Impact of Farm Equipment Loading on Rigid Pavement Performance Using Finite Element Analysis

The increase in agricultural product sales in recent years has led to the use of larger hauling and application equipment to transfer farm productions. This rapid shift in equipment size has raised a concern about their potential to cause significant damage in pavements and bridges. The study reported in this paper (part of a larger pooled fund study initiated in 2007) discusses the impact of farm equipment loading on rigid pavement performance based on Finite Element (FE) analysis. The study considered various types of farm equipment to determine the pavement responses and to quantify their damage on rigid pavement systems. The ISLAB2005 FE pavement response model was employed for numerical modeling and analysis of the test sections subjected to farm equipment loading. The results of FE analysis demonstrated that the rigid pavement damage caused by farm vehicles is governed by their axle weight rather than the gross vehicle weight. The FE analysis also showed that the damage resulting from farm equipment loading coupled with PCC slab curling could have a devastating effect on concrete pavement performance

Effects of Implements of Husbandry (Farm Equipment) on Pavement Performance

The effects of farm equipment on the structural behavior of flexible and rigid pavements were investigated in this study. The project quantified the difference in pavement behavior caused by heavy farm equipment as compared to a typical 5-axle, 80 kip semi-truck. This research was conducted on full scale pavement test sections designed and constructed at the Minnesota Road Research facility (MnROAD). The testing was conducted in the spring and fall seasons to capture responses when the pavement is at its weakest state and when agricultural vehicles operate at a higher frequency, respectively. The flexible pavement sections were heavily instrumented with strain gauges and earth pressure cells to measure essential pavement responses under heavy agricultural vehicles, whereas the rigid pavement sections were instrumented with strain gauges and linear variable differential transducers (LVDTs). The full scale testing data collected in this study were used to validate and calibrate analytical models used to predict relative damage to pavements. The developed procedure uses various inputs (including axle weight, tire footprint, pavement structure, material characteristics, and climatic information) to determine the critical pavement responses (strains and deflections). An analysis was performed to determine the damage caused by various types of vehicles to the roadway when there is a need to move large amounts agricultural product

Performance of Concrete Pavements, Volume II: Evaluation of Inservice Concrete Pavements

DTFH61-91-C-00053With the goal of improving future concrete pavement design and construction practices, this project evaluated the performance of 303 inservice concrete pavement sections located throughout North America. An extensive field testing program, consisting of pavement condition surveys, drainage surveys, falling weight deflectometer (FWD) testing, coring/boring operations, and roughness testing, was conducted in order to collect the information needed for analysis. Because many of these pavement sections are part of State-level studies on concrete pavements, a range of design variables (e.g., load transfer, slab thickness, joint spacing, drainage) thought to affect concrete pavement performance are present. Over one-third of the sections was evaluated under a preceding Federal Highway Administration study, meaning that 5-year performance trends are available for some of the sections. Additional pavement performance data are also available for 96 European concrete pavement sections and for 21 Chilean concrete pavement sections. The average age and average cumulative equivalent single axle loads (ESALs) for the North American sections are 16 years and 7.1 million, respectively, compared to 21 years and 21.8 million for the European sections and 9 years and 5.9 million for the Chilean sections. This volume examines the performance of the North American concrete pavement sections included in the study. This examination primarily consists of an evaluation of the effect of concrete pavement design features on concrete pavement performance. Design features investigated include slab thickness, joint spacing, joint orientation, load transfer, joint sealant, base type, drainage, shoulder type, reinforcement, and pavement type. The results of an examination of the backcalculation results are also presented, as are the significant findings of an evaluation conducted on the performance of European and Chilean concrete pavements

Study of (cyclic peptide)-polymer conjugate assemblies by small-angle neutron scattering

We present a fundamental study into the self-assembly of (cyclic peptide)–polymer conjugates as a versatile supramolecular motif to engineer nanotubes with defined structure and dimensions, as characterised in solution using small-angle neutron scattering (SANS). This work demonstrates the ability of the grafted polymer to stabilise and/or promote the formation of unaggregated nanotubes by the direct comparison to the unconjugated cyclic peptide precursor. This ideal case permitted a further study into the growth mechanism of self-assembling cyclic peptides, allowing an estimation of the cooperativity. Furthermore, we show the dependency of the nanostructure on the polymer and peptide chemical functionality in solvent mixtures that vary in the ability to compete with the intermolecular associations between cyclic peptides and ability to solvate the polymer shell

The Application of Permeable Pavements in Highways and Urban Roads

This policy brief summarizes findings from the research project on successful application of permeable pavement design and performance with special emphasis on stormwater management, water quality benefits, and identification of knowledge and data gaps

Hydrogel and Organogel Formation by Hierarchical Self-Assembly of Cyclic Peptides Nanotubes

Breaking away from the linear structure of previously reported peptide-based gelators, this study reports the first example of gel formation based on the use of cyclic peptides made of alternating d- and l-amino acids, known to self-assemble in solution to form long nanotubes. Herein, a library of cyclic peptides was systemically studied for their gelation properties in various solvents, uncovering key parameters driving both organogel and hydrogel formation. The hierarchical nature of the self-assembly process in water was characterised by a combination of electron microscopy imaging and small-angle X-ray scattering, revealing a porous network of entangled nanofibres composed by the aggregation of several cyclic peptide nanotubes. Rheology measurements then confirmed the formation of soft hydrogel