Answers

The rebound hammer test method is based on the principle that the rebound of an elastic mass depends on the hardness of the concrete surface against which the mass strikes. The operation of the rebound hammer is shown in figure-1. When the plunger of the rebound hammer is pressed against the concrete surface, the spring-controlled mass in the hammer rebounds. The amount of rebound of the mass depends on the hardness of the concrete surface.

Thus, the hardness of concrete and rebound hammer reading can be correlated with the compressive strength of concrete. The rebound value is read off along a  graduated scale and is designated as the rebound number or rebound index.  The compressive strength can be read directly from the graph provided on the hammer’s body.
For more details on principle, procedure, advantages & disadvantages of rebound hammer test, kindly check the article below-

Rebound Hammer Test on Concrete – Principle, Procedure, Advantages & Disadvantages

Dear Gurkirtan Sharma,

The design procedure for all the floors in the multi-storage building remains the same. However, the loads and other design parameters shall change depending upon the floor.

For more details, kindly check the below article-

Structural Systems for Construction of Multistory Building

Rolling shutters are among the most common types of doors where the large size of openings, safety, protection against fire, and theft are a concern. The rolling shutter is made from heavy steel strips interlocked and hinged for maximum strength. These shutters are fixed with coiled springs for smooth operation. Rolling shutters give complete protection and high resistance power against wind, rain, and burglary.

The rolling shutter doors are classified based on materials, operations of the shutter, application.

Read more- Types of Rolling Shutter Doors

The first and foremost reason is leakages which are caused due to joints in the roof. If it is a sloping roof, then chances are there at the joints and junctions.

One of the reasons why roof tiles break is simple wear and tear. In addition to wear and tear, harsh weather conditions may cause tiles to fall apart. If it is a flat roof, the chances of leakages are due to poor workmanship or cold joints in the concrete.

The roof leakage can be fixed by following repair methods-

1. Rubber Roofing Repair
2. Built-up Roofing Repair
3. Tile Roof Repair

The cost of repairing a flat roof is generally affordable but really depends upon the extent of the damage, the location of the project, and the availability of repairing agencies.

To read in detail about the repair procedure and cost incurred for fixing roof leakage, read the article-

Roof Repairs – Guidelines for Repairs of Roof for Damages and Leakages