The ratio of 1:1:4 for cement, water and aggregate is one possible cement proportion. The strongest concrete is created when the water part of the mixture is as low as possible without impacting workability.
Concrete is made up of three main parts, cement, aggregate and water, but entrained air is a fourth component present in some mixes. Concrete is formed when the cement and water combine to create a paste that covers the aggregate. When this dries and hardens, it creates a very smooth, durable surface that is resistant to cracks. The exact strength of the concrete will depend on what proportion of materials is used.