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CORROSION OF REINFORCEMENT IN CONCRETE The damage to the concrete due to corrosion of reinforcement is considered to be one of the most serious problems. It is an universal problem and property worth of crores of rupees is lost every year. Due to corrosion problem in bridges, buildings and other RCC structures, India incurs heavy loss of about Rs. 1,500 crores annually. This paper deals with various causes of corrosion and remedial measures thereon. Corrosion process and mechanism : Corrosion of reinforcement steel is a complex phenomenon involving chemical, electrochemical and physical processes. When reinforcement steel rusts, the volume of iron oxide formed is 2-4 times greater than the steel corroded, which results in bursting stresses in the concrete surrounding the bar. This causes cracking, spalling and delamination of concrete. Another consequence of corrosion is reduction in cross- Sectional area of the steel at anode, thus reducing its load ca

REBOUND HAMMER TEST The SCHMIDT rebound hammer, developed by a Swiss Engineer Ernst Schmidt in 1948 is one of the most frequently used methods worldwide for non-destructive testing (NDT) of concrete structural elements. The test is based on the principle that the rebound of an elastic mass depends on the hardness of the surface against which the mass impinges. The hammer consists of a plunger connected with a spring-driven metal mass. The plunger is held against at 90 to the smooth concrete surface, firmly supported and pressed. This will impart a fixed amount of energy. Upon release, the metal mass rebounds, the plunger being still in contact with concrete. The distance travelled by the metal mass or the amount Larger is the rebound. higher is the strength of concrete. of rebound is noted on a scale that gives an indication of the concrete strength. The rebound hammer test is sensitive to local variations in the concrete: for instance, the presence o

Micro concrete Micro Concrete is a flowable mortar for repairs to damaged reinforced concrete members. The quantity of aggregate which can be incorporated may be limited by the method of placing. If a simple pouring technique is used, 10 m aggregate may form 50% of the total dry materials, but if pumping is preferred the aggregate size and quantity will need to be reduced to suit the limitations of the pump. When the repair section exists in only one plane, i.e., a simple vertical section, it is sufficient to pour the material in from the top of the shutter, it will not suffer the severe segregation which occurs with normal concretes. If the repair is more than 1.5 m wide it is advisable to have two pouring points being fed simultaneously. It is also necessary to consider venting the top of the cavity if it is enclosed.  shows the placing of superficial micro concrete in a vertical section.                                        Placing of superfic

Cement is the most common and important material in civil construction, so everyone involved in the construction field must carry basic knowledge about the test performed on cement. In this post, I'll discuss some basic tests of cement. The physical tests which are generally performed to determine the acceptability of cement are – Fineness Test Consistency Test Setting time Test Soundness Test Strength Test Heat of Hydration Test Specific Gravity Test 1. Fineness Test Fineness is the mean size of cement grain. It is done to measure the mean size of cement grain. The finer the cement the surface area for hydration will be large and it increases the strength of cement. But the fineness varies in different  types of cement . One of the following three methods can be applied to test the fineness of cement- Sieve method Air Permeability method Sedimentation method 2. Consistency Test This physical test