Now showing 1 - 3 of 3
  • Publication
    Impact of thermal transfer on hydration heat of a Soundless Chemical Demolition Agent
    This paper explores thermal transfer effects in Soundless Chemical Demolition Agents (SCDA). In a 10°C water bath, quadrupling the volume of SCDA in a pipe accelerated peak hydration onset and resulted in a 700% increase in expansive pressure and a 20% increase in volumetric expansion. An equivalent sample in a constant temperature chamber showed an almost 5°C greater hydration heat than in the water bath, which resulted in a six-fold expansive pressure difference after 4 days of testing and an order of magnitude more pressure in the first 24 h, thereby demonstrating limitations of previous SCDA experimental work and providing a temperature-based reason for discrepancies between large-scale testing and manufacturers’ predictions. Since most construction projects have scheduling requirements, understanding how to achieve sufficiently high pressures within a single work shift is important for evaluating the field viability of SCDAs on a particular project.
    Scopus© Citations 38  537
  • Publication
    Cold and moderate ambient temperatures effects on expansive pressure develop-ment in soundless chemical demolition agents
    This paper explores cool and moderate temperature (2–19 °C) impacts on hydration heat and expansive pressure development in two commercial soundless chemical demolition agents (SCDAs). Experimental results showed (1) product-specific, linear relationships between the ambient temperature and time to peak hydration heat; (2) peak hydration heats to be consistently 1.5 times the ambient temperatures at 10–19 °C; outside of this range the factor was greater; (3) a linear relationship between peak hydration heat time and the onset of expansive pressure development; (4) a largely proportional relationship between ambient temperature and volumetric expansion of 1.1–1.4 times the original volume.
    Scopus© Citations 69  597
  • Publication
    Chemical Demolition of Unit Masonry: A Preparatory Study
    Chemical demolition of concrete and rock has been conducted on a commercial basis since the 1970s, although not widely adopted. Furthermore, to date there have been no publications on the application of this class of products to unit masonry. To begin to fill this gap, this paper documents a laboratory study on the insertion of a soundless chemical demolition agent into a series of unit masonry wallettes. The paper introduces initial steps towards developing a procedure for the non-percussive demolition of such a wall and observations on the progressive nature of cracking in such arrangements. Although neither the assembled units nor the mortar in these tests were of historic material, the paper provides critical insight into the application of this technology into a building configuration in which it is not usually seen. The results show the promise this technology holds for highly selective material removal, without endangering the surrounding material for historic brick and stone buildings.
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