GB2030558A - Treatment of buildings for demolition - Google Patents

Abstract

Buildings (or parts of buildings) of masonry are treated to reduce dust during demolition by thoroughly soaking the masonry to be demolished internally and externally with water, and applying a solid, fine-particled, hygroscopic salt, in which a non-ionic wetting agent is incorporated, to the soaked masonry.

Description

SPECIFICATION Demolition of buildings This invention relates to the demolition of buildings (or parts of buildings). Our copending U.K.

Patent Application 16547/78 describes a method for the demolition of buildings or parts of buildings made of masonry which is substantially dustfree.

In. that application, the masonry to be demolished is treated with an aqueous solution of a hygroscopic salt, in which solution a non-ionic wetting agent is also present.

In the preferred method an aqueous solution containing calcium chloride, magnesium chloride or a mixture of these alkaline-earth metal chlorides in a quantity of from 3 to 30% by weight and also from 0.1 to 0.5% by weight of a non-ionic wetting agent is distributed from a storage container by means of a pump to a network of perforated tubes which are laid in the building to be demolished. In this way the internal walls and floors as well as the external walls are impregnated from within with the alkaline-earth metal chloride solution commencing at the uppermost storey and working downwards. It has now been found however that it can be advantageous in some cases if the alkaline-earth metal chloride solution used for the treatment of the masonry is first formed in the masonry itself.

According to the invention, there is provided a method for the treatment of buildings (or parts of buildings) of masonry to reduce dust during demolition, which comprises thoroughly soaking the masonry to be demolished internally and externally with water, and applying a solid, fine-particled, hygroscopic salt, in which a non-ionic wetting agent is incorporated, to the soaked masonry to form an aqueous solution.

The masonry (brickwork) can be soaked in the simplest way by spraying it with a water hose which is connected to the local water mains. In general it is not necessary to provide a special pump as suggested in Patent Application No. 16547/78. After the entire masonry has been thoroughly soaked internally and externally and the surplus water has drained off, solid, fine-particled hygroscopic salt, preferably calcium chloride, magnesium chloride or a mixture of these two alkaline-earth metal chlorides, is applied to the soaked surfaces. The salt to be applied also contains a non-ionic wetting agent, such as an alkyl phenol oxyethylate (ethoxylated alkyl phenol).By virtue of such wetting agents, which are already active in high concentration solutions of the salts to be used according to the invention, i.e. which considerably reduce the surface tension of the resultant solution droplets, the distribu tionofthe solution both in the salts still remaining undissolved and in the material is to be treated is accelerated.

The finer the particles of these hygroscopic salts applied to the soaked surface are, the faster they dissolve. However, it should be noted that a salt, whose particles are too fine, may possibly be a source of inconvenience during application because it may blow away. Particles of between 1 and 3 mm are not usually blown away; however, they do not adhere at ali or only very poorly to vertical or steeply inclined surfaces and should therefore preferably be used on horizontal surfaces. In contrast, particles of less than 0.1 mm are necessaryforvertical and steeply inclined surfaces. It is advisable to use a mixture of these particle sizes so that the position of the surface to be treated is then irrelevant. The quantity ofhygroscopicsaltto be used is generally from 2 to 10 kg per m3 of masonry.It may be advantageous to divide this quantity into corresponding portions and apply it in two or three operations.

The advantage of the method of the invention over the method of Patent Application No. 16547/78 lies in the fact that particularly in the case of vertical and steeply inclined surfaces the utilisation of the hygroscopic salts and wetting agents is greatly increased. While in the previous method any surplus soaking solution drained off and was not used, in the method of the invention generally only that amount of solution is produced which the masonry can absorb. Particularly when the salt is applied in several small amounts loss can be avoided to a substantial extent.

Example A building which is to be demolished has a built volume of 2000 m3, a surface area of approximately 4000 m2 and a solid mass of 350 m2. In order to prevent the surroundings from being covered with dust during demolition provisions is made for prior treatment of the masonry. For this purpose the building is sprayed with 40 m3 of water internally and externally. The walls and ceilings are then completely soaked. Afterthe surplus water, which the walls and ceilings can no longer absorb, has drained off, solid, powdered calcium chloride with 85% by weight of CaCI2, to which 1% by weight of a non-ionic wetting agent (such as that mentioned above) has been added and whose particle size is less than 0.1 mm, is applied to all surfaces. The vertical and steeply sloping surfaces receive their application in two parts.A total of 2000 kg of powdered calcium chloride equivalent to 5.7 kg per m3 of masonry is used. After a reaction period of at least 18 hours demolition is commenced and can be carried out without any notable dust production.

1. A method for the treatment of buildings (or parts of buildings) of masonry to reduce dust during demolition, which comprises thoroughly soaking the masonry to be demolished internally and externally with water, and applying a solid, fine-particled, hygroscopic salt, in which a non-ionic wetting agent is incorporated, to the soaked masonry to form an aqueous solution.

2. A method according to claim 1, wherin from 2 to 10 kg of the fine-particled hygroscopic salt incor porating the wetting agent is used per m3 of brickwork.

3. A method according to claim 1 or 2, wherein the hygroscopic salt used is calcium chloride, magnesium chloride or a mixture thereof.

4. A method according to any preceding claim, which includes the step of demolishing the masonry.

5. A method according to claim 1, substantially

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Demolition of buildings This invention relates to the demolition of buildings (or parts of buildings). Our copending U.K. Patent Application 16547/78 describes a method for the demolition of buildings or parts of buildings made of masonry which is substantially dustfree. In. that application, the masonry to be demolished is treated with an aqueous solution of a hygroscopic salt, in which solution a non-ionic wetting agent is also present. In the preferred method an aqueous solution containing calcium chloride, magnesium chloride or a mixture of these alkaline-earth metal chlorides in a quantity of from 3 to 30% by weight and also from 0.1 to 0.5% by weight of a non-ionic wetting agent is distributed from a storage container by means of a pump to a network of perforated tubes which are laid in the building to be demolished. In this way the internal walls and floors as well as the external walls are impregnated from within with the alkaline-earth metal chloride solution commencing at the uppermost storey and working downwards. It has now been found however that it can be advantageous in some cases if the alkaline-earth metal chloride solution used for the treatment of the masonry is first formed in the masonry itself. According to the invention, there is provided a method for the treatment of buildings (or parts of buildings) of masonry to reduce dust during demolition, which comprises thoroughly soaking the masonry to be demolished internally and externally with water, and applying a solid, fine-particled, hygroscopic salt, in which a non-ionic wetting agent is incorporated, to the soaked masonry to form an aqueous solution. The masonry (brickwork) can be soaked in the simplest way by spraying it with a water hose which is connected to the local water mains. In general it is not necessary to provide a special pump as suggested in Patent Application No. 16547/78. After the entire masonry has been thoroughly soaked internally and externally and the surplus water has drained off, solid, fine-particled hygroscopic salt, preferably calcium chloride, magnesium chloride or a mixture of these two alkaline-earth metal chlorides, is applied to the soaked surfaces. The salt to be applied also contains a non-ionic wetting agent, such as an alkyl phenol oxyethylate (ethoxylated alkyl phenol).By virtue of such wetting agents, which are already active in high concentration solutions of the salts to be used according to the invention, i.e. which considerably reduce the surface tension of the resultant solution droplets, the distribu tionofthe solution both in the salts still remaining undissolved and in the material is to be treated is accelerated. The finer the particles of these hygroscopic salts applied to the soaked surface are, the faster they dissolve. However, it should be noted that a salt, whose particles are too fine, may possibly be a source of inconvenience during application because it may blow away. Particles of between 1 and 3 mm are not usually blown away; however, they do not adhere at ali or only very poorly to vertical or steeply inclined surfaces and should therefore preferably be used on horizontal surfaces. In contrast, particles of less than 0.1 mm are necessaryforvertical and steeply inclined surfaces. It is advisable to use a mixture of these particle sizes so that the position of the surface to be treated is then irrelevant. The quantity ofhygroscopicsaltto be used is generally from 2 to 10 kg per m3 of masonry.It may be advantageous to divide this quantity into corresponding portions and apply it in two or three operations. The advantage of the method of the invention over the method of Patent Application No. 16547/78 lies in the fact that particularly in the case of vertical and steeply inclined surfaces the utilisation of the hygroscopic salts and wetting agents is greatly increased. While in the previous method any surplus soaking solution drained off and was not used, in the method of the invention generally only that amount of solution is produced which the masonry can absorb. Particularly when the salt is applied in several small amounts loss can be avoided to a substantial extent. Example A building which is to be demolished has a built volume of 2000 m3, a surface area of approximately 4000 m2 and a solid mass of 350 m2. In order to prevent the surroundings from being covered with dust during demolition provisions is made for prior treatment of the masonry. For this purpose the building is sprayed with 40 m3 of water internally and externally. The walls and ceilings are then completely soaked. Afterthe surplus water, which the walls and ceilings can no longer absorb, has drained off, solid, powdered calcium chloride with 85% by weight of CaCI2, to which 1% by weight of a non-ionic wetting agent (such as that mentioned above) has been added and whose particle size is less than 0.1 mm, is applied to all surfaces. The vertical and steeply sloping surfaces receive their application in two parts.A total of 2000 kg of powdered calcium chloride equivalent to 5.7 kg per m3 of masonry is used. After a reaction period of at least 18 hours demolition is commenced and can be carried out without any notable dust production. CLAIMS

1. A method for the treatment of buildings (or parts of buildings) of masonry to reduce dust during demolition, which comprises thoroughly soaking the masonry to be demolished internally and externally with water, and applying a solid, fine-particled, hygroscopic salt, in which a non-ionic wetting agent is incorporated, to the soaked masonry to form an aqueous solution.

2. A method according to claim 1, wherin from 2 to 10 kg of the fine-particled hygroscopic salt incor porating the wetting agent is used per m3 of brickwork.

3. A method according to claim 1 or 2, wherein the hygroscopic salt used is calcium chloride, magnesium chloride or a mixture thereof.

4. A method according to any preceding claim, which includes the step of demolishing the masonry.

5. A method according to claim 1, substantially as described in the Example.