EFFECT OF MINERAL ADMIXTURES ON CEMENTITIOUS MATERIALS - 275 Words

EFFECT OF MINERAL ADMIXTURES ON CEMENTITIOUS MATERIALS (Research Paper Sample) Content: Name Instructor Course Date Effect of Mineral Admixtures on Microstructure of Cementitious Systems 1.0 Introduction Admixtures are included in the concrete to help improve the concrete quality. Some of the notable mineral admixtures include the fly ash (FA), the granulated blast furnace slag (GGBS), the silica fume (SF), metakaolin (MK) and the rice husk ash (RHA). These minerals establish different characteristics that influence the concrete property. The notable advantage of the mineral admixtures is the hardening features exhibited in concrete materials. On the other hand, it is also true that these mineral admixtures can influence the quality nature of wet concrete between the mixing and hardening time. This occurs in one of the following ways; affecting the demand for water, hydration heat, reactivity, setting time and bleeding (Setzer, Rainer Auberg, and Keck 213). Literally, literature that summarizes mineral admixtures influence on the microstructure of cementitious systems. Further, the impact of the mineral admixtures on durability and mechanical properties of concrete is an important po int of focus. Besides, the effect of mineral admixtures on concrete properties is vital since the presence of these properties affects the mechanical and durability qualities of concrete (Bartos 126). There are a variety of comparative studies have been undertaken, primarily the effect of blast furnace fly ash and slag when hydrating the fresh cement pastes, impact of the silica fume (SF), the metakaolin (MK), ground granulated blast furnace slag (GGBS) and fly ash during the setting of the high-strength concrete. The aim of this paper is to examine the effect that mineral admixtures have on the microstructure of cementitious systems (Bartos 135). At the same time, the paper makes a distinctive comparative assessment of the mineral admixtures on the hydration heat, water demand, bleeding, setting time and the concrete reactivity. Additionally, the effect of chemical and physical characteristics of silica fume (SF), ground granulated blast furnace slag (GGBS), fly ash (FA), the rice husk ash (RHA) and metakaolin (MK) on the microstructure of cementitious systems (Bartos 201). In this case, therefore, examining C à ¢Ã¢â€š ¬Ã¢â‚¬Å" S à ¢Ã¢â€š ¬Ã¢â‚¬Å" H (Calcium Silicate Hydrate) will be the critical point of examination in this paper. 2.0 Background Coal FA (fuel ash) was first used in concretes in the year 1934. Afterward, based on different research work that was made during the 1950s, several dams were constructed in the United Kingdom by utilizing FA as the partial cementitious material. From this period, these structures have since been exhibiting outstanding conditions (Brebbia and Klemm 233). Pulverized à ¢Ã¢â€š ¬Ã¢â‚¬Å"fuel ash (PFA) or FA obtained from coal materials is a pazzolan that emanates in a low-permeable and durable concrete (Setzer, Rainer Auberg, and Keck 219). This type of concrete can withstand ingress of the deleterious chemical components. Initially, the pazzolan was identified as the controller of the damaging alkali à ¢Ã¢â€š ¬Ã¢â‚¬Å" silica reactions (the ASR) during the year 1949 (Barbero 198). The presence of alkali in the FA concrete is often higher than the cementitious materials lacking the FA (Barbero 206). Hence, this confirms that the presence of FA is important as it protects cementitious mat erials from ASR effects. Therefore, utilization of FA in concretes has been investigated for a long period and each time, good conditions of the material have been reported. The ground granulated blast furnace slag (GGBS) was first discovered in 1862, and commercial productions started later on in 1865 (Bentur, Arnon, and Kovler 278). The concrete forms that contain GGBS have been identified in a variety of pieces of literature as the slag concrete. This material is being successfully used in different countries as it has many benefits. The SF materials were first obtained during the filtration of exhaust gases from the furnaces in the form of fumes. A great portion of fumes was made up of the fine form of powder with a high silicon dioxide percentage (Brebbia and Klemm 238). Since then, gas filtration has been done on a large scale and during 1976, the first standard of NS 3050 was recommended for use in the factories producing cement. SF is hence, one of the high-quality material used in concrete and cement industry (Kringos 322). Notably, it is stated that adding 8 à ¢Ã¢â€š ¬Ã¢â‚¬Å" 10% by the weight SF in the concrete material; the resulting effect will range between 50, 000 à ¢Ã¢â€š ¬Ã¢â‚¬Å" 100,000 microspheres per cent particles (Bentur, Arnon, and Kovler 293). This implies that the concrete mix becomes highly cohesive and denser because of the presence of the fine particles of SF. MK refers to processed form of amorphous silica components. It is acquired from the calcination of the kaolin at the temperature of 600 à ¢Ã¢â€š ¬Ã¢â‚¬Å" 8500C (Siddique 219). Kaolin materials occur naturally. Its mineralogical and chemical compositions are based largely on the source rock (Tanabe 217). It occurs widely as white clay that results from naturally decomposing feldspar and it is utilized as paper filler, manufacturing of the porcelain materials and textiles as well as an absorbent in the medicines. Lastly, rice husk refers to the outer cover of rice grain characterized by high silica concentration within a range of 80% to 85%. The rice husk makes up 30% of the total weight of the rice kernel. Structurally, it consists of 80% organic components and around 20% non-organic components (Tanabe 414). These materials have a large content of pozzolanic activities because of non-crystalline silica and particular surface area. It is often utilized in the lime pazzolan mixes to replace Portland cement partly. 3.0 Calcium Silicate Hydrate 3.1 What is C à ¢Ã¢â€š ¬Ã¢â‚¬Å" S - H? 2The Calcium silicate hydrate (C-S-H) refers to the main binding components of the Portland cement paste containing 60 à ¢Ã¢â€š ¬Ã¢â‚¬Å" 70% of fully hydrated paste. In the Portland cement, ÃŽÂ ² à ¢Ã¢â€š ¬Ã¢â‚¬Å" C2S and C3S hydrate forming calcium hydroxide (CH) and C-S-H. The shorthand nomenclature of cement is utilized through this research paper, whereby C = CaO, S=SiO2, A = Al2O3, H = H2O. C-A-S-H and C-S-H mean a variable constituent of the main species. C-S-H is almost an amorphous, contains a variety of stoichiometry (Tseng 102). Additionally, the material is capable of incorporating the guest ions, especially aluminum. Mostly, the natural component of calcium silicate hydrate tobermorite has been utilized largely for modeling the molecular structure of the C-S-H. Most probably, aluminum incorporation into the structure of C-S-H plays a vital role in the mechanical and chemical behavior of the C-S-H (Tseng 49). The Supplementary Cementitious Materials (SCMs) may be adde d to the concrete mixtures as a way of increasing the quality of the cement properties. The commonly used SCMs, slag and fly ash is made up substantial quantities of the reactive aluminum. Notably, it is possible to incorporate aluminum into natural calcium silicate hydrate tobermorite. C-A-S-H is a form of C-S-H that has been substituted by aluminum and it is formed after dehydrating the presence of the Al3+ ions from Portland cement. Al3+ ions become present in the component when slag and fly ash is dissolved in the water (Scheirs, John, and Long 209). Therefore, the quality of C-A-S-H is achieved in the concrete when SCMs which contains reactive aluminum components to the concrete mixtures. 3.2 What are different C-S-H phases? According to (Finch, Robert and Bullen 178), there are two types of the C à ¢Ã¢â€š ¬Ã¢â‚¬Å" S à ¢Ã¢â€š ¬Ã¢â‚¬Å" H phases. C à ¢Ã¢â€š ¬Ã¢â‚¬Å" S à ¢Ã¢â€š ¬Ã¢â‚¬Å" H is described as the basic hydration product exhibited in the form of a corrugated platelet. The two types of C à ¢Ã¢â€š ¬Ã¢â‚¬Å" S à ¢Ã¢â€š ¬Ã¢â‚¬Å" H are type I and II. In type C-S-H (I) the ratio of Calcium à ¢Ã¢â€š ¬Ã¢â‚¬Å" Silicate is about 0.8 à ¢Ã¢â€š ¬Ã¢â‚¬Å" 1.5 while for type C-S-H (II), the ratio is 1.0 à ¢Ã¢â€š ¬Ã¢â‚¬Å" 2.0. Based on these two phases, the crystal nature of the phases increases with the Calcium à ¢Ã¢â€š ¬Ã¢â‚¬Å" Silicate ratio. The C à ¢Ã¢â€š ¬Ã¢â‚¬Å" S à ¢Ã¢â€š ¬Ã¢â‚¬Å" H (I) is exhibited in the electron micrographs in the form of flakes. On the other hand, the C à ¢Ã¢â€š ¬Ã¢â‚¬Å" S à ¢Ã¢â€š ¬Ã¢â‚¬Å" H (II) is exhibited in the forms fiber. These fibers correspond to a rolled platelets having the CH layers as shown in the following figure; Figure 1: The Rolled C à ¢Ã¢â€š ¬Ã¢â‚¬Å" S à ¢Ã¢â€š ¬Ã¢â‚¬Å" H (II) Platelets Source: Nano and microstructure of Portland Cement Paste A B à ¢Ã¢â€š ¬Ã¢â‚¬Å" the C à ¢Ã¢â€š ¬Ã¢â‚¬Å" S à ¢Ã¢â€š ¬Ã¢â‚¬Å" H layers C à ¢Ã¢â€š ¬Ã¢â‚¬Å" The interlayer region D à ¢Ã¢â€š ¬Ã¢â‚¬Å" The spaces between rolled leaves E à ¢Ã¢â€š ¬Ã¢â‚¬Å" The internal spaces in the roll There are five varieties of the C à ¢Ã¢â€š ¬Ã¢â‚¬Å" S à ¢Ã¢â€š ¬Ã¢â‚¬Å" H phases that grow during the hydration process. They are described as needle-like, gel-like, sword-shaped and flake-shaped phases. In this regard, therefore, it can be noted that the C à ¢Ã¢â€š ¬Ã¢â‚¬Å" S à ¢Ã¢â€š ¬Ã¢â‚¬Å" H phases can undergo different morphological changes when C3S is hydrated. 3.3 How to Investigate Different C-S-H Phases? Different C à ¢Ã¢â€š ¬Ã¢â‚¬Å" S à ¢Ã¢â€š ¬Ã¢â‚¬Å" H phases can be investigated using classical X à ¢Ã¢â€š ¬Ã¢â‚¬Å" ray on concrete and mortar material in a laboratory setting. In this way, the investigator can examine the distribution and quantify the phases that occur in the structure. This new technique is capable of enabling the evaluation of the microstructure of the cementitious system through a 3 à ¢Ã¢â€š ¬Ã¢â‚¬Å" dimensional imaging (Davidovits 129). To begin, one will select two different forms of mortar bars that are fabricated in accordance with the DIN. The first mortar can be fabricated from the mixtures of norm sand and cement in a ratio of 1: 3 while the second bar which contains 75% sand composition the remaining 25% partially replaced by the waste of glass powder (Malhotra 118). It is expected that when cement is replaced by the reactive wastes of glass powder it results in porosity reduction especially ...

High Arts Importance in the World - Free Essay Example

Pablo Picasso, a famous painter, sculptor, and poet, declared, The purpose of art is washing the dust of daily life off our souls (Sherzai). Art gives people a reason to question society and look at the complexities of life. Life is boring and unvalued without craftsmanship. Art, whether it is music, drawing, or painting, gives people a way to express what they are really feeling and gives people an outlet from their daily life. In Aldous Huxleys book, Brave New World, art is banned and destroyed. No one is allowed to read, see, or have any contact with any form of art. Without literature, people will never think and learn of course they will live in a stable society where nothing will ever change, but people pay the price of creativity and the ability to think (Gehlhaus). The leaders in Brave New World suggest that youve got to choose between happiness and what people used to call high art. Weve sacrificed the high art(Huxley 220). Huxley depicts the true nature of man. Man would rather be happy than learn and grow as a person. In todays world, art teaches and explains values and when art is sacrificed in Brave New World, its people lose the valuable teachings and growth it brings. In fact, high art should not be sacrificed because art is filled with values and teachings that man can always learn from. For example, it is through art that human beings have found the real meaning of beauty and are able to make it a reality in their lives as well(Sherzai). Without art, humans have no idea what true beauty is because they would have no reference of true beauty. There would not be no images or relations of the amazing wonders art can bring. Subsequently, high arts impact on humans cause the expansion of ideas and creativity. Nobody wants to live in a world where everything is boring and unexciting. If it is difficult to live without science, living without art would be tasteless and colorless (Sherzai). In Brave New World, it is exactly that, tasteless and colorless. The citizens live their lives day to day doing nothing but what they have always done; nothing is different and nothing makes them think. If they very start to question why, they just use soma, a halluc inogen that helps people escape from troubling times, to get rid of those thoughts. Art not only has made life interesting and colorful but arts have enriched the human culture, influenced their way of living and even their thinking (Sherzai). Humans are not dolls to be manipulated by whoever and whenever. They have their own thought, opinions, and ideas. Art gives them a way to express those ideas but it also provides people with the opportunity to learn about those different ideas or opinions. If everyone is only fed one concept or belief then that is all they are going to believe, but if everyone is fed a multitude of diverse beliefs then they will have the option of what they want to believe in. High art gives that option to be different and explore various ideas. That is why the leaders in Brave New World banned all high art; they did not want contrasting ideas than their own floating around the world. Moreover, high art should not be sacrificed because of the multitude of posi tive impacts it has on human beings. In particular, high art needs to be valued because of the valuable growth it brings. Humans are very conditioned to live life for money. They go to school so they can earn a good job to make lots of money for their future. Humans do not stop to smell the roses and see the beauty of the world. They have a one track mind and do not lift their foot off the gas pedal, but art can stop the constant self-centered life. Art can teach us how to go into life with the ability to see the beauty of everything in the natural world (Unknown). With high art, not only will people stop their one track minds but they will be able to appreciate the beauty in life. Also, Art teaches you how to see the world in your own imagination (Unknown). It is one thing to see the world, but it is another to see it through ones own lense. Everyone has different interpretations of the world that helps them grow as a person. If every person thought the same way, this world would be very boring and unattractive. One th ing that makes this world amazing and beautiful is the diversity and uniqueness it is filled with, and that is all thanks to high art and its valuable teachings. High art deserves to be valued and taught. It not only impacts human perspective but the way they live their lives. Humans can easily get sidetracked by how important science and math are but if art is not taught, humans will not get the opportunity to express themselves in diverse ways. In Brave New World, the world leaders were only focused on math and science. They did not care about any high art or anything that creates different answers than their own. Since their primary focus was on science, people turned into robots. They only followed one schedule everyday, when something was difficult they would take soma, and everyone thought and felt the same way. After all, what people care the most about reflects who they are. Since, art searches beauty, finds it, and brings it to human life (Sherzai), there is no real question as to why there was no beauty in their world. They had nothing to bring in beauty to their world; they were forced to live in a bland and boring world. For examp le: Take the collective memory from our museums; remove the bands from our schools and choirs from our communities; lose the empathetic plays and dance from our theatres or the books from our libraries; expunge our festivals, literature and paintings, and youre left with a society bereft of a national conversationabout its identity or anything else. (Bazalgette) Arts Council chief Peter Bazalgette just gave the perfect picture of what an art free world looks like. No music, books, paintings, nothing that would give a society its culture. High art has more of an impact on daily life than one would expect. Every which way has something influenced by art. High art not only gives people a voice but it gives them culture and meaning to their lives. When high art is left behind, everything would change and life as one knows it would be different. Art is not just important because of the beauty it brings, but the identity it delivers. In Brave New World, Huxley emphasizes that in order for a utopian society to achieve a state of stability, loss of individuality, and the undoing of Mother Nature must occur. Successfully engineering these conditions produces a world where people are finally living happily ever after, but at a great cost(Gehlhaus). Those great costs are losing anything that causes people to be different; high art, religion, and any unrelatable books were the first to go. They did not care nor see the impact they were causing by banning the arts. They lost all sense of beauty, free thought, imagination, and different styles of thinking. In their world state motto, they endorse community, identity, and stability but they have no sense of identity if everyone is the same. Even though their world is fictional, it still plays a prominent role today. It shows what will happen if high art is left behind and what will come of it. If art ends up being left behind, the world will become unbeautiful, colorless, unimaginative, uncreative, and robotic in days to come.