WO1987002411A1

WO1987002411A1 - A demolishing method and an agent for this

Info

Publication number: WO1987002411A1
Application number: PCT/SE1986/000083
Authority: WO
Inventors: Ka^owe KA^oWERT; Sven-Erik Johansson
Original assignee: Cementa Byggprodukter AB
Current assignee: Cementa Byggprodukter AB
Priority date: 1985-10-11
Filing date: 1986-02-26
Publication date: 1987-04-23
Anticipated expiration: 1988-04-11
Also published as: EP0241475A1; SE8504729D0

Abstract

At breaking by means of burnt lime which is added together with water in order first to form a hard body which will then expand and break, an endothermic reaction and corresponding agents are used to brake the exothermic reaction of the burnt lime so that the added water does not start to boil and blows the agent out of the bore. An endothermic reaction is preferably chosen that does not start until water is added and/or a certain temperature is reached.

Description

A demolishing method and an agent for this

In the last decades agents for demolishing/breaki ng roc k, concrete and the l i ke have been developed as alternatives to detonating explosives without the disadvantages accombanying explosives that make these unsuitable in constructional activities in buildings and densely built-up areas. These new demolishing agents have a considerably slower effect eliminating sonic bangs, explosion gases, dust formation and minimize the required protective measures. Demolishing agents and associated methods used so far are aimed at adding burnt lime and reaction agents by means of a special υrocess in order to reduce the reaction time of the lime, thickeners and water. The demolishing compound is then filled into prebored holes e.g. in rock or stone which break after some time.

The chemical reactions are strongly temperature dependent in such a way that low temperatures give a long breaking time and high temperatures sive a short reaction and breaking time. Therefore different composite materials have been υroduced for different temperature ranges. As examples of practical results it can be mentioned that a breaking time of 25 hours must today be calculated at an ambient temperature of 2-6°, at a temperature of between 18 and 22° a breaking time of 7 hours and, if the ambient temperature is as high as 28-32°, 4 hours.

Apart from the fact that the relatively long breaking times are not desired and that breaking agents must be carefully chosen all according to temperature which is made still more difficult in that the temperature for the Iong times concerned may vary very much It is of course desirable for economical reasons to obtain a more ranld process. However, it has so far been found to be difficult to achieve this i.a. due to the fact that when the reaction times are shortened the chemical reactions can take place at such a rate that the arising temperatures (the reactions are exothermic) amount to more than 100º before the compound has hardened which results in the water In the mixture being evaporated and the compound being blown out of the bores (blow-out) instead of hardening. It is the object of the invention to remove the above disadvantages and to obtain a more rapid breaking process as well as agents for this, said agents, moreover, being useful within a greater temperature range with minor variations of breaking time.

This object is accomplished in accordance withthe Invention in that an endothermic reaction is arranged in parallell with the exothermic reactions to a certain extent, the expression endothermic being understood in a wide sense, i.e. a reaction is intended that can absorb heat. This reaction need not be chemical but can also be a physical one. Nor is it necessary that the reaction goes in one direction, only, so that absorbed heat remains blocked but it is also possible that the absorbed heat can be given off again when the temperature decreases. It is also possible within the scope of the invention to use an endothermic reaction having a retarding effect on the working eτothermlc reactions of the demolishing agent.

Endothermic reactions with threshold values are preferably used, i.e. below these temperatures no absorption of energy or brakinc: of temperature takes place. Of course these threshold temneratures need not be distinct temperatures but can consist of reaction gradients.

The endothermic reaction can be accomplished by adding substances capable per se of reacting endothermically at dissolution in water or at melting, vaporizing, or which give an endothermic reaction only together with water. As water is added to all the agents found on the market the endothermic reaction need not necessarily have any threshold value in this case as it is initiated and takes place in parallell with the exothermic reactions.

By the parallell arrangement of an endothermic reaction one can permit oneself to carry the exothermic reactions at such a great velocity that they give themselves (controlled by the endothermic reaction) an enough high temperature in order that the reactions might take place rapidly. In this way fast breaking or demolishing processes are made possible also at lower plus temperatures at the same time as it will be possible to use the same agent for higher temperatures. The endothermic substances or agents added are only used in the quantities required for the desired effect. However, it is essential that the threshold value of the endothermic reaction is below 100° or, alternatively, that the endothermic reaction has started so much already below 100°C that it prevents the temperature from rising above 100°C.

It should especially be pointed out that the risk of uncontrolled rapid reactions is greater at larger diameters of the holes In which the demolishing compound is placed. This means in turn that it will be possible by the invention to use larger bore diameters which in turn gives greater total breaking forces, and consqeuently the distances between the holes can be increased.

It is also possible within the scope of the invention that the additive responsible for the endothermic reaction is added only in connection with the mixture of the demolishing agent with water. In an extreme case the water can be added only after the d emollshina. agent has been positioned in its hole. Within the scope of the invention there is nothing preventing one from uti lizing agents aiding in the formation of a solid body for the endothermic reaction.

Within the scope of the Invention extremely rapid reaction processes within the demolishing technique are possible.

To permit gas or vapor possibly formed to leave rapidly the demolishing powder material can be sintered in one form or the other, e.g. in the form of tablets with sufficient grain density. As the tablet agent, in any case at the start, is permeable as a consequence of the spaces between the tablets, possible vapor or gases are prevented from creating blow-out tendencies.

If the powder agent is made enough permeable for a sufficient time demolishing agents having an extremely rapid reaction can be used in this technique at high temperatures, big hole diameters and small hole distances without any blow-out being obtained but resulting in blow-outs/breaking within some hour.

Claims

Patent Claims

1. A method at demolition and breaking by the aid of an agent that will in use first harden and then expand, c h a r a c t e r i z e d in that an endothermic reaction is used to adjust the reaction velocity, especially during the exothermic hardening phase.

2. The method of claim 1, c h a r a c t e r i z e d in that the endothermic reaction has a threshold value so that it will first start at temperatures above a definite temperature.

3. The method of claim 2, c h a r a c t e r i z e d in that the endothermic reaction starts in the temperature range 20-80°C, preferably 40-60°C.

4. The method of any one of the foregoing claims, c h a r a c t e r i z e d in that the endothermic reaction is initiated or made possible when water is added to the demolishing agent for use.

5. A demolishing agent for carrying out the method of claim 1, c h a r a c t e r i z e d in that it comprises a substance or substances capable of creating an endothermic reaction.

6. The demolishing agent of claim 5, c h a r a ct e r i z e d in that it has a temperature threshold for the endothermic reaction so that no heat energy is absorbed below this threshold whereas absorption takes place above this threshold.

7. The demolishing agent of claim 5 or 6, c h a r a c t e r i z e d in that the endothermic organic or inorganic addition to the agent is dissolved or has Its melting point in the desired range of temperature adjustment and that the heat absorption corresponds to the melting heat or, alternatively, the dissolution heat.

8. The demolishing agent of any one of claims 5 - 6, c h a r a c t e r i z e d in that the endothermic additive in the demolishing agent reacts with water through hydration.