TITLE:
Effect of Filler and Binder Contents on Air Voids in Hot-Mix Asphalt for Road Pavement Construction
AUTHORS:
Isooba John, Mugume Rodgers Bangi, Muhwezi Lawrence
KEYWORDS:
Aggregate Gradation, Dense Bituminous Macadam, Marshall Properties
JOURNAL NAME:
Open Journal of Civil Engineering,
Vol.11 No.3,
July
30,
2021
ABSTRACT: Filler
and binder make up a small proportion of bituminous mixtures, hence they are
considered as important ingredients of mixtures. Sometimes due to equipment
error during production, some mixtures retain extra or a reduced amount of
filler or binder as compared to the design mix formula. It is thought that the
poor performance of bituminous mixtures is a result of inadequate proportioning
of materials and the use of inappropriate compaction tools. This study was
intended to appreciate the influence of contents of filler and binder in
relation to durability in asphalt mixtures. Filler used was crushed stone
passing 0.075 mm sieve, while the binder was 35/50 penetration grade. Several
trial mixes were prepared following Ugandan specifications for Road and Bridge
Works, and the Asphalt Institute in MS-2. Marshall design method was used,
studying volumetric properties with an average stability value of 22.3 kN,
average flow value of 3.7 mm, VA of 4.4%, VFB of 69.3%, and VMA of 14.2%. Also,
compaction of mixtures to assess its performance at optimum filler and binder
contents was done. Compaction was done using an Automatic Impact Hammer, a
Vibrating Hammer, and a Superpave Gyratory compactor aimed at simulating
secondary compaction by traffic and assessing the retained air voids which was
3.3%, 1.3%, and 0.7% respectively. Generally, in bituminous mixtures when a
vibrating hammer or a gyratory compactor is recommended for compaction, coarser
mixes would be the best choice.