Freeze and Thaw

Wet track Abrasion can tell us a lot about the integrity of slurries and microsurfacings. When a pavement freezes and thaws and the asphalt/aggregate matrix expands and contracts several effects may occur. The material may crack If there are significant voids they may have retained water and this will expand when the water freezes. This can cause cohesive failure- effectively blowing the matrix apart. Cooling of the asphalt binder will cause it to stiffen, if it embrittles then it can fracture under traffic leading to stone loss. Freeze thaw can cause weakening of the asphalt/aggregate bond. This will result in stone loss due to tire action. Cracking is a function of the low temperature tensile strength of the binder. It has been shown in other work. This shows that addition of latex and use of softer binders improves low temperature fracture resistance. Freezing of water in voids is not usual in slurry surfacings as the materials are dense graded and have relatively high binder contents. Loss of stone due to freezing is reduced by addition of latex and use of softer binders. This is shown below in figure 1. Freeze Thaw effects can be minimized by use of latex and softer binders. The polymer acts as a flexibilising and reinforcing matric making the brittle point lower. Thus the binder is less stiff. Also SBR latex has excellent low temperature adhesion holding the bond even under freezing and freeze thaw. Emultech LMCQS-1h and Emultech Microsurfacing emulsions (MSE) have excellent low temperature properties.
Figure 1
Figure 2

Last Updated (Monday, 14 December 2009 16:59)