Concretes, Mortars, and Plasters

Lime (CaCOj is a common material used for making a hard and water-resistant cement. It is found in many parts of the earth as a component of limestone. It can be chemically altered by heating to produce stronger binding agents and it can be rather easily ground to a fine powder. Lime burned at 900°C turns into quicklime (CaCOj), which can be combined with water in the absence of carbon dioxide to produce slaked lime (CaCOH) ). This wet mass sets slowly with the loss of water to produce interwoven crystals of CaCOH) and then combines with carbon dioxide in the air to produce lime (Fig. 3.12). 

Barba and colleagues have reported a fascinating study of the sources of lime for 

There are a number of distinctive areas in the planned city, including pyramids. 

Barba and his colleagues sampled the three outcrops of limestone to determine their distinctive signatures. This information was compared to lumps of calcium carbonate found in the finished plaster in the city. The group of scientists used several different techniques to examine the samples. The major element composition of the geological samples was determined by XRF. The major element composition of the lumps was determined by SEM-EDS. Trace element composition was determined by LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry) to measure the elemental composition of the plaster and the limestone. This methodology is well suited for analyses of very small lumps with microscopic spot sizes. The LA-ICP-MS method is able to analyze a large number of trace and rare earth elements with speed, precision, and high resolution, especially in cases where the major chemical composition does not appear to be particularly distinctive. The instrument worked extremely well for the characterization and determination of the provenance of the Ume plaster source material. 

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Concrete, Mortar, and Plaster. Citric acid and citrate salts are used as admixtures in concrete, mortar, and plaster formulations to retard setting times and reduce the amount of water requited to make a workable mixture (172—180). The citrate ion slows the hydration of Portland cement and acts as a dispersant, reducing the viscosity of the system (181). At levels below 0.1%, citrates accelerate the setting rate while at 0.2—0.4% the set rate is retarded. High early strength and improved frost resistance have been reported when adding citrate to concrete, mortar, and plaster. 

Concrete, mortar, and plaster attack zinc, but the attack ceases after the materials have dried and the amount of attack is just sufficient to give a good bond. Because zinc is very resistant to mildly alkaline conditions, unlike steel and aluminum, it is to be preferred for such contacts, notably in its use as a coating on steel. Caution is needed if the zinc alloys with higher contents of aluminum are to be used with concrete or other alkaline materials. 

Three other compounds of s-block elements—calcium oxide (CaO, known as lime ), sodium hydroxide (NaOH), and sodium carbonate (Na2 CO3)—are among the top 15 industrial chemicals in annual production. Lime is perennially in the top 10 because it is the key ingredient in construction materials such as concrete, cement, mortar, and plaster. Two other compounds, calcium chloride (CaCl2 ) and sodium sulfate (Na2 SO4 ), rank just below the top 50 in industrial importance. 

On the surface of concrete, finishing plaster or the other building materials the processes generated by the impact of gaseous air components or rain component occirr. Apart from the corrosion phenomena due to the acid rains, the carbonation of calcimn hydroxide influenced by CO2, is of highest importance. This process refers especially to concrete, mortar and cement plasters. 

Other uses - Diatomite is used as a nonscratching abrasive in polishes and cleansers, in concrete, mortars, grouts, plasters, and stucco for improved plastic and cured properties, in asphalt products to decrease cracking caused by rapid temperature changes, in catalyst carriers, in chromatographic supports, and as a silica source in the production of synthetic calcium and magnesixun silicates. 

Iron is an element almost ubiquitous in nature, occurring most commonly as ferric oxide ( rust ). The sand used for concrete and mortar, for example, contains up to 4% iron, while Portland cement contains between 2 to 5% iron.97 In general, the iron - in the form of rust - is the reason why building and similar materials (concrete, mortar, plaster, but loam and clay as well) are frequently ochre or red. 

Construction Materials In tape joint compounds in gypsum spray plaster in ceramic tile adhesives, grouts, and mortars in cement mortars, stuccos, and plasters in concrete as wallpaper adhesive as a ceramic processing aid as a thickener for latex paint... 

Cement is a binder that sets and hardens by itself or binds other materials together. The most widely known application of cements is in construction a second one is the area of bone cements. Cements used in construction are characterized as hydraulic or nonhydraulic and mostly for the production of mortars and concrete. Hydraulic cements set and harden after combining with water. Most construction cements are hydraulic and based on Portland cement, which consists of calcium silicates (at least 2/3 by weight). Nonhydraulic cements include the use of nonhydraulic materials such as lime and gypsum plasters. Bone cements and bone cement composites refer to compounds that have a polymer matrix with a dispersed phase of particles. For instance, polymethylmethacrylate (PMMA) is reinforced with barium sulphate crystals (for radio-opacity) or with hydroxyapatite... 

Thanks to all these properties, the dolocarbonate seems promising for different applications, first of all for all the applications of traditional low density mineral fillers. This material could for instance be used as a component in thermal insulating materials like panels or foams, as a filler in mortars or plasters or concretes to decrease their thermal conductivity, as a filler in polymer or rubber compositions to improve their fire and/or mechanical properties, as a filler in paints, papers, cosmetic compositions, as a rheology modifier (viscosifying agent) in mineral slurries, glues, bitumen or asphalts, polymer compositions, as an ad- or absorbant in different applications such as water or flue gas treatment or even in the field of catalysis, as e.g. a catalyst support, or as a carrier for perfumes, aromas, active substances, medicines... 

Improved pumpability of concrete, machine grouts, and spray plasters Improved workability of trowel-applied mortars and pastes... 

Concrete, plaster, mortar, and cements also cause superficial etching of aluminum, most of which occurs during the curing period. The surface attack involves dissolution of the natural oxide film and some of the metal, but a new film is formed that prevents further corrosion. Coupling with more cathodic metals has little effect on aluminum embedded in these materials except in those that contain certain curing or antifreeze additives. 

Into this category come the water-based plasters, mortars, cements and concretes which set at room temperature as the result of a chemical reaction between water and a powder. Some of these have been known... 

Bases also have their domestic uses. The various kinds of soda found in the home - baking soda, washing soda and caustic soda - are all bases. But the widest used base of all is lime. Besides its agricultural use, lime is a vital ingredient in cement, mortar, plaster and concrete. The lime reacts with carbon dioxide in the air and hardens the mixture as it dries out. 

Tn the construction materials colorant sector, the chemical stability, light fastness and weathering stability of synthetic iron oxide pigments are important. Concrete bricks, paving stones, roofing tiles, asbestos cement, mortar, bitumen and facade plaster are all currently colored with iron oxide pigments. 

Hydraulic limes are used for making mortar, plaster and concrete, particularly in Italy, France and Germany (see section 16.10 for their production). In the UK, their use is largely restricted to conservation and restoration work, where their slow set times and relatively low strengths are considered to be of particular benefit when used on weathered stonework [26.41]. 

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