Early Age Thermal Measurements of Soil-Cement Mixtures for Quality Control during Paving

Abstract

Cementitiously stabilized soil (i.e., soil-cement) is popular among some state departments of transportation (DOTs) for subbase and base pavement layers, particularly, states with limited supplies of quality aggregates. When constructed properly, soil-cement has proven to be a well-performing and economically beneficial product for multiple DOTs; however, there is still a growing need to better characterize soil-cement properties in the laboratory and especially during construction. This need could partly be met with thermal profile measurements of hydrating soil-cement mixtures. The overall purpose of this article is to investigate the potential use of thermal measurements as a quality control tool for compacted soil-cement mixtures used in pavement layers. A compaction device, referred to as the Plastic Mold (PM) device, was central to the approach presented in this article to perform thermal measurement and unconfined compressive strength (UCS) testing on the same specimen. Based on data presented in this article, thermal profile measurements of soil-cement mixtures are feasible and have some merit as a quality control tool. Variability analysis under laboratory conditions showed measured thermal profile results were less variable or equally as variable as UCS measurements. Under field conditions, thermal profile testing was observed to be sensitive to initial material temperature, thermal device insulation, and surrounding environment temperatures. Implementation of thermal measurements into soil-cement quality control seems to be best suited as supporting information only for cases in which UCS measured by the PM device needs more explanation.

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

“…Reference ratios were added for 1,200:1, which defines the Level 2 relationship for soil-cement as defined by the Mechanistic-Empirical Pavement Design Guide (MEPDG; 18), and 2,500:1 and 4,500:1, which define the mid-and upper-bound values of soil-cement trends seen for Mississippi materials (11). The average E:UCS ratio for the Alabama materials tested here was 2075:1 where E:UCS ratios for different size PM specimens and compaction efforts ranged from 1736:1 for PM3 3 6 [7] to 2690:1 for PM4 3 8 [9]. These ratios were similar to previously reported E:UCS values for Mississippi materials.…”

“…Previous research by the authors has outlined advancements toward implementing the PM Device into soil-cement construction practices in Mississippi (4,(6)(7)(8)(9)(10)(11)(12)(13). Initial efforts to understand the PM Device focused on producing viable and repeatable specimens with a 2:1 aspect ratio in a controlled laboratory setting (4,(6)(7)(8)(9).…”

“…Previous research by the authors has outlined advancements toward implementing the PM Device into soil-cement construction practices in Mississippi (4,(6)(7)(8)(9)(10)(11)(12)(13). Initial efforts to understand the PM Device focused on producing viable and repeatable specimens with a 2:1 aspect ratio in a controlled laboratory setting (4,(6)(7)(8)(9). Once PM Device specimens could successfully be produced in a laboratory setting, the PM Device was used on several construction sites to begin to establish QC techniques (10,11,22).…”