Applicability of cement-based grout for ground heat exchanger considering heating-cooling cycles

Moonseo Park, Sunhong Min, Jeehee Lim, Jong Min Choi, Hangseok Choi

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

The applicability of cement grout (or cement-based grout) has been considered as an alternative to bentonite grout commonly used to backfill closed-loop vertical ground heat exchangers. In a geothermal heat pump system, repeated heating-cooling cycles may cause adverse effects on the integrity of cement grout in the ground heat exchanger. To account for the temperature cycling effect, the strength degradation of cement grout due to temperature cycling has been examined by measuring the unconfined compression strength of cured specimens in a humidity-temperature controlling chamber with applying temperature cycles between -5°C and 50°C. There is a tendency that the unconfined compression strength decreases with an increase in the number of temperature cycles. On the other hand, an equivalent hydraulic conductivity of a pipe-embedded cement grout specimen was evaluated by carrying out a modified flexible wall permeameter test equipped with a water circulating system to control temperature inside the pipe section. The applied operating temperature range was from 5 to 35°C. After three cycles of heating-cooling circulation, the equivalent hydraulic conductivity becomes asymptotic to a constant value, which implies there is no severe detachment of the pipe from the cement grout.

Original languageEnglish
Pages (from-to)1661-1667
Number of pages7
JournalScience China Technological Sciences
Volume54
Issue number7
DOIs
Publication statusPublished - 2011 Jul 1

    Fingerprint

Keywords

  • bentonite grout
  • cement grout
  • equivalent permeability coefficient
  • thermal conductivity
  • workability

ASJC Scopus subject areas

  • Engineering(all)
  • Materials Science(all)

Cite this