During the visit of the visit to San Marcos we saw a building which I found most interesting the cement and its uses. CEMENT
• Definition:
is a finely powdered substance made of gypsum plaster able to form a soft paste when mixed with water and hardens spontaneously on contact with air
Cement is a material that combines the fragments detritus (sand or gravel) in some clastic rocks (sandstones and conglomerates). In general the cement of these rocks is caused by chemical precipitation, being the most common cementing substances silica, carbonates and iron oxides.
Cement is a dry powder made of silica, alumina, lime, iron oxide and magnesium oxide, which hardens when mixed with water.
· Properties
physical and chemical properties of cement:
cements belong to the class of materials called binders under construction, such as air lime and plaster (not hydraulic), the cement hardens rapidly and reaches high resistance, that due to complicated reactions combination of lime - silica. Ex
Chemical analysis of cement: 63% CaO
(Cal)
20% SiO2 (Silica)
6% Al2O3 (alumina)
3% Fe2O3 (Iron Oxide)
1.5% MgO (magnesium oxide)
K2O + 1% Na2O (Alkali)
2% Loss on ignition 0.5% insoluble residue
2% SO3 (sulfur dioxide)
Residue 1% CaO (lime free) Chemical characteristics
_Módulo
_Compuestos flux on ignition side _Perdida
insoluble _Residuo
Physical
_Tiempo
_Superficie setting specific _Falso
volume setting
_Estabilidad _Resistencia
mechanical air
_Contenido _Calor
hydration of cement
· Types
PORTLAND CEMENT: Portland cement without addition, is the product obtained by spraying a mixture clinker and calcium sulfate with water (hydrated gypsum).
CEMENT STEEL: The product obtained from the joint mixture of clinker, basic slag and granulated blast furnace cast. Granular basic slag, is the product obtained by quenching the melt non-metal, which results in the treatment of iron ore in a blast furnace. If you have less than 30% of basic slag, Portland cement is called Iron and Steel.
CEMENT WITH ADDED A: It is the product obtained by grinding together with clinker, and plaster aggregate type. The aggregate type A is a mixture of substances, consisting of a calcium-clay material, which has been calcined at temperature above 900 º C, and other materials based on oxides of silicon, aluminum and iron. If it contains less than 30% of the aggregate type is called Type A Portland Cement, and if you are between 30 and 50% is called Cement Type A. CEMENT
PUZOLÁMICO: The product obtained by joint milling of the clinker, pozzolana and gypsum. The pozzolan is silica-alumina material, but has no binding properties by itself, develops when finely divided and in the presence of water, chemical reaction with calcium hydroxide at room temperature. PORTLAND CEMENT
:
hydraulic cement produced by pulverizing clinker consisting essentially of hydraulic calcium silicates usually containing one or more of the forms of calcium sulfate as an addition during milling.
PORTLAND CEMENT TYPE:
Type I normal Portland cement is intended for general concrete work, when they do not specify the use of another type. (Buildings, industrial structures, housing complexes) releases more heat
hydration than other types of cement.
Type II: moderate sulfate resistance, portland cement is intended for general concrete works and works exposed to moderate sulphate action is required or where moderate heat of hydration, where be specified. (Bridges, concrete pipe)
Type III: High early strength, as when you need to get the concrete load as soon as possible or as needed stripping a few days of discharge.
Type IV: low heat of hydration requires that there should be no expansion during setting.
Type V: Used where high strength is required the concentrated action of sulfates (channels, culverts, port works)
TYPES Portland pozzolan cement, Type IP Portland pozzolan
: Where the addition of pozzolan is 15 -40 % of the total. Portland pozzolan
Type I (PM): Where the addition pozzolan is less than 15%
Portland pozzolan type Q: Where the addition of pozzolan is over 40%
SPECIAL CEMENT-Portland Cement White Masonry Cement
-
-aluminous cement-Cement
compounds
CEMNETOS RECOMMENDED THEIR EFFECTS ON CONCRETE
The conditions to be taken into account to specify the concrete cement suitable and appropriate for selecting a play, can be determined by the timely investigation of two aspects:
1) the characteristics of the structure and equipment and procedures required to build it.
2) the exposure conditions and service Specifically, given the characteristics of the environment and the means of contact and foreseeable effects resulting from the use for the structure.
There are several aspects of the behavior of concrete in fresh and hardened, which can be modified by using an appropriate cement, to adapt to the specific requirements given by the conditions of the work. The main characteristics and properties of concrete that can be influenced and modified by different types and grades of cement are: Cohesion and manageability
fresh concrete slump loss and bleeding
Settlement Setting time
strength Acquisition Concrete
hardened heat generation resistance to attack by sulfates
Dimensional Stability (volumetric changes)
Chemical Stability (cement-aggregate reactions) PRODUCTION
manufacturing _proceso
REMOVING QUARRY
In the stone quarries limestone is extracted and clays by drilling and blasting with explosives.
CRUSHING the quarry material is fragmented into crushers, hopper which receives the raw material, the effect of impact or pressure is reduced to a maximum size or half an inch.
raw mill is performed through a vertical steel mill, which grinds the material by the pressure exerted by three roller bearings rolling on a turntable grinding . They are also used for this phase horizontal mills, within which the material is pulverized by means of steel balls.
BAKING
is the core of the process, which employ large kilns within which to 1.400 ° C transforms the raw meal in clinker, which are small dark gray modules 3 to 4 cm.
CEMENT MILL
The clinker is ground by steel balls of different sizes in its passage through both houses of the mill, adding the plaster to lengthen the time the cement. BAGGING
Cement is sent to storage silos, from which is extracted by pneumatic or mechanical systems, being transported to where it will be packed in paper bags or bulk supply directly. In both cases can be shipped by truck, rail or boat chutes.
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