DO THIS, NOT THAT
Concrete bonding issues.
If yours is a 20th-century house (or perhaps even late-19th-century), it’s likely you have some aging concrete: steps or walkways spalling after many icy winters, a basement floor cracked from years of heavy use or water infiltration. You may have been told that replacement is the only option. If you are looking for a way to resurface deteriorated concrete without the mess and expense associated with removal and replacement, you do have other options. Fresh Portland cement does not easily form a hard chemical matrix around old material—hence the lack of a good bond. If you’ve ever added a topcoat of ordinary concrete to the surface of existing concrete, you know that the new mix either didn’t adhere or failed in short order.