Several Medfield roads have recently been resurfaced using the infamous “oil and chip” technique, sometimes also referred to as “tar and chip”, “chip seal”, or “seal coat”. An asphalt/oil/polymer emulsion is spread on the substrate (usually the existing, but cracked and worn asphalt surface), and then loose aggregate is applied on top of the “oil”. The aggregate is then rolled into the “oil”. The idea is that the “oil” will bind with the aggregate and form a durable top layer that protects the road and slows further erosion of the surface. The “oil” and the aggregate are made from the same materials as regular blacktop (tar and stone). (more…)