Office/Administration
PCC Pavement
Rigid pavements are so named because the pavement structure deflects very little under loading due to the high modulus of elasticity of their surface course. A rigid pavement structure is typically composed of a PCC surface course built on top of either (1) the subgrade or (2) an underlying base course. Because of its relative … Read more
Cement Production
Example Operation – Lafarge Seattle An example operation of cement production is taken from Lafarge Seattle. Below Figures 1 and 2 show the relation of the Lafarge plant to Downtown Seattle and 3D imagery of the Lafarge plant respectively. Overall Lafarge has 20 plants in North America, 16 of which produce portland cements and four … Read more
Pavement Condition Rating Systems
Based on measurements of roughness, surface distress, skid resistance and deflection, pavements can be assigned a score that reflects their overall condition. This score, sometimes called a pavement condition rating, quantifies a pavement’s overall performance and can be used to help manage pavement networks. By carefully choosing the rating scale (called the condition index), pavement … Read more
Overlay
An overlay is any operation that consists of laying either Portland Cement Concrete (PCC) or Hot Mix Asphalt (HMA) over an existing pavement structure. This is different than a total replacement of the structure, and is typically done when there is only minor to modest damage to the existing pavement structure. When constructing an overlay, … Read more
Cold Plant Mix Recycling
AAPTP Project 05-01 Cold plant mix recycling, the less common of the two cold recycling methods, involves mixing RAP with an asphalt emulsion or foamed asphalt at a central or mobile plant facility. A rejuvenating agent can be added to improve the recycled asphalt binder viscosity and new aggregate can also be added to improve … Read more
Non-Structural Overlays
Non-structural overlays (Figure 1) do not involve extensive structural design and generally contribute little, if anything, to a pavement’s structural capacity. Non-structural overlays are generally thin surface overlays on the order of 12.5 mm (0.5 in.) to 37.5 mm (1.5 in.) that are used to (NAPA, 1995[1]): Improve ride quality. Correct minor surface defects. Improve … Read more
Material Transfer Vehicles
Material transfer vehicles (MTVs) are used to assist the paver in accepting HMA. Most pavers are equipped to receive HMA directly from end dump or live bottom trucks, however in certain situations it can be necessary or advantageous to use an MTV. Paving using bottom dump trucks and windrows requires a windrow elevator MTV (Figure … Read more
Paving Equipment
Stabilizers/Reclaimers A stabilizer/reclaimer is a vehicle with a dual purpose. These machines have a large rotor blade which may be used to cut and pulverize damaged or old pavement, but which also may be used to mix lime, fly ash, or cement into the subbase in order to stabilize poor soils. Milling Machines A top … Read more
Fog Seals
A fog seal is a light application of a diluted slow-setting asphalt emulsion to the surface of an aged (oxidized) pavement surface. Fog seals are low-cost and are used to restore flexibility to an existing HMA pavement surface. They may be able to temporarily postpone the need for a surface treatment or non-structural overlay. Purpose … Read more
Pavement Structure
HMA pavements are flexible pavements. Flexible pavements are so named because the total pavement structure deflects, or flexes, under loading. A flexible pavement structure is typically composed of several layers of material each of which receives the loads from the above layer, spreads them out, then passes them on to the layer below. Thus, the … Read more
Sponsors
