| Popis: |
Hot-poured bituminous sealants are typically selected based on standard, but empirical tests such as penetration, resilience, flow, and bond to cement concrete briquettes (ASTM D3405). There is, however, no indication of the pertinence of these standard tests to predict field performance. In an effort to bridge the gap between sealant fundamental properties and field performance, performance-based guidelines for selection of hot-poured crack sealants are currently being developed. A procedure to measure sealant viscosity is proposed as part of that effort. Using a sealant with an appropriate consistency at the recommended installation temperature would provide a better crack filling, and would ensure appropriate bond strength. Therefore, to ensure that sealant-crack wall adhesion is achieved and that the sealant penetrates hot-mix asphalt (HMA) during installation, a testing procedure for bituminous based crack sealant viscosity atinstallation temperature is suggested. This paper proposes the use of a rotational viscometer to measure the viscosity of hot-poured crack sealant materials. Based on the results of this study, the measured viscosity of hot-poured crack sealant using SC4-27 spindle at 60rpm at the recommended installation temperature is reasonably representative of sealant viscosity at shear rates resembling field application. To ensure measurement consistency and stability, a 20min melting time and a 30-s waiting time prior to data collection are recommended. The repeatability of the measurements was acceptable with an average coefficient of variation less than 5%. Variability between operators and variability between sealant samples wereacceptable. |
