Viscosity determination of hot-poured bituminous sealants

Hot-poured bituminous sealants are typically selected on the basis of empirical standard tests such as penetration, resilience, flow, and bond to cement concrete briquettes (ASTM D3405). Yet there is no indication of the pertinence of these standard tests to predict field performance. 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 during installation, a testing procedure for bituminous-based crack sealant viscosity at installation temperature is suggested. This paper proposes use of a rotational viscometer to measure viscosity of hot-poured crack sealant materials. From results of this study, the measured viscosity of hot-poured crack sealant using a SC4-27 spindle at 60 rpm at the recommended installation temperature is reasonably representative of sealant viscosity at shear rates resembling field application. To ensure measurement consistency and stability, a 20-min melting time and 30-s waiting time before data collection are recommended. Repeatability of measurements was acceptable, with an average coefficient of variation of less than 5%. Variability between operators and variability between sealant samples were acceptable.