Improvement of bituminous concrete using cement as filler material

Abstract

Current development in the design of asphalt concrete especially in the upper layers of flexiblepavements contains about acceptable proportion of mineral fillers, which contributes towards the mixcohesion, resistant to rutting and improves serviceability. It is well recognized that mineral fillers playan important role in the properties of mastics and Hot-Mix Asphalt (HMA) mixtures. Better understanding of the effects of fillers on the properties of mastics and HMA mixtures is crucial to goodmix design and high performance of HMA mixtures. This study presents a laboratory investigation intothe effects of different fillers on some properties of HMA mixtures and also the actual behavior of bituminous material on existing road network.

It has long been recognized the importance of the role of fillers in the hot mix asphalt (HMA) behavior. The filler fills the voids between the coarse and fine aggregates in the mixtures and changes the properties of asphalt binders, because it acts as an active part of the mastic. In the HMA design, the mastic influences the lubrication of the larger aggregates particles and affects the voids in mineral aggregate, the compaction characteristics and the optimum asphalt binder content. The HMA volumetric properties are necessary requirements to ensure a good performance, and these properties are directly influenced by the mixture grading, aggregates surface characteristics and compaction energy.

In this study, 1 (One) filler type (Portland cement),05 (Five) filler contents and 1 (One) loading patterns (Heavy Loads)are used toinvestigate the effect of filler / asphalt ratio on the characteristics of HMA mixtures on Laboratoryusing the Marshall Mix design method. These mixtures were prepared using Portland cement with varying the content by the total mixtureand their effects on Marshall Properties are assessed. Optimum Bitumen Content (OBC) is found as 5.60%. Different Cement Content (0.00%,0.50%, 1.00%, 1.50% and 2.50%) as filler material in mixtures having OBC is 5.625% are collected from secondary source by performing Tensile Strength Ratio (TSR) test. The indirect tensile strength (using Cement Content as filler of 0.50%) determined by TSR test is 85.03% which represents the mixture having good ability against moisture damage under a variety of temperatures and stress levels that simulate the conditions of a pavement that is subjected to moving wheel loadsconstruct a road strip so that it could explore the actual scenario of bituminous characteristics.

The Life Cycle Cost Analysis (LCCA) of the typical section of a flexible pavement having the properties obtained from this study represents the two probable results e.g., Deterministic and Probabilistic result. From the Deterministic results, the LCCA method shows that the Flexible pavement (per Km) using 60/70 Bitumen with 0.50% cement as filler material has Lowest Present Value Agency Cost. From the RHD schedule of rates, 2018, cement modified pavement needs routine maintenance having BDT 0.80 Lac where as normal pavement needs rehabilitation with cost of BDT 36.86 Lac.