Laboratory evaluation of organic and chemical warm mix asphalt technologies for SMA asphalt

Abstract

Warm mix asphalt (WMA) technologies allow significant lowering of the production and paving temperature of the conventional hot mix asphalt (HMA), which promise various benefits, e.g. lowering the greenhouse gas emissions, reduction of energy consumption, improved working conditions, better workability and compaction, etc. However, in order to reach widespread implementation of WMA, it is necessary to prove that it has the same or better mechanical characteristics and long-term performance as HMA. This article presents a laboratory study that has been conducted to evaluate two different WMA technologies -chemical (using Rediset WMX) and organic (using Sasobit) for the use with stone matrix asphalt (SMA). The properties of two types of bitumen after modification with two different dosages of each WMA additive have been tested by traditional empirical test methods and with the Dynamic Shear Rheometer for a wide temperature range. Asphalt testing has been performed for SMA11 type mixture. At first, the necessary changes in testing conditions were determined by means of asphalt stiffness -the results suggested that for adequate comparison with reference HMA, at least two hour asphalt aging is essential before preparing test specimens. The properties of asphalt were determined for specimens that were prepared at four different compaction temperatures by means of two compaction methods -Marshall hammer and gyratory compactor. The test results show that it is possible to reduce the compaction temperature of 155 °C for HMA to at least 125 °C for both WMA products with maintaining similar density and mechanical characteristics at intermediate to high temperatures.

Warm Mix Asphalt

“…Bonaquist (2011b) reports low temperature grade reduction between 0.5 to 3°C, depending on the technology and production temperature, which promises increased resistance to low temperature cracking of asphalt pavement. However, while Bonaquist's study did not show such an effect, some other studies have reported that the addition of wax might increase the low temperature grade by 2-3°C (Wanger et al 2008;Chowdhury and Button 2008) and Fraas temperature by 1-5°C (Zaumanis et al 2012b).…”

Review of very high-content reclaimed asphalt use in plant-produced pavements: state of the art

“…The methods for compensating for the aged, stiff binder and ensuring adequate pavement performance include the use of rejuvenating or softening additives, use of softer virgin binder grade and increase in total mixture binder content (Tran et al 2012). The utilisation of warm mix technologies can reduce further ageing of binder (Zaumanis et al 2012b). These methods are discussed in Section 6.…”

“…The reduced mixing temperature of WMA significantly limits the undesirable ageing process which compensates for stiffer RAP bitumen . Most WMA technologies also provide temporary reduction of bitumen viscosity and/or improve lubrication that allows to sufficiently coat the aggregates and improve workability International Journal of Pavement Engineering 47 without raising the temperature (Arnold et al 2012, Zaumanis et al 2012b. .…”

Rheological behaviour of n-alkane modified bitumen in aspect of Warm Mix Asphalt technology

“…On the other hand high amount of wax in bitumen does not limit its usefulness as a material for the pavement construction and some new generations of wax additives can improve binder properties, e.g. stiffness and viscosities at service intermediate temperatures [10,11,14] and rutting resistance [15][16][17][18].…”