Snyman, BJ, van der Spuy, B & Correia, LDC 2014, 'A critical look at uniaxial test procedures applied in the backfill industry', in Y Potvin & T Grice (eds), Mine Fill 2014: Proceedings of the Eleventh International Symposium on Mining with Backfill, Australian Centre for Geomechanics, Perth, pp. 161-173, https://doi.org/10.36487/ACG_rep/1404_11_Snyman
(https://papers.acg.uwa.edu.au/p/1404_11_Snyman/)
Abstract: Uniaxial/unconfined compressive (UCS) strength testing and triaxial testing are two of the most commonly used test procedures to assess the shear strength of backfill today. Some of the backfill test procedures currently in use were originally developed by other engineering disciplines and modified to meet the requirements of the mining industry. For example, UCS tests are performed by geotechnical, concrete and rock engineers. 
When using procedures developed for other engineering disciplines it is important to think critically about the intended purpose behind specifications and requirements and the applicability of these related to backfill.
This paper compares the most commonly used UCS test procedures. The paper will then investigate the effect of the most important parameters influencing test results, such as specimen shape, size and aspect ratios, by presenting laboratory test results for a specifically designed test campaign.
A graphical model is presented demonstrating the relationship between strength, water content and parameters influencing backfill pumpability.