The National Academies Press

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From page 6... ... 6 This chapter presents the background for the causes and mechanism of moisture damage in asphalt pavements. The factors that cause and contribute to moisture damage can be classified as either intrinsic material and/or mixture properties, or as external factors pertaining to the pavement itself. Read the entire page →
From page 7... ... Literature Review: Assessing and Mitigating Moisture Susceptibility 7 incompletely coated or ruptured asphalt film and displace the asphalt molecules (3) Read the entire page →
From page 8... ... 8 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements Unmodified asphalts tend to have a negative surface charge, and hence they do not bond well with negatively-charged rocks. Asphalt compatibility with aggregate can be modified to some extent by the use polymer additives and anti-stripping agents. Read the entire page →
From page 9... ... Literature Review: Assessing and Mitigating Moisture Susceptibility 9 Among mixture types, mixtures with high permeability or high air void content tend to be more susceptible to moisture damage. This is because the interconnected void space allows for easy water penetration and water accumulation within the mixture, if adequate pavement drainage is not provided. Read the entire page →
From page 10... ... 10 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements 2.2.1 Boiling Water Test A simple and rapid test to visually assess the loss of adhesion in asphalt mixtures is the Boiling Water Test, ASTM D3625 (26) Read the entire page →
From page 11... ... Literature Review: Assessing and Mitigating Moisture Susceptibility 11 single-sized aggregate and emulsion (or cutback) are mixed, cured and cooled to room temperature. Read the entire page →
From page 12... ... 12 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements in split-tension mode to determine the indirect tensile strength, and the results of each subset are averaged. Strength testing is done at room temperature, with a loading rate of 50 mm/min (Figure 1) Read the entire page →
From page 13... ... Literature Review: Assessing and Mitigating Moisture Susceptibility 13 submerged under water at test temperature. The reciprocating action of the wheel, along with its sinusoidally varying position along the track, causes the wheel to spend an equal amount of time in the front and back portions of the samples. Read the entire page →
From page 14... ... 14 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements 2.2.6 Moisture-Induced Stress Tester As mentioned earlier (Section 2.1) , one of the factors that contributes to the moisture damage problem is vehicular traffic over saturated pavement as it leads to the movement of water in the interconnected void spaces. Read the entire page →
From page 15... ... Literature Review: Assessing and Mitigating Moisture Susceptibility 15 This test can be conducted on 4″- or 6″-diameter specimens, either lab-compacted or obtained from the field cores. Depending on the thickness of the specimens, two or three specimens can be tested concurrently. Read the entire page →
From page 16... ... 16 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements researchers at North Carolina State University (43) Read the entire page →
From page 17... ... Literature Review: Assessing and Mitigating Moisture Susceptibility 17 The force used to insert the coated plate up to a certain depth is measured and used to calculate the contact angle between the binder and the solvents. Figure 6 shows the schematic of the Wilhelmy plate along with the force components acting on the film. Read the entire page →
From page 18... ... 18 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements those prone to stripping. But these methods often fail to correctly evaluate the susceptibility of marginal mixtures and show poor correlation with field performance. Read the entire page →
From page 19... ... Literature Review: Assessing and Mitigating Moisture Susceptibility 19 above saturated surface-dry (SSD) condition, respectively. Read the entire page →
From page 20... ... 20 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements Wheel-Track Test. In this case, the improved high temperature stiffness resulting from the addition of >1% PPA was apparently "neutralized" by the addition of amine-based LAS. Read the entire page →
From page 21... ... Literature Review: Assessing and Mitigating Moisture Susceptibility 21 Some polymers can also form a waterproof barrier around the aggregate particles, and thus improve bonding between the asphalt and aggregate (50) Read the entire page →
From page 22... ... 22 Practices for Assessing and Mitigating the Moisture Susceptibility of Asphalt Pavements mixtures with low saturation levels did not provide useful information with respect to identifying mixtures with low or poor resistance to stripping. At the higher saturation levels (specification recommended) Read the entire page →

From page 6...

... 6 This chapter presents the background for the causes and mechanism of moisture damage in asphalt pavements. The factors that cause and contribute to moisture damage can be classified as either intrinsic material and/or mixture properties, or as external factors pertaining to the pavement itself.