A Comparative Study on Various Antistripping Agents in Bituminous Mixes

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A Comparitive Study On Various Antistripping Agents In Bituminous Mixes

A Comparative Study on Various Antistripping Agents in Bituminous Mixes

Abstract

A Comparative Study On Various Antistripping Agents In Bituminous Mixes The presence of water in porous asphalt mixtures has detrimentally affected the bonding between binder-aggregate interface and cohesive failure within the binder-filler mastic, making them prone to stripping which contributes to performance and durability. This paper presents the effect in porous asphalt mixes of anti-stripping additives.

Damage to moisture is one of the most common reasons for the premature deterioration of Hot Mix Asphalt (HMA) pavements. Scientists and engineers have conducted extensive research on this topic over the years ; however, pavements still succumb to early failure from infiltrating moisture.

A very popular method of minimizing asphalt pavements ‘ susceptibility to moisture is the use of anti-stripping agents. These additives are chemical substances that alter the asphalt’s physicochemical properties by making it more hydrophobic. This study focuses on the effect of anti-stripping agents on the susceptibility of Bituminous Concrete (BC) mixture to moisture.

Hydrated lime and Zycosoil were the anti-stripping agents used. Three types of mix were studied, namely: BC mix without additive, BC mix with hydrated lime and BC mix with Zycosoil. Viscosity Grade (VG) 30 bitumen was used in all three sample groups.

Conclusion

By diffusion in the binder, water can damage the porous asphalt mixtures and influence their strength, resulting in the asphalt film’s loss of cohesion. From this study, PMD porous specimens exhibit higher ITS, better water damage resistance.

Lower air voids, however, decreased the coefficient of permeability and abrasion loss compared to mixes incorporating OPC and quarry dust. Porous specimens incorporating PMD as a filler can better resist damage to moisture and improve disintegration resistance compared to those specimens incorporating OPC and quarry dust. Adding anti-stripping additives improves the bulk density of the bituminous concrete mix.

The stability of Marshall is significantly increased with the addition of anti-stripping additives. Adding the anti-stripping additive slightly lowers the volume of air voids of the mixes at OBC. Also, the flow, VMA and VFB values did not show any significant variation between additive and non-additive samples. 

From the ITS results, the addition of anti-stripping agent increases the ITS value for both conditioned and unconditioned samples. The addition of hydrated lime and Zycosoil improved the TSR ratio by 4 percent and 8 percent, using the untreated mix as a reference point.