Influence of cement content and environmental humidity on asphalt emulsion and cement composites performance

Abstract

Asphalt and cement concrete are the most popular materials used in the construction of roads, highways, bridge deck surface layers and pavements in airports and other areas with heavy wheel roads. Whereas asphalt possesses, compared to concrete, the advantages of a short curing period, high skid resistance and easy maintenance, it also shows lower fatigue durability, ravelling and rutting due to repeated concentrated loads and susceptibility to temperature changes and moisture. On the other hand, concrete pavements are initially more expensive, have lower driving comfort and are susceptible to cracking due to volume changes and to salt damage. A material with low-environmental impact and with advantages of both asphalt and concrete may be obtained by combining bitumen emulsions and a cementitious material. In this paper, cold asphalt mixtures with different amounts of cement were tested with Marshall stability tests. Selected mixtures were also cured at different environmental relative humidity (35, 70 and 90 % RH). By monitoring the mass of the specimens and estimating the water bound by the cement, the total water remaining in the mixtures was calculated. Details of the microstructure in the mixtures were examined with X-ray microtomography. According to the results of the present study, cement contributes to the hardening of cold asphalt mixtures both by creating cement paste bridges between the aggregates and by removing water from the mixtures through cement hydration. Asphalt and cement composites appear to be promising materials for implementation in real pavements, although their rate of hardening needs to be improved further.

Curing and temperature sensitivity of cement–bitumen treated materials

“…At low cement content, the hydration products disperse inside the bituminous mortar increasing its viscosity and improving the resistance of the mixture to permanent deformations. At higher cement content, the volume of hydration products grows forming a stiffer matrix that connects coarser aggregate particles (Garcia et al 2013).…”

The Effect of Curing on the Mechanical Behavior of Cement-Bitumen Treated Materials

“…This fraction of potentially evaporable water is probably trapped inside the surface porosity of the aggregate or inside the bituminous mortar (Garcia et al 2013).…”

“…Basically, the curing process of CBTM can be explained through the combination of three phenomena that occur within the recycled mixture: emulsion breaking, moisture loss and hydration of cementitious compounds (Cardone et al 2014;Garcia et al 2013;Kim et al 2011). In particular, emulsion breaking takes place in the early phases (i.e.…”

“…after mixing and compaction), whereas moisture loss and cement hydration continue over time. Several research studies (Cardone et al 2014;Garcia et al 2013;Kim et al 2011) highlighted that while the curing process of bituminous emulsion is strictly related to moisture loss, the hydration of cement requires the presence of water.…”

Characterisation of high-performance cold bitumen emulsion mixtures for surface courses

“…Promotion of CBEMs and their performance has recently been a significant aim of many researchers using high OPC content (García et al 2013, Fang et al 2014. In contrast, the aim of this study is to improve the mechanical properties and the durability of CBEMs with low cement content and different by-product materials, namely FA and GGBS.…”