Masonry Magazine May 2003 Page. 28
GROUTING EQUIPMENT
decide what type of mixer they would use. Most contractors today prefer to use fine grout because it's so much easier to get into the cores of the blocks. They go to this fluid mix of concrete, sand and cement and then they reconsolidate it and make sure it's mixed well."
Slump is the fluidity of the mix. Harwell notes, "When I first started in this business they tried to hold us to a slump of about four to five inches, just like you would if you were pouring a curb, gutter or house slab. It wasn't fluid enough to get down in the cavities of the block, past all the rebar. So now they let us use up to 10- or 11-inch slump, a very fluid concrete."
Slump is tested with a cone. The cone is 12-inches tall, the material is put in, and the measure of fluidity is by how much it slumps down when they pull the cone off. A high-tech method it's not.
Placing the grout
AFTER THE GROUT is delivered to the jobsite or mixed on site, there are only a few ways of getting it into the masonry walls. The three most widely used methods are buckets, a grout pump, or a Grout Hog. According to Harwell, "Typically what you do is get so much wall built up, and then come back and grout it. Then they'll pull the masons off and go to another wall while that grout sets. If they are using a pump, they'd pull everybody off, but if they've got a labor crew or they're coming behind it doing low lift grouting, they just take buckets or a Grout Hog and grout right behind the masons as they're working on the wall and then they really don't lose any time, they just don't skip a beat."
Grouting with buckets is the least desirable of the three methods. Using five gallon buckets is labor intensive and time consuming even when grouting in small quantities. This method requires more men and extra energy from each one of them. The energy these men use during the grouting process greatly reduces their production the rest of the day. Studies show that after a person lifts so many pounds in a day's time, production begins to drop. The more weight they handle pouring grout, the greater the drop in production.
Contractors often prefer grout pumps for grouting inside walls or placing large quantities in each pour (generally eight or more yards per pour). Grout pumps work great for these pours. However, grout pumps do require a greater amount of time to clean, and, if not used properly, there is a chance they could plug and stop production.
When grouting in smaller pours (two to eight yards), the Grout Hog-introduced in 1999-has become very popular. This system allows grouting to be done with only two laborers while a forklift supports the weight of the grout instead of the weight being on the laborers' backs. The Grout Hog is ideal on any walls that are accessible with a forklift. On larger projects, the savings provided by Grout Hog use allows you the option to have an extra forklift on your jobsite. Once it is used in the grouting process, the forklift is then available to stock block and help increase production.
With the grouting process becoming more and more a factor in masonry projects today, the mason contractor needs to prepare a strategic attack plan to handle the process as efficiently as possible. To do that, consideration must be given to every step of the process from ordering the materials, to method of loading the mix, mixing equipment, and delivery. Cost, efficiency, availability and size of the pours are all important factors to be examined. However, with the right combination, grouting masonry walls can actually become a profit center on your jobsite.