Final answer:
Modern mortar for block walls in above-grade basement foundations is similar to Roman concrete, comprising Portland cement, lime, sand, and water, creating a strong and durable bond.
Step-by-step explanation:
The type of mortar used on block walls for a basement foundation above grade typically includes a mix similar to what was developed by the Romans, known as Roman concrete or opus caementicium. Modern mortar used for this purpose usually consists of a combination of Portland cement, lime, sand, and water. The Portland cement provides strength and durability, while lime can improve the mortar's workability and sand acts as a filler. Above-grade basement walls require a mortar that can withstand various weather conditions and potential moisture intrusion, so the durability of this mix is of utmost importance. The addition of water activates the cement, which binds the mixture together and, upon curing, creates a strong and durable bond between the masonry blocks.
Portland cement is a type of hydraulic cement that hardens through a chemical reaction with water. It is commonly used in construction due to its strength, durability, and ability to set and harden underwater.
When using Portland cement mortar for block walls, it is important to follow the manufacturer's instructions for mixing ratios and curing times to ensure a proper bond and long-lasting foundation.