Roger W. Surdahl

A Kinetic-Based Method for Interpreting ASTM C 1260

A proposed kinetic-based method for interpreting ASTM C 1260 test results is introduced that appears capable of overcoming some of the shortcomings currently encountered using a percent expansion criterion for defining potentially reactive aggregate. The method is based on nucleation and growth or phase transformation reaction kinetics where the percent expansion is exponentially related to a power of time. Solving the logarithmic form of the kinetic equation by a least-squares fit yields two parameters, lnk and M, where lnk is the intercept and M is the slope of the regression line, which can be used to determine potential reactivity. A plot of M versus lnk yields two separate domains—one containing reactive aggregate and one containing innocuous aggregate. Values of lnk

Stabilization and dust control at the Buenos Aires national wildlife refuge, Arizona

The objective of this study was to evaluate road stabilizers and dust palliatives on a construction project of FHWAs Central Federal Lands Highway Division for long-term performance and to recommend products with acceptable performance for use on other projects. The evaluation addressed product performance for dust control, rutting, washboarding, raveling, material stabilization, and cost-effectiveness. Roadway stabilization or dust abatement products are classified into the following seven categories: water, water absorbing, organic petroleum, organic nonpetroleum, electrochemical, synthetic polymer, and clay additives. Six soil stabilizers were applied, each on a 1.6-km (1-mi) section to a depth of 150 mm (6 in.) at the Buenos Aires National Wildlife Refuge in south central Arizona, and were monitored at 6-month intervals for 2 years. Visual evaluation included effectiveness in controlling dust, washboarding, and raveling. Physical evaluation included moisture and density, gradation, liquid limit, plastic limit, R-value, California bearing ratio, and silt loading. Analysis included an overall ranking of the six materials and their performance. All products performed well for this semiarid desert location and nonplastic roadway material. The best-performing group had two organic nonpetroleum plus water-absorbing combination products. The second group had one water-absorbing and one organic nonpetroleum product. The third group had two electrochemical products and one synthetic polymer product.

Influence of Mixture Design and Environmental Factors on Continuously Reinforced Concrete Pavement Cracking

The influence of concrete mixture design and environmental factors on cracking in a continuously reinforced concrete (CRC) pavement was documented on Interstate 90 in Hanson County, South Dakota. A project evaluated three mix designs, which were placed in the eastbound direction in 2005. From the study, it was shown that crack frequency was directly related to the initial concrete temperature as specifically contributed by the aggregate in the mix–and a reduced cement content making a less workable concrete. The study recommends an application of curing compound within 30 min to reduce CRC cracking, and wetting the aggregate stockpiles in hot weather to cool them overnight to reduce concrete temperature. Construction of CRC test sections containing at least 510 lb/yd3 of cement with 112 lb/yd3 (15% cement replaced with 18.75%) Class F fly ash is under way to examine the effects of the rate of early strength gain on cracking.

Effects of Design and Material Modifications on Early Cracking of Continuously Reinforced Concrete Pavements in South Dakota

Newer continuously reinforced concrete pavements (CRCPs) in South Dakota have exhibited undesirable levels and types of transverse cracking. This poor performance was not expected under the current recommended design practices. Research was undertaken to identify design, construction, and material issues that may be contributing to the undesirable cracking. After preliminary surveys of existing projects and analysis of the available Long-Term Pavement Performance CRCP data, a systematic construction program was initiated whereby changes in design and materials were incorporated and monitored for any beneficial effects. Beneficial changes were incorporated into projects scheduled for construction the following year and parameters were modified in order to distinguish with minimum ambiguity each parameters effects on cracking behavior. The preliminary results are a series of recommended changes in design, construction, and materials, yielding normal and more desirable cracking patterns.

Capturing a Layer Response during the Curing of Stabilized Earthwork Using a Multiple Sensor Lightweight Deflectometer

AbstractThe lightweight deflectometer (LWD) is a portable device that measures surface deflections and applied force, from which dynamic stiffness and elastic modulus can be estimated. The inclusion of radial offset sensors with LWD testing, referred to here as multiple sensor LWD testing, stemmed from the well-established falling weight deflectometer (FWD) testing method. However, little research exists in the literature addressing LWD use on stabilized or lightly bound layers with multiple sensors, or exploring the applicability of backcalculating/isolating layer moduli from multiple sensor LWD tests. To this end, over 200 multiple sensor LWD tests on stabilized base materials were performed at five sites and rigorously analyzed to determine if the test could capture growth in stabilized base stiffness while the underlying subgrade layer remained unchanged. Deflection results demonstrate that the LWD test is capable of detecting changes in the stiffness of the stabilized base material during curing as i...

Comparison of Multiple Sensor Deflection Data From Lightweight and Falling Weight Deflectometer Tests on Layered Soil

The lightweight deflectometer (LWD) and falling weight deflectometer (FWD) are in situ dynamic plate load tests used to estimate the stiffness and elastic moduli of bound and unbound materials. The inclusion of radial offset sensors with LWD testing stemmed from the well-established FWD testing method of using deflections at the load plate center and at radial offsets to generate a deflection bowl to estimate the moduli of individual layers in a multi-layer system. Due to the similarities between the LWD and FWD tests, several studies have explored the relationship between center deflection results of the two tests. However, little research exists in the literature addressing LWD testing with multiple sensors and how well those deflections correlate with FWD deflections at the same radial offsets. To this end, 114 multiple sensor LWD and FWD tests were performed on stabilized base materials at three sites and rigorously analyzed to determine if there is a consistent relationship between LWD and FWD center and radial offset deflections across all sites and if the estimated moduli from the same backcalculation approach produce similar or correlated results. The results demonstrated that while relationships are site specific for deflections and moduli estimated from the load plate center, a consistent relationship across all sites is demonstrated from the radial offset measurements. Finite element analysis was conducted to understand the difference in induced strains from the two tests to support and better understand the observed differences in FWD and LWD deflections and backcalculated layer moduli.

New Procedure for Selecting Chemical Treatments for Unpaved Roads

There is increasing interest in the use of chemical treatments to reduce maintenance and gravel replacement on gravel roads. However, the choice of the most appropriate chemical treatment is difficult because of the proprietary nature of many of the available treatments. A new approach to the selection of an appropriate chemical treatment is based on the practitioners understanding of the roads that require treatment in terms of traffic, climate, geometry, and materials; of the different chemical treatment categories; and of the objective for applying a chemical treatment. From the information collected, the most appropriate chemical treatment categories for a given situation can be selected from a series of charts and ranked by using a simple arithmetical formula. The ability to rank the treatments available differentiates this procedure from previous procedures documented in the literature. The selection can be refined by evaluating expected performance with prediction charts that are based on material properties determined from the same simple, inexpensive laboratory tests required as inputs to the selection procedure.

Effects of Base Type on Modeling Long-Term Pavement Performance of Continuously Reinforced Concrete Sections

Newer continuously reinforced concrete (CRC) pavements in South Dakota have exhibited undesirable levels of transverse cracking. This poor performance was not expected under the current recommended design practices. Long-term pavement performance (LTPP) CRC pavement data, previously analyzed by others, also could not account for the cracking. To seek an explanation, the original LTPP CRC data was reanalyzed with a more thorough approach. With multiple regression techniques on selected LTPP CRC data sets of comparable accuracy, consequential conclusions can be drawn once the base types are separated into subsets in the database. A similar model was developed for newer CRC pavements in South Dakota, and they showed the same response variables as the LTPP subset for granular bases. Significant correlation was found between cracks and steel depth, cracks and steel size, and cracks and pavement thickness, such that recommendations are made for South Dakota to decrease the steel depth and decrease the steel siz...