When it comes to repairing concrete, there are two main types of repair mortars available: those based on organic binders such as epoxy or polyester resin, and those based on inorganic binders like Portland cement. It is important to note that using Portland cement mortars to repair old buildings originally constructed with lime mortar can be problematic. This is because lime mortar is softer than cement mortar, allowing the masonry to have a certain degree of flexibility to adapt to ground movement or other changing conditions. Cement mortar, on the other hand, is harder and allows little flexibility, which can cause masonry to crack when both mortars are present in the same wall. One example of a repair mortar is EUCO HB, a lightweight, high build, low shrinkage, trowel-applied material.
This type of material is often used for precast tunnel segments or any hand-applied concrete repair where a quick finish and return to service is required. Before introducing the mortar into the space by hand, it is necessary to pre-wet the substrate and prime the steel and concrete. The repair should be finished flush with its surroundings and allowed to cure. Another option for repairing concrete is one-component, latex-modified shotcrete materials. These are useful in situations that require shotcrete to fix large repairs.
MAPEI offers a variety of concrete repair mortars specially formulated for vertical and overhead applications. The term “construction chemistry” is often used in the dry-mix mortar industry to refer to finishing or repair mortars. In addition, many other (waste) materials and their combinations have been tested as repair mortars at the laboratory level. In the United States and other countries, five standard mortar types (available as dry ready-mixed products) are commonly used for both new construction and repair. Concrete petrography can also be used to evaluate rehabilitation strategies, repairs and repair methods by assessing the depth at which sound concrete begins. Sam describes concrete repair mortars and the two product options available, outlining their differences and best uses. Concrete repairs can also be carried out at low temperatures to ensure continuous progress of the work from spring through autumn.
Lime, lime mortar and plaster of Paris plaster are often used in the repair and grouting of historic buildings and structures in order to make the repair materials similar in performance and appearance to the original materials. As a practical, multi-purpose product, repair mortar is suitable for all treatment groups from builders to building conservators and general suppliers. A cluster of polypropylene fibres (brightly coloured) within a patented repair mortar for concrete repair; XPT, ×150, 1mm wide. Conventional patch repairs involve breaking down the surface of the concrete before applying a bond coat. The surface of any exposed reinforcement should also be prepared by applying a protective or bond coat before applying a repair mortar that should be compacted and cured. Finish coats are applied with a typical thickness of 1 to 3 mm to provide a fair finish to the repaired concrete. In addition, as the roughness of the concrete substrate affects the performance of most patch repair mortars, it becomes necessary to artificially increase its roughness (most often using sandblasting), regardless of the cleaning operation.
Specimens repaired with alkali activated mortar with 1 day cure have a higher bond strength than specimens repaired with current commercial products after 28 days cure.