DE3111536A1 - Process for producing lightweight concrete - Google Patents

Abstract

A process is described in which, by admixture of open-cell foamed plastics in the form of particles, a lightweight concrete which does not show any desegregation phenomena even during wet processing (as from K2), in a simple and inexpensive manner. This lightweight concrete can be produced in any desired quantities without having to fear any adverse effects on the end product due to the foamed plastic particles mixed in. Foam flakes of polyurethane or polyethylene or polyester, which arise in foam-processing establishments as waste product and are thus cheaply available, are preferably used for this purpose.

Description

description

The invention relates to a method in the preamble of Claim 1 explained Art.

In a known method of this type is in the wet concrete a plastic foaming agent is injected in liquid form.

However, such a method leads, at least when mixing smaller amounts of concrete or in smaller concrete plants, where these foaming agents are injected into the mixer with spray guns, unsatisfactory results. There are no fine cracks in the prefabricated parts and a crumbly concrete structure avoid. In the case of reinforced concrete parts, additional precautions for the rust protection of the steel reinforcement can be taken.

It is also known that concrete fillers, usually single-pore Add mineral substances such as expanded clay and slate, pumice or slag. All of these substances are specifically lighter than concrete; a satisfactory one Accordingly, the degree of mixing is only achieved with relatively dry processing, i.e. with tough processing Emphasize, (K1) achieved. The lighter fillers float in more humid concretes (from K2) and do not allow themselves to be interfered permanently.

The invention is based on the object of showing a method with the easy dry process even with relatively moist processing Concrete can be produced with a homogeneous distribution of lightweight materials, which has good building properties having.

The object is achieved by the invention specified in claim 1.

Since the open-pored plastic foam particles are removed when they are introduced Soak in the damp concrete, there is a segregation through the different specific gravity does not take place; the foam plastic particles can be homogeneous to distribute. Nevertheless, a surprisingly high weight reduction is achieved. With This process can be used to mix even the smallest quantities of concrete without. after cracks appear after setting. The light concrete produced by the process is fireproof and sawable. He has both sufficient compressive strength, so that it can be used as static concrete, as well as high dimensional stability, good thermal insulation and high resistance to de-icing salt.

The foamed plastics listed in dependent claim 2 have proven to be proved particularly advantageous. In addition, such foam flakes fall into every plastic foam processing company, for example in the manufacture of upholstery, as waste and are therefore available relatively cheaply.

Particularly advantageous results are achieved when the density of the foam plastic used in the from the dependent claims 3 and 4 apparent Areas.

Foamed plastic and concrete are preferred in the dependent claim 5 given proportions mixed.

Particularly favorable results are achieved if according to the dependent claim 6 shows the method according to the invention with the addition of agents for increasing the gas content is combined. In particular, the known method mentioned at the outset can be used in the liquid plastic foaming agent can be injected into the concrete, thereby can be significantly improved that the foam plastic particles do not replace the liquid foaming agent, but in addition to this are introduced into the concrete. Possibly the gas bubbles of the show from the plastic particles "enclosed" and enclosed in the open-pored structure, creating cohesion the actual concrete components are not disturbed. In any case, the Addition of foam plastic particles the disadvantage of this known method, the Cracking and poor strength and fragility of the concrete produced, the has hitherto prevented economic use on a larger scale, surprisingly eliminated.

The light concrete mixed by the method according to the invention can can be used both as in-situ concrete and for the production of prefabricated parts.

Concrete parts produced by the method according to the invention, in particular Building panels can be seen in enlarged excerpts from the drawing. The figures show: FIG. 1 a plate produced by the method according to the invention without an additional increase in the gas content, and FIG. 2 shows one according to the invention Method manufactured plate with additional increase in gas content.

In Fig. 1, the plate consists of a concrete matrix 1 with enclosed, Foam plastic flakes soaked with concrete 2, which are illustrated here are clearly drawn, although they are hardly visible in the finished concrete step. The foam plastic flakes consist in particular of polyurethane.

But good results have also been achieved with polyethylene or polyester. The plastic foam flakes are open-pored or open-celled. The pores, some of which are soaked with cement pulp are denoted by 3.

The density of the foam plastic used should be approx.

13 to 60 kg / 3, preferably 28 to 30 kg / m3. He will by the mixing process compresses like a sponge and soaks up with cement slurry fully.

The ratio of foam plastic to concrete can be further Limits vary. For every n3 of finished concrete, between approx. 30 and 800 1 foam plastic flakes are required mixed in.

Depending on the mixing ratio, with a larger proportion of foam plastic you get a concrete with a higher thermal insulation or, with a larger proportion of concrete, a constructive concrete that is able to withstand higher compressive forces.

The plate of Fig. 2 additionally contains a means for increasing the Gas content. This creates gas pores, 7 mostly in the pore structure The foam plastic flakes are contained, but also in the concrete matrix Find.

The procedure is carried out by removing the foam plastic particles simply mixed into the concrete in the desired weight ratio. Maximum- or minimum quantities of concrete, if they are exceeded or not reached by mixing of the foam plastic particles, there were no disadvantages in the end product will. Particularly moist concretes (from K2) could be mixed well; a segregation also did not occur during setting.

If means are used to increase the gas content, these are also introduced during the mixing process. Injection is particularly useful of a liquid plastic-based foaming agent.

Since the concrete produced with the method according to the invention can be processed without further precautions as the well-known lightweight concrete should The protection also extends to prefabricated parts made from them, such as building boards.

Claims (6)

Method for producing lightweight concrete Patent claims 1 method for the production of light concrete by inserting a pore-forming plastic in the damp concrete, there is no indication that a ready-foamed, open-pored plastic in particle form is mixed into the concrete. 2. The method according to claim 1, d a d u r c h g e k e n n -z e i c h n e t that polyurethane or polyethylene or polyester foam flakes in the concrete be mixed in. 3. The method according to claim 1 and / or 2, d a d u r c h g ek e n n notices that a foam plastic with a density of 13 to 60 kg / m3 is used. 4. The method according to claim 3, d a d u r c h g e k e n n -z e i c h n e t that a foam plastic with a density of 28 to 30 kg / m3 is used will. 5. The method according to one or more of claims 1 to 4, 3 d a it is indicated that per m3 of finished concrete approx. 30 - 800 1 Foam plastic particles are mixed in. 6. The method according to any one of claims 1 to 5, d a d u r c h g e k Note that in addition to the foam plastic particles in the concrete an agent for increasing the gas content, in particular a foaming agent, mixed in will.