Enhancing the viscoelastic properties of bituminous binders via thiourea-modification

Abstract

Although added in a very low concentration, bitumen controls the final properties and performance of the resulting asphalt mixture. As an alternative to classic bitumen modification with polymers, we herein propose the use of thiourea, which has proved to efficiently enhance the binder thermo-rheological properties in a broad temperature interval. As revealed by thermogravimetric and chemical analysis, benefits above may derive from new structures, probably formed by the interaction between ammonium thiocyanate and bitumen most polar fraction. Thus, flexural DMTA and dynamic shear tests demonstrated an improvement in the binder flexibility and an increase in its elasticity, at low and medium/high in-service temperatures, respectively. In addition, this research emphasizes the use of isothermal frequency sweep tests (and frequency/temperature-dependence conversion) as a means of achieving glass transition temperature values which, in contrast to isochronal temperature sweep tests, do not depend on the selected heating rate.

Dodecylbenzenesulfonic Acid as a Bitumen Modifier: A Novel Approach To Enhance Rheological Properties of Bitumen

“…Eventually, the decrease obtained in the thermal events of the non-reversing heat flow component for both additives provides evidence of lower degrees of molecular ordering in the different bituminous phases, involving a reduction in the crystalline domains, in favor of the amorphous content . In the case of DBSA, it is further accompanied by a decrease in T g1 and T g2 , which translates into improved mechanical performance against fracture at low-to-intermediate temperatures. ,, …”

“…32 In the case of DBSA, it is further accompanied by a decrease in T g1 and T g2 , which translates into improved mechanical performance against fracture at low-to-intermediate temperatures. 30,31,33 3.5. Compositional Characterization.…”

“…It is worthwhile to point out that the shape of the peaks obtained from TLC/FID can also reveal valuable information about chemical changes affecting the polarity of the bituminous fractions. 33 In this sense, the dispersive effect of DBSA on asphaltene aggregates under certain DBSA and asphaltene concentration ranges, which would eventually split the aggregates or prevent asphaltenes from aggregating, would presumably affect the polarity of the resulting structures. When DBSA interacts with asphaltenes, charges on the surface tend to be balanced, reducing asphaltene polarity while seeing their stability increased in nonpolar medium.…”

Study on Miscibility, Thermomechanical Behavior, and Thermoregulation Performance of Paraffin Wax/Bituminous Blends for Solar Thermal Energy Storage Applications

“…With increasing concentrations of paraffin wax added to base bitumen, three different effects are noticed: (i) saturate fractions increase significantly, (ii) aromatics and resins decrease progressively, and (iii) asphaltenes remain almost constant. It has been reported that the asphaltene fraction is the most sensitive to change after chemical bitumen modification; − however, the chromatographic results indicated that paraffin wax addition significantly affects other families of SARAs compounds since the initial relative proportion of asphaltenes, aromatics, and resins is not conserved. Therefore, it is expected a notable modification of the colloidal arrangement of bitumen compounds.…”

Chemically modified bitumens with enhanced rheology and adhesion properties to siliceous aggregates

“…Cuadri et al [31,32], the bitumen modification route through thiourea is related to adducts derived from the interaction between the asphaltenes and the ammonium thiocyanate (NH4SCN), arising from the melting/thermal decomposition of Th during its mixing with bitumen at 180 ºC. As a result, thiourea and its derivatives containing N-H bonds contribute to enhance the colloidal structure of bitumen by developing a hydrogen-bond network.…”