Abstract: This article describes the effect of heat aging and styrene-butadiene-styrene (SBS) content in bitumen on the adhesion properties of mastics (bitumen-filler mix) to concrete and steel substrates. Test results showed that the adhesion strength of bituminous mastics to concrete and steel substrates decreased as the SBS content increased. Bitumen types modified with 9%-12% of SBS, commonly used in waterproofing materials, showed an approximately three times weaker bond with concrete and steel substrates than the nonmodified equivalents. Results also showed that after heat aging, the adhesion strength of the nonmodified bitumen was always higher than that of the unheated bitumen modified with 9%12% of SBS.
Key words: bitumen, heat aging test, adhesion strength.
Resume : Cet article decrit l'effet du vieillissement du a la chaleur et du contenu du bitume en styrene--butadiene--styrene (SBS) sur les proprietes d'adherence des mastics (melange bitume--filler) aux substrats beton et acier. Les resultats des tests ont montre que l'adherence des mastics bituminoux aux substrats beton et acier diminue lorsque le contenu en SBS augmente. Des types de bitume modifie avec 9%-12 % de SBS, couramment utilises dans les materiaux impermeables, ont montre un lien environ trois fois plus faible avec les substrats de beton et acier que les equivalents non modifies. Les resultats ont egalement montre qu'apres le vieillissement du a la chaleur, l'adherence du bitume non modifie etait toujours plus eleve que celui du bitume modifie avec 9%-12 % de SBS non chauffe.
Mots-cles : bitume, essais de vieillissement du a la chaleur, force d'adherence.
[Traduit par la Redaction]
Introduction
In most countries, the styrene--butadiene--styrene (SBS) copolymer is the most common modifying polymer used in bitumen-based waterproofing building materials. The addition of SBS to bitumen not only improves the heat aging resistance of bitumen and the low-temperature flexibility of the material, but also increases its resistance to temperature changes. Roofing membranes, bitumen glues, and liquid products made of SBS-modified bitumen have been widely used in construction for over 20 years, despite the fact that their prices are higher than those of traditional standard bitumen products.
The author of this article made a comparison of SBS-modified bitumen products, such as roofing membranes, coating, and bonds, with those made with nonmodified bitumen and noticed that the performance of SBS-modified bitumen products was very similar to that of nonmodified bitumen that have been in service for the same period of time, with the latter performing slightly better. For example, nonmodified roofing membranes adhere better to the substrate, whereas liquid bitumen and glues give more durable bonds.
The objective of this work was to assess the effect of heat aging and SBS content on the adhesion properties of two bitumen types to concrete and steel substrates.
Experimental
Tests were carried out in the laboratory of the Institute of Structural Engineering at Poznafi University of Technology, Poland. To investigate the effect of heat aging on the adhesion properties of SBS-modified bitumen to concrete and steel, two types of soft bitumen commonly used in the manufacture of waterproofing building materials were tested. One type was the paving-grade bitumen 160/220 (EN 2004a) and the other was its oxidized version 40/175 (PN 1976), which has a similar softening point and penetration at 25[degrees]C. Bitumen …
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