Expansive cements and soundless chemical demolition agents : state of technology review

Expansive cements and soundless chemical demolition agents (SCDAs) were first introduced in the early 1970s but failed to gain widespread adoption for selective removal of rock and concrete due to their proprietary nature and a lack of usage guidelines. Nearly 40 years later, the patents have expired, and a large number of competitive products have entered the market. These factors coupled with a heightened interest in their potential environmental benefits have greatly expanded their usage. Specifically, these chemicals can be introduced into a pattern of small, drilled holes in concrete and/or rock. After a specific period (usually less than 24 hours), the in-situ material will crack sufficiently that it can be removed without the use of traditional explosives or further percussive efforts. The products generate substantially less noise and vibration than usually associated with the removal of rock and concrete. This paper provides a state-of-the-technology review of five available products. The focus is on the proposed applicability of various products under specific conditions. Special attention is paid to the viability of such agents under varying temperatures and with materials of particular strengths.