Charles T. Jahren

A systematic review of research on the flipped learning method in engineering education

Abstract: The purpose of this article is to describe the current state of knowledge and practice in the flipped learning approach in engineering education and to provide guidance for practitioners by critically appraising and summarizing existing research. This article is a qualitative synthesis of quantitative and qualitative research investigating the flipped learning approach in engineering education. Systematic review was adopted as the research methodology and article selection and screening process are described. Articles published between 2000 and May 2015 were reviewed, and 62 articles were included for a detailed analysis and synthesis. The results indicated that flipped learning gained popularity amongst engineering educators after 2012. The review revealed that research in engineering education focused on documenting the design and development process and sharing preliminary findings and student feedback. Future research examining different facets of a flipped learning implementation, framed around sound theoretical frameworks and evaluation methods, is still needed to establish the pedagogy of flipped learning in teaching engineering. [ABSTRACT FROM AUTHOR]

Effects of Recycled Materials on Long-Term Performance of Cold In-Place Recycled Asphalt Roads

Within three to five years following construction of asphalt pavements, reflected cracks may be observed, one of the primary forms of distress in hot-mix asphalt overlays of flexible pavements. Reflected cracks affect ride quality when rolled down and allow water to penetrate into the pavement and the base, causing the asphalt mix to deteriorate and the base to soften. Consequently, the service life of pavements is reduced. Cold in-place recycling (CIR) provides an economical rehabilitation method that mitigates crack reflection by pulverizing the asphalt pavement surface, thus destroying the old crack pattern in the recycled layer. While the performance of recycled roads is generally good, there is some inconsistency. Several years after recycling, some roads are in excellent condition, while more cracking and rutting is observed on other roads. These differing behaviors can be observed on roads constructed in the same county by the same contractor in the same construction season. Thus, the difference in performance is probably not from such factors as weather, equipment, contractor experience, and construction procedures. Rather, other factors more prominently affect pavement performance, such as recycled pavement age, traffic volume, support conditions, and aged engineering properties of the CIR materials. This paper discusses a partially completed investigation to identify how aged engineering properties of the CIR materials and other factors affect pavement performance. A selection matrix consisting of 18 sample roads was developed based on previous study. These 18 sample roads represent various ages (young/medium/old), traffic volumes (high/medium/low), and support conditions (strong/weak) in a geographically balanced sampling in Iowa. Pavement condition index (PCI) ratings were collected using an automated pavement distress digital image collection and analysis system. Engineering properties of CIR materials (density, compressive strength, indirect tensile strength, resilient modulus, and asphalt and aggregate content) will be examined through field and lab tests. Statistical analysis will be conducted to describe the relationships between pavement performance and the prominent factors. It is expected that the conclusions and recommendations from this study can be used to improve the performance of future CIR projects in Iowa and other states.

Long-Term Field Performance of Cold In-Place Recycled Roads in Iowa

Cold in-place recycling (CIR) is one of the most effective methods to rehabilitate asphalt pavements. In fact, most CIR roads have performed well at low cost in Iowa since the first CIR road was constructed in 1986. However, some CIR roads have reached failures earlier than their expected design lives because there is no design standard for designing CIR roads with a limited amount of past performance information. Some of the most prominent problems seemed to have come from selecting CIR in areas where there are poor subgrades. Therefore, it is critical to collect CIR performance data along with Falling Weight Deflectometer (FWD) data in order to develop performance models. The main purpose of this paper is to document that effort. The performance models were developed on the basis of historical data collected from CIR roads in Iowa. First, an inventory of CIR roads was created which includes construction information, subgrade and base characteristics, and traffic levels. In consideration of pavement age, level of traffic and subgrade condition, twenty-six test sections were selected from the inventory of CIR roads and pavement surface distress surveys were conducted on these roads using an automated image collection system (AICS). Distress data were then compiled to compute Pavement Condition Index (PCI) for each test section. FWD data were collected from each test section to determine its relative soil support condition. Finally, to determine their long-term performance, the PCI values were plotted against pavement age for each group of pavements categorized by their soil support conditions and traffic levels. Overall, it can be concluded that the CIR roads in Iowa, all under traffic level of AADT of 2,000, have performed very well and predicted to last up to 25 years before reaching the poor condition (PCI = 40) when the pavements are to be rehabilitated. The CIR roads with a good subgrade support, however, are predicted to last up to 35 years.

An In-situ Device for Rapid Determination of Permeability for Granular Bases

This paper describes a new in-situ Air Permeameter Test (APT) device developed for estimating the hydraulic conductivity of drainable granular base materials. The device is assembled from commonly available components including air flow meters and differential pressure gages. Using prescribed air flow and pressure measurements from the APT, a theoretical relationship is derived to calculate the saturated hydraulic conductivity. The geometric factors for the device, sample boundary conditions, partial saturation, compressibility and viscosity of the permeant fluid (i.e. air), and the Brooks-Corey pore size distribution index are considered in the derivation. Attempts at correlating in-situ APT calculated hydraulic conductivity values for compacted granular base materials to hydraulic conductivity values from reconstituted laboratory compaction mold permeability tests show that the in-situ values are generally higher and more variable. The in-situ variability is attributed to segregation and is shown to be spatially correlated to the fines content (passing No. 200 sieve).

VIRTUAL CONSTRUCTION PROJECT FIELD TRIPS USING REMOTE CLASSROOM TECHNOLOGY

J. E. Dunn Construction Group and Iowa State University have collaborated in an innovative distance education program. By utilizing a micro-PC, digital camera and hands-free headset and microphone; jobsite personnel at the J. E. Dunn headquarters building construction site transmitted, via wireless technology, video imagery and voice information of real-time construction events to students in Iowa State Universitys Construction Engineering Program. Remote students seated in a high technology classroom were able to observe and discuss actual jobsite activity as it occurred 225 miles away. A series of “virtual” field trips were conducted covering several phases of the project, including site work, foundations, building structure and interior finishes. One of the virtual tours was led by J.D. Dunns Leadership in Energy and Environmental Design (LEED) specialist. In this tour, the guide specifically identified those building components earning LEED points for the project. Students, by and large, were pleased with the virtual site tours as the remote tours were less disruptive to their schedules and accomplished the same educational objective. Although this approach incurred certain technical difficulties, the information technology system performed satisfactorily and demonstrated promise for increased application of virtual construction site tours for many project stakeholders such as owners, architects, engineers, and lender representatives.

A decision support system to load containers to double-stack rail cars

Abstract This paper investigates intermodal rail terminal operations and describes the development of a computerized decision support system to load containers on double-stack trains efficiently. The support system, referred to as the Double Stack Planner (DSP), simulates many tasks performed by rail personnel who manually assign containers to rail car locations. DSPs rule base may be modified to load trains according to a variety of loading strategies, however, all maintain platform and truck load restrictions. Comparisons of these loading strategies illustrate the sensitivity of different criteria to the load quality of a train.

Special Issue on Construction Engineering: Opportunity and Vision for Education, Practice, and Research

Engineering is an applied science. In no other engineering specialization is this more relevant than in construction engineering. A challenge among construction engineering academics (both faculty and students) and industry practitioners is to transfer a method, technology, or practice that can be supported in the theoretical sense, whether in a laboratory or classroom setting, and make it applicable to the rarely ideal industry jobsite. This bridge between engineering in the theoretical sense and practice requires intimate collaboration and continuous communication, which has not always occurred between the university and the jobsite. As described by Dr. Michael C. Vorster, professor emeritus at Virginia Tech and conference keynote speaker, the dilemma from the academic perspective is that “we teach too much and our students learn too little.” A primary focus of the Construction Engineering Conference held at Virginia Tech from September 30 to October 2, 2010, was to bring academics and industry leaders together to share experiences, practices, and ideas. This interaction was intended to strengthen the connection between theory and practice for mutual benefit. The Construction Engineering Conference was a unique opportunity in the sharing of knowledge across aisles. The purpose of this special issue is to archive and disseminate the knowledge for current and future generations of construction engineers. Each conference speaker submitted a manuscript that was peer-reviewed by academic and industry reviewers. In many cases, industry speakers coauthored the manuscript with a construction engineering academic. In all, this special issue includes 28 manuscripts that cover a broad range of construction engineering topics. A debt of gratitude is owed to the authors for their thoughts and efforts in this overall body of work, which makes a significant contribution to the overall body of construction engineering knowledge. Furthermore, the editors are especially grateful to the reviewers, who ensured that the manuscripts maintained the rigorous standards for publication in the ASCE Journal of Construction Engineering and Management. Finally, the editors are grateful for the support provided by the Construction Engineering Conference committee and the senior editorial boardmembers of the Journal, especially Dr. JesusM. de la Garza. Without their guidance and advice, this special issue would not have been possible.

LEARNING OUTCOMES FROM CONSTRUCTION SIMULATION MODELING

Abstract Repetitive construction processes exhibit improvement in production rate as repetitions increase. A learning curve can be developed for such construction processes that can improve the predictive accuracy for the early portions of project schedules. This paper discusses a method for incorporating learning development in a construction simulation model. The case study model represents the construction of a guide wall for a lock using a mobile cofferdam. The impact of including learning development on model results is reported as well as a sensitivity analysis.

Evaluation of Dynamic Cone Penetration Quality for Cohesive Soil Embankment Construction: Pilot Project for New Specification for Quality Control and Quality Assurance

A pilot project at US-34 in Iowa recently required the use of a new quality control (QC) and quality assurance (QA) specification involving dynamic cone penetration (DCP) testing in concert with conventional moisture and density testing. The contractors QC test results were verified with occasional QA testing by Iowa State University and the Iowa Department of Transportation. Cone penetration testing and laboratory unconfined compressive strength testing were conducted on samples obtained on natural fill material before excavation and afterwards on the compacted fill to evaluate the performance properties of the final product. The research findings documented in this paper focus on (a) statistical comparisons between contractor QC and independent QA test data, (b) statistical analysis of the contractor QC data, and (c) evaluation of the performance of a completed embankment. The study findings show that the DCP can be used for QC and QA testing for cohesive soils to evaluate stability and vertical uniformity.

Performance-Based Design Method for Gradation and Plasticity of Granular Road Surface Materials

Granular-surfaced roads frequently experience severe surface damage and degradation, which adversely affects traffic safety and significantly increases maintenance costs. The importance of the gradation and plasticity of granular-surfaced road materials have long been recognized. However, very few studies have focused on quantifying the effects of gradation and plasticity on the resulting mechanical performance of granular roadways. In this study, laboratory tests and statistical analyses were conducted to quantify the effects of variations in gradation and plasticity on the mechanical performance of granular road surface materials. A performance-based design method was developed using Fuller’s model to replace the commonly used arbitrary gradation band specifications. To validate the performance of the proposed method, field test sections were constructed then tested through a seasonal freeze–thaw period. Compared with existing gradation band specifications, the laboratory and field test results demonstrated that the proposed method is more closely tied to performance and can be used to develop specifications with more precise targets. To help secondary roads agencies implement the method while also recycling existing surface materials, a gradation optimization program was developed to determine the mixing ratios of existing roadway aggregate and two to three new quarry materials to come closest to the theoretical gradation for optimum performance. A complete set of testing, design, and construction procedures is also recommended to provide more cost-effective solutions to building or reconstructing granular-surfaced roads.