When concrete is permeable it can cause corrosion in reinforcement in presence of oxygen, moisture, CO2, SO3- and Cl- etc. This formation of rust due to corrosion becomes nearly 6 times the volume of steel oxide layer, due to which cracking develops in reinforced concrete and spalling of concrete starts. So, if the concrete is(…)
Material Testing Guide
CONCRETE CUBE TEST RESULTS ACCEPTANCE
ACCEPTANCE OF CONCRETE CUBE TEST RESULTS ACI-5.6 2008 requires that all the tests to be performed on fresh, hardened or old concrete are to be performed by qualified field testing technicians. They should collect and prepare all the specimens for testing and should record temperature and other important information about the fresh concrete. 1. Frequency(…)
TESTING OF CONCRETE CORES
The testing of concrete cores is carried out according to the ASTM Standard C 42. The diameter of core specimens for the determination of concrete compressive strength should preferably be at least three times the nominal maximum size of the coarse aggregate used in the concrete, and must be at least twice the maximum size of the coarse aggregate in the core sample.
MEASURING REINFORCEMENT CORROSION IN CONCRETE
There is need to know the extent of corrosion in pre-stressing steel as well as that of reinforcing steel in concrete. No instrument / technique is available, at present, which can measure the extent of corrosion of steel. However, measurement of concrete properties, such as resistivity and potential of concrete can assess the probability of(…)
MEASURING LOSS OF PRESTRESS IN PRESTRESSED CONCRETE
Instruments for measuring loss of prestress in prestressed concrete: The initial pre-stressing force applied to the concrete element reduces due to elastic shortening of the concrete, anchorage losses, frictional losses etc. The pre-stressing force further reduces with the passage of time due to creep, shrinkage, temperature effect and relaxation of steel. The loss of pre-stressing(…)
INSPECTION & TESTING OF WELDS IN STRUCTURAL STEEL
The method of inspection of welds in structural steel should be according to IS: 822 and extent of inspection and testing shall be in accordance with the relevant applicable standard. The inspection of welds during all stages of fabrication and erection should be done for the following objectives.: i) To check the conformity with the(…)
COMPRESSIVE STRENGTH TEST ON CONCRETE CORE
Compressive Strength Test on Drilled Concrete Cores is required to determine the strength of hardened concrete in structure. Following are the specification for drilled concrete cores to be suitable for compressive strength test: Diameter of concrete core: The diameter of the core specimen for the determination of compressive strength in load bearing structural members shall (…)
TIPS FOR CORE EXTRACTION & TESTING OF CONCRETE
Core extraction and testing of concrete covers obtaining, preparing, and testing cores drilled from concrete for compressive strength test of casted concrete structures. Reference Standard codes: ASTM code C 42 IS 516 IS 1199 General Tips of Core Extraction: Concrete strength is affected by location of the concrete in structural element, with concrete at the(…)