Better Roads Magazine, 13 November 2011
The Missouri DOT (MoDOT) is spearheading extensive research on the environmental benefits of using concrete made with a new cement product in the construction of highways. The cement used in the concrete is blended with photo-chemically-active titanium dioxide (TiO2). Marketed under the trade name “TX Active,” TiO2 is capable of reducing environmental pollutants from vehicle exhaust.
Starting this fall, the mainline pavement material will be applied using a two-lift paving strategy, which involves the placement of two wet-on-wet layers of concrete instead of a single, homogeneous layer. The lower, base-level layer is expected to be constructed with less expensive materials (e.g., a low cementitious-material content base lift) that will then be overlaid with a thinner top wearing-course of concrete containing cement blended with TX Active.
The shoulder pavement element of this research effort involves cement blended with TX Active. In this instance the cement blended with TX Active will be used in a pervious (rather than conventional) concrete application. Together, this set of innovative mainline and shoulder paving materials, including both a two-lift photocatalytic mainline pavement and a photocatalytic pervious shoulder pavement, are believed to represent one of the most technically-advanced and environmentally-friendly concrete pavement systems ever employed, according to MoDOT.