Evaluation silica fume addition on some properties of cold bitumen emulsion mixtures (CBEMs)

Cold mix asphalt is an alternative to hot mix asphalt that consists of aggregate and filler with asphalt emulsion as a binder material rather than asphalt cement.It has many benefits such as save energy and less emissions.

The major objective of this paper is determining the effects of adding silica fume on some properties of cold bitumen emulsion mixtures (CBEMs). This was done by adding three proportions of silica fume (1, 2, and 3%) as a replacement for limestone dust and then conducting tests including indirect tensile strength, compressive strength, Marshall stability, flow test, bulk specific gravity (G_mb), and air voids, The mixtures were also evaluated for moisture sensitivity by means of their tensile strength ratios, retained Marshall stability, and a double punch shear test.

The results showed that the addition of silica fume increased the indirect tensile strength, compressive strength, Marshall stability, and bulk specific gravity (G_mb) by (18.5, 68, 78.4, and 0. 4) %, respectively, and decreased the flow values and air voids to about 13.5 and 6.6) %, respectively for 3% of replacement. Moreover, the addition of silica fume gave different behaviours in terms of moisture resistance; in general, there was an improvement in moisture resistance compared to that seen in the control mix. (paper)