Carrying out NDT for strength assessment of existing civil structures at BARC staff colony

Amount

Extraction of concrete (75mm dia) cores from locations specified and testing for crushing strenght, water absorption & unit weight. The quoted rate shall include charges for filling back the core holes with polymer modified mortar and finishing etc. complete.

Conducting ultra sonic pulse velocity test, at all locations prepaired after chipping the paster, on columns, beams and portal frames to assess the intigrity of concrete as per BIS/ASTM specifications etc. complete.

Conducting rebound hammer test as per BIS/ASTM standards etc. complete

Chloride content shall be determined from concrete core dust sample ( Powdered samples by drilling and collecting them from different depths) or core samples of concrete, primerly, the level of chloride near the steel concrete interface is of prime importance. chlorides present in concrete are liked (water insoluble) as well as free (water soluble). Though it is the water soluble chloride ions which are of importance from corrosion risk point of view , yet total acid soluble (fixed as well as free) chloride contents are determined and compared with the limiting values specified for the concrete to assess the risk of corrosion in concrete. the total acid soluble chlorides are determined in accirdance with IS 14959 (Part 2) 2001. Extraction and testing of concrete drill dust samples from the structures. 3 drill the samples from depths 0- 15mm , 15-30mm and 30-45mm shall be collected from each location. The samples shall be tested for floride sulphates, PH alklinity.

On Core

On Powder

Carbonation test (Core): To evaluate the depth of carbonation in the RCC structure carbonation test shall be perform as per (IS: 516 Part 5 Sec 3 : 2021 ) standard procedure carbonation test shall be carried out on all structures representative sample as directed by EIC. Depth of the carbonation shall be evaluated on concrete core separately.

Crabonation Test (Powder): Depth of carbonation used to determine weather moisture has reached the depth of the reinforcing bars and hence corrosion may be occuring. Carbonation of concrete occurs when the carbon dioxide, in the atmosphere in the presence of moisure, reacts with hydrate cemnet minerals, to produce carbonates, e.g. calcium carbonate. the carbonnation process is also called De- Passivation. Carbonation penetrates below the exposed surface of concrete extreamely slowly. The significance of carbonation is that the usual protection of the reinforceing steel generaly present in concrete due to the alkine conditions caused by hydrated cement paste is neutralied by carbonation. Thus, if the entired concrete cover over the reinforcing steel is carbonated, corrosion of the steel would occur if moisture and oxygen could reach the steel. The test shall be performed to determine the depth of concrete affected due to combined attack of atmospheric carbon dioxide and moisture causing a reduction in level of alkanity of concrete. The test shall be conducted by drilling a hole on the concrete surface to different depths up to cover concrete thickness, removing dust by air blowing and spraying 0.2% solution of phenolphthenalein with physician's injection syringe and needle o n such freshly drilled/ broken concrete and observing the colour change. The change of colour of concrete to pink indicates that the concrete is in good health; it is suggestive of carbonation-affected concrete. b. PH value the sample of mortar collected by drilling from the site shall be dissolved in distilled water and thereby titration in laboratory. Thhe analyzing of sample be done and PH value be determined. c. chloride content test shall be performed on sample of mortar collected by drilling from the site or core samples of concrete to determine the chlorides present . chlorides present in concrete are fixed (water insoluble) as well as free (water soluble). The level of chloride near the steel=concrete is of prime importance. d. Sulphate content:- Sulphates are present in most cements and in some aggregates, excessive amounts of water- soluble sulphate from these or other mix cinsituents can cause expansion and disruption of concrete.

Conducting Profometer scan at specified location of the structure for reforcement steel location, size and cover measurement etc. complete.

Conducting half- cell potential meter test at all location to assess the risk of corrosion including exposing the reinforcement for carrying out the test. The test shall be conducted as per BIS/ASTM specifications. The quoted rate shall include charges for filling back areas chipped for exposing the reinforcement with polymer modified mortar. 5 potential observations taken at one location will form a unit for measurement.

Conducting Linear Polarization Test: (LPR) as per the specifications and directed by Engineer-In-Charge.

Prepairation and submission of two copies of draft report as specified followed by five copies of final report along with soft copy of the same on diskette covering Non Destrictive Test Observatios analysis, interpretation and conclusion of NDT observations, drawing out measures for durability make up, estimation of repair quantities, rate analysis for major repair items. the report should consist of each structure seprately and they together constitute one job.

Providing and fixing double tubular scaffolding system using H- frames with cup lock type on the exterior side upto seven story height made with 40 mm dia M.S. tube 1.5 m centre to centre horizontal and vertical tubes joining with cup and lock system with M.S. tubes, M.S. tube challies, M.S clamps and M.S staircase system in the scaffolding for working platform etc. and maintaining it in a serviceable condition for the required duration as approved and removing it thereafter. The scaffolding sys tem shall be stiffened with bracings, runners, connection with building etc. wherever required for inspection of work at required locations with essential safety features for the workmen etc. complete as per directions and as approved by the Engineer -in - charge. The elevational area of the scaffolding shall be measured for payment purposes. The payment shall be made once irrespective of duration of scaffolding

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