Resumen

KANDA, M.J.  y  STACEY, T.R.. Tensile strength sensitivity of thin spray-on liners to changes in environmental conditions. J. S. Afr. Inst. Min. Metall. [online]. 2020, vol.120, n.4, pp.251-259. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/955/2020.

Thin spray-on liners (TSLs) are an areal support with the perceived ability of promoting rock mass stability, based on their high tensile strength and elongation capacity. However, these benefits are not always realized in the mining environment, which has resulted in some scepticism regarding the utilization of TSLs. The research described in this paper was carried out to measure the tensile strengths of TSLs after they had been subjected to underground-like conditions. This was achieved by exposing prepared samples to three environmental conditions: a 'standard' room-temperature and humidity condition; a saturated room-temperature condition; and a saturated, high-temperature (50°C) condition. Periods of exposure extended up to 112 days. The test results showed that humidity and temperature have an adverse impact on TSL uniaxial tensile strength, deformation modulus, and elongation. Some TSLs available commercially may therefore completely underperform in humid and higher temperature conditions, and some even under normal laboratory conditions. Water-based TSLs indicate good suitability for use in humid conditions, but their performance declines when higher temperatures are involved. Therefore, it is inappropriate to design underground support systems using TSLs based on strength and deformation properties determined under normal laboratory conditions.

Palabras clave : areal support; thin spray-on liner; TSL; tensile strength; UTS.

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