WO2022146345A2

WO2022146345A2 - Lime-pozzolan mortars with bio-aggregate for sound absorption and therm at, insulation purposes

Info

Publication number: WO2022146345A2
Application number: PCT/TR2021/051422
Authority: WO
Inventors: Miyase Merve KAPLAN; Ayşe TAVUKÇUOĞLU; Mehmet Çalişkan; Emine Nevin SALTIK
Original assignee: Orta Doğu Tekni̇k Üni̇versi̇tesi̇
Priority date: 2020-12-30
Filing date: 2021-12-16
Publication date: 2022-07-07
Also published as: TR202022342A2; WO2022146345A3

Abstract

The invention is related to a mortar comprising pure lime (Ca(OH)2) as binder, pozzolanic additive, and wheat straw as a bio-aggregate, that provides sound and thermal insulation. Multi-layered and multifunctional plaster systems or insulation board systems are produced according to the purpose, with mortars having different "bindenpozzolanic additive:bio- aggregate" ratios.

Description

LIME-POZZOLAN MORTARS WITH BIO-AGGREGATE FOR SOUND

ABSORPTION AND THERMAL INSULATION PURPOSES

Technical Field of the Invention

The invention is related to the construction materials industry, which is generally produced for the purpose of heat and sound insulation, and in particular, to the production of mortar products with different "binderpozzolanic additive:bio-aggregate" ratios that provide heat and sound insulation. These mortar products can be used both in the repairs of historic buildings and in new structures, as sound absorptive thermal insulating plasters, multi-layered and multifunctional plaster systems or multi-layered insulation board systems. In addition, these mortar products, which can be used as a multi-layered plaster system, are plaster products that can also be used as “lath-and-plaster" on wooden elements or laths.

State of the Art (Prior Art)

Thermal insulation materials widely used in the building sector can also be used for sound insulation/noise control purposes as a result of their open porous structure. Today, insulation materials, such as mineral wools (rock wool-fiberglass), polyurethane (PUR/PIR), expanded polystyrene (EPS) or extruded polystyrene (XPS), produced with a very low thermal conductivity and in different forms, such as mat, board, foam, are the most preferred thermal insulation materials around the world. These materials have the highest market share in the insulation material industry.

The concept of sustainability, which has gained importance over the years and has become widespread all over the world, and accordingly, policies to reduce the "Global Warming Potential (GWP)" in the world have led to the evaluation of construction materials under various criteria such as "being environmentally friendly products", "having low CO2 footprint", "being healthy products", "not being flammable and toxic gas releasing products". Commonly used insulation materials have also been affected by this process. The need for insulation materials to be produced energy efficiently and comprising features such as having a low CO2 footprint, being less damaging to the environment, not releasing toxic gas or volatile vapor has become prominent, and this approach led to the production of new insulation materials by using alternative sources.

Thermal insulation materials widely used in the building sector (such as rock wool, glass wool, polyurethane foam, EPS, XPS) are known to be harmful to the environment and human health due to their use of non-recyclable raw materials, high energy needs during production, high carbon (CO2) footprints and toxin contents (Asdrubali, Schiavoni & Horoshenkov, 2012). However, these materials are still predominantly preferred due to their superior thermal insulation performance properties and widespread production networks. Polyurethane, EPS, and XPS are petrochemical products, whereas the goal is to reduce oilbased production worldwide. It is known that they are harmful to human health due to their composition. The high amounts of carbon monoxide (CO) they release in case of fire and toxic gases (such as hydrogen cyanide (HCN) produced by PUR foam combustion) that vary according to their components are extremely toxic (Jelle, 2011). These products are insulation materials that have been proven to release volatile organic compounds (VOCs), which are known to be harmful to the health of the living, and are not biodegradable in nature. Even though mineral wools such as glass wool and rock wool are more reliable insulation materials in combustion conditions, their production processes consume a lot of energy. Mineral wools’ very fine fibrous structures cause serious diseases in the eyes, skin, and upper respiratory tract in humans during the application stages of these products (World Health Organization, 2002).

Alternative insulation materials using natural resources have been on the agenda of the construction material industry in recent years since their global warming potential (GWP) is lower than synthetic-based materials and they can exhibit similar heat and sound insulation performances. Insulation materials produced from sustainable and organic biological resources such as cellulose, cork, wood wool and fibers, flax, hemp, and sheep wool have taken place in the market as alternative products to existing insulation materials. However, the market shares of these products of organic origin are few compared to those of widely used mineral and polymer-based insulation materials.

There are board products with a cement binder and containing wood particles, wood wool, and similar organic fibers in their mixture (Heraklite, Tepe Betopan, etc.) in today's construction material industry. Products such as Betopan are referred to in the market as cement bonded particleboards and they are used as exterior panels and their thermal insulation qualities are better than cement boards. Products such as Heraklite are cement bonded wooden wool boards and they are insulation boards used for thermal insulation and acoustic control. However, various problems are observed in using cement-based materials in old and new structures. Since cement-based mortars and plasters used in the repair of historic buildings are incompatible with the historical texture, they may cause deterioration in the original layers of construction materials. Cementitious products inherently have high thermal conductivity, high mechanical strength, high bulk density and low porosity. Therefore, these cementitious materials may cause many problems in the historic structures (chemical deterioration, moisture problem, etc.) as they are not compatible with the original material layers in terms of properties such as porosity, water vapor permeability and mechanical strength. In addition, it is known that cement manufacturing and application processes cause major environmental problems due to the high carbon footprint.

The patent application TR2017/21388 is related to a "load-bearing or infill wall block" product obtained from a mixture of local soil with a pozzolan nature and hydraulic lime. The basic physical and mechanical properties of the construction material produced as a wall block have been defined; however, it is not intended to be a product with heat and sound insulation qualifications.

The patent application TR 2019/14851 is related to a "wall construction material" produced by a mixture composed of hydraulic lime and cement binder and additives, such as clay, silt, sand, coal slag, perlite, paddy husk, straw, com silage, bitumen, brick ballast, etc., wrapped and pressed with jute wire. It was stated that polyurethane foam was added to this product on the exterior walls.

The patent application number TR 2015/08375 is related to a lightweight decorative insulation plaster which provides thermal sound, water and moisture insulation, also having antibacterial properties, resistant to fire and acidic rain, and reduces magnetic radiation. It has numerous components such as white cement, calcite, dolomite, zinc stearate, calcium stearate, quartz powder, melamine, vinyl acetate-vinyl versatate copolymer resin, powdered lime, aluminum sulfate, calcined colemanite boron ore, microfiber, expanded perlite, melamine formaldehyde sulfonate and methyl cellulose as well as lime and metakaolin. The patent application number TR 2019/08556 is related to a "mineral insulation material" obtained from a mixture of water, Si O2, slaked lime, cement and a hardening accelerator, and to a "production method", having special production stages such as foam preparation using a surfactant and steam curing in an autoclave.

The patent application number TR 2013/12066 is related to a "thermal insulation and sound insulation material", which has numerous inorganic additives, fiber and filling materials, organic and inorganic water repellent additive and impregnation additive, water and cement/gypsum/lime binder in its mixture, and to a special "manufacturing method" that includes the production stages of this material.

In addition to lime binder, cement binder was used in the mixtures of four of the products mentioned in the above patent applications (TR2019/1485, TR2019/08556, TR2015/08375 and TR2013/12066); and fine sand aggregate was used in the mixture of three (TR2019/14851, TR2019/08556 and TR2015/08375). All of the products mentioned in these five patent applications uses lime as additive or binder, however, none of them uses pure lime. An industrial curing method, such as steam curing in the autoclave causing water and energy consumption is used to finalize the products mentioned in these five patent applications. It is also seen that there are many components in the mixtures of these products. Some of these products have negative effects on human health and indoor air quality due to the presence of volatile organic compounds and plastic-based components.

Naima BELAY ACHI et al. aims to produce a new lightweight construction material obtained with mixtures containing straw (wheat, barley), lime and water. Two types of binders were used in the mentioned mortar products. The first of the binders is Tradical PF70, an industrial product, which is commercially available and contains 75% air lime, 15% hydraulic lime and 10% pozzolan. The presence of impurities in the components of the Tradical PF70 lime binder (i.e. impurities in the hydraulic lime) and the presence of the hydraulic lime in the Tradical PF70 mixture as a component already indicate that the Tradical PF70 binder is certainly not pure lime binder. Hydraulic lime is defined as a type of lime with an impurity content of at least 10% and 10% to 30% in the standards (TS EN 459-1 : 2015, ASTM C51- 18: 2018). For this reason, the lime binder used in the products mentioned in the Naima DI publication is not pure lime, but an artificial hydraulic lime. The other binder contains 75% air lime, 15% hydraulic lime and 10% Portland cement. This type of binder, which contains Portland cement and hydraulic lime, is certainly not equivalent to pure lime.

Brief Description and Objects of the Invention

The invention is a mortar composition consisting of pure lime, straw, metakaolin (low- temperature baked kaolin clay), and water and all components are available from local sources. Pure lime, which is preferred as a binder in the invention, is calcium hydroxide obtained by slaking the quicklime (calcium oxide) which involves impurities, such as clay less than 5%; and hardens slowly by the exposure of carbon dioxide and moisture in the air. Due to the presence of burnt clays and impurities in the hydraulic lime, the activity of its parts showing the hydraulic properties is largely terminated before the mortar is formed. In short, the part of the hydraulic lime that provides the hydraulic property has a minor role in carbonation and pozzolanic reactions (C-S-H formations) after the initial reactions are completed. Self-repair of the micro cracks that may occur in the mortar over time due to the differences in humidity and temperature is important. Pure lime has the feature of removing micro cracks (healing by filling). Pure lime lumps remaining in the mortar have the potential to penetrate into the cracks under high relative humidity or wetting conditions, dissolve at high relative humidity and refill the cracks with recrystallization (with its ability to maintain its binding nature thus to regenerate carbonation reactions). Therefore, in terms of raw material properties, the invention has much more sustainable, self-healing and healthy qualities that do not harm human health compared to the products known in the art.

With the invention, it is aimed to produce mortars with different "binderpozzolanic additive:bio-aggregate" ratios, and thermal and sound insulating plasters, multi-layered and multifunctional plaster systems, or multi-layered insulation board systems by using these mortars.

Another aim of the invention is to obtain a plaster that can be used in the repairs of historic timber frame structures, that is compatible with the wooden material, and that can be applied directly on the inner or outer side of the wall and on the lathing.

Mortar/pl aster products, whose binder is pure lime, and that are reinforced with straw fibers in the form of bio-aggregate, reinforced with pozzolanic additive, that can be used both in the repairs of historic buildings and in new structures, that have thermal and sound insulation properties, superior breathability, ability to increase the indoor air quality, self-healing property, and environmental sensitivity and that do not contain harmful materials for human health, are obtained with the invention.

Since the plaster products obtained by the invention are highly breathable, they are compatible with wooden materials. , and they are plaster products compatible with wooden materials and traditional timber-framed wall systems in terms of their composition properties (being pure lime-based, not containing cement and sand, exhibiting pozzolanic properties, etc.) and original sound and thermal insulation properties. It is superior to the standard recipe lath-and-plasters currently mixed on the construction sites in terms of performance and composition properties.

As being the main binder used in the invention, pure lime, by its nature, has properties of self- healing by its nature and improving the indoor air quality by reducing the CO2 concentration in the indoor environment.

Mortar/pl aster products with the following properties have been obtained by the invention, compared to mortar/pl aster products with cement binders or a large number of chemical/polymer components commonly used in the construction material industry;

□ Good sound and thermal insulation qualities,

□ Highly breathable, thus eliminating the trapped moisture problem in the building walls, and

□ Obtained from a small number of easily available components that do not pose a threat to local, environmental and human health,

□ Self-repairing micro cracks,

□ Improving indoor air quality,

□ Suitable for local production and industrial production,

□ That can be produced at a lower cost, and

□ Suitable as a “multi-layered plaster or board” application not only in new buildings, but also in historic buildings and traditional timber-framed structures.

The fact that these products have the above-mentioned performance properties means; □ Providing healthier and more comfortable indoor conditions for people and living bodies who live within four walls,

□ The walls plastered or coated with these mortar/plaster products will be less exposed to problems such as moisture or condensation, thus extending the life of the existing building walls, and

□ They are more economical mortar/plaster products.

Definition of the Figures Illustrating the Invention

Figure 1: XRD (X-ray Diffractometer) traces of L3W1 (left) and L1.5M1.5WT (right) products (P: Portlandite, C: Calcite, Q: Quartz, T: Tobermorite): XRD analyses of the L3W1 sample showing that pozzolanic reaction occurred between pure lime and to form CSH reaction products (Tobermorite and similar products) in and on the surfaces of the mortar product. It is revealed that straw is pozzolan since it has an electrical conductivity value of 1,97 mS/cm and that 1 gram of it can dissolve 40 mg Ca(OH)₂.

Figure 2: Graph showing the relationship between the bulk density values and the thermal conductivity values belonging to the thermal insulation materials widely used in the building sector, thermal insulation materials produced from alternative sources, some board products mentioned to have thermal insulation properties and the invention products.

Figure 3: Thermal conductivity/bulk density graph of thermal insulation materials widely used in the building sector, thermal insulation materials produced from alternative sources and invention products (on the left); Thermal conductivity/bulk density graph of some board products mentioned to have thermal insulation feature and invention products (on the right).

Detailed Description of the Invention

The invention is related to a mortar group comprising pure lime (Ca(OH)₂) as a binder, pozzolanic additive, and wheat straw as a bio-aggregate that provides sound and heat insulation. Metakaolin is preferred as the pozzolanic additive in the invention. Multi-layered and multifunctional plaster systems or insulation board systems are produced with mortars with different "binderpozzolanic additive:bio-aggregate" ratios. The types of mortar samples produced with various mixtures according to their compositions are summarized in Table 1. Mortar samples as the ones with pozzolanic additive (LMW) and without pozzolan additive (LW) were produced in two types with various mixtures. Many pozzolan-free mortars (L and LW) were produced with various binderbio-aggregate mixtures in the range of 1 :0 to 3: 1 ratios by mass; many mortars with pozzolan (LM and LMW) were produced with various binder:pozzolan:bio-aggregate mixtures in the range of 1 : 1 :0 to 1.5: 1.5: 1 ratios by mass. It is understood that, based on the mechanical properties of pozzolanic additive mortars (LMW), a much more fibrous mortar product can be produced by adding more straw to the binder:pozzolan:bio-aggregate mixture with the ratio of 1.5: 1.5: 1 by mass.

Table 1. Types of mortar products produced in different mixtures according to their components

All mortar types with mixtures in different proportions of were mixed by adding distilled water to have a flow consistency of ±15 cm and poured into molds. The flow consistency of the fresh mortar was measured as described in the standard "TS EN 1015-3: Determination of of consistence of fresh mortar by flow table". Mortar samples were kept in climate chambers (with an average of 90% relative humidity, a temperature of 21 ±3 °C and a CO2 concentration of 2000 ppm) where controlled conditions were provided for a total of 28 days; 7 days in and 21 days out of the mold. Afterward, they were taken to room conditions at an average temperature of 21±2°C and 32% relative humidity and they were kept in dry desiccators until they reached a constant weight to start performance analyses. The basic physical, physico- mechanical, mechanical, acoustical and thermal properties of bio-aggregated (strawcontaining) products (LW and LMW) are summarized in Table 2. The basic physical, physico-mechanical, mechanical, acoustical, and thermal properties of bio-aggregate-free mortar products (L and LM) are summarized in Table 3. Table 2. Physical, physico-mechanical, mechanical, acoustical and thermal properties of LW and LMW mortar products

Table 3. Physical, physio-mechanical, mechanical, acoustic and thermal properties of L and

LM mortar products

All produced bio-aggregated lime mortars (LW and LMW) are the products with bulk densities in the range of 0,4-0, 7 g/cm³, porosities in the range of 70-80% and water vapor permeability resistance values in the range of 1-2 (unitless). In short, these products are very lightweight, highly porous and highly water vapor permeable construction materials. It has been observed that mortar products become lighter and more porous as the amount of bioaggregate in the mixture increases.

These mortar products are highly breathable plaster types thanks to their high water vapor permeability. This quality is an important performance in terms of the longevity of the wooden material. These are plaster types that can be applied directly on laths for repair or maintenance purposes in timber-framed structures.

Bio-aggregated mortar products with a high level of breathability have high water absorption capacity. For this reason, they are the products that should be protected from water with a topcoat plaster. The lime plaster (L), which has a much lower water absorption capacity, is capable of this function.

The pozzolan added mortar sample (L1.5M1.5W1), which has the highest straw ratio, has the highest thermal insulation performance, with a thermal conductivity value of 0,06 W/mK, compared to other mortar products. It is possible to obtain a mortar product with a lower thermal conductivity as the amount of straw increases.

The pozzolan-free mortar sample (L3W1), which has the highest straw ratio, has the highest sound absorption performance, with 0,46 noise reduction coefficient and 0,40 weighted sound absorption coefficient values, compared to other mortar products. The same product has a good thermal insulation quality with a thermal conductivity value of 0,08 W/mK. In short, it can be used as a plaster mortar with good qualities in terms of both sound and thermal insulation.

Bio-aggregated lime mortars (LW and LMW) with different sound and thermal insulation properties can be used as infill mortar in the production of a multi-layered board. Such a use makes it possible to use a thicker layer of bio-aggregated mortar within a multi-layered board, thereby producing boards that provide better thermal and sound insulation.

The physico-mechanical and mechanical properties of bio-aggregated lime mortars (LW and LMW), which have good qualities in terms of thermal and sound insulation, are weak, but when they are used as infill mortar between two durable protective layers, a multi-layered insulation board (sandwich panel) can be produced. Pozzolan added lime mortar (LM), which has good physico-mechanical and mechanical properties, is a product that will provide a protective layer function. In short, sandwich insulation panel production is possible with the combination of infill material produced from LW and LMW mortars between two protective boards produced from LM mortar. The plastering of this panel with pure lime plaster (L) will prevent the water from penetrating into the multi-layered board.

In the case of the production of large-scale sandwich insulation panels, it is possible to apply LM and L products, which are protective layers, together with the wire lath and to increase the strength of these layers.

All bio-aggregated mortar products have a fibrous texture of different heterogeneities as a result of the use of different amounts of straw. The pozzolanic reaction of wheat straw and the use of metakaolin as a pozzolanic additive form a bond structure that holds multiple fibrous heterogeneous tissues together (Figure 1). The fact that the mortars produced have pozzolanic properties means that these mortars have strong bonding properties with each other. In short, it is possible to produce multi-layered board (sandwich panel) that will maintain its structural integrity thanks to the pozzolanic properties of the lime mortars of the invention.

The mortar products of the invention are construction materials completely different from the widely used mineral-based and polymer-based insulation materials, especially in terms of physical and composition properties. Alternatively, they are thought to be closer to the organic product group available on the market. However, they differ from the group of organic-based insulation materials produced as fiber and wool blanket sheets in terms of physical and composition properties.

Typical thickness, bulk density, water vapor diffusion resistance coefficient and thermal conductivity values of thermal insulation materials widely used in the building sector, thermal insulation materials produced from alternative sources, some board products that are mentioned to be have thermal insulation properties and the invention products are summarized in Table 4.

These industrially-manufactured products are produced in various thicknesses and bulk densities. All thermal insulation materials widely used in the construction material industry or the ones produced from alternative sources are lightweight (with low bulk density) and have low thermal conductivity values (Figure 2 and Figure 3) in any case. Board products, which are claimed to have high thermal insulation performance in the market, are products that are heavier (with higher bulk density) and provide less insulation (with higher thermal conductivity coefficient) compared to thermal insulation materials (Figure 2 and Figure 3). Even though the mortar/pl aster products of the invention show physical properties close to board products, they have slightly higher bulk density but lower thermal conductivity properties compared to these products; in short, they are denser but more thermally insulating products (Figure 2 and Figure 3). In addition, they have much superior breathing properties compared to all other products (water vapor diffusion resistance coefficient values (p value) are very low) (Table 4).

Table 4. Typical thickness, bulk density, water vapor diffusion resistance coefficient and thermal conductivity values of widely used thermal insulation materials in the building sector, thermal insulation materials produced from alternative sources, some board products mentioned to have thermal insulation properties, and invention products are shown.

Claims

1. A building and insulation material that provides thermal and sound insulation characterized in that it is a mortar that comprises pure lime (Ca(OH)₂) as binder, straw and water as bio-aggregate.

2. A building and insulation material according to claim 1, characterized in that the binderbio-aggregate ratios are in the range of 3 : 1 to 9: 1 by mass.

3. A building and insulation material according to claim 1, characterized in that it comprises pozzolanic additive.

4. A building and insulation material according to claim 3, characterized in that the pozzolanic additive is metakaolin.

5. A building and insulation material according to claim 4, characterized in that the binderpozzolanic additive ratio is 1 : 1 by mass.

6. A building and insulation material according to claim 4, characterized in that the binder: pozzolanic additive:bio-aggregate ratio is in the range of 1,5: 1,5: 1 to 4, 5:4, 5: 1 by mass.

7. A building and insulation material according to claim 4, characterized in that the binder:pozzolanic:bio-aggregate ratio is 1,5: 1, 5: 1 by mass.

8. A building and insulation material according to claim 1, characterized in that the binderbio-aggregate ratio is 3: 1 by mass.

9. A building and insulation material according to claim 1, characterized in that it comprises wheat straw as bio-aggregate. A building and insulation material according to claim 1, characterized in that it is in panel form. A building and insulation material according to claim 1, characterized in that it is in the form of a sandwich panel. A construction material in sandwich panel form according to claim 11, characterized in that it comprises a mortar layer with a binder:pozzolanic:bio-aggregate ratio of 1,5: 1, 5: 1 by mass and/or binderbio-aggregate ratio of 3: 1 by mass, which provides thermal and sound insulation on the inside of the sandwich panel, and a mortar layer with a binderpozzolanic additive ratio of 1 : 1 by mass, which protects the structure against mechanical effects on the outside.