Mechanical strength and hydration exothermic behavior of cemented paste backfill with early-strength agent under low temperature

ABSTRACT

Low ambient temperature is not conducive to hydration of cement material, resulting in low strength for cemented paste backfill (CPB). Therefore, the aim of this study is to investigate the effect of early-strength agent (ESA) on mechanical strength and hydration exothermic behaviour of CPB under low temperature. Influence factors including the ESA types, superposing patterns and dosages were evaluated on CPB by conducting unconfined compressive strength (UCS), hydration exothermic tests and thermogravimetric analysis. The obtained results show that with exception of sodium chloride (NaCl), the single ESAs of sodium sulphate (Na₂SO₄), calcium chloride (CaCl₂), lithium bromide (LiBr) and triisopropanolamine (TIPA) exert positive effect on UCS of CPB. The optimal dosages of Na₂SO₄, CaCl₂, LiBr and TIPA are 2.0-, 1.0-, 0.3- and 0.08- wt.%. By means of superimposing optimisation, the binary ESA that consists of 0.08 wt.% TIPA and 2.0 wt.% Na₂SO₄ is obtained. Adding different ESAs at optimum dosages can facilitate hydration reaction of cement. Both hydration exothermic rate, cumulative heat release and internal temperature increase, thereby more amount of hydration products form inside CPB. This contributes CPB to obtain higher initial temperature and UCS under low temperature.

KEYWORDS:

• Cemented paste backfill
• low temperature
• early-strength agent
• unconfined compressive strength
• hydration exothermic
• thermogravimetric analysis

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the [National Key Technologies Research & Development Program] under Grant [number 2018YFC0808403]