The main objective was to develop mix designs for concrete incorporating minimally processed reclaimed asphalt pavement (RAP) materials to be used in the Florida Concrete Test Road. The laboratory program was conducted in two phases. Phase I involved testing of twelve (12) trial mixes to identify feasible mixes which could meet the Florida Department of Transportation (FDOT) specification requirements for pavement concrete. Based on the preliminary test results from the trial mixes, ten (10) production mixes were identified and evaluated more extensively in Phase II to establish the optimum concrete mixes incorporating RAP to be recommended. Concrete mixtures, with 0% to 40% RAP as aggregate replacement and using 20% fly ash and 50% slag as cement replacement, were designed using the optimized aggregate gradation (OAG) technique instead of the American Concrete Institute (ACI) method. Among the RAP concrete evaluated, the 20% RAP concrete mixes with 0%, 20% fly ash, and 50% slag as cement replacement were able to meet Florida Department of Transportation’s (FDOT) over-design compressive strength of 29 MPa (4200 psi) at 28 days. Using 20% and 40% RAP in concrete could result in saving in the total cost of aggregate by 9% and 17%, respectively. When the RAP is not refined (e.g., no washing of RAP, and no separating of coarse and fine portions), it is recommended that 20% of RAP can be used as aggregate replacement in pavement concrete.

This study focused on investigating the early-age thermal behavior of drilled shafts under different surrounding soil’s thermal properties. Four 1.8 m (6 ft) diameter drilled shafts were constructed using two different concrete mixes and two different soil conditions. A finite element (FE) model was developed to estimate the temperature development of drilled shafts at early-age and validated using temperatures measured from full-scale drilled shafts constructed in the field. The validated analytical model was then used to perform a parametric analysis to evaluate the effects of the surrounding soils at different moisture conditions on change in thermal behavior of drilled shafts at early-age. Results indicated that the FE model developed was capable of accurately predicting temperature development of drilled shafts at early-age. A drier surrounding soil (i.e., gravimetric moisture content of 0% through 6%) was able to serve as a better insulating material that leads to reduced temperature difference in the drilled shafts. Also, it was identified the use of high-volumefly ash concrete mix in conjunction with relatively low heat of hydration can reduce the temperature difference in the drilled shaft.

This article presents an investigation on the early-age thermal behavior of drilled shafts with different geometric dimensions through numerical analysis. Finite-element models by using DIANA software were developed to analyze the thermal behavior of drilled shafts. In order to validate the finite-element model, four concrete drilled shafts were constructed and evaluated under Florida conditions for monitoring their actual thermal behavior. The calculated temperatures from the analytical model matched well with the measured values from the constructed shafts. All the drilled shafts with a diameter greater than 1.83 m (6 ft) produced a high maximum temperature and a maximum temperature differential which failed the allowable temperature set by the American Concrete Institute and the Florida Department of Transportation to prevent thermal cracking. Also, it was found that the dimension of the drilled shaft had the greatest influence on the maximum temperature inside a shaft. Analysis was performed to investigate whether the use of drilled shafts with a centroid void in the shaft could reduce the maximum temperature and maximum temperature differential. The results indicated that this is a viable alternate shaft design for controlling the maximum temperature and maximum temperature differential in concrete drilled shafts at an early age.

This study focused on the development of an effective methodology for instrumentation and data analysis to more accurately measure and to assess strain profiles from full-scale test slabs in consideration of the effects of localized traffic wander and missing data within an array of sensors. An effective instrumentation plan and analysis methodology were identified, and their applicability was evaluated using analytical results and a full-scale field experiment. The results indicated that sensor spacing significantly affected maximum strains interpolated, and load-induced strain profiles from strain gauges were highly influenced by localized wheel wander. The accuracy of predicted maximum strain was not affected by one missing data point; however, it would be greatly reduced if data from two sensors at the center of the array were missed. An array of uniformly spaced six gauges with 15 cm (6 in.) intervals around the wheel path was used and an interpolation methodology was developed to accurately capture the load-induced maximum strain based on strain profiles obtained from a full-scale concrete slab, taking into account the effects of localized traffic wander and missing data.