Evaluation of Bond between Bituminous Pavement Layers

Abstract

The bond of pavement l ayers plays an important role to achieve good performance of a flexible pavement. It has been observed that the poor  bonding b etween  pavement  layers  causes  pavement  overlay distresses such as compaction difficulty, top down cracking, pot holes, premature  fat igue  and  surface  l ayer delamination. Slippage failure i s the most  commonly  observed  problem often  occurring at the  locations where traffic accelerates, decelerates or turns.

In order to prevent such distresses, t ack coat  will be sprayed between the pavement l ayers. A variety of Asphalt materials are used for t ack coats. A tack coat is an application  of a bituminous  emulsion  or bituminous binder between an existing bituminous / concrete surface and a newly constructed bituminous overlay. . Normally,  hot bituminous binders,  cutback  bitumen  or bituminous  emulsions are  used  as  tack coat  materials. This  s tudy is aimed to evaluate the  bond  st rength at the  interface between  pavement  layers by performing laboratory t ests.  In this  three  special  attachments  are  fabricated  for  use  in  Marshall Loading Frame to finding the performance of tack coat laid at the interface between Bituminous Concrete ( BC) and Dense Bituminous Macadam ( DBM) layers in the laboratory. In this study, the  results  of the specimens prepared with 100 mm and 150 mm diameter specime ns using  two  types  of normally  used emulsions, named CMS - 2 and CRS- 1 as tack coat of application rates varying at 0. 30 kg/ m ² , 0. 35 kg/ m ² and 0. 40 kg/ m ² made at 25⁰ C temperature are presented.  It is observed that CRS - 1 as tack coat provides higher interface bond strength value compared to CMS - 2.