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This paper outlines the design, construction, and fabrication of seven laboratory exercises and a design project for a sophomore level integrated statics and mechanics of materials course. The academic setting in which the course was created is given along with an overview of the course content. Each laboratory and design project is described in detail, including photographs, drawings of the equipment, student work requirements, principles demonstrated, and equipment design and fabrication. The experiences of the authors and their students with these projects during the Fall 1999 offering of the course are presented, and other classroom activities to enrich student learning are suggested.

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A preliminary assessment is made of the impact of increasing the gross vehicle weight (GVW) from current legal limits to 100,000 lb (45 400 kg) on vehicles hauling sugarcane, rice, timber, and cotton. Sections of road were chosen in each area of Louisiana where commodities are produced, the amount of each commodity hauled was estimated, and the effects of increasing the GVW were evaluated for each section using pavement design models. Design data were secured from the Louisiana Department of Transportation and Development computer database and project files to determine the pavement design parameters and traffic estimates for each road. The number of vehicles hauling the 1998 harvest payload was estimated, a projected increase in the production of each commodity was estimated on the basis of government statistics, and rehabilitations were designed with the use of the 1986 AASHTO Design Guide for a 20-year analysis period. Present worth (PW) was calculated for each GVW scenario for each roadway. Comparisons of PW between the weight scenarios showed that increases in GVW have more effect on state and U.S. highways than they do on Interstate highways. Any increase in GVW over current limits increases the cost of overlays and decreases the length of time before an overlay is required. The cost increase due to increasing the GVW is substantial. Fee structures should be modified by the legislature so that these costs are paid for either through the current registration and overweight permit fee structure or through some new tax, such as a ton-mile tax.

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The Louisiana Transportation Research Center (LTRC) recently conducted a research effort using the Accelerated Loading Facility (ALF). Nine test sections were constructed for this research using the same wearing course material but having different thicknesses of crushed stone and soil cement bases and subbases. The soil cement base is the most commonly used base material in Louisiana, and crushed stone is a preferred base material in northern Louisiana. The performance of several configurations of crushed stone and soil cement constructed at the Pavement Research Facility and tested using the ALF machine is compared. The comparisons are based on rutting, roughness, and crack development measured on each lane during ALF loading. From the analysis it was found that the combination of crushed stone base over a soil cement subbase, known as an inverted pavement, provided better performance than the soil cement bases and resisted rutting and retarded the occurrence of reflection cracking. This finding confirmed results from other research conducted previously. On the basis of the analysis, it is recommended that an inverted pavement section definitely be considered for use in Louisiana even in those areas where the subgrade is relatively soft. In addition, soil cement bases of 4 percent cement and mixed in place should be constructed and their performance observed and compared with that of the more standard 10 percent mixed-in-place soil cement bases.

Using the accelerated loading facility (ALF), the Louisiana Transportation Research Center recently conducted an accelerated pavement test of nine test sections that consisted of the same asphalt wearing course but had different types and thicknesses of crushed stone and soil cement bases and subbases. One of the aims of the project was to compare observed field performance with that predicted with use of the VESYS 3A-M mechanistic prediction model, which predicts the development of rutting, cracking, and roughness, along with serviceability [present serviceability index (PSI)] over time. It was found that VESYS provided a reasonable prediction of observed rutting and PSI—albeit an underestimation—but a poor estimate of surface cracking. This was probably related to the fact that the observed cracking was due to shrinkage of the soil cement rather than fatigue cracking under the load, and also to the fact that VESYS is generally used to model unbound granular materials that have a modulus no greater than 690 MPa (100 ksi). The modulus of soil cement material tested by ALF was 105 MPa (150 ksi) and its behavior under load would be different from that of an unbound granular material. More research is needed into the behavior of soil cement bases, their influence on the cracking of asphalt surfacings, and the most appropriate input into VESYS to model this behavior.