27 Mar 2025

Toward a Method to Predict Thermo-Mechanical Properties of High-Strength Concrete Placements

Abstract: In this article, the merits of a thermo-mechanical framework to estimate properties of high-strength concrete are evaluated for potential standardization as a test method. Previous work conducted by the authors was summarized to show the individual advancements toward development of a laboratory testing framework. Most notably, laboratory-based curing protocols have been shown to produce temperature profiles that were similar to mass placements and achieving peak temperatures that were within 2°C of peak temperatures recorded in a mass high-strength concrete placement. Additionally, current testing methods to determine thermo-mechanical properties of mass concrete placements were reviewed, and a clear disconnect was noticed between methods that are predictive as well as a direct measure of mechanical properties. Based on this review of literature and the advancements summarized by the authors, a testing framework is proposed that takes the first steps toward filling this gap in literature of creating a predictive testing protocol that is also a direct measurement of mechanical properties.

29 Sep 2021

Backward Erosion Testing: Magnolia Levee

Abstract: Using a confined flume device, an experimental study investigated the critical horizontal gradient of soils obtained from a site identified as potentially vulnerable to backward erosion piping (BEP). Tests were conducted on glacial outwash material obtained from a sand and gravel quarry in the vicinity of Magnolia Levee in the community of Magnolia, OH. The two bulk samples collected from the quarry had similar grain-size distributions, grain roundness, and depositional environments as the foundation materials beneath the levee. Samples were prepared at various densities and subjected to gradual increases of flow in a wooden flume with an acrylic top until BEP was observed. The critical average horizontal gradient ranged from 0.21 to 0.30 for a bulk sample with a coefficient of uniformity of 1.6, while tests conducted on a bulk sample with a coefficient of uniformity of 2.5 yielded critical average horizontal gradients of 0.31 to 0.36. The critical average gradients measured during these tests compared favorably to values in the literature after applying adjustments according to Schmertmann’s method.

28 Sep 2021

Backward Erosion Progression Rates from Small-Scale Flume Tests

Abstract: Backward erosion piping (BEP) is an internal erosion mechanism by which erosion channels progress upstream, typically through cohesionless or highly erodible foundation materials of dams and levees. As one of the primary causes of embankment failures, usually during high pool events, the probability of BEP-induced failure is commonly evaluated by the U.S. Army Corps of Engineers for existing dams and levees. In current practice, BEP failure probability is quantitatively assessed assuming steady state conditions with qualitative adjustments for temporal aspects of the process. In cases with short-term hydraulic loads, the progression rate of the erosion pipe may control the failure probability such that more quantitative treatment of the temporal development of erosion is necessary to arrive at meaningful probabilities of failure. This report builds upon the current state of the practice by investigating BEP progression rates through a series of laboratory experiments. BEP progression rates were measured for nine uniform sands in a series of 55 small-scale flume tests. Results indicate that the pipe progression rates are proportional to the seepage velocity and can be predicted using equations recently proposed in the literature.