testing limestone

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Testing limestone

• A similar form may well be utilized for sand

• and gravel or crushed rock analyses where the

• geologist requires special test work on his or

•

her samples, such as size analysis, aggregate• crushing value (ACV), or polished stone value

• (PSV) to name but a few.

• Limestone rocks are sedimentary rocks that are made of mineral calcite whichcomes from the beds of evaporated seas, lakes and sea animal shells. This rock isused in concrete and is an excellent building stone for humid regions

• The aggregate shall in general comply with M.S 7.5. All aggregate shall be hard,

strong, durable, clean and free from adherent coating and shall not containharmful materials in sufficient quantity to affect adversely the strength ordurability of the concrete or to attack the reinforcement. Aggregate shall be storein such a manner as to prevent contamination by undesirable substance.



• The aggregates shall not contain clay lumps exceeding 1% by weight

• WHEN TO DRILL AND WHEN TO STOP

• One of the hardest decisions in exploration is

• to decide when to start drilling, and an even

•

harder one is when to stop.• The pressure to drill will be evident when

• the program has identified surface mineralisation.

• Setting up a drilling program

• The geologist in charge of a drilling program is

• faced with a number of problems, both logistical

•

and geological. There must be a decision on• the type of drilling required, the drillhole spacing

• (see section 10.4.4), the timing of drilling,

• and the contractor to be used. The logistics of

• drilling should be considered carefully as the

• drill will need drill crews, consumables, and

•spare parts; this will require helicopter support

• in remote areas and vehicle access in more

• populated areas. Many drills require vehicle

• access and access roads must be made and pads



• The pattern of drilling used is dependent

• on the assumed attitude and thickness of the

• drilling target. This depends on the available

• information which may, of course, be inaccurate.

• Drilling often causes reconsideration of

• geological ideas and prejudices. Vertical boreholes

• are the easiest and cheapest to drill and

• widely used for mineralisation with a shallow

•

dip or for disseminated deposits. However,• inclined holes are usually preferred for targets

• with steep dips.

• Drilling is used to define the outlines of any

• deposit and also the continuity of mineralisation

•for purposes of resource estimation. The

• initial pattern of drilling will depend on surface

• access, which may be very limited in moun



• . The uses of a limestone depend on its physicalproperties, mechanical properties, chemicalproperties or a combination of all three

• There are relative levels of

• chemical impurities, which usually restrict thegenerally high purity grade

•

calcium carbonates (minimum content of 97%).Silica and chert are the most

• common types of impurity, occurring asdisseminated grains or as concentration

• of nodules, lenses, or beds. Organic matter canalso cause problems, as can the

• varying degrees of dolomitisation which may exist



• Physical properties are more important if thelimestone is used for aggregate or buildingstone. Strength and durability are of primeimportance in the assessment of limestone foraggregate as well as other properties, such asporosity and water absorption.

• The density of a rock is one of its mostfundamental properties. It is principallyinfluenced by the mineral composition andthe amount of void space. Strength andhardness principally relate to density, porosity,moisture and homogeneity of a deposit.



• Geological Survey

• An assessment should begin with an initial fieldinvestigation involving field mapping, sectionmeasuring and sampling. Geological mappingaims to define the stratigraphical relationship andstructure of the limestone formations, as well as

determine lithologies. Further field investigationsmay include topographic and section surveys,sampling from exposures and drill core forsubsequent laboratory analysis

• In-situ mechanical strength of the rock mass oflimestone can be obtained with a handy Schmidthammer



• Physical and Mechanical Study

• The representative samples were tested and used to

• investigate the physical and mechanical properties of the

• limestone according to the Jordanian standards laboratory

• tests. The results show that Ma’an limestone can beclassified

• into different categories according to uniaxial unconfined

• compressive stress values (CS), water absorption

percentage• (WA), surface abrasion (SA) , seismic velocity (SV) and

• specific gravity (SG)

• limestone is amorphous: it has no internal structure,therefore no cleavage. So, it cannot break along cleavage

lines. It can only fracture in random directions, along smallcracks and areas of weakness present in the rocks.



• Hardness, lustre, and streak are aids toidentifying minerals. Limestone is composed

mainly of the mineral calcite. Calcite has a Mohshardness of '3', it's lustre is vitreous, and it has awhite streak.

• limestone is amorphous: it has no internal

structure, therefore no cleavage. So, it cannotbreak along cleavage lines. It can only fracture inrandom directions, along small cracks and areasof weakness present in the rocks.

• Limestone does not have a luster. It's mainconstituent, the mineral calcite, has a vitreous orglassy luster.



• Limestone can easily be dissolved by acids. If some vinegar is droppedonto a limestone, it will fizz Put a limestone rock into a plastic jar andcover it with vinegar. Cover the jar and watch the bubbling of the calciumcarbonate and also the disintegration of the rock over a few days,

• Carbonate Rocks.

• Limestone aggregate is one of carbonate rocks. Like other rocks, carbonaterocks are classified on the basis of their minerals and textures. The mineralcompositions are limited and the textures of carbonate rocks are assumedof added importance. Some carbonate rocks are crystalline, and the othersare clastic. Most rocks contain both crystalline and clastic elements

Limestone is composed predominantly of calcite, namely Magnesiumcalcite, aragonite and dolostones, dolostones consists primarily ofdolomite, aragonite and dolostones are the two main types of carbonaterocks.

• Magnesium calcite and aragonite are particularly subject to diageneticchange and therefore calcite and dolomite are the most common phases

in older carbonate rocks. Chemically, CaO, MgO and CO2

are leadcarbonate rocks and the content of oxygen and carbon are significant inthe analysis.



• Limestone (Biochemical)

• Limestone is formed in various colour such as white, grey,cream or yellow. It’s texture is highly variable from very

fine-grained, and porcellaneous, to coarsely crystalline andof sugary appearance. Its structure bedding is usually formthe formation fossil layers.

• Usually limestone light is white or grey but can also beblack if many impurities are present. It’s grain is typically

fine, but it ranges from the microscopic to the size of acoral reef, which technically corresponds to one grain

• However, the formation of calcite or another carbonate cantherefore be identified by dropping dilute hydrochloric acidonto its surface.The calcite rock releases carbon dioxide,

and fizzes vigorously which indicates the presence of fossils• Calcium carbonate normally comprises 50% of calcite, and

the balanced are clay, sand, dolomite, carbon and ironoxides.



• In general, limestone is such as weathered rocks arecrinoidal limestone, chalk, shelly limestone andfossiliferous fresh water limestone. Weathering oftendevelops a thin white coating on pure limestone.

Commonly the appearance of the limestone pebblesare grey and it is compact at the rock center andporous at the surface. Since limestone is formed inseveral ways and contains numerous impurities, manyvariations are found. This is includes shaly orargillaceous limestone, sandy or arenaceous limestone,lime conglomerate, bituminous limestone andglauconitic limestone.

• The specific gravity of a mineral is the ratio of its

weight compared with the weight of an equal volumeof water.

• A calcite crystal laid upon a graph paper with blue linesshowing the double refraction

http://en.wikipedia.org/wiki/Calcite

http://en.wikipedia.org/wiki/Calcite



• Calcite (CaCO3) is a trigonal mineral with a

wide range of forms (more than 300 different

varieties have beendescribed). Rhombohedralcleavage is perfect, as illustrated in Fig. 3.25.

Calcite defines H = 3; G = 2.71.

• Calcite is usually white, but many coloured

varieties occur. It is readily identified by its

crystal form, hardness, birefringence and

reaction with dilute HCl

testing limestone

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