Nebraska LTAP
Date of this Version
2019
Document Type
Article
Citation
Hansen, D., and Halsey, L. (2019). Validation of the Mechanical Rocker Test Method for Ice Melting Capacity (MRT-IMC). NDOT Research Report.
Abstract
The anti-icing and deicing industry has interest in the development of an objective, repeatable test procedure for the evaluation and comparison of anti-icing and deicing products. Pursuant to this goal, the Nebraska Department of Transportation (NDOT) funded research at the University of Nebraska-Lincoln (UNL) to investigate methods for evaluating deicing products, beginning in 2011[1]. Researchers at UNL developed the procedure for the Mechanical Rocker Test for Ice Melting Capacity (MRT or MRT-IMC) in 2014[2].
From 2017-2019, NDOT evaluated the MRT-IMC procedure for validity and suitability as a standard test procedure for assessing deicer performance. NDOT also explored opportunities to improve the procedure that could improve precision. This included testing temperature, freezer configuration, timing critical steps, rocking effect, ice-cube breakage, and the effect of settleable solids. Following exploration in these areas, the MRT-IMC was modified to minimize error. NDOT first validated the MRT-IMC and determined an intra-laboratory, single operator precision. NDOT then shared the modified procedure with three collaborating labs to conduct an inter-laboratory study for further validation of the MRT-IMC.
NDOT initiated round-robin testing of two NDOT approved deicing products (D1 and D2) to establish a single-operator and multi-laboratory precision and bias in accordance with ASTM C802, Standard Practice for Conducting an Inter-laboratory Test Program to Determine the Precision of Test Methods for Construction Materials[3]. A precision statement was developed in accordance with ASTM C670*, Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials[4]. Two individual testers from NDOT (L1, L2) and four testers from three independent labs (L3, L4, L5, and L6) participated in the inter-laboratory study. Each lab tested 29 samples of each D1 and D2 for a total of 58 samples. Engineers at NDOT analyzed all 58 samples and established preliminary precision and bias. The MRT-IMC yielded a single-operator Coefficient of Variation (CV) of 2.66% and a multi-laboratory CV of 5.65%.
The results of this validation study indicate that the MRT-IMC is a valid and repeatable standard test method for assessing ice melting capacity of a deicing product. NDOT validation of the method included the modification of the procedure by shortening time windows that ice is exposed to the ambient temperature in the lab.