Mortar is a term used to describe a thick mixture of sand, cement and water most often utilised to hold building materials like stone or brick together in walls. Masonry repair mortars are designed to be durable, just like cement concrete, but they achieve their durability through finesse. More workable and much creamier than concrete, repair mortars are used for finer applications.
There are two ways to make repair mortars. Traditionally, repair mortars have been produced by mixing portland cement and hydrated lime with fine sand. However, a new, alternative method involves mixing fine sand with masonry cement instead. The results of the two methods are the same – the only reason to choose lime mortar over mortar made using masonry cement is the availability of the latter.
Establishing the difference between mortar, cement and concrete can be especially confusing for beginners. Even tradespeople whose daily work involves these products often incorrectly reference them, especially as the term cement is often used to mean concrete. The basic difference between the three is that cement is a fine binding powder which is always used alongside other materials, and mortar is composed of sand and cement while concrete also has gravel amongst its components.
Unlike concrete, which can create standalone structures, mortar is used for holding together stones, bricks and other similar hardscape components. Brick patios, for instance, can include repair mortars between bricks, although that’s not always the case as extreme winter conditions could cause the repair mortar to crack. A solution would be to intentionally add air bubbles in the repair mortar as, when water expands in low temperatures, it has a place to go without causing damage.
While it might seem like the only difference between concrete and mortar is how each is used, they do in fact have very different properties leading to each being used in a specialist area. Therefore, even though both mortar and concrete are widely used building materials, the integrity of a build could be compromised if they are inappropriately substituted for each other.
Since the water to cement ratio is higher in repair mortar than in concrete, mortar is a much thicker substance when mixed and is perfect to use as a quick fix glue for brick and other building materials. While mortar is a better bonding element, it’s impractical for structural projects, as it needs to be replaced every few decades – in such cases the more durable, stronger concrete is used.
There are a number of different types of repair mortar used within the construction industry. These can be split into four categories based on the materials used to prepare the mix:
Another way to classify mortar is based on their bonding properties and flexibility, and their compressive strength. Each type of mortar includes a specific ratio of cement, lime and sand which define the properties of the mixture. Depending on the intended use of the mortar, the adhesion and sealing requirements, and the resistance and strength specifications, builders have a choice between N, O, M and S types.
Aside from concrete repair mortars, which are used to restore deteriorated structures, smoothing mortars are also available for times when concrete requires levelling or coating in order to fill the surface pores. Repair mortar bonding primers are used in specific occasions, for either small area or large scale application, to enhance the bonding behaviour of repair materials.
Using mortar to rehabilitate, restore and repair concrete structures which have deteriorated due to water infiltration, corrosion or structural damage has a number of benefits. Concrete repair mortars are high build, and provide a cost-effective solution for those seeking strong adhesion and smooth finishing for their repair works.