Most likely, you would use a shovel to mix the concrete with the cement. Then you would use it again once you start filing where you want that to stay. But, if you are going to fill something big then you can't expect to use a shovel as that would take a long time. It won't be worth it since you can do a lot of things during those time. You would be better off hiring a truck operator to do the job for you as they would drive a cement truck to the area and pour it on. It is more efficient that way and you don't have to waste lots of energy and most of your precious time doing that over and over again. Work smart and don't work hard.
In this game, you need to pour the cement in a large area, but the challenge is getting to that area. You need to follow the map located at the upper portion of your screen to get to the area. Try not to bump into anything as that would damage your truck. When your truck can't take any damage anymore then the game is over. The game gets more challenging as you make some progress.