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.
Highlights
Ganapati and Adiseshu [1] defined Dense Bituminous Macadam (DBM) mixes as mixtures consisting of bitumen as an adhesive to bind the mineral aggregate which provides strength and toughness to the mix
Some aggregates used in Dense bituminous macadam (DBM) mix design have some porosity which tends to absorb bitumen into the pore structure and the absorbed bitumen is not considered as a binder in the asphalt mixtures [5]
Since the aim of this study was to appreciate the influence of filler and binder on the engineering properties, the following were investigated; Marshall Tests, Stability, Flow, Percent of Air Voids (VA), Voids in Mineral Aggregate (VMA), and Percent Voids Filled with Bitumen (VFB)
Summary
Ganapati and Adiseshu [1] defined Dense Bituminous Macadam (DBM) mixes as mixtures consisting of bitumen as an adhesive to bind the mineral aggregate which provides strength and toughness to the mix. Garcia and Hansen [2] described dense-graded hot-mix asphalt as a bituminous construction material that can be used effectively in all pavement layers for all traffic conditions. The performance of any DBM mixture is achieved by careful aggregates selection [4]. Some aggregates used in DBM mix design have some porosity which tends to absorb bitumen into the pore structure and the absorbed bitumen is not considered as a binder in the asphalt mixtures [5]. Deepesh and Yadav [7] noted that variations in the aggregate gradation within the limits specified can affect the DBM mix design properties
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