Before we move onto how these footings are poured, and how masonry structures are erected upon them, we must first take a second to understand concrete and mortar. Both of these common construction materials are made from cement, a crucial component used within modern construction. Cement is a chemical substance that is produced globally and has been used in varying construction applications for thousands of years. In modern construction, cement is sold as a fine powder, available in the UK in 20kg paper or waterproof plastic bags. The cement itself comes in different shades such as white and grey, each affected by the exact chemical composition of the product. Cement is composed of a mixture of chemicals such as calcium, silica, alumina, and iron, among others. The exact mixture and ratio vary between manufacturers. The chemicals are ground down into powders from raw resources, with limestone and seashells being the most common source of ground calcium. Once the materials are ground down, they are mixed together and heated to extreme temperatures to drive off any present moisture, and altering the chemical structure of the powder.  

When water is added back to the cement, a slurry is made that hardens into a solid mass over a short period of time through an exothermic reaction. As the water and cement are mixed together, heat is produced, curing the mixture into a hard material as the excess water evaporates. As the mixture dries, it adheres to the surfaces it is touching, forming both a chemical and physical bond with the surface. This basic mix of cement and water can be used to create a cement based self-levelling compound. When mixed with water in the correct ratio, this thin slurry can be used to level out uneven floor surfaces before the installation of flooring. 

When fine sand is added to this cement and water mix, mortar is created. The sand serves to bulk out the mixture, stretching the properties of the cement further, and adds a more coarse, stable material to the mix. Different types of sand, mined from different locations affect the colour and coarseness of the finished mortar, as well as its consistency when wet. This mortar is mixed on site by hand or in a cement mixer and is used as a material component in the construction of masonry walls. A smooth consistency is achieved through the correct ratio of the mix in combination with a mortar plasticizer - another chemical which helps the individual components to come together correctly, preventing the water from separating from the sand after mixing. A common mortar mix for regular masonry applications is 5:1 parts sand to cement. Water is added to this mixture in increments until a good consistency is achieved. If the mixture is too wet, the application becomes difficult, and the longevity of the mortar over time in the elements is greatly reduced. If too much cement is present, then the mortar's shrinking resistance is affected and will surely crack over time. If too much sand is present, then the mortar will not cure to a fully hard state, remaining powdery and comparatively weak.   

A bed of mortar is laid between each course of bricks or blocks, as well as vertically between each piece. As the mortar begins to dry, it can be finished or “pointed” with special tools to give it an aesthetic look. Once cured, the mortar securely holds the masonry in place.

Concrete is a very durable cement-based material, that is created through a mixture of cement, sand, and aggregates (stones), in the presence of water. Depending on the exact ratio, weaker or stronger finished products can be created. The hardness and compressive resistance of dried concrete is rated on a “C” scale in relation to the strength of the mix. The number following the “C” describes the force in newtons per millimetre that the cured concrete (approximately 28 days post-pour) can withstand. The higher the number, the denser and more resistant the concrete is. This also means that the higher the “C” class, the more cement is used in the mix in relation to the other components. For example, a C10 mix is commonly used in residential construction for the concrete oversight of a standard strip foundation. This mix when cured can withstand 10 newtons per millimetre and requires less cement in the mix than higher “C” classes. When an engineer is drafting the plans for a construction, the load that is directed downwards onto the foundations is calculated and a “C” class is specified on the drawings for the mix. Specific “C” class mix ratios can be purchased ready-mixed from specialist concrete suppliers. These companies can deliver ready-mixed concrete on site in large quantities for pouring foundations and other concrete applications.

Additionally, the ratio of the mix and water content can be assessed on site during the pour through the use of a slump test. A slump test is a method of accurately measuring the correct ratio of a mix by measuring how much a set quantity of wet concrete deforms over time from a specific starting point.  

For a common C20 mix, mixed by hand in small quantities for concrete pads or small concrete footings in low load bearing applications, the mix is as follows - 1:2:4. This is 1 part cement, to 2 parts sand, to 4 parts aggregate. 

Alternatively, if premixed bags of ballast are being used that contain both sand and stone, 1 part cement to 6 parts ballast is appropriate. 

More or less water can be added to the mix to thicken or loosen it depending on the working and finishing requirements of the concrete. 

As the concrete is poured, it must often be vibrated through the use of a vibrating poker, to free up air pockets and bring them to the surface. This being said, improper vibrating techniques can cause the aggregate to separate from the mix, leading to an uneven distribution within the finished product.  

Once poured, the concrete will harden rapidly, and can typically be walked on the next day, though full strength through curing is not achieved for around 28 days.  

Screed is another cement product that is commonly used in construction. In modern UK residential construction, floor screed is the final layer that is installed within a building to establish the finished ground floor level. Screed is made from coarse sand and cement, mixed with a small amount of water to create a dry mixture. This mixture can be worked with a level or rule to create a flat floor finish. Screed is most often brought onto site having been ready mixed by a specialist company. It can often contain reinforcing fibres that give it more strength, or chemicals that help it cure faster to allow walking on it sooner. As a rule of thumb, once installed, the screed will take 1 day per millimetre of its thickness to fully cure and expel all of its moisture. Another often stated drying rule is 1 week per 10mm of screed. Therefore, for a 70mm thick layer of screed, it will take around 7 weeks to fully cure from the point of being laid. Whilst the screed can often be walked upon within the next few days after having been laid, it's important not to turn on underfloor heating that runs under freshly laid screed until it is cured. Premature operation of the underfloor heating can cause cracks in the surface of the finished screed. The common mix ratio of screed is 1:4 parts cement to sand.