Different types of repair materials for concrete structures
Generally, cement and steel are frequently used to repair various types of damage works. In various conditions non-shrinking cement or an admixture similar to aluminium powder in the ordinary portland cement will be suitable. Steel is available in different forms like bolts, rods, angles, channels, expanded metal and welded wire fabric. Wood and bamboo are considered as the most common material for arranging temporary supports and scaffolding etc., and will appear in the form of rounds, sleepers, planks, etc.
Besides, there are special materials and methods to make the repair and strengthening operations superior. Given below, the details of these methods :-
Under shotcrete method, sand and portland cement are combined and mixed pneumatically and conveyed in dry state to the nozzle of a pressure gun, where water is added and hydration start just before expulsion. The material ties rightly to perfectly arranged surface of masonry and steel. It is suitable for curved or uneven surfaces. With its extreme strength after application and strong physical characteristics, it provides extra structural strength in walls and other elements.
Epoxy resins are exceptional binding agents containing extreme tensile strength. The compositions of the chemical preparations can be modified according to needs. The epoxy components are amalgamated just before using them. The product contains low viscosity and can also be infiltrated in small cracks. The higher viscosity epoxy resin is suitable for surface coating or filling bigger cracks or holes. The epoxy mixture strength is based on the temperature of curing (lower strength for higher temperature) and method of utilization.
For bigger empty spaces, epoxy resins containing low viscosity or higher viscosity should be blended with sand aggregate to develop epoxy mortar. Epoxy mortar mixture contains greater compressive strength, extreme tensile strength and a lower modulus of elasticity as compared to Portland cement concrete. In this way, the mortar does not become a rigid material for substituting reinforced concrete. The epoxy is also a combustible material hence it is not applied separately. The sand aggregate mixed to develop the epoxy mortar produces a heat sink for heat generated and it offers increased modulus of elasticity too.
Gypsum cement mortar
It has some limitations for structural application. It contains lowest strength at failure among these three materials.
Quick-setting cement mortar
This material is patented and can be applied as a repair material for reinforced concrete floors adjoining to steel blast furnaces. It belongs to a non-hydrous magnesium phosphate cement with two components, a liquid and a dry, which are blended in the same way as applicable for portland cement concrete.
Mechanical type of anchors utilize wedging action to offer anchorage. Some of the anchors offer both shear and tension resistance. Such anchors are produced to provide adequate strength. On the other hand chemical anchors amalgamated in drilled holes polymer adhesives are utilized.