Despite the recent development of clearer bracing requirements during construction, contractors are still losing walls due to wind gusts. I believe the main reason lies in our industry's reluctance to use low-lift grouting methods.
While our associations spend thousands of dollars each year to come up with improved bracing standards, not once have we recognized that perhaps the biggest reason walls are blowing over during construction is that the grout is not always placed in low-lift pours.
Workers should not be near ungrouted walls when winds are exceeding 20 mph and gusting.
My opinion is that grout should not be poured in 24-foot-high lifts. Grout should be poured in 4- to 6-foot lifts. This will improve not only the integrity of the project but also the safety of our workers.
My experience has been that when we grout in low lifts, 4-foot lifts versus lifts of 6 feet or more, masons and even inexperienced laborers are much more likely to place grout properly. Management does not then have to constantly monitor the pour.
If grout is placed in 4-foot lifts, the slump could be 6 to 8 inches. The stiffer grout reduces segregation and shrinkage and on a 4-foot lift can easily get to the bottom of the pour and around rebar properly when rodded or vibrated. Also, the stiffer grout will save the masonry contractor a lot of money because a lot less grout will be required.
When you low-lift grout block walls, you are bracing the walls with concrete as you go up the wall. As you go higher and higher up the wall, your previously poured grout lifts are gaining strength and can withstand a much stronger wind load because of the low-lift method of grouting.
Bracing is still necessary.
Low-lift grouting improves both integrity and safety time after time. I believe it was not a coincidence that during high winds other masonry contractors, using high-lift grouting, lost walls containing thousands of blocks due to wind gust. We have had our scaffolding blown over on some projects, but our walls have stayed upright without losing a single block. That's why we at Lang Masonry Contractors are true believers in the success of low-lift pours.
Without a cost-effective way to low-lift grout, the options were bucket brigade or grout pumps. These options brought with them labor-intensive costs, plugging problems, and scheduling issues. Faced with those same dilemmas, we developed a forklift-based grout delivery system, which allows grouting with only two people and which we feel makes low-lift grouting the better option. It has worked well for us.
Masonry contractors can reduce the chance of fallen walls by focusing on the integrity of the project and the safety of workers when they choose low-lift grouting.