By definition, a pozzolan is “a siliceous or siliceous and aluminous mate¬ria that reacts chemically with calcium hydroxide (lime) to form com¬pounds having cementitious properties.” In early civilizations, natural pozzolans were mixed together with lime to produce hydraulic cements, whereas today natural or artificial pozzolans are usually used together with portland cement. The hydration of the calcium silicate compounds, C3S (or alite) and C2S (or belite), in portland cement produces abundant calcium hydroxide through the reactions represented by following equations (see Table.1 for cement chemistry nomenclature).
2C3S + 11H → C3S2H8 + 3CH
2C2S + 9H → C3S2H8 + CH
Table 1. Cement Chemistry Nomenclature
Abbreviation Formula
S SiO2
A Al2O3
C CaO
F Fe2O3
M MgO
N Na2O
K K2O
S SO3
C CO2
H H2O
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The actual calcium-to-silicon atomic ratio is typically greater than the value of 1.5 represented by C3S2H8 and may vary up to 2 or more. Because of the variable composition this phase is often simply referred to as calcium silicate hydrate or C-S-H. The C-S-H is the principal cementing compound in portland cement concrete and is largely responsible for providing strength and other properties to the concrete. In addition to C-S-H and CH hydrated portland cement contains aluminofer¬rite phases (AFm and AFt) produced by the hydration of the other portland cement clinker compounds, C3A and C4AF, in the presence of
Investigation of the reaction between hydrochloric acid and marble chips A chemical reaction is when two or more substance called reactants are chemically bonded to form a new product, as a result of the process, for a reaction to take place, the particles must have enough kinetic energy to collide and form new bonds , this is called a successful collision. The minimum amount of energy needed for a successful collision is activation energy, which is “The energy that an atomic system must acquire before a process can occur”. Chemical reaction is different to a physical reaction, chemical reaction are not reversible and results in a new product, however a physical reaction can be easily reversed as it only changed its state. The activation energy is able to loosen particles and enable them to from new bonds to produce new products. The faster the molecules are moving the bigger the chance of a successful collision, so the faster and stronger the reaction will be , the more kinetic energy a reactant has the easier it is for the new bonds the collide and produce new bonds.
Investigating Factors that Affect the Rate of Reaction Between marble and Dilute Hydrochloric Acid The local Council are concerned about the effect of acid rain on the marble statues in the local park. Investigate a factor that affects the rate of reaction between marble (calcium carbonate) and dilute hydrochloric acid. There are three main factors that affect the rate of reaction. These are: Particle size Concentration Temperature With investigating any of these, there are slight problems which make them not as reliable as they could be. With particle size, it is extremely difficult to get control of the sizes, e.g. large, small, medium.
It is unknown when people first knew about calcium and when people used compounds of calcium. Limestone is a compound of calcium and Limestone was usually used for buildings. The common name for limestone is calcium carbonate. Early Greeks and ancient Egyptians used mortar which was made from heated limestone. It was named for its natural occurrence in limestone with was a common building material, which in itself is an oxide of calcium with the molecular formula being CaCO3. The Latin name for limestone being calx, hence
The Pantheon was a Roman concrete structure. Roman concrete is a mixture of lime and volcanic ash (pozzolana, found near modern-day town Pozzouli). Roman concrete is also called hydraulic cement-based concrete. It is known for curing relatively rapidly, even in damp condition, thus it could be used for massive construction. The most daring thing about the use of Roman concrete in the Pantheon is that Portland cement needs steel reinforcement due to tendency of cracking caused by tension forces, meanwhile the Pantheon did not. The Pantheon still stands today is because of its special structure.
Calcium and Potassium modifications are specialized individual according to a specific disease, age and inadequate amounts of calcium or potassium higher or lower than normal value.
As the reaction was taking place, the water in the measuring cylinder was being displaced – indicating that the calcium carbonate (in the form of marble chips) was displacing the hydrogen in the hydrochloric acid.
Nowadays, it will not be inept to inform that the universe is going over a construction boom. In truth, in the past few decades an entire affair of construction has altered dramatically like all other aspects of life. Currently, construction is no more just about keeping one brick above the other, but a diverse more than that. With the present scenario, the construction work encompasses all the aspects of construction like, performance, optimization, developing and designing. As an outcome, construction chemicals have become an essential part of the world construction industry. These chemicals are typically utilized to impart different properties into the layout.
Limestone's Reaction With Hydrochloric Acid Planning the experiment. This experiment will show how much limestone fizzes when added to hydrochloric acid. I will gather the gas released from the fizzing and measure how long it takes to gather a certain amount of gas. Burette [IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE][IMAGE] The light blue area represents the hydrochloric acid, and the white blobs are the limestone. The grey area is the carbon dioxide released from the HCl and CaCO3 reaction, heading in the direction indicated by the arrows.
Concrete and masonry products contain silica sand and rock containing silica. Since these products are primary materials for construction, construction workers may be easily exposed to respirable crystalline silica during activities such as the following:
There are two areas that calcium is used the most, food and manufacturing. First, calcium is used in the food industry in many areas. It is found in dairy products, dark leafy greens, almonds, and soybeans to name a few. Consuming calcium-rich foods can help people lose weight, help fight cancer, and help decrease the risk of type 2 diabetes. These are just a few of the many uses of calcium in food products and their benefits. Calcium is also used in the production of construction materials. Calcium carbonate, also known as limestone, is used for making cement. Live Science states in their article on calcium, “Gypsum, or calcium sulfate, is used in making plaster and also "plaster of Paris," a heavy white powder that, when mixed with water, hardens into a cast to set fractured bones.” They also say that calcium in its purest form can be used as a reducing agent in preparing other metals. These are just a few of the many uses for
Concrete is a composite material used widely in the construction industry. Concrete is basically a mixture of cement, water, aggregates and admixture (sometimes). Cement is a fine gray powder that consists of oxidizes calcium, silicon and aluminum. The aggregate used is normally gravel, crushed stone or sand. Admixture is a solid or liquid substance that gives a certain characteristics of the concrete. The cement reacts with water chemically and binds the aggregates together through a process called hydration during hardening or curing of concrete. It means that water helps in the hardening of the concrete while the cement bind the aggregate and also react with water to form a solid mass.
Opus caementicium or Roman concrete is a synthetic construction substance that’s composed of an aggregate, a binding agent, and water. In Rome’s case, as discovered by UC Berkley with the extensive analysis of a sample of Roman concrete taken from a breakwater in Italy’s Pozzuoli Bay it was developed by using lime and volcanic rock which formed a mortar, the mortar and volcanic rock were then packed into wooden forms and when seawater was added a chemical reaction occurred, bonding everything together to create concrete (History, 2013). It is uncertain when Roman concrete was developed, but it was clearly in widespread and customary use from about 150 BC; some scholars believe it was developed a century before that.
Chemical reactions involve the making and breaking of bonds. It is essential that we know what bonds are before we can understand any chemical reaction. To understand bonds, we will first describe several of their properties. The bond strength tells us how hard it is to break a bond. Bond lengths give us valuable structural information about the positions of the atomic nuclei. Bond dipoles inform us about the electron distribution around the two bonded atoms. From bond dipoles we may derive electronegativity data useful for predicting the bond dipoles of bonds that may have never been made before.
Lime-soda ash is used to remove the carbonate hardness by precipitation. It does not completely remove the hardness however it is effective in reducing it. It is effective if used to soften temporary hardness. To remove the calcium bicarbonate from the water slaked lime is used. By reacting with the calcium bicarbonate it forms a soluble calcium carbonate, which is then removed by filtering. However a restriction of using lime-soda ash is that it will not work on a lab scale experiment. “An additional deterrent to home use of the lime-soda ash treatment is the size of the equipment necessary, together with the high cost of this method of treatment.” (Lime-Soda Ash Water Treatment Method)
What exactly is a chemical engineer? Many would say that it is simply a "chemist who builds things" or an "engineer who makes chemicals. However, neither of these statements is completely true. The term "chemical engineer" is not meant to actually describe what it is a chemical engineer does, but to describe what sets it apart from the other branches of engineering: civil, mechanical, and electrical. On average, chemical engineers are numerically the smallest but also the highest paid. It is not a profession the must dwell on the past for comfort and support, for its greatest accomplishments are still yet to come.