Effects of WMA additives on bond strength of asphalt-aggregate systems using SFE and BBS

What is it about?

The present study was undertaken to evaluate the effects of different warm mix asphalt (WMA) additives on bonding behaviour of asphalt binder and aggregates using two different approaches: (i) The surface free energy (SFE) method and (ii) The asphalt bond strength (ABS) test. The results indicated that Sasobit and Advera effectively contributed in enhancing the cohesive energy of control binder, whereas Rediset decreased the cohesive energy of control binder. Bond strength of WMA modified binder depends on both aggregate type and WMA additives. The results show that asphalt binder with Sasobit can have better bonding performance with limestone (basic) aggregate, whereas, asphalt binder after addition of Advera showed better bonding performance with granite (acidic) aggregate. After wet conditioning, asphalt binders with limestone (basic) aggregate combinations exhibited cohesive failure showing minimal effect of water on bond strength compared to binders with granite (acidic) aggregate combinations which showed adhesive failure. The comparison of bond strength by mechanical ABS test and energy-based SFE methods have shown a fair correlation between bond strength ratio (BSR) and energy ratio (ER).

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Why is it important?

Very few studies have been conducted for evaluating the bond strength of WMA modified binders using SFE and ABS methods. Also, as per the authors’ knowledge, comparison between SFE and ABS for evaluating the bond strength of WMA modified binders has not been available in open literature.

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