WO2002032829A1

WO2002032829A1 - Insulating plaster blocks comprising the incorporation of granular cork

Info

Publication number: WO2002032829A1
Application number: PCT/PT2001/000026
Authority: WO
Inventors: João António BATISTA LABRINCHA
Original assignee: Corticeira Amorim - Industria, S.A.
Priority date: 2000-10-18
Filing date: 2001-10-16
Publication date: 2002-04-25
Also published as: PT102524A

Abstract

The present invention refers to the production of plaster or plaster of Paris blocks comprising granular cork. Two approaches were taken one involving the production of said blocks from an intimate mix of the two constituents and the other involving the production of bi-layer products their component layers comprised of the two single materials.

Description

INSULATING PLASTER BLOCKS COMPRISING THE INCORPORATION OF GRANULAR CORK

DETAILED DESCRIPTION

The present invention refers to a new plaster of Paris based product for plaster finishing, or for the production of building blocks and interior surface finishing plates. It also refers to the production process of the above-mentioned items. The novel product (herein referred to as MB) is achieved by thorough mixture of said plaster of Paris with granular cork, and has enhanced acoustic and/or thermal insulation properties. One alternative embodiment of the present invention comprises the manufacture of products (herein referred to as BB) by gluing together layers of the two above-mentioned components, instead of mixing them, each one of the said layers being independently produced, and under conditions similar to the standard production conditions for each type of component material. In addition to the an enhancement in their acoustic and/or thermal properties the products according to the invention show, mainly in the case of BM samples, appearance variations that are potentially interesting from an aesthetic point of view. The present invention employs a combination of materials, cork being used as an element for the enhancement of the thermal and acoustic insulation characteristics of the products thereof, the current state of the art being the use of only plaster of Paris for the production of similar products.

The processing conditions used to manufacture the products according to the present invention are closely similar to the standard conditions used for the manufacture of plaster products. Furthermore the present invention uses, as a material, fine granular cork that frequently is considered as waste or only used as fuel in the cork transformation plants. Therefore the invention has an ecological aspect by incorporating said granular cork in a new product.

(A) Materials and Preparation Conditions

Use was made of a commercial plaster of Paris for plaster finishing, this material having well defined mineralogical and granulometric characteristics, and the usual setting conditions, without additives and at ambient temperatures, were studied. The granular cork is produced by the company Cortiςeira Amorim Indύstria, Portugal, and this product results from the recycling of cork pieces or waste resulting from the manufacture of cork products, namely, cork stoppers. The granulometric fractions used were the ones classified as Micro-Fine, as they are processed, under perfectly controlled conditions, in the said industry. Table 1 lists some of the granular cork characteristics used in the present invention, the complete specification thereof being strictly controlled by the producing company.

Table 1 - Granular cork generic characteristics.

The use of the fractions with the lowest particle sizes is preferred (particle sizes up to 200 μm - MF1) since these fractions are not commonly used in the cork industry.

The processing conditions, particularly the component mixing, for the products of the present invention were optimised so that they were as similar as possible to the usual processing conditions for plaster of Paris based products, thus avoiding significant changes to these processing conditions. The optimised processing comprises the following stages for MB products:

(i) Dry mixing of the solid components in a rotary mill for 30 minutes. (ii) Water addition in controlled amounts, the amount of water being such as to assure the correct moulding characteristics of the mix.

(see Table 2). (iii) Pouring of the thus made suspension into casting moulds until the block cure and hardening is complete, (iv) Block drying, after releasing from the moulds, at 40°C, in order to remove excess water, the moisture percentage in the material being evaluated by difference of weigh.

Table 2 lists some of the optimised values for the production of the above- mentioned mixes.

For bi-layer products (BB) use was made of plates comprised only of plaster of Paris or of the inventive cork/plaster of Paris mix, and cork plates (ref. 8236), said plates being alternatively layered and bond one to the other with plaster binder. The production conditions for the mix plates were similar to the ones referred above.

Table 2 - Adjusted mixing conditions for plaster with different particle size granular cork and block moisture content.

(B) Sample Characterization

The cured sample characterization was made according to standard procedures for this king of products, the following properties having been measured:

(i) the bulk density of the MB samples (ISO 7322); (ii) the mechanical flexural (EN 100) and compression (ISO 7322) strengths, using a universal mechanical testing machine; (iii) the thermal conductivity, using the ANACOM method (based on the BS874 standard); (iv) the air borne sound insulation index of four partition elements (in this case only for blocks comprising about 30 % of MF1 granular cork), according to NP-2073.

Comparing the test values for the invention products with standard values for plaster products, produced under the same conditions, provides a measure of the effect of granular cork incorporation on the characteristics of these products. Tables 3-9 list the main characteristics of the several of the manufactured products.

Table 3 - Bulk density of MB plates. The value for plaster of Paris only plates is 1.05 g/cm³.

Table 4 - Mechanical flexural strength of MB plates. The value for plaster of Paris only plate is 3.72x10 Pa.

Table 5 - Mechanical compression strength of MB plates. The value for plaster of Paris only plates is 8.48xl0⁸ Pa.

Table 6 - Mechanical flexural and compression strengths of BB plates.

Table 7 - Thermal conductivity of MB plates. The value for plaster of Paris only product is 0.192 W/m.°C.

Table 8 - Thermal conductivity of BB products. The value for plaster of Paris only products is 0.192 W/m.°C.

Table 9 - Air borne sound insulation index values. The MB blocks were produced with about 30% of granular cork.

The potential of the inventive new products are clearly shown by the results in the above tables, since it is shown that the inventive products characteristics are good when compared with those of similar plaster of Paris only products.

The products produced using cork are lighter and with better acoustic and thermal insulation performance than the standard plaster of Paris products, and the use of cork creates no adverse effects on the mechanical resistance properties, at least with a granular cork content up to 30% v/v. Also the transport of such products and the modular construction are easier due to their lighter weight. The use of different granular cork types produces only produces slight changes in the properties of the plates made with said granules, these changes reflecting the differences in the particle sizes and density of the different types of cork granules used.

Considering the bi-layer products the gluing of the several layers of the two products (plaster and cork granules) is a critical step in the processing of the finished product, therefore needing careful adjustment.

Claims

C L A I M S

1. Plaster or plaster of Paris insulating blocks for the building of new interior walls or for renewal works of interiors characterized in that they are produced by incorporation of granular cork.

2. Plaster or plaster of Paris insulating blocks according to claim 1 characterized in that the granular cork used for the production of said blocks is a granular cork consisting of the thinner granulometric fractions (up to 500 μm).

3. Plaster or plaster of Paris insulating blocks according to claim 2 characterized in that they are produced by intimate dry mixing, under carefully controlled conditions, of the two component materials plaster of Paris and cork (these blocks being referred to as mix blocks -MB)

4. Plaster or plaster of Paris insulating blocks according to claim 3 characterized in that they consist of bi-layer plates of plaster of Paris and cork (these blocks being referred to as bi-layer blocks - BB) produced by gluing together plates comprised of the two component materials plaster of Paris and cork.

5. Plaster or plaster of Paris insulating blocks according to the previous claims characterized in that the above mentioned MB products the cork content is up to 50% v/v.

6. Plaster or plaster of Paris insulating blocks according to the previous claims characterized in that their density decreases as the cork content increases (from 1.05 for samples without cork to 0.76 for mixes with 50% v/v of cork), and in that values of the flexural and compression mechanical strengths are essentially constant for cork contents up to 30% v/v, these values decreasing with the increase of cork content for contents above 30% v/v (ranging from 3.98 to 1.07 MPa, and from 935 to 193 MPa for the flexion and compression, respectively of MB; ranging from 1.57 to 1.24 MPa, and from 763 to 623 MPa, for the flexion and compression, respectively of BB).

7. Plaster or plaster of Paris insulating blocks according to the previous claims characterized in that the thermal conductivity said blocks decreases with the increase of cork content (ranging from 0.37 to 0.11 Wm^K^"1 with a cork content of 50% v/v for BM, and ranging from 0.43 to 0.21 Wm^K^'1 for BB), and an increased air borne sound insulation index (43 dB for 45 dB for products with cork contents of 30% v/v).