Backcasting and forecasting stabilized soil mechanical properties for mechanistic-empirical pavement design

Alabama Field Project to Evaluate Variability in Soil–Cement Specimens Compacted with the Plastic Mold Device

“…The average core UCS from the second acceptance lot was 310 psi after 7 days (345, 266, and 320 psi). Since PM Device specimens were tested at 28 days, specimen strengths were backcast to the approximate 7-day strength using an equation initially developed by Wen et al ( 16 ) where constants were optimized by Carey and Howard ( 17 ) for A-2-4 soil, commonly used in the southeast United States. This constant optimization utilized approximately 600 PM Device specimens that were both PM3×6 and PM4×8 as well as a combination of field and laboratory compaction.…”

“…The second is that coring is not needed to test for mechanical properties, which eliminates the need for several coring attempts to obtain one testable specimen ( 13 ). The PM Device has been shown to be capable of producing viable specimens using several materials ranging from cement-stabilized FDR ( 13 ) and cold in-place recycling with steel slag ( 20 ), lime stabilized subgrade ( 13 ), and several different types of cement-stabilized soil ( 17 ).…”

“…Sullivan et al reported an average E:UCS value of 2,000:1 for several AASHTO M 145 A-2-4 soils compacted both in field and laboratory settings using the PM Device (7), whereas the average E:UCS for specimens mixed and compacted on site during the construction of I-269 was 2,478:1 (11). Additionally, data from multiple mixtures of A-2-4 soil mixed and compacted in a laboratory setting that were first reported in Carey and Howard (17) yielded an average E:UCS ratio of 2,620:1. The similarity between E:UCS ratios reported here to (b) values found in the literature indicates that results can be consistently obtained in different state DOT environments where construction practices and materials can potentially vary.…”

Demonstrating Field Use of the Plastic Mold Device on Full-Depth Reclamation Projects in Mississippi

“…The PM device can be used interchangeably in the laboratory or the field. Representative photos of PM device specimens are shown in Figure 1, c and d. To date, the PM device has successfully been used on field projects with chemically stabilized A-2-4 base soil in Mississippi and Alabama, at a research test track, and in a laboratory setting with a range of soils and stabilizing materials including lime, as well as with coarse aggregates in a laboratory (22)(23)(24)(25)(26). The PM device has been shown to work for a range of materials and compaction locations; however, its use with coarse FDR material in a field setting has not been documented before this paper.…”