What is the maximum allowable loading for openings smaller than #4?

The maximum allowable loading for openings smaller than #4 is specified as 7 kg per sieve area. This standard is crucial for ensuring the proper functioning and reliability of the sieving process in aggregate and soil testing. The number #4 sieve (which has openings of 4.75 mm) serves as a transition point in material classification. Openings smaller than #4 require careful consideration regarding loading because excessive weight could lead to compaction of the material, hinder accurate sizing, or damage the sieve itself.

Setting the limit at 7 kg allows for effective separation of materials while maintaining the integrity of the test. This specified loading ensures that the tests yield reliable results, which is essential for meeting compliance with construction and engineering standards. In aggregate testing, adhering to these loading limits helps in the accurate determination of material properties critical to quality control processes in construction projects.