Masonry Magazine April 2000 Page. 29
IBC
by John Chrysler, PE
Masonry Grout
One of the most significant changes that will be imposed is the requirement for reinforcement in hollow unit masonry. Hollow unit masonry constructed without reinforcement, or unreinforced masonry, is a construction method in use for years in many parts of the country. Unreinforced masonry was permitted in Seismic Zone 4 until 1933, when the Long Beach, California earthquake showed this method can have catastrophic results.
The benefit of reinforced masonry far outweighs seismic issues alone. Specifically, reinforced masonry will provide building performance in high wind, tornado and hurricane conditions, as well as unexpected loads. Specific conditions associated with a particular type of building can also make the performance of grouted reinforced masonry far superior to other building elements, including unreinforced, ungrouted masonry. Examples of such applications would be any building that might encounter a blast condition, either intentional or accidental, or a warehouse, where equipment, such as a forklift, would unintentionally, but regularly, bump the masonry wall. The reinforcement ties the entire wall system of many elements into a single homogeneous system. The catalyst of the masonry reinforcement is the grout, which bridges the continuity of reinforcement to the individual masonry units.
Another widespread application of grouted reinforced masonry is in detention facilities. This is usually a security rather than a structural use; however, the placement of the grout should be done with no less care so that the walls perform to their intended security design.
The masonry industry often reflects on the concrete industry for design and practice. It is difficult to imagine a poured-in-place concrete wall or tilt-up concrete building without reinforcement. Surely no one can argue that the aesthetics of a creatively designed masonry wall cannot be equaled by any other building system, so shouldn't the user have structural integrity equal to concrete? A reinforced and grouted masonry system provides just that.
Masonry grout can be prepared a number of different ways. For a solid grouted masonry system, it is typically practical to provide the grout in ready-mixed form, that is, ready mix batched and shipped by concrete mixer truck in quantities of up to 10 cubic yards per load.
Since unloading the ready-mix trucks is usually a slow process and may require special equipment, such as a masonry grout pump, it may be desirable to use different means. Companies that provide pre-blended mortar in sacks or silos typically provide grout in dry pre-blended form, also in silos and sacks. This method is particularly advantageous in congested areas, such as parking structures or when placing small quantities of grout. The grout is controlled by proportion measurement, therefore the manufacturer will certify compliance with ASTM C 476 Standard Specification for Grout for Masonry, assuring conformance with Code requirements.
With the International Building Code just around the corner, we all must reevaluate design and construction of masonry, as we have known it. For many, there will be little or no change with respect to the construction of masonry, but for others, there will be significant changes.