There are few reasons to have a concrete surface that's only 1 inch thick. It's too thin to be used as a floor alone; however, if you need to coat damaged concrete, a 1-inch layer is a good amount. The old surface is prepared for the new concrete to adhere, then the new cement is added. Concrete can be strong and durable, but only if it is thick enough. Are you pouring a concrete slab for a DIY shed or patio floor? This is the most common application for DIY concrete pouring.
Make sure you don't make your slab thinner than four inches for any application. Six inches is the minimum thickness for a concrete slab that can withstand any type of heavy vehicle traffic. The minimum thickness for pouring concrete onto concrete is 1.5 inches. In most cases, I don't recommend pouring new concrete less than 2 inches thick. Two inches of concrete (or more) attached give you adequate strength for a wear surface, especially if you drive on it.
Simply paint it with a roller or scrub brush. Allow it to dry, it takes about an hour or two, pour over it. Using a bond breaker will keep the two concrete slabs separate and cracks will be much less likely to be reflected through the new slab. The thinnest generally used when pouring concrete, is generally about 2 to 2 ½ inches. That also applies to this pouring of new concrete on old concrete.
The coverage mix you mentioned is OK. The day before laying the concrete, moisten the surface and keep it moist until you place concrete, but there is no standing water on the slab during laying. Use a 50% mixture of Portland cement and sand and make a paste out of it. You can use a 50% mixture of water and latex bonding agent (such as Acryl 60) to make the suspension. Clean or sweep existing floor grout just before concrete placement with a stiff broom.
The grout should not dry out before laying concrete on it. If you are pouring concrete, plan to pour it at least 3.5 inches thick to match building codes; four inches is a good round number and will improve the strength of the slab a little. Most importantly, you need to ensure that the concrete has a minimum compressive strength of 3,000 PSI. Using a bond breaker will keep the two concrete slabs separate and cracks will be much less likely to be reflected through the new slab. Nobody wants a concrete project to crack, but don't rely on the type of standard welded wire mesh normally used for concrete reinforcement. But the bottom line is YES, use some type of reinforcement in your new concrete to help control cracks that may develop and prevent them from spreading. If a concrete slab is too long, a few hundred pounds of weight can cause it to crack and crumble, even though that weight is well below its measured compressive strength.
Avoid the Top 12 Concrete Pouring Mistakes and You'll Have a Project to Be Proud of for a Long Time. This is probably the easiest concrete mistake to make because properly mixed concrete seems too dry to flow and trowel properly. The concrete should be approximately 2 inches thick and quickly ensure that the new concrete is level and smooth before using the seals. If you don't use a bonding agent such as Weld-Crete, there is no guarantee that the new concrete will stick to the old concrete. If smoothing a sample concrete pile does not create a smooth, wet and muddy surface in three trowel passes, the concrete is likely to be too dry. These thin, short strands of plastic add a lot of strength and crack resistance to any type of concrete project. Similarly, if you pour concrete on a slope, you are sure to use a larger slab thickness at the bottom of the slope.
When considering how thick you want the new concrete to be, it's important to consider the environment the concrete will be in.
