive strength and for identifying materials incompatibility.

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