core cutting test "نلخص إختبار القلب الخرساني بالصةر " :

75mm, 100mm or 150mm diameter cores are taken on site using state of the art core cutting machines. Cover meter is used to locate the reinforcement steel before core cutting. This prevents structural damage to the RCC member by avoiding the reinforcement. These cores are dressed in our lab and tested using standard compression testing methods to determine compressive strength and arrive at equivalent cube strength of concrete.

IS Codes applicable: IS : 456 / IS : 516 / IS : 1199


Applications:
Assessment of strength.
Study of aggregates used in the mix design.
Assessing probable causes of failures/problems.

Equipment Used:
Core cutter.
Core compression testing machine.

Test basis:
A core sample is the actual representation of the material used in the structural element. When processed and subjected to load, it fails at a particular load, giving a fair idea of its compressive strength.

Methodology:
Step1: Reinforcement Mapping.
By using a special instrument, based on eddy currents, the reinforcements are mapped in the structural member.

Step 2: Core cutting.
Cores are taken using special diamond cutters of 75 mm, 100 mm or 150 mm diameter. Locations are selected to avoid steel so as to minimize the damage to the structure.

Step 3: Dressing.
The edges of the core are smoothend using grinding and cutting wheels and epoxy mortar is applied on both sides for capping. This ensures that the ends are approximately at 90% to the axis and are within 0.05 mm plane ness.

Step 4: Immersion in water

The core samples are immersed in water for 48 hours. The cores are weighed before and
after immersion.

Step 5: Compression testing.

The cores are then subjected to compression forces on compression testing machine. The breaking point is observed.
Step 6: Reporting.
Based on the lab report, sizes of the core etc. an equivalent cube strength is calculated for the concrete applying necessary correction factors. The density, core strength and equivalent cube strength are reported.
Influencing factors:
Core diameter and length (h / d ratio)
Proper capping and hydration of the cores as per IS code.
Old/new/Mixed (jacketed) concrete.
Understanding results:
The result is normalized for comparison with compressive test results of a standard cube. This is done so that the cube results can be compared with the core results. Standard correction factors as per IS code are used for this purpose. This value may not be the same as the core strength.
We report results as per IS code. IS code does not take into account the core cutting effect. When accounted for, the results can be higher than those reported. Discussion on this can be taken up with consultants as a separate assignment.
Visual observations of the aggregate, failure pattern and probable causes of failure and suitalble remedies can be discussed separately and are not a part of the scope of conducting the test and reporting results.

التصنيف : هندسي