Memorial Day closure

Most City of Portland offices will be closed Monday, May 27, in observance of Memorial Day.

Microsurfacing, explained

The Portland Bureau of Transportation (PBOT) uses microsurfacing as preventive maintenance on deteriorated roads that are not yet bad enough to warrant full reconstruction.
Microsurfacing diagram

Microsurfacing is a design mixture of polymer-modified emulsified asphalt, mineral aggregate, mineral filler, water, and other additives proportioned, mixed, and uniformly spread over a properly prepared surface.

The mixture is made by a specialized machine and placed on a continuous basis by mixing the materials simultaneously in a pug mill. Figure 1 shows the process in the microsurfacing machine, which results in a free-flowing composite material spread on the underlying pavement using a spreader box. The mixture’s consistency permits even spreading over the pavement, forming an adhesive bond to the pavement.

It is used as a pavement preservation and maintenance treatment to improve the functional characteristics of the pavement surface and extend its service life.  It can be used on pavements suffering from the following conditions:

N Michigan Resurfacing - microsurfacing in action
  • Loss of skid resistance
  • Oxidation
  • Raveling
  • Surface permeability
  • Rut damage


  • Reduces life-cycle cost 25-45% compared to traditional resurfacing methods.
  • Reduces greenhouse gases by 44% and energy use by 54% or more compared to traditional resurfacing methods.
  • Reduces raw material by 35% or more compared to traditional resurfacing methods.
  • Return to traffic within one hour
  • Adds 6-8 years or more when applied for optimum preservation performance.
N Michigan Resurfacing - without and with
This photo shows a roadway divided by two counties. The one on the left went the Mill & Fill route while the one on the right chose to add a micro-surfacing treatment to the mix. The difference between the two surfaces four years later are dramatic!

Learn more about microsurfacing here.