Absolutely not. Even food items such as coffee grounds and flour can adhere to water and stick to your pipes, causing blockage. Imagine how much more damage cement can do as it hardens. You might be able to get away with one incident, but if you work or have a business in the construction industry and regularly get in contact with cement, the number of times you have to wash it down your kitchen sink does add up more quickly. You can just wash the cement off your skin and your tools outside your yard.
If you’ve already made the mistake a few times and have noticed that your kitchen sink is draining poorly, it might be time to schedule a professional visit to diagnose the problem. A reputable company such as London Drains Direct could also spot installation issues that may be causing blocked drains in London.