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Geomechanics and Engineering
  Volume 29, Number 4, May25 2022 , pages 421-434
DOI: https://doi.org/10.12989/gae.2022.29.4.421
 


The study of strength behaviour of zeolite in cemented paste backfill
Hasan Eker and Atac Bascetin

 
Abstract
    In the present study, reference samples were prepared using ore preparation facility tailings taken from the copper mine (Kure, Kastamonu), Portland cement (PC) in certain proportions (3 wt%, 5 wt%, 7 wt%, 9wt% and 11 wt%), and water. Then natural zeolite taken from the Bigadic Region was mixed in certain proportions (10 wt%, 20 wt%, 30 wt% and 40 wt%) for each cement ratio, instead of the PC, to prepare zeolite-substituted CPB samples. Thus, the effect of using Zeolite instead of PC on CPB's strength was investigated. The obtained CPB samples were kept in the curing cabinet at a temperature of 25C and at least 80% humidity, and they were subjected to the Uniaxial Compressive Strength (UCS) test at the end of the curing periods of 3, 7, 14, 28, 56, and 90 days. Except for the 3 wt% cement ratio, zeolite substitution was observed to increase the compressive strength in all mixtures. Also, the liquefaction risk limit for paste backfill was achieved for all mixtures, and the desired strength limit value (0.7 MPa) was achieved for all mixtures with 28 days of curing time and 7 wt%, 9 wt%, 11 wt% cement ratios and 5% cement – 10% zeolite substituted mixture. Moreover, the limit value (4 MPa) required for use as roof support was obtained only for mixtures with 11% cement – 10% and 20% zeolite content. Generally, zeolite substitution seems to be more effective in early strength (up to 28th day). It has been determined that the long-term strength losses of zeolite-substituted paste backfill mixtures were caused by the reaction of sulfate and hydration products to form secondary gypsum, ettringite, and iron sulfate.
 
Key Words
    cement; cemented paste backfill (CPB); tailings; uniaxial compressive strength (UCS); zeolite
 
Address
Hasan Eker: Eskipazar Vocational School, Property Protection and Safety Division, Occupational Health and Safety, Karabuk University, Karabuk, Turkey
Atac Bascetin: Department of Mining Engineering, Mining Faculty, Istanbul Technical University, Maslak, Istanbul, Turkey
 

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