The four essential features of a successful repair are: 1. Expediency: The longer the repair is left, the more work has to be done, and the less likely that the repair will blend in. 2. Cleanliness: when repairing concrete, care must be taken to remove any dirt or dust that will prevent the repair concrete(…)
SHEAR WALL – ITS TYPES AND POSITIONING
SHEAR WALL In reinforced concrete framed structures the effects of wind forces increase in significance as the structure increases in height. Codes of practice impose limits on horizontal movement or sway. Limits must be imposed on lateral deflection to prevent: Limitations on the use of building, Adverse effects on the behavior of non-load bearing elements,(…)
FACTORS AFFECTING STRENGTH OF CONCRETE
FACTORS AFFECTING CONCRETE STRENGTH Concrete strength is effected by many factors, such as quality of raw materials, water/cement ratio, coarse/fine aggregate ratio, age of concrete, compaction of concrete, temperature, relative humidity and curing of concrete. 1. Quality of Raw Materials: Cement: Provided the cement conforms with the appropriate standard and it has been stored correctly(…)
GROUTING PROCEDURE FOR CRACKS IN CONCRETE
Procedure for cement grouting of cracks in concrete structures: Holes are drilled in structure along cracks and in an around hollow spots. If there are several cracks, holes can be drilled in a staggered manner at 500 to 750mm spacing in both directions covering adequately the area proposed to be grouted. Holes spacing can be (…)
TEMPERATURE EFFECTS ON CONCRETE
THERMAL MOVEMENT IN CONCRETE As with any material, concrete will expand and contract as the temperature rises and falls. The size of movement depends upon the change in temperature and the coefficient of thermal expansion o f concrete. The coefficient of thermal expansion of concrete is influenced largely by the coefficient of thermal expansion of(…)
CEMENT GROUTING FOR CRACKS IN CONCRETE AND MASONRY
Cement Grouting in cracks in concrete and masonry: Wide cracks, particularly in mass concrete abutments / piers and masonry substructures can be repaired by filling with portland cement grout. This method is effective in sealing the crack in concrete, but it will not structurally bond cracked sections. Applications of cement grouting: i) When cracks are(…)
REINFORCEMENT COVER AND PRE-CONCRETE CHECKS
Reinforcement Cover: It is essential that the steel reinforcement bars are surrounded sufficient impermeable concrete to protect them from corrosion, and to allow the combined strength of the reinforcement and concrete to be effective. From the diagram above, we can see how the process unfolds. When the binding has set, the steel bars are placed(…)
FORMWORK AND GOOD FORMWORK PROPERTIES
What is formwork? When concrete is fresh and in its liquid state it must be restrained within a mould in order for it to set in its required shape. Formwork is the term used to describe this mould. For most in-situ pours, the formwork is made of wood. A smooth outer surface provides the main(…)