Viscosity determination of hot-poured bituminous sealants

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.Les mat\ue9riaux d'\ue9tanch\ue9it\ue9 bitumineux appliqu\ue9s \ue0 chaud sont g\ue9n\ue9ralement s\ue9lectionn\ue9s au moyen de tests standard mais empiriques, tels que la p\ue9n\ue9tration, la r\ue9sistance, le flux et le liant dans les briquettes de b\ue9ton de ciment (ASTM D3405). Rien ne d\ue9montre toutefois l'efficacit\ue9 de tels tests standard \ue0 pr\ue9voir la performance sur le terrain. Afin de combler l'\ue9cart entre les propri\ue9t\ue9s fondamentales des produits de calfeutrage et la performance sur le terrain, des directives, fond\ue9es sur la performance, quant \ue0 la s\ue9lection des produits de calfeutrage appliqu\ue9s \ue0 chaud sont en cours de r\ue9daction. On y propose entre autres une m\ue9thode de mesure de la viscosit\ue9 des produits de calfeutrage. Un produit dont la consistance est appropri\ue9e, utilis\ue9 \ue0 la temp\ue9rature recommand\ue9e, comblera davantage les fissures et constituera un liant plus efficace. Ainsi, afin d'assurer l'adh\ue9sion du produit de calfeutrage aux parois et sa p\ue9n\ue9tration lors de l'application de l'asphalte m\ue9lang\ue9 \ue0 chaud, on sugg\ue8re une m\ue9thode d'essai de la viscosit\ue9 des produits de calfeutrage \ue0 base de bitume \ue0 la temp\ue9rature ad\ue9quate. Ces m\ueames directives proposent de mesurer la viscosit\ue9 des produits de calfeutrage appliqu\ue9s \ue0 chaud \ue0 l'aide d'un viscosim\ue8tre rotatif. Selon les r\ue9sultats de l'\ue9tude, la viscosit\ue9 des produits de calfeutrage appliqu\ue9s \ue0 chaud \ue0 la temp\ue9rature recommand\ue9e, mesur\ue9e au moyen d'un fuseau SC4-27 \ue0 60 tours/minute, correspond raisonnablement \ue0 la viscosit\ue9 des produits de calfeutrage dont la vitesse de cisaillement s'apparente \ue0 l'application sur le terrain. Afin de maximiser la coh\ue9rence et la stabilit\ue9 de la mesure, on recommande un temps de fusion de 20 minutes et un d\ue9lai de 30 secondes avant la collecte de donn\ue9es. Les r\ue9sultats de la mesure ont r\ue9v\ue9l\ue9 un taux de fid\ue9lit\ue9 acceptable et un coefficient moyen de variation inf\ue9rieur \ue0 5 %. La variabilit\ue9 entre les op\ue9rateurs et celle entre les \ue9chantillons de produits de calfeutrage se sont av\ue9r\ue9es acceptables.Peer reviewed: YesNRC publication: Ye