PERFORMANCE EVALUATION OF DENSE BITUMINOUS MACADAM MIX - A REFUSAL DENSITY APPROACH

Abstract

Secondary compaction is a state; where the pavement which is compacted with the conventional compactio n has been further compacted due to the movement of traffic and which corresponds to the ultimate density which can be at tained on the bituminous pavement called as “Refusal density” of the pavemen t. Secondary compaction has to be studied in detail and it is understood that the 75 blows of the Marshall test does not determine th e actual field circumstances. The Marshall design a ctually in the field will not simulate the field conditions hence there will be a reduction in the air voids at the refusal density. Then due to fineness of the mix, this causes the plastic deformation on the pavement surf aces. Hence an attempt has been made to study the a ir void content at refusal density. Also the Bulk Density, Air voids (Va), Voi ds in mineral aggregate (VMA),Voids filled with Bit umen (VFB) of the mix at the refusal density are also studied. For the simulatio n of the field density in the laboratory a Hugo ham mer is used. The usage of the Polymer Modified Bitumen reduces the plastic deform ation and other distresses of the pavement.