Material Constituents and Proportioning for Roller-Compacted Concrete Mechanical Properties

Roller-compacted concrete (RCC) is increasingly becoming an alternative pavement type because of its construction expediency, reductions in material and construction costs, sustainability benefits, and overall structural capacity. Current RCC pavement mix design procedures select mix constituents and proportions based on strength requirements, workability, and field density. Discrepancies in mechanical properties are known to exist between field and laboratory compacted specimens. In order to move toward designing and constructing performance-based RCC mixtures—the effects of various mixture constituents, proportions, and compaction methods must be quantified. The gap between laboratory and field properties must be minimized as well. A wide range of RCC aggregate gradations were batched, tested, and found to impact RCC properties—especially compressive strength. The coarse-fine aggregate ratio was the parameter linked most directly to RCC compressive strength. Aggregate type (recycled aggregates, siliceous rounded sand and gravel, manufactured sand, and crushed aggregates) was also shown to affect aggregate packing density and RCC properties. Fly ash or ground granulated blast furnace slag replacement of cement statistically reduced the early-age RCC strength and likely would delay opening the RCC pavement to traffic. In general, fracture properties of RCC with virgin and recycled aggregates were similar or greater than fracture properties of conventional Portland cement concrete (PCC) pavements—which suggests similar or greater slab capacities and fatigue lives for RCC relative to PCC for the same slab thickness. Several types of macro-fibers incorporated into RCC were shown to statistically improve the RCC compressive strength as well as provide residual strength comparable to conventional fiber reinforced concrete. Past researchers have demonstrated that the gyratory compactor has the potential to be an alternative RCC mix design tool to the modified Proctor procedure. The gyratory compactor provides similar compaction mechanisms and energies relative to construction equipment for RCC (and asphalt) pavements. It also significantly reduces operator error in specimen preparation. The gyratory compactor was employed in this research to evaluate several laboratory mixture proportions and constituents focusing on aggregate gradations and cementitious content. It was also used to compare companion gyratory results to already constructed RCC pavements. The gyratory compactor was verified to be more sensitive to changes in aggregate gradation and cementitious content compared to the modified Proctor and vibratory hammer—which are commonly used methods for RCC mix design and specimen fabrication, respectively. It was also useful in evaluating the potential for delayed compaction on RCC mixtures with different admixtures, delay times, and mixture temperatures.IDOT-R27-149-2Ope

Pavement Rehabilitation Strategy Course Development

Pavement rehabilitation and preservation treatments have become standard practice for state and local transportation agencies. The ultimate goals include maintaining a safe and reliable level of service for all users, maximizing pavement service life, and optimizing budget allocations for infrastructure construction projects. The essential key to meet these goals requires transportation agencies to identify the right treatment for the right pavement at the right time. Based on the manuals of Bureau of Design and Environment (BDE) within the Illinois Department of Transportation (IDOT), training course materials were developed in this project. The goals of the training course are to enhance the understanding of fundamental concepts of pavement rehabilitation and preservation strategies, establish consistent practices following the guidance manuals and minimize potential errors by selecting appropriate treatments. The training course is designed to be completed in one-and-a-half days, covering seven blocks: (1) Introduction, (2) Preservation and Rehabilitation Definitions, (3) Distresses, (4) Condition Rating Survey, (5) Testing, (6) Treatments, and (7) Selection Guidelines. The final completed deliverables of this project include PowerPoint slides for in-class instruction, a stand-alone online platform, and review and final examination questions for the initial three blocks.IDOT-R27-170Ope

The DOE E3SM Coupled Model Version 1: Overview and Evaluation at Standard Resolution

This work documents the first version of the U.S. Department of Energy (DOE) new Energy Exascale Earth System Model (E3SMv1). We focus on the standard resolution of the fully coupled physical model designed to address DOE mission-relevant water cycle questions. Its components include atmosphere and land (110-km grid spacing), ocean and sea ice (60 km in the midlatitudes and 30 km at the equator and poles), and river transport (55 km) models. This base configuration will also serve as a foundation for additional configurations exploring higher horizontal resolution as well as augmented capabilities in the form of biogeochemistry and cryosphere configurations. The performance of E3SMv1 is evaluated by means of a standard set of Coupled Model Intercomparison Project Phase 6 (CMIP6) Diagnosis, Evaluation, and Characterization of Klima simulations consisting of a long preindustrial control, historical simulations (ensembles of fully coupled and prescribed SSTs) as well as idealized CO2 forcing simulations. The model performs well overall with biases typical of other CMIP-class models, although the simulated Atlantic Meridional Overturning Circulation is weaker than many CMIP-class models. While the E3SMv1 historical ensemble captures the bulk of the observed warming between preindustrial (1850) and present day, the trajectory of the warming diverges from observations in the second half of the twentieth century with a period of delayed warming followed by an excessive warming trend. Using a two-layer energy balance model, we attribute this divergence to the model’s strong aerosol-related effective radiative forcing (ERFari+aci = -1.65 W/m2) and high equilibrium climate sensitivity (ECS = 5.3 K).Plain Language SummaryThe U.S. Department of Energy funded the development of a new state-of-the-art Earth system model for research and applications relevant to its mission. The Energy Exascale Earth System Model version 1 (E3SMv1) consists of five interacting components for the global atmosphere, land surface, ocean, sea ice, and rivers. Three of these components (ocean, sea ice, and river) are new and have not been coupled into an Earth system model previously. The atmosphere and land surface components were created by extending existing components part of the Community Earth System Model, Version 1. E3SMv1’s capabilities are demonstrated by performing a set of standardized simulation experiments described by the Coupled Model Intercomparison Project Phase 6 (CMIP6) Diagnosis, Evaluation, and Characterization of Klima protocol at standard horizontal spatial resolution of approximately 1° latitude and longitude. The model reproduces global and regional climate features well compared to observations. Simulated warming between 1850 and 2015 matches observations, but the model is too cold by about 0.5 °C between 1960 and 1990 and later warms at a rate greater than observed. A thermodynamic analysis of the model’s response to greenhouse gas and aerosol radiative affects may explain the reasons for the discrepancy.Key PointsThis work documents E3SMv1, the first version of the U.S. DOE Energy Exascale Earth System ModelThe performance of E3SMv1 is documented with a set of standard CMIP6 DECK and historical simulations comprising nearly 3,000 yearsE3SMv1 has a high equilibrium climate sensitivity (5.3 K) and strong aerosol-related effective radiative forcing (-1.65 W/m2)Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151288/1/jame20860_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151288/2/jame20860.pd

An Analytical Approach to computing joint opening in concrete pavements

Satisfactory performance of the transverse joints is crucial for achieving the intended service life of jointed plain concrete pavement. An accurate prediction of joint opening and movement is desired in order to quantify the effects of the environment, base type, concrete material constituents, and slab geometry on the concrete pavement responses. In this paper, an analytical model based on elasticity theory is presented to predict joint opening using a bilinear slab-subbase interfacial constraint assumption. The proposed model predicts the mean joint opening based on uniform temperature change and drying shrinkage through the slab thickness. To account for the temperature curling effect, a ???correction??? term to the joint opening is proposed using a closed-form solution derived from Westergaard???s temperature curling deflection equation. Initial model calculation using in-situ measured pavement temperature profile suggests that proposed analytical model generates reasonable joint opening during the monitoring period.published or submitted for publicationis peer reviewe

Thermal Stress Analysis in Ultra-Thin Whitetopping Pavement

Minimizing joint opening is crucial to ensure adequate load transfer across the joints in ultra-thin whitetopping (UTW) pavement. Several UTW parking lot projects completed at the University of Illinois indicated that the initial joint cracks occurred at every 5 to 8 joints (for 4 by 4 ft panels). The result of this large crack spacing was wider openings at these initial crack locations and reduced load transfer. The primary objective of this theoretical thermal stress calculation for UTW was to determine if the initial crack spacing at early ages (e.g., 24 hours) can be approximately predicted for UTW sections, and if it is possible to promote additional cracks to propagate at early ages. The two types of thermal stresses considered are axial thermal stress due to uniform temperature change in the slab and curling stress due to temperature differential through the slab thickness. Temperature profile data and laboratory elastic and fracture parameters are presented for several concrete mixtures at early ages. The analytical model coupled with the measured data revealed that 4 by 4 ft UTW panels will not crack at every saw-cut joint for the concrete mixtures and climatic conditions evaluated. Larger joint spacing, such as 6 by 6 ft, is sufficient but still may not propagate cracks at every joint. Initiating more joint cracks at early ages can be attained by higher stresses in the concrete layer (e.g., more slab restraint or longer slab sizes), lower material fracture properties, or a deeper notch depth.Illinois Center for Transportation; the Illinois Department of Transportation, Division of Highways; and the U.S. Department of Transportation, Federal Highway Administration.published or submitted for publicationis peer reviewe

Innovative Algorithm to Solve Axisymmetric Displacement and Stress Fields in Multilayered Pavement Systems

This paper presents an innovative algorithm to calculate the displacement and stress fields within a multilayered pavement system using Layered Elastic Theory and Hankel and Laplace integral transforms. In particular, a recurrence relationship, which links the Hankel transform of displacements and stresses at any point P(r, z) within a multilayered pavement system with those at the surface point Q(r, 0), is systematically derived. The Hankel transforms of displacements and stresses at any point within a multilayered pavement system can be explicitly determined using the derived recurrence relationships, and the subsequent inverse Hankel transforms give the displacements and stresses at the point of interest. Theoretical and computational verification of the proposed algorithm justify its correctness. The proposed algorithm does not use a numerical linear system solver employed in the traditional approach to solve the axisymmetric problems in multilayered pavement systems. Due to the explicitly-derived recurrence relationships for displacements and stresses, the proposed algorithm provides a more rapid solution time than the stress-function-based approach utilized in existing layered elastic theory programs.The work of the first author was partially supported by the 2008 Dwight David Eisenhower Graduate Fellowship.published or submitted for publicationis peer reviewe

Analytical Approach to Predicting Temperature Fields in Multilayered Pavement Systems

An accurate and rapid estimation of the pavement temperature field is desired to better predict pavement responses and for pavement system design. In this paper, an innovative method to derive the theoretical solution of an axisymmetric temperature field in a multilayered pavement system is presented. The multilayered pavement system was modeled as a two-dimensional heat transfer problem. The temperature at any location r , z and any time t in an N-layer pavement system can be calculated by using the derived analytical solution. The Hankel integral transform with respect to the radial coordinate is utilized in the derivation of the solution. The interpolatory trigonometric polynomials based on discrete Fourier transform are used to fit the measured air temperatures and solar radiation intensities during a day, which are essential components in the boundary condition for the underlying heat transfer problem. A FORTRAN program was coded to implement this analytical solution. Measured field temperature results from a rigid pavement system demonstrate that the derived analytical solution generates reasonable temperature profiles in the concrete slab.Illinois Department of Transportationpublished or submitted for publicationis peer reviewe

Characterization of Effective Built-in Curling and Concrete Pavement Cracking on the Palmdale Test Sections

Differential expansion and contraction between the top and bottom of a concrete slab results in curling. Curling affects stresses and deflections and is an important component of any mechanistic-empirical design procedure. A significant portion of curling can be attributed to the combined effects of nonlinear "built-in" temperature gradients, irreversible shrinkage, moisture gradients, and creep, which can be represented by an effective built-in temperature difference (EBITD).Several instrumented test sections utilizing several design features were constructed and evaluated using the Heavy Vehicle Simulator (HVS) in Palmdale, California. These instrumented slabs were loaded with a half-axle edge load without wander in order to study the effects of curling and fail the slab sections under accelerated pavement testing. A procedure for estimating EBITD using loaded slab deflections was developed using the HVS results. The advantages of using loaded slab deflections are that they can be used for measuring EBITD of slabs with high negative built-in curl and can also be adapted for a Falling Weight Deflectometer, making the procedure efficient and cost-effective for the back-calculation of EBITD of in-service pavements. Differences in restraints and variability in concrete material properties resulted in EBITDs ranging from –5�C to greater than –30�C.The HVS field tests were also used to examine Miner's hypothesis along with various fatigue damage models. Results indicate test slabs cracked at cumulative damage levels significantly different from unity. New models that incorporate stress range and loading rate along with peak stresses were developed. The coefficients for these models were developed to incorporate transverse cracking, longitudinal cracking, and corner breaks. The models can also be used for slabs that exhibit high negative EBITD. For slabs susceptible to high shrinkage gradients, microcracking resulting from restraint stresses during early ages can significantly reduce the slab's nominal strength. Early-age restraint can vary considerably from one slab to another, depending on restraint. A procedure to model slab strength reduction and slab size was developed using nonlinear fracture mechanics principles. A parameter called the "effective initial crack depth" is introduced to characterize the early-age surface microcracking

Characterization of Effective Built-in Curling and Concrete Pavement Cracking on the Palmdale Test Sections

Differential expansion and contraction between the top and bottom of a concrete slab results in curling. Curling affects stresses and deflections and is an important component of any mechanistic-empirical design procedure. A significant portion of curling can be attributed to the combined effects of nonlinear "built-in" temperature gradients, irreversible shrinkage, moisture gradients, and creep, which can be represented by an effective built-in temperature difference (EBITD).Several instrumented test sections utilizing several design features were constructed and evaluated using the Heavy Vehicle Simulator (HVS) in Palmdale, California. These instrumented slabs were loaded with a half-axle edge load without wander in order to study the effects of curling and fail the slab sections under accelerated pavement testing. A procedure for estimating EBITD using loaded slab deflections was developed using the HVS results. The advantages of using loaded slab deflections are that they can be used for measuring EBITD of slabs with high negative built-in curl and can also be adapted for a Falling Weight Deflectometer, making the procedure efficient and cost-effective for the back-calculation of EBITD of in-service pavements. Differences in restraints and variability in concrete material properties resulted in EBITDs ranging from –5�C to greater than –30�C.The HVS field tests were also used to examine Miner's hypothesis along with various fatigue damage models. Results indicate test slabs cracked at cumulative damage levels significantly different from unity. New models that incorporate stress range and loading rate along with peak stresses were developed. The coefficients for these models were developed to incorporate transverse cracking, longitudinal cracking, and corner breaks. The models can also be used for slabs that exhibit high negative EBITD. For slabs susceptible to high shrinkage gradients, microcracking resulting from restraint stresses during early ages can significantly reduce the slab's nominal strength. Early-age restraint can vary considerably from one slab to another, depending on restraint. A procedure to model slab strength reduction and slab size was developed using nonlinear fracture mechanics principles. A parameter called the "effective initial crack depth" is introduced to characterize the early-age surface microcracking

Characterization of Effective Built-in Curling and Concrete Pavement Cracking on the Palmdale Test Sections

Differential expansion and contraction between the top and bottom of a concrete slab results in curling. Curling affects stresses and deflections and is an important component of any mechanistic-empirical design procedure. A significant portion of curling can be attributed to the combined effects of nonlinear "built-in" temperature gradients, irreversible shrinkage, moisture gradients, and creep, which can be represented by an effective built-in temperature difference (EBITD). Several instrumented test sections utilizing several design features were constructed and evaluated using the Heavy Vehicle Simulator (HVS) in Palmdale, California. These instrumented slabs were loaded with a half-axle edge load without wander in order to study the effects of curling and fail the slab sections under accelerated pavement testing. A procedure for estimating EBITD using loaded slab deflections was developed using the HVS results. The advantages of using loaded slab deflections are that they can be used for measuring EBITD of slabs with high negative built-in curl and can also be adapted for a Falling Weight Deflectometer, making the procedure efficient and cost-effective for the back-calculation of EBITD of in-service pavements. Differences in restraints and variability in concrete material properties resulted in EBITDs ranging from –5�C to greater than –30�C. The HVS field tests were also used to examine Miner's hypothesis along with various fatigue damage models. Results indicate test slabs cracked at cumulative damage levels significantly different from unity. New models that incorporate stress range and loading rate along with peak stresses were developed. The coefficients for these models were developed to incorporate transverse cracking, longitudinal cracking, and corner breaks. The models can also be used for slabs that exhibit high negative EBITD. For slabs susceptible to high shrinkage gradients, microcracking resulting from restraint stresses during early ages can significantly reduce the slab's nominal strength. Early-age restraint can vary considerably from one slab to another, depending on restraint. A procedure to model slab strength reduction and slab size was developed using nonlinear fracture mechanics principles. A parameter called the "effective initial crack depth" is introduced to characterize the early-age surface microcracking.UCPRC-RR-2005-09, Civil Engineering