Apparent Molecular Weight Distributions for Investigating Aging in Polymer-Modified Bitumen

The oxidative aging of bituminous binders affects the performance and durability of pavements. In the case of polymer-modified binders, aging involves both bitumen and polymers and has a strong impact on the whole architecture of the material. Rheology may help in understanding these structural changes, and interesting information may be obtained by analysing the evolution of apparent molecular weight distributions. This was demonstrated with a bituminous binder modified with a poly(styrene-butadiene) block copolymer and subjected to prolonged artificial aging. Isothermal frequency sweep tests were used to construct master curves of the phase angle and magnitude of the complex modulus. The master curves were then used to calculate relaxation spectra and apparent molecular weight distributions of the binders, as well as simulated temperature sweep tests. A comparison of the behaviour of the base and modified bitumen highlighted the role of the polymer in aging. Polymer degradation significantly damages the elastomeric network, yet the residual polymer chains still interact with the bitumen molecules and reduce their oxidative aging. The apparent molecular weight distributions were deconvoluted to create an aging index specifically developed for polymer-modified bitumen.

Asphalt Concrete for Binder Courses with Different Jute Fibre Content

Since the beginning of modern road construction, there have been effort to make durable, long life pavements. But no one pavement can fulfil designed purpose forever. On the other hand, some natural resources are limited, so it is important to maximize use of renewable resources. In recent years, there is a visible pursuit of this trend, in road construction represented mostly by use of waste materials, such as industrial by-products or recycled asphalt pavement itself. Within the effort, fibrous additives were established on the market to prolong life of pavement layers. Some commercial ones are synthetic polymer based, so it does not go well with the renewable part of pavement life cycle if we want to secure sustainable future. This paper describes use of fibres from natural renewable resource, specifically jute plant (Corchorus). Three asphalt mix variants with jute fibres were designed and further compared. Fibre content was 0.1 %, 0.2 % and 0.3 % by weight. Several tests were conducted to examine the effect of fibres on mixture properties, with aim on stiffness modulus (IT-CY) and crack propagation (SCB). Furthermore, indirect tensile strength ratio was calculated as a parameter showing performance of the mixture under the wet conditions. Control mixtures with paving grade and polymer modified bitumen were tested for better comparison and evaluation of the results.

Investigation the effect of newly used polymer modified bitumen on the performance of hot mix asphalt containing reclaimed asphalt pavement

The current research focuses on investigating the effect of using reclaimed asphalt pavement (RAP) on performance of hot mix asphalt (HMA) prepared with polymer modified bitumen (PMB) binder. This PMB used for the first time with HMA contained RAP. The mechanical properties and performance of HMA were assessed using several standard tests including Marshall, indirect tensile strength, creep compliance, and wheel track test. The RAP replacement was conducted up to 70% of total aggregate in HMA with an increment of 10%. The results of investigation showed, that the use of PMB binder prepared by addition novolac (phenol formaldehyde solid resin) and hexamine to conventional bitumen, significantly improved the performance of HMA contained RAP. Also, the optimum percentage of RAP replacement was found to be 50% of total aggregate in HMA. For this level of replacement, the rut depth reduced up to 38% of its original value.