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5 tests that are done on bridges and buildings

Bridges and buildings require periodic tests to analyse their integrity. Most of the bridges are subjected to adverse weather conditions which compromise their load carrying capacity as time goes.

Some of the tests done on these bridges are;

1. Carbonation test- this is a test that is used to estimate the effective good cover of concrete. The test is usually done using the phenolphthalein indicator which turns it's colour to pink in regions where carbonation has not occured due to the alkaline nature of cement. A small hole is dug as the indicator sprayed to determine the uncarbonated layer. The effective good cover(the remaining uncarbonated layer) is obtained by;

Effective good cover= Concrete cover - Carbonation depth.

2. Concrete hardnes test- the concrete is usually done using the Schmidt hammer, Which has a spindle on which when released it hits the test object. The hummer has a scale that gives the rebound number depending on how hard the surface is. Each number gives the coresponding concrete strength. The higher the rebound number, the higher the concrete strength.

Schmidt Hammer/rebound hammer

3. Utrasonic pulse velocity test- this is a test that is done on most bridges and buildings to determine the homogeneity and the quality of concrete. There are two ways that the machine can be used to give the homogenity and quality, these ways are;

a) Direct transmission- which is used to give to quality to concrete. The time that the pulse passes through the concrete medium is recorded and the distance divided by the time taken. The higher the pulse velocity means the higher the quality of concrete.

b) indirect transmission- this is a method used to determine the homogenity of concrete ie. how well the concrete mixture was done. Time are recorded when the pulse passes the concert at several intervals usually intervals of 150mm to 1000mm. A graph of distance against time is plotted, if the points are on a straight line then the concrete mixture is homogemous but if the points don't follow a straignt line then the mixture in non homogeneous.

4. Electromagnetic tests- these are tests done to map the rebars that were used during contraction to determine the rebar type and the specings used if they are as the standard specifications.

5. Resistivity tests- this is a test done inorder to estimate the probability of corrosion happening on the concrete structure.

Content created and supplied by: Star_Updates (via Opera News )

Schmidt Schmidt Hammer Utrasonic

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