Effectiveness of Loaded Wheel Tracking Test to Ascertain Moisture Susceptibility of Asphalt Mixtures

Abstract

Moisture damage of asphalt mixtures is a major distress affecting the durability of asphalt pavements. The loaded wheel tracking (LWT) test is gaining popularity in determining moisture damage because of its ability to relate laboratory performance to field performance. However, the accuracy of LWT’s “pass/fail” criteria for screening mixtures is limited. The objective of this study was to evaluate the capability of the LWT test to identify moisture susceptibility of asphalt mixtures with different moisture conditioning protocols. Seven 12.5 mm asphalt mixtures with two asphalt binder types (unmodified PG 67-22 and modified PG 70-22), and three aggregate types (limestone, crushed gravel, and a semi-crushed gravel) were utilized. Asphalt binder and mixture samples were subjected to five conditioning levels, namely, a control; single freeze–thaw-; triple freeze–thaw-; MiST 3500 cycles; and MiST 7000 cycles. Frequency sweep at multiple temperatures and frequencies, and multiple stress creep recovery tests were performed to evaluate asphalt binders. LWT test was used to evaluate the asphalt mixture samples. Freeze–thaw and MiST conditioning resulted in an increase in stiffness in the asphalt binders as compared with the control. Further, freeze–thaw and MiST conditioning resulted in an increase in rut depth compared with the control asphalt mixture. The conditioning protocols evaluated were effective in exposing moisture-sensitive mixtures, which initially showed compliance with Louisiana asphalt mixture design specifications.

The Use of Steel Slags in Asphalt Pavements: A State-of-the-Art Review

“…As far as moisture resistance is concerned, the threatening water presence in asphalt mixtures is believed to represent one of the main reasons for flexible pavement failures, leading to structural and functional degradations [217,218]: these phenomena, caused by adhesive (aggregate-mastic bonding) and cohesive (bitumen film bonding) failure [219], are widely influenced by the properties of aggregates, binders, aggregate-binder interfaces, and mixing temperatures [220]. The moisture susceptibility of asphalt mixtures is generally evaluated through the determination of the typical parameters (that may not be representative of the fundamental material characteristics) of unconditioned and water-conditioned samples prepared with the same method: a common procedure is Indirect Tensile Strength Ratio (ITSR) analysis, i.e., the ratio of the indirect tensile strength of water-conditioned specimens to the indirect tensile strength of unconditioned samples [221,222]. Furthermore, ITSR can be substituted or integrated by the analysis of other parameters, such as the retained stability (Marshall Stability Ratio, MSR), the Resilient Modulus Ratio (RMR), and Fracture Energy Ratio (FER), or by energy-based parameters, such as the Dissipated Creep Strain Energy limits (DCSEf) [223,224].…”

Evaluation of moisture‐induced damage on the fatigue life of asphalt mixtures using failure tests of asphalt binders, interfaces, and mixtures

“…Some authors address moisture damage to the aggregate-binder interface properties [11][12][13][14][15] but others suggest that its occurrence is at the isolated binder. 16,17 Either way, asphaltic materials are susceptible to moisture damage and that such distress may be affected by constituent materials and interfacial properties. When it comes to test methods to investigate moisture susceptibility, a variety of analyses are possible.…”

Empirical Model for the Retained Stability Index of Asphalt Mixtures Using Hybrid Machine Learning Approach

“…Many laboratory testing methods were used to evaluate and measure the moisture susceptibility of asphalt mixtures. Some of the tests include immersed wheel-tracking configurations such as the Hamburg wheel-tracking test and the Asphalt Pavement Analyzer device [9,10], while others evaluate moisture damage by calculating the ratio of strength or stiffness of water-conditioned compacted Hot-Mix Asphalt (HMA) samples to that of unconditioned samples [4]. The latter includes several testing protocols such as the immersion-compression test, the resilient modulus test, the double-punch method, the tensile strength ratio (TSR) or modified Lottman (AASHTO T 283), the Retained Stability Index (RSI), and others [11][12][13][14].…”

“…This refers to the fact that they do not consider the fundamental measurements of material properties that influence the mechanisms of moisture-induced damage in asphalt mixes [8]. Also, adopting a single test from among these methods as an ideal procedure for characterizing the moisture sensitivity performance of mixes is impractical due to the wide variety of conditions, factors, and material properties that impact the moisture susceptibility of asphalt pavement [9][10][11]15].…”