What is the maximum distance allowed between insertion points when internal vibration is used for consolidating a flexural strength test specimen?

The maximum distance allowed between insertion points when using internal vibration for consolidating a flexural strength test specimen is 6 inches. This requirement is based on the need to ensure uniform compaction of the material throughout the specimen. When the distance between the insertion points is too great, it can lead to insufficient consolidation in certain areas, potentially resulting in non-representative test results.

The use of internal vibration is intended to eliminate air pockets and ensure that the concrete mix is evenly distributed. Maintaining a maximum distance of 6 inches ensures that the vibrational effect reaches all parts of the specimen adequately, contributing to a consistent density and homogeneity essential for accurate strength testing.

In the context of concrete testing, proper consolidation directly influences the mechanical properties of the specimen being tested. Therefore, adhering to the specified distance between insertion points is critical in achieving reliable and valid flexural strength measurements.