Effects of temperature and age on physico-mechanical properties of cemented gravel sand backfills

Abstract

Cemented backfill used in deep mines would inevitably be exposed to the ambient temperature of 20–60 °C in the next few decades. In this paper, two types of cemented gravel sand backfills, cemented rod-mill sand backfill (CRB) and cemented gobi sand backfill (CGB), were prepared and cured at various temperatures (20, 40, 60 °C) and ages (3, 7, 28 d), and the effects of temperature and age on the physico-mechanical properties of CRB and CGB were investigated based on laboratory tests. Results show that: 1) the effects of temperature and age on the physico-mechanical properties of backfills mainly depend on the amount of hydration products and the refinement of cementation structures. The temperature has a more significant effect on thermal expansibility and ultrasonic performance at early ages. 2) The facilitating effect of temperature and age on the compressive strength of CGB is higher than that on CRB. With the increase of temperature, the compressive failure modes changed from X-conjugate shear failure to tensile failure, and the integrity of specimens was significantly improved. 3) Similarly, the shear performance of CGB is generally better than that of CRB. The temperature has a weaker effect on shear strength than age, but the shear deformation and shear plane morphology are closely related to temperature.

Keywords

cemented backfill / gravel sand / temperature / physico-mechanical properties / deformation characteristics

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