Реферат содержит: материал перевода 15252 печатных знаков (6 стр.), перечень использованной литературы – 5 источников, словарь научных терминов – 300 слов.
Цель работы – провести тематический обзор зарубежных источников по определению материалов на основе гипса и методов подготовки и использования.
Хотя гипс является одним из самых экологически чистых связующих веществ, его использование в зданиях относительно ограничено, и поэтому желательно расширить ассортимент продуктов из гипса.
Одной из возможностей является разработка легких гипсовых материалов с лучшими теплоизоляционными свойствами, привлекательными акустическими свойствами, а также более низкими транспортными издержками. Легкие гипсовые материалы могут использоваться аналогично аэрированному автоклавированному бетону (AAC), потребление энергии которого при производстве в несколько раз выше.
Даны данные об основных понятиях гипса. В работе описаны и сопоставлены основные методы подготовки легких материалов на основе гипса.
АНАТАЦЫЯ
МАТЭРЫЯЛЫ НА АСНОВЕ ГIПСУ: МЕТАДЫ ПАДРЫХТОЎКІ І ВЫКАРЫСТАННЯ
Ключавыя словы: гіпс, лёгкія гіпсавыя матэрыялы, гіпсакардон, метад, шпатлёўка
Рэферат змяшчае: матэрыял перакладу 15252 друкаваных знакаў (6 стр.), пералік выкарыстанай літаратуры – 5 крыніц, слоўнік навуковых тэрмінаў – 300 слоў.
Мэта работы – правесці тэматычны агляд замежных крыніц па вызначэнні матэрыялаў на аснове гіпсу і метадаў падрыхтоўкі і выкарыстання.
Хоць гіпс з'яўляецца адным з самых экалагічна чыстых злучных рэчываў, яго выкарыстанне ў будынках адносна абмежавана, і таму пажадана пашырыць асартымент прадуктаў з гіпсу.
Адной з магчымасцяў з'яўляецца распрацоўка лёгкіх гіпсавых матэрыялаў з лепшымі цеплаізаляцыйнымі ўласцівасцямі, прывабнымі акустычнымі ўласцівасцямі, а таксама больш нізкімі транспартнымі выдаткамі. Лёгкія гіпсавыя матэрыялы могуць выкарыстоўвацца аналагічна бетону (AAC), спажыванне энергіі якога пры вытворчасці ў некалькі разоў вышэй.
Прыведзены звесткі аб асноўных паняццях гіпсу. У працы апісаны і супастаўленыя асноўныя метады падрыхтоўкі лёгкіх матэрыялаў на аснове гіпсу.
SUMMARY
GYPSUM BASED MATERIALS: METHODS OF PREPARATION AND UTILIZATION
Keywords: gypsum, lightweight gypsum materials, plasterboard, method, filler
Abstract includes: material translation 15252 symbols (6 pages), references – 5 sources, list of terms – 300 words.
Purpose – a thematic review of foreign sources by definition of the gypsum based materials und methods of preparation and utilization.
Although gypsum is one of the most environmentally friendly building binders, its use in the buildings is relatively limited and therefore the broadening of the gypsum product portfolio is desirable.
One possibility is the development of the lightweight gypsum materials with better thermal insulation properties, attractive acoustic properties and also lower transportation costs. The lightweight gypsum materials can be used in a similar way as an aerated autoclaved concrete (AAC), whose energy consumption at production is several times higher.
Data are provided on the basic concepts of gypsum. The main methods of the preparation of gypsum-based lightweight materials are described and compared in the work.
INTRODUCTION
Gypsum is one important material that has been used as mortar and plaster in different periods in architecture. This is produced in some methods that were applied from many years ago to today. By making modern and industrial production methods, the traditional methods don’t use or their usage have been reduced.
In the past few decades, gypsum-based renders and plasters have become the material of choice for indoor finishing in many countries. Excellent performance, attractive appearance, easy application, and its healthful contribution to living conditions have made gypsum a most popular finishing material for centuries. Availability, the relatively low level of start-up investments, and a favorable market situation, all provide conditions for growth and the profitable industrial production of gypsum-based materials.
The majority of gypsum-based composite materials (GBCM) can be specified within the following groups:
- plasters and renders,
- adhesives,
- jointing/filling compounds.
Contemporary requirements for gypsum-based composite materials (GBCM) for rendering or plastering include controlled setting time, good workability, sag resistance, high compressive and flexural strength, perfect bond to concrete or brick, water resistance, and improved heat and noise insulation.
We describe and compare the main methods of the preparation of gypsum-based lightweight materials are described and compared.
BASIC PART
About gypsum
Gypsum is a rock like mineral commonly found in the earth’s crust, extracted, processed and used by Man in construction or decoration in the form of plaster and alabaster since 9000 B.C. Plaster was discovered in Catal-Huyuk in Asia in an underground fresco, and in Israel Gypsum floor screeds were found from 7000 B.C. During the time of the Pharaohs, Gypsum was used as mortar in the construction of the Cheops Pyramid (3000 B.C.). In the Middle Ages and the Renaissance, decorations and artistic creations were made of plaster. Since then, the range of construction-related uses have continued to multiply [5, p. 4].
Gypsum (calcium sulfate dihydrate) is a well-known mineral that is obtained from natural resources and used as different building materials. Gypsum is burned to calcium sulfate hemihydrates or anhydrite [1, p.1].
The gypsum is a large used material in building construction by its diverse applications. However it is up till now a material with a lack of know-how, mainly at research level. The European production of extracted gypsum attained 21milions in 1996. The European industry has 220 factories that produce gypsum products and employ, direct or indirectly, more than 400 000 people [4]. The building sector consumes about 95% of total gypsum produced. It is calculated that about 80 to 90% of finishing interior work and partition walls in buildings are made of gypsum products, such as plaster and card gypsum. According to those thermal and acoustical properties, these products contribute significantly for the comfort of millions of persons. Having an extraordinary resistance to fire, the gypsum products contribute for the buildings security, particularly in public buildings such as cinemas [4].
One of biggest deficiencies of gypsum as construction material is the low resistance to water presence. Although, actually, this aspect can be partially solved by adding to the gypsum some compounds based on silicones or other polymers, namely in gypsum card boards. This way, gypsum can be submitted to humid conditions, but even so do not permit utilization in external environments because of its low resistance to long direct contact with water.
The modern use of gypsum in construction: Plasterboard
The modern use of Gypsum as a building material was discovered in 1888 when the American Augustine Sackett invented a machine for producing plasterboards (also known as wallboards and dry walls) composed of several layers of paper with Gypsum in-between.
The first plasterboard plant was built in the USA in 1901. In 1908, the plasterboard technique was improved by the American Stephen Kelly who patented plasterboard with a Gypsum core and one layer of paper on the front and back side. The modern plasterboard was born.
Since then plasterboard technologies have developed to include new properties (acoustic and fire resistance) maintaining, however, the basic technique invented by Stephen Kelly.
In Europe, the first plasterboard plant was built in Liverpool in 1917 and the second one in London in 1926. In continental Europe, the first factory was completed in Riga in 1938.
Nowadays, the manufacturing of plasterboards is increasing worldwide. In Eastern and Western Europe, there are currently more than 200 factories producing plasterboards [5, p.5].
Uses of gypsum products in home interiors
More than 1,500 million m2 of European interior surfaces are covered every year with plasterboards, blocks or plaster.
A. Plasterboards
Plasterboard is used for partitions and the lining of walls, ceilings, roofs and floors. The properties of plasterboard can be modified to meet specific requirements, such as fire resistance, humidity resistance, impact resistance, etc.
B. Decorative Plaster
Plaster powder, mixed with water, manually or through the use of silo-supplied spray systems, is used to create an effective and aesthetically-pleasing lining for brick and block walls, and for ceilings.
Gypsum’s adaptability in application lends itself to moulding and shaping. Since time immemorial, Gypsum has been used by skilled craftsmen to create decorative plaster mouldings.
C. Building plaster
Gypsum plaster is used for walls and ceilings.
D. Plaster blocks
Gypsum blocks are used for partitions and Gypsum tiles for ceilings.
E. Gypsum-based self-levelling screed
Anhydrite or Alpha-Hemihydrates are used in the production of selflevelling floor screeds.
F. Gypsum Fibreboards
Gypsum fibreboard is used for partitions and the lining of walls, ceilings, roofs and floors. Standard Gypsum fibreboard offers good performance when it comes to impact resistance, sound insulation and humidity resistance [5, p. 6].
Indirect lightening
The simplest method to prepare lightweight material is the use of the lightweight fillers that can be added to the gypsum paste. This method is largely applied in the production of the lightweight concretes, but for gypsum-based materials is not so common. The fillers are not usually added to the gypsum paste, they are not necessary here since the gypsum does not shrink during the setting (contrary to cement and lime). Nevertheless, the indirect lightening of the gypsum-based materials is used, although in the smaller extend than in the cementbased materials. As a lightweight filler both the inorganic and organic materials can be used.
Utilization of inorganic fillers is advantageous from the point of fire resistance, but the organic materials are usually lighter and less expensive.
Inorganic fillers
The most common fillers in the commercially available products are expanded perlite and vermiculite. Perlite is an amorphous volcanic glass and vermiculite is phyllosilicate mineral, both of them contain relatively high amount of bound water and when subjected to heat, they expand and create very lightweight aggregate. The bulk density of the gypsum with inorganic fillers is usually higher than 800 kg/m3, exceptionally the materials with the lower bulk density (under 300 kg/m3) are commercially available. Demir and Baspinar put the perlite in the amount of 5%–10% by mass into the fly ash–lime–gypsum material with the silica fume addition. They obtained material with the bulk density about 730 kg/m3 (i.e. ca 20% lower than material without perlite) and its compressive strength was 2.3 MPa. Genzel et al. [4] used the vermiculite together with the polypropylene fibres. With 20% of vermiculite they achieved only slight decrease of bulk density (about 10%) at the strength loss about 30%. The thermal conductivity decreased by 30%.
As an interesting experiment seems to be use of the expanded silica gel granules. Baspinar and Kahraman expanded silica gel at the temperature 1,200°C. Expanded granules were then added in the amount 5%–15% by mass into the gypsum slurry. Considering the relatively high price of the silica gel and the high-energy consumption at the expanding process the material is not competitive on the market.
Direct lightening
The term direct lightening is used when the pores are incorporated directly into the gypsum matter, either chemically or mechanically. The pores can be introduced into the gypsum material by gas-releasing chemical reaction or by mechanical frothing using surface active substances.
Chemical lightening by gas
There is significant difference between the chemical composition of the gypsum and other inorganic binders. Whereas cement and lime contain calcium hydroxide and are strong basis, gypsum (CaSO4·0,5H2O) is neutral or mildly acid. Therefore the gas-releasing chemical reactions have to be different from the reactions, which are utilized for the lightening of the cement or lime.
As a foaming gas the carbon dioxide is used mostly, because there can be applied several suitable chemical reactions. The most common is the reaction of carbonate (or hydrocarbonate) with the acid component (1).
As a carbonate component the calcium carbonate (e.g. in the form of chalk or grounded limestone or marble dust), sodium bicarbonate (NaHCO3) or ammonium bicarbonate (NH4HCO3) can be used.
As an acid components mostly inorganic acids or salts are usually used (e.g. aluminium sulphate, sulphuric acid, boric acid), but organic acid can be used also. Gamarra in the first patent concerning the chemically foamed gypsum [18] describes the acid component composed from tartaric acid and calcium chloride.
Typical reactions are the reaction of the aluminium sulphate with the calcium carbonate (1) or the decomposition of the ammonium bicarbonate in the water (2).
CONCLUSION
Lightweight gypsum is a material resembling the AAC, and therefore, it can be used in similar way. The lightweight blocks and panels for walls, partitions and acoustic constructions could be made from it, similarly to the AAC. In addition to the interior thermal-insulating plasters, light weight fireproof plasters, ready-to-use dry mortars and the core of the thermal insulating gypsum boards may be also produced from the lightweight gypsum materials.
The main disadvantage of gypsum-based materials, compared to AAC is that gypsum could not be used in the wet environment. Gypsum is partially soluble in water and its strength decreases with the increasing moisture of the material, therefore the gypsum products have to be protected against water.
Nevertheless this disadvantage is compensated by the significantly better ecological and economical properties of the gypsum. In comparison, AAC is made from quicklime, burned from the limestone at the temperature about 1,000°C. AAC also has to be autoclaved (cured in pressurized steam) to obtain final properties, so another energy demanding technology is utilized in its production. On the contrary, gypsum is prepared at the relatively low temperature under 200°C, and it could be produced from several waste products (e.g. from FGD gypsum or phosphogypsum). Gypsum industry is also one of the forerunners in transformation to the circular economy in the construction industry, because gypsum products are indefinitely and fully recyclable. With regard to these facts the larger utilization of the gypsum-based products is highly desirable.
LIST OF TERMS
1. abundance – изобилие
2. accelerators – ускорители
3. accordingly – в соответствии
4. acoustical properties – акустические свойства
5. activities – деятельность
6. actual – действительный
7. additives – добавки
8. adhesive – клей
9. admixture – примесь
10. adverse – неблагоприятный
11. alabaster – алебастр
12. allocation – распределение
13. analysis – анализ
14. annealing – отжиг
15. appearance – появление
16. application – применение
17. area – площадь
18. architecture – архитектура
19. asbestos – асбест
20. asset - актив
21. autoclave – автоклав
22. balance – баланс
23. binder – связующее вещество
24. brick – кирпич
25. building materials – строительные материалы
26. building sector – строительный сектор
27. bulk – масса
28. burning – обжиг
29. by-product – побочный продукт
30. calcium sulfate dihydrate – дигидрат сульфата кальция
APPENDIX
Gypsum Products’ Unique Properties
1. Fire Properties
• Fire Resistant
Due to the natural composition of Gypsum, gypsum plasterboards are inherently fire resistant. It offers a high qualitative solution to prevent the spread of fire in buildings and effectively protect the householder from fire. The chemical formulation of Gypsum is CaSO4, 2H2O – Calcium Sulphate Dihydrate -. In nature, Gypsum occurs in the form of crystals.
Thanks to the presence of water in Gypsum (H2O), one square meter of plasterboard of 15 mm thickness contains around 3 litres crystal water.
Through the action of fire, the crystal water evaporates and a protective layer of Gypsum is formed. Behind this layer, the material under fire attack remains at constant temperature around 100oC as long as water is released from the Gypsum, impeding the spread of a fire to other parts of the building.
The inclusion of glass fibres in Gypsum boards enhances their fire protection performance by maintaining the integrity of the board in a fire. So Gypsum is a powerful fire retardant element in the construction sector due to its non-combustibility and ability to delay for up to 4 hours
- according to the number of plasterboards in the corresponding system
- the progression of fire.
• Non-combustible
The European Classification System (Euroclasses), devised for the classification of reaction to fire, is part of the ongoing harmonisation of European standards.
Reaction to fire has traditionally been assessed using at least 30 different national standards across Europe. Not only is the Euroclass system new, but it includes new tests designed to better evaluate the reaction of building products to fire.
Уникальные свойства гипсовых изделий
1. Противопожарные свойства
• Огнеустойчивый
Благодаря природному составу гипса гипсокартонные плиты по своей природе являются огнестойкими. Он предлагает высокое качественное решение для предотвращения распространения пожара в зданиях и эффективной защиты домовладельца от пожара. Химический состав гипса представляет собой CaSO4, 2H2O - дигидрат сульфата кальция. В природе гипс встречается в виде кристаллов.
Благодаря наличию воды в гипсе (H2O) один квадратный метр гипсокартона толщиной 15 мм содержит около 3 литров кристаллической воды.
Благодаря действию кристалла кристаллическая вода испаряется и образуется защитный слой гипса. За этим слоем материал, находящийся под огнем, остается при постоянной температуре около 100 0C до тех пор, пока вода высвобождается из гипса, что препятствует распространению огня в другие части здания.
Включение стекловолокна в гипсокартонные плиты повышает их огнезащитные свойства, поддерживая целостность плиты в сборе. Таким образом, гипс является мощным защитным элементом в строительном секторе из-за его негорючей способности и способности задерживать огонь на срок до 4 часов:
- в зависимости от количества гипсокартона в соответствующей системе;
- прогрессирования огня.
• Негорючий
Европейская система классификации (Euroclasses), разработанная для классификации реакции на огонь, является частью продолжающейся гармонизации европейских стандартов.
Реакция на огонь традиционно оценивалась с использованием по меньшей мере 30 различных национальных стандартов по всей Европе. Новая система Euroclass включает в себя новые тесты, призванные лучше оценивать реакцию на производство строительных изделий.
