Grout Could be the Answer to your Troubles
Grout is one of masonry's misunderstood marvels. Grout is definitely not mortar and it is not quite concrete either. Grout rather lies somewhere in between the two. This murky definition commonly confuses masons but with a little extra research grout could possibly be the answer to all of your troubles.
Grout is comprised of cement and water but its consistency is much soupyer than actual concrete. While grout, cement, and mortar all harden into a stonelike mass, it is important to note that each materials plasticity/fluidity differs initially (as stated above). In its initial stages, mortar is super stiff with a slump test of only five to eight inches. Concrete is also extremely stiff in its initial stages with a slump test of only two to six inches. Concrete is a controlled substance as its ratio of water to cement will directly reflect its slump abilities aka the more water you add the larger its slump and visa versa. This is a major variance between grout and concrete as grouts water to cement ratios are to be followed precisely. Concretes form is also spread apart relatively far due to the large sizing of the member allowing it easy and exact placement. It is almost the exact opposite to grout, an aggregate material.
Mortar on the other hand is a plastic material with a vastly low water to cement ratio, leaning the higher side toward cement content. Mortar must remain relatively stiff at all times in order to be handled and spread evenly onto a masonry unit. The stiffness required by mortar allows masonry buildings to remain intact without deforming during the construction process. Plus, any water remaining in the mortar after construction will be absorbed into the masonry unit itself, much like grout. The absorption creates a sealed bond between the masonry unit and mortar material which aids in cultivating a sound structure.
Although grout may have similar ingredients to both concrete and mortar, its plasticity/fluidity is much greater than both aforementioned materials. Grout is meant to be utilized in the hallow cells of masonry units as well as the narrow spaces of brick constructs. Grout can even be utilized at highs of over twenty five feet (high lift grouting). Contrary to cement and mortar, grout must remain fluid at all times to be able to completely fill all cells, grout space, or joints required by the masonry units. Once grout dries it will become solid and homogenous to the masonry unit (wall).
It is good to remember that stiff grout will not fully flow into the space required but will rather stop short and leave voids within the unit. Grout fluidity is of utmost importance and should reach a slump of eight to ten inches, flowing almost freely. Fluidity is key in grout consistency. Grout must pass throughout a space entirely, allowing the structure to reinforce and bond effectively.
Grout's water to cement ratio is determined by the design of the mix at hand. Water is grouts placement vehicle and aids the material in flowing throughout the masonry unit. Any excess water found in grout will, much like mortar, be absorbed by the masonry unit regardless if it is brick or block. This further absorption will reduce the grouts water to cement ratio to a hardening point of strength. Follow each grout mix instruction carefully to ensure it is in accordance with state specifications and code requirements.
Grout just may be the material to help reinforce your next masonry unit!