Laboratory study of retention and clogging performance of no-fines concretes

Abstract

No-fines concrete (NFC) relief well screens function similarly to filters; thus, the retention and clogging performance of NFC should be accurately assessed. The Silveira model was adopted to predict the constriction size distribution for NFC, and the results were compared with those of slicing tests. The flow in NFC was also tested, and it was proved to be a non-Darcy flow that was well matched with the Slepicka formula. With quartz sand injection into pores seven times, the permeability of NFC changed from sharp decline to gradual stabilisation; whereas, it could be largely recovered after high-pressure water flushing. Uniform sand, continuously graded sand and discontinuously graded quartz sand were applied as base soils in a series of horizontal seepage tests in the model box, with the protection of various NFC specimens. It was found that the retention effectiveness of NFC was determined by the stability of the self-filtration layer, which was related to the interfacial ratio, soil gradation, soil density and hydraulic condition. Moreover, to prevent clogging, the hydraulic gradient should be restricted in the base soil.

Keywords:

• Well screen
• no-fines concrete
• constriction size
• retention criterion
• clogging

Acknowledgement

The authors gratefully acknowledge the support by Guangdong Natural Science Foundation (Grant No. 2018A030313383), and there is no potential conflict of interest between them.

Disclosure statement

No potential conflict of interest was reported by the authors.