Why not make mortar as strong as concrete
n America isn’t bigger better? Not with mortar. When you build a wall you want the block or brick to be the strongest part of the wall. When the wall shifts, and almost all do over time, the weakest part is going to break. If the brick or block were to break, then the fix would be building a new wall. If the mortar crumbles, provided you don’t let it go on for years, you simply need to repoint the wall (that means sticking mortar back in where the old mortar fell out). This is a simpler and more inexpensive fix. One important reason why masonry cement or a portland/lime blend works well in a mortar joint and straight portland does not is the high air content. Many walls are exposed to rain and water. In the winter many of these are in area where temperatures often dip below freezing. The mortar contains a certain amount of water. When water freezes it takes up more space than water. This means that it will expand and crack whatever is next to it. By intentionally putting lots of tiny air bubbles in the mortar, the expanded ice has somewhere to go without causing damage. Concrete generally has enough mass that this isn’t a problem.