This challenge can't be met by just any cement product or grout. What's required is a product that not only will fill the gap between the core and the remaining pavement, but will mechanically bond the core into the pavement in such a way that the reinstated road system will again be able to perform as a system, sharing the traffic loads.
Independent testing has shown that many commonly available bonding compounds and grouts do not meet the 30- minute test time. The ability to gain strength quickly is an important element in being able to safely reopen the road to traffic. And the ability to move the utility crew and equipment quickly to the next worksite reduces costs and improves efficiency.
Convenience of use, reduced waste, and longer shelf life are also important factors in choosing the right bonding compound. The bonding strength of every cementitious grout depends on an accurate ratio of water to dry materials. Using a calibrated measuring pail to accurately combine the exact amount of water to the dry material not only eliminates guesswork in the field, but is essential to performance. Too much water will reduce the bond strength while too little will reduce fluidity to completely encompass the kerf of the core, which can cause premature core failure.
Look for products packaged in a sealed waterproof pail, rather than a paper bag, to help extend shelf life and eliminate waste. Once a bag has been opened or torn it is no longer watertight and hydration can begin, lowering the grout quality.
All of these are important factors in selecting the appropriate bonding compound to be used in core reinstatement. While you may pay more for a premium product, you'll find that these materials have faster strength gain, greater ultimate strength, are easier to use, are packaged to minimize waste, have long shelf life, and ensure accurate mixing ratios.
Marshall Pollock is President and CEO of Utilicor Technologies, Toronto,Ontario, Canada.