Dan Zollinger | Texas A&M University (original) (raw)

Papers by Dan Zollinger

Proceedings of the 12th International Conference on Concrete Pavements

This research was based on the findings from a field study of slab placements representing differ... more This research was based on the findings from a field study of slab placements representing different combinations of curing conditions and placement times. One of the key objectives was to collect data with respect to slab setting characteristics as a function of the quality of curing provided for each slab. The set is referred to herein terms of a gradient that forms due to environmental effects on temperature and moisture profile variations during the initial days after placement. These profile variations effect the degree of slab support. In other words, early-age concrete temperature and moisture history is a key factor affecting the set gradient, as well as a factor in slab curling and warping behavior (corner displacement). There is also a strain profile associated with the set gradient creating a level of stress that can be related to the development of early-age cracking similar to slab curling and warping. This early-aged behavior is mostly drying shrinkage driven, and is o...

2014 TEXAS TRANSPORTATION INSTITUTE The Texas A&M University System

Accompanying the documents is a design spreadsheet for the purpose of incorporating the test proc... more Accompanying the documents is a design spreadsheet for the purpose of incorporating the test procedures described and creates results regarding the best subbase option for a given concrete pavement scenario. As this design tool is being altered into a software program, the tool will be housed with the Pavement Structures Division of the National Ready Mixed Concrete Association. This division is able to run design scenarios and encourages outreach for further discussion (please contact Amanda Hult at

Journal of Materials in Civil Engineering, 2020

AbstractThe microstructural, mechanical, and shrinkage characteristics of cement mortar containin... more AbstractThe microstructural, mechanical, and shrinkage characteristics of cement mortar containing 100% fine reclaimed asphalt pavement (RAP-mortar) were revealed through an extensive experimental ...

This report explains why a mechanistic-empirical (ME) based pavement design method will allow Tex... more This report explains why a mechanistic-empirical (ME) based pavement design method will allow Texas Department of Transportation (TxDOT) to optimize pavement structures to best utilize the limited financial resources available.

Transportation Research Record, 1995

Transport in Porous Media, 2016

A set of governing equations comprising linear momentum, mass, and heat transfer is presented for... more A set of governing equations comprising linear momentum, mass, and heat transfer is presented for thermoelastic freezing of a porous material. The theory of unsaturated freezing porous media is introduced to model deformation of concrete, a traditional building material, whose pore network is pressurized by the wet air, frozen ice, and unfrozen water. A general solution scheme is provided for the appropriate boundary conditions pertaining to the primary concrete containment in a liquefied natural gas tank, and simulated results are analyzed for fully and partially saturated non-air-entrained concrete and fully saturated air-entrained concrete. Effect of cooling rate is also demonstrated. It is found that high cooling rate results in high expansion provoked by high hydraulic pore pressure and the corresponding suppression of pore liquid freezing temperature. It is also revealed that air-entrained concrete, by allowing quick dissipation of the displaced pore water and accommodating the ensuing ice formation, shows less contraction and subsequently less crack initiating stresses than the high-porosity, non-air-entrained concrete. Similar outcomes are observed near the concrete surfaces subjected to evaporation prior to cryogenic freezing. High hydraulic pressure, induced by the delayed dissipation of excess pore water, is likely to generate at the center of surface-dried concrete walls.

This paper discusses an approach to enhance the accuracy and selection of fatigue damage calibrat... more This paper discusses an approach to enhance the accuracy and selection of fatigue damage calibration coefficients by addressing more directly the effect of the set gradient on performance. The approach was originally introduced over 20 years ago in a paper by Zollinger and McCullough when calibration and mechanistic-empirical (ME) methodologies were becoming a topic of interest. A method to extract the set gradient from performance data through analysis is outlined and presented in detail. The correlation of the set gradient to key performance parameters is also discussed along with the factors that influence the magnitude of the set gradient that forms in a concrete pavement soon after construction.

Transportation Research Record, 2002

Cracking of concrete slabs at saw-cut notches under a given combination of weather and slab condi... more Cracking of concrete slabs at saw-cut notches under a given combination of weather and slab conditions is a major concern in the early stages of construction. Several factors affect crack initiation such as material strength parameters, the method and quality of curing, slab–subbase stiffness, and concrete shrinkage and creep. Early-age creep and shrinkage also appear to be key factors in stress and crack development at the tip of the saw-cut notch. These two factors were analyzed and characterized by experiments that provide some insight relative to how shrinkage and creep strain affect crack development. These results can be useful in evaluating the behavior of concrete and the development of cracking at saw-cut notches. The German cracking frame was used to provide restraint and the means to initiate cracking at an artificial notch during early-age strength development in the concrete while the concrete was undergoing creep and shrinkage strains. The cracking frame tests were conducted under constant temperature and relative humidity conditions in the laboratory. A fracture mechanics approach was followed to determine concrete strength at the saw-cut notch. It can be concluded that the development of creep strain in the concrete affects the cracking tendency of the concrete. The data seemed to suggest that a greater cracking tendency at the saw-cut notches did not result until after the incremental creep strain in the concrete had diminished sufficiently. The role of creep and shrinkage under field conditions relative to the control of cracking due to saw cutting in newly constructed concrete slabs is also considered indirectly.

Transportation Research Record: Journal of the Transportation Research Board, 2012

The Mechanistic–Empirical Pavement Design Guide (MEPDG) makes available a mechanistic–empirical p... more The Mechanistic–Empirical Pavement Design Guide (MEPDG) makes available a mechanistic–empirical punchout prediction tool based on a comprehensive analysis of many design factors in continuously reinforced concrete (CRC) pavement. The punchout model is based on the idea that accumulated fatigue damage induces longitudinal cracking between two narrowly placed transverse cracks as a result of repeated loading, diminished load transfer, loss of support, and environmental stresses. Most factors are considered directly in the punchout prediction except those related to subbase support. For instance, stiffer support conditions reduce deflection, with smaller interfacial shear stresses than subbase shear strength as a result, and thus lower erosion. However, the MEPDG predicts a higher rate of punchouts with increasing k-value because a punchout is assumed to be analogous to longitudinal fatigue cracking. The unfortunate consequence of this assumption is that the predicted rate of punchout ...

Airfield and Highway Pavement, 2006

Gravel aggregates have been used for many years in the construction of continuous reinforced conc... more Gravel aggregates have been used for many years in the construction of continuous reinforced concrete (CRC) pavements in Texas. However, these pavements are in many instances subject to delamination and spalling distresses, and thus costly to maintain and repair. Evidence collected from extensive field studies has indicated that the bond of aggregate-mortar interface at an early age is one of the most significant factors affecting the development of delamination and eventual spalling. In this research, a factional factorial design (the Taguchi method) was applied to investigate the methodology for improving delamination resistance of CRC pavements. Four factors (i.e., aggregate type, water/cementitious ratio, replacement of ultra-fine ash, and curing method) with three levels for each factor based on the orthogonal array were considered. A fracture mechanics parameter, fracture roughness, was used to represent the aggregate-mortar bond strength. The significances of each factor to achieve better fracture toughness were determined, and the optimum design combination was subsequently chosen and validated. The consistency between the results from the experimental design and laboratory validation provides highway agencies valuable recommendations and aid in selecting design factors for the use of gravel in paving construction to relieve delamination and further spalling distresses. A comprehensive investigation on overall aggregate contribution to pavement bonding performance will be considered in future research to ensure the integrity of the evaluation and analysis.

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2014, 2014

This study evaluates the damage potential of concrete of different mix designs subjected to cryog... more This study evaluates the damage potential of concrete of different mix designs subjected to cryogenic temperatures, using acoustic emission (AE) and permeability testing. The aim is to investigate design methodologies that might be employed to produce concrete that resists damage when cooled to cryogenic temperatures. Such concrete would be suitable for primary containment of liquefied natural gas (LNG) and could replace currently used 9% Ni steel, thereby leading to huge cost savings. In the experiments described, concrete cubes, 150 mm x 150 mm x 150 mm, were cast using four different mix designs. The four mixes employed siliceous river sand as fine aggregate. Moreover, limestone, sandstone, trap rock and lightweight aggregate were individually used as coarse aggregates in the mixes. The concrete samples were then cooled from room temperature (20°C) to cryogenic temperature (-165°C) in a temperature chamber. AE sensors were placed on the concrete cubes during the cryogenic freezing process. The damage potential was evaluated in terms of the growth of damage as determined from AE, as a function of temperature and concrete mixture design. The damage potential observed was validated with water permeability testing. Initial results demonstrate the effects of the coefficient of thermal expansion (CTE) of the aggregates on damage growth. Concrete damage (cracking) resistance generally decreased with increasing coarse aggregate CTE, and was in the order, limestone ≥ trap rock << lightweight aggregate ≥ sandstone. Work is in progress to fully understand thermal dilation and damage growth in concrete due to differential CTE of its components.

Transportation Research Record: Journal of the Transportation Research Board, 2007

Undesirable expansion of concrete due to a reaction between alkalis and certain type of reactive ... more Undesirable expansion of concrete due to a reaction between alkalis and certain type of reactive siliceous aggregates known as alkali-silica reactivity (ASR) continues as a major problem worldwide. Renewed interest in minimizing distress resulting from ASR emphasizes the need to develop predictable modeling of concrete ASR behavior under field conditions. Current test methods are either incapable of that or need long testing periods, which offer only limited predictive estimates of ASR behavior in a narrow band of field conditions. Therefore, an attempt was made to formulate a robust performance approach based on basic aggregate and concrete ASR material properties derived from dilatometry and a kinetic-based mathematical expression for ASR behavior. Since ASR is largely an alkali as well as a thermally activated process, the use of rate theory (Arrhenius relationship between temperature and alkali solution concentration) on the dilatometer time-expansion relationship provides a fun...

Transportation Research Record: Journal of the Transportation Research Board, 2000

Spalling is a distress form in concrete pavements that often manifests as the breakdown of the jo... more Spalling is a distress form in concrete pavements that often manifests as the breakdown of the joint of a slab within 15 cm (6 in.) of the joint or crack and can occur at both longitudinal and transverse joints. Efforts have been under way at Texas A&M University to formulate mechanistic spalling models derived from data gathered in recent Texas Department of Transportation studies related to spall development. Extensive field studies have led to the establishment of a spalling mechanism consisting of a step-by-step process that can be characterized with engineering mechanics. These findings indicate that spalling is the result of damage initiated in the form of a shear delamination that is oriented parallel to and at a shallow depth below the surface of the pavement. Conditions necessary for formation of the delaminations include low interfacial strength between the aggregate and mortar and sufficient evaporation of pore water from the hydrating concrete, resulting in differential ...

Transportation Research Record, 1996

A one-part self-leveling silicone joint sealant material was experimentally investigated in the l... more A one-part self-leveling silicone joint sealant material was experimentally investigated in the laboratory. It was found that strain and age had apparent effects on the relaxation modulus of the material. Relaxation tests were conducted under different strain levels. The test samples were exposed to ultraviolet radiation and moisture for artificial aging before testing. For this largely deformable material, finite strain formulas were used in analysis of experimental data. Strain and age effects were successfully normalized in the relaxation master curve by using the superposition principle. On the basis of the master curve, a material model of the generalized Maxwell model in parallel type was constructed. The real time was scaled to the reduced time by time-strain shift and time-age shift factors so as to characterize the strain and age effects. This model is mathematically simple and can be easily applied in finite element programs for concrete pavement joint analysis.

Journal of Transportation Engineering, 1996

Journal of Transportation Engineering, 2005

ABSTRACT A concrete slab was constructed at Texas A&M University to investigate environme... more ABSTRACT A concrete slab was constructed at Texas A&M University to investigate environmental effects in terms of temperature and moisture effects on the behavior of jointed plain concrete pavements. The slab behavior was delineated relative to equivalent linear temperature and humidity differences as a function of time. As expected, the trends of these differences were found to relate with the trends of ambient temperature and relative humidity. The slab had daily periods of tensile and compressive strain corresponding to the daily changes in the ambient temperature and relative humidity. Furthermore, the trends in the slab displacements were clearly dependent upon the changes in ambient temperature and slab temperature gradients. Drying shrinkage and creep strains primarily in the vicinity of the top surface appeared to cause an overall shift in the slab movements. This shift manifest in both the strain and vertical displacement of the slab was determined from data collected up to 2 years after placement of the concrete.

Journal of Transportation Engineering, 2009

Gravel aggregates have been used extensively in the Houston District for continuously reinforced ... more Gravel aggregates have been used extensively in the Houston District for continuously reinforced concrete (CRC) pavements construction for many years. However, some of these pavements have been subject to early-age delamination and eventual spalling damage. A series of studies since the early 1990's have been conducted to gain a better understanding of mechanisms, material properties, and construction practices related to delamination and spalling. This paper describes a systematic and methodical approach for selecting construction measures to counter the negative effects of using gravel aggregates in concrete paving as it pertains to minimizing early-age delamination distress. The approach was developed based on laboratory measures and practices, numerical approaches for assessing delamination potential, and test sections established in the Houston District, Texas. The testing programs in the laboratory and the field, as well as the analytical results, are presented in this paper. The analysis of the results leads to a step-by-step approach for evaluating and selecting construction measures.

Journal of Transportation Engineering, 1992

A one‐dimensional model for predicting the structural response of continuously reinforced concret... more A one‐dimensional model for predicting the structural response of continuously reinforced concrete (CRC) pavement due to increasing temperature and alkali‐silica reaction (ASR), considering slip between concrete and reinforcing bar and friction between concrete and subbase material, is presented in this paper. The slip‐stress function is modeled by a three‐part linear function. The subbase friction stress function is modeled by a two‐part linear function. The solution procedures of displacement functions for a semi‐infinite length slab are given. The unknown coefficients in the displacement functions are determined by finding the roots of the system of nonlinear equations. A simple no‐slip model is also used both for providing an initial guess and for verifying the numerical results. This model provides a more rational approximation of the structural response of CRC pavement.