Masonry Magazine May 1978 Page. 9
High-Lift Grouting
The use of high-lift grouting in reinforced brick masonry is not new. It has been used for many years, but only recently has it been used to its full potential. The early use of high-lift grouting was primarily to fill voids in the masonry, with little or no attempt to achieve high compressive strength. The emphasis was placed on tight, well-bonded masonry more than on strength.
One admixture of the group was found to perform as desired, giving excellent results. There are perhaps others that would do well, but they have not as yet been submitted to the construction industry with adequate test data.
The final proposed method was tested in some full-sized panels, with 24-foot high pours, and it was found that the method was as anticipated; that is, high strength in compression, shear and bond. Some were well over 400 pounds per square inch in shear.
The high compressive strength was apparently due to the removal of excess water and to the intimate contact bond between the grout and the brick. Excellent water tightness was due, obviously, to the homogeneous character of the wall. Accordingly, the specifications were issued for use of the design professions.
An improvement made to the original procedures is that of placing the vertical steel after the masonry is up. This expedites the work of the mason, both as to speed and quality. The earlier procedure was to tie all the steel in place; therefore, giving assurance to the inspectors, or anyone else, that the steel was tied properly in position. However, this is now achieved, in Southern California in general, by the use of positive positioners that also act as ties.
In most jobs, the high-lift grouting procedure will result in a better job for less money, which is reversing the usual trend of quality and price relationship in these modern days of upward spiraling economy. Some masons have found, however, that their initial trial of the method would not be as smooth as the method to which they were accustomed, and there would be loss of time, such that all the gain possible would not be realized until after more practice.
The following specifications are generally used in both Northern and Southern California.
High Lift Grout Construction
# Foundation
The foundation surface which is to receive brickwork shall be clean and damp, the laitance removed (by sandblasting, if necessary) and the aggregate exposed.
# Laying Brick
Mortar in all bed joints shall be held back 4-inch from edges of brick adjacent to grout space or be beveled back and upward from the grout space. The grout space shall not be less than 3 inches in width.
The thickness of head and bed joints shall be as specified or shown. Head joints shall be solidly filled with mortar as brick are laid, and bed joints shall not be deeply furrowed with the trowel.
All brick shall be shoved at least 2-inch into place. Where necessary to stop off a longitudinal run of masonry, it shall be done only by racking back one-half brick length in each course. Toothing will not be permitted unless special approval is given by the architect for the job.
# Cleanouts
Cleanouts shall be provided at the bottom of the walls by omitting alternate bricks on one wythe of the wall. Cleanout holes shall not be sealed until the brickwork and the final cleaning of the foundation surface have been approved by the masonry inspector.
# Barriers
Vertical barriers shall be provided in the grout space not more than 30 feet apart and where most convenient to confine the lateral flow of grout. These barriers shall be formed of brick across the grout space (in full vertical and horizontal joints of mortar) to the full height of the wall.