Effect of non-explosive splitting compounds and rational work parameters

Abstract

Non-explosive splitting compounds have come into use in construction, and also at certain dimension-stone quarries.Non-explosive splitting compositions (NSC) have come into certain use in construction, and also at some dimensionstone quarries. They are capable of splitting stone materials (concrete, reinforced-concrete, rocks) without the familiar negative factors inherent to the blasting method: scattering of fragments, effect of air-shock and seismic waves, liberation of poisonous gases, acoustic manifestations, and disruption of the mass of the beyond the perimeter by blast-induced cracks. This make it possible to use NSC under the following cramped conditions: in an urban setting, and during reconstruction of existing establishments, including power-generating facilities, when the entity being split is in close proximity to others for which total safety should be provided. This applies, for example, to the reconstruction of concrete elements in the beds of power plants. In addition, it should be considered that use of NSC is appreciably more expensive than drill-and-blast operations.The procedure used for NSC reduces to drilling "blast" holes in the material to be split over a certain layout grid, filling them with an effective NSC mixture (dry powder with the addition of the required amount of water); after a certain time (usually from 10 h to two days), this will cause the material to split along lines of the blast-hole arrangement, followed by separation of the material.The P. P. Budnikov Institute VNIISTROM has developed the NRS-1 compound, which is manufactured by the Stroimaterialy Plant (settlement of Kraskovo, Moscow Oblast', Russia). A large number of similar compounds (bristar in Japan, betonamite in the German Federal Republic, tsevamite in Czechoslovakia, demeks and snigmamit in Sweden, etc.) are produced abroad. At the same time, development of a procedure for use of NSC has been inadequate. Available publications are fragmented and incomplete, inadequately characterize the working conditions, and occasionally contain improper recommendations, especially for the distance between blast holes (for example, [2]).From outward appearances, NSC is a powdery or granulated material, which is neither combustible, nor explosive, has an alkali reaction, and is very hygroscopic in nature. When the powder is mixed with water, an effective mixture (suspension), which will be poured into a blast hole, where it hardens and sets, increasing significantly in volume, is formed. This will lead to gradual development of stresses in the walls of the hole, and to their propagation into the material surrounding the hole. If the stresses exceed the strength of the material, cracks will form in the latter. As a result, the entity being treated can be split into blocks with dimensions dependent on the scheme used to arrange the NSC-filled holes.The splitting compounds must include free calcium oxide CaO, and additives, which regulate the hydration rate of the calcium oxide, and plasticize the compounds. The hydration equat...

Impact of thermal transfer on hydration heat of a Soundless Chemical Demolition Agent

“…In the water bath experiments, expansive pressure development was higher at the middle of the pipe (Figs. [8][9][10][11]. The pipe bottoms had slightly lower expansive pressure and hydration heat levels than those recorded at mid-height.…”

“…Experimental results presented herein generally showed that bigger diameter specimens resulted in larger expansive pressures (Figs. [8][9][10][11]. However, the expansive pressure development rate was not linear with borehole diameter.…”

“…For example, calcium silicate (in the form of belite) was reported by Soeda and Harada [14], and the SCDA manufacturer's product literature used in herein (Bristar 150), reports the presence of calcium silicate in the forms of both alite and belite (10-20% by weight) [15]. When the SCDA-generated stresses exceed the tensile strength of the surrounding materials, cracks will form and then propagate over time [10].…”

Effect of longitudinal reinforcement on the soundless chemical demolition degree of reinforced concrete columns

“…Subsequently, tensile stress is generated around the hole. When it exceeds the ultimate tensile strength at the weakest point around the hole, the concrete cracks 12,28–30 . Therefore, the crushing degree of concrete depends on the relative size of the resistance of the concrete and the expansive pressure generated by the SCDAs.…”

Procedure for nonexplosive demolition of concrete during reconstruction of hydroelectric generating sets

“…They can be used under restricted conditions: in a dense urban setting, during reconstruction of active establishments, and when the entity being demolished is situated in a zone of operating mechanisms for which complete safety should be ensured. This applies, for example, to the reconstruction of concrete components in the bases of power-generating equipment [2].…”