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Precast Concrete Pavements (PCP) can be used as an accelerated rehabilitation technique for concrete pavements. The goals of this research study was to develop a PCP system approval process for potential implementation by state Departments of Transportation (DOTs) using current PCP specifications and practices. For this, a survey was conducted among 18 states regarding their specifications that are used for PCP and their approval processes for implementation of PCP. Based on the survey conducted, eight state specifications have been developed for PCP. Each specification focuses on four major PCP components: (i) dimensional and strength requirements, (ii) base stabilization materials, (iii) panel placement and alignment, and (iv) encasement grout materials. Based on the specifications and recommendations of state DOTs, a general approval process was developed for PCP systems. The generalized approval process included verification of PCP (i) material properties and precast plant capabilities and (ii) historical performance. The approval process outlines three different tracks in which the PCP contractor can describe past performance (ranging from low to high risk for state DOTs). Overall, this study provides state DOT agencies the necessary specifications and general approval process to improve and accept PCP systems as a pavement rehabilitation technique. [ABSTRACT FROM AUTHOR]

[Display omitted] • RAC has higher water sorptivity than natural aggregate concrete. • Water sorptivity has a strong negative linear relation with electrical resistivity. • The air content of RCA affects the sorptivity of RAC. • RAC sorptivity and saturation rate can be predicted using electrical resistivity. This paper examines the water sorptivity of recycled aggregate concrete (RAC) and shows how sorptivity can be predicted using electrical resistivity as the main predictor. The measurements in 48 RAC specimens show that RAC has higher water sorptivity and lower electrical resistivity than regular concrete. RAC sorptivity and rate of saturation prediction models were developed using multiple linear regression analysis. The prediction models include electrical resistivity, percent volume of coarse recycled concrete aggregates, and air content of residual mortar as explanatory variables. A graphical calculating device based on the sorptivity regression models was also created. [ABSTRACT FROM AUTHOR]

[Display omitted] • High coarse aggregate porosity significantly increases concrete permeability. • RCPT measurement is strongly correlated with electrical resistivity. • Water permeability is strongly correlated with formation factor. • The RCPT measurements of RAC are higher than LWAC and NWAC. • The water permeabilities of LWAC are higher than NWAC and RAC. The established relationships between concrete's electrical resistivity and permeation properties are not applicable and might differ when porous aggregates are used. In this study, the relationships of electrical resistivity with the permeation properties of lightweight aggregate concrete (LWAC) and normal weight aggregate concrete (NWAC) were determined and compared to the permeation properties of recycled aggregate concrete (RAC). Differences in the regression slope of the three concrete types were found. At the same electrical resistivity, RAC has higher chloride permeability than LWAC and NWAC. But at the same formation factor, LWAC has higher water permeability than RAC and NWAC. [ABSTRACT FROM AUTHOR]

Fiber-reinforced resin (FRR) plates are being incorporated into structural joints to correct thermal bridging issues to create more energy-efficient buildings. The purpose of this study was to evaluate the behaviors of simple shear and moment connections that include FRR thermal barrier plates under service-loading conditions. Tests included two thicknesses and two grades of barrier plate. The shear connection tests showed that the coefficient of friction between steel and an as-received FRR plate was significantly lower than that of steel on steel. However, roughening the FRR plates by blasting with aluminum oxide increased the coefficient to nearly the same as or greater than steel on steel. In moment connections the presence of thermal barrier plates increased the joint rotation at the connection. A 25-mm (1-in.) thermal barrier plate increased the joint rotation by 10% compared to a joint without the barrier plate. The increase was 20% for a 50-mm (2-in.) plate. The thermal barrier plates did not affect the dynamic response of the test fixture at structurally important frequencies. [ABSTRACT FROM AUTHOR]

Externally applied composite reinforcement can be used to provide additional strength or ductility to concrete members as part of a seismic retrofit or repair to a structure, but the composite reinforcement may be exposed to elevated temperatures. In this study, concrete cylinders were wrapped with a composite reinforcing system, exposed to a range of elevated temperatures and allowed to cool. Subsequent compression testing of the cooled cylinders indicated there was no statistically significant loss of strength until the treatment temperature was more than 30°C above the glass transition temperature of the epoxy. Additionally, the predominant mode of failure of the composite system changed from hoop split to seam debonding at the same temperature. This study also examined the role of a fireprotective coating that forestalled the onset of the transition of failure modes by almost 30°C. [ABSTRACT FROM AUTHOR]

The Accreditation Board for Engineering and Technology (ABET) and practitioners recognize professional practice issues as important in undergraduate civil engineering education. This paper describes a creative approach for incorporating professional practice issues into the civil engineering curriculum through a course entitled “Civil Engineering Practice.” This course has the following advantages: (1) It encourages active learning via activities as opposed to a traditional seminar; (2) forms long-term teaching partnerships with engineering professionals; (3) offers a venue where important yet distinct topics can be presented systematically; (4) provides the local engineering community with the opportunity to share its accomplishments and to further continuing education credits; (5) reinforces the professional practice elements of the capstone design project; and (6) supplies structured time where students can interact with potential employers and vice-versa. The course feedback from students, faculty, engineering professionals, and ABET evaluators has been overwhelmingly positive. [ABSTRACT FROM AUTHOR]

The objective of this paper was to evaluate the deterioration of Portland Cement Concrete (PCC) slabs throughout trafficking. A full-scale accelerated pavement testing at the National Airport Pavement Test Facility (NAPTF) was conducted on Construction Cycle 6 (CC6) on rigid pavements with low, medium and high flexural strengths on both a concrete and asphalt stabilised base. Heavy Weight Deflectometer (HWD) testing was conducted on the test sections to backcalculate the stiffness of the layers. The majority of PCC deterioration occurred roughly within the first 1500–2000 passes of trafficking. On average, the MRS-1 (low flexural strength) PCC elastic modulus was found to decrease by 20%, from 5.0–.4 × 106(34.5–37.2 GPa) to 4.0–4.3 × 106 psi (27.6–29.7 GPa), whereas the PCC elastic modulus of MRS-2 and MRS-3 was found to decrease by 17% and 22%, respectively. However, neither the MRS-2 nor MRS-3 elastic modulus was found to drop below 5.0 × 106 psi (34.5 GPa) after 15,000 passes. [ABSTRACT FROM AUTHOR]

Load-transfer efficiency (LTE) of jointed concrete pavement is typically measured by the ratio of unloaded and loaded slab deflection. However, the maximum tensile stress in a slab is one of the critical mechanical responses that influences the performance of the jointed concrete pavement. Therefore, stress-based load-transfer efficiency, defined as stress reduction in the loaded slab because of the presence of an adjacent unloaded slab, is often considered an appropriate way to quantify LTE. Strain gauge data from full-scale tests collected by the Federal Aviation Administration were analyzed to compute the stress-based LTE of joints under moving loads. The effect of static aircraft gear loads and slab size on the LTE of joints was analyzed by using a two-dimensional finite-element program. FEM-calculated stress-based LTE under static aircraft loading on average was 38% lower than that measured under moving loads. LTE values were similar under various gear positions, gear configurations, and different slab sizes. [ABSTRACT FROM AUTHOR]

In perpetual pavements, damage from bottom-up cracking can be limited to the top surface lift through using a very thick surface layer or a binder-rich intermediate layer. This can be attained by maintaining tensile strains at the bottom of the hot-mix asphalt (HMA) layer below a certain value known as the fatigue endurance limit (FEL). This paper presents a method for estimating a strain-based FEL for flexible airfield pavements. The proposed method is based on the concept that a 50% reduction in HMA layer modulus would indicate initiation of fatigue cracking. Falling weight deflectometer (FWD) testing results, collected from National Airport Pavement Test Facility (NAPTF) flexible pavement sections, were analyzed to determine at which loading pass each section had a 50% reduction in HMA layer modulus (Nf50). NAPTF tensile strain data were also used to determine the tensile strain at Nf50 for each pavement section by averaging the peak tensile strains. The proposed approach was validated by comparing its results to those obtained using a common FEL estimation model known as the rate of dissipated energy change (RDEC) model. To further verify the results of the proposed approach, peak tensile strain was plotted vs. number of loading cycles for all sensors. Using these plots, the peak tensile strain at which the variability in the strain gauge data increased was used as an estimate of a possible FEL. The Nf50 tensile strains estimated using the proposed method were comparable to the values determined from RDEC and variability approaches. [ABSTRACT FROM AUTHOR]