1 under water.[4] There are two basic

1        Lime Lime has been used in historic building as a binderin mortars for over last decades. Today, lime is still used as the primarybinder in many mixes or in the conservations of old historic buildings, usuallyin the form of lime putty or hydraulic lime. Hydrated lime is used in moderncement based mortars mainly for its properties as a plasticizer.2        Occurrence of Lime Lime is obtained from calcination of calcareous rockwith high percentages of calcium carbonate, from which calcium oxide(quicklime) is obtained by heating it at high temperature. 800o                                                                      CaCO3               CaO + CO2   Quicklime is very reactive in the presence of waterand cannot be used before being transformed to calcium hydroxide by reactionwith water.6,13        Slake Lime When an excess of water is added in to the calciumoxide (quicklime) to produced calcium hydroxide.

The paste is known as slakedlime and this process of hydration is known as slaking of lime. 1                                     CaO + H2O                    CaOH2 + Heat   4        Lime PuttyIt is produced by slaking quicklime (CaO ) with an excessof water for extended periods of time (may 2-3 months) until a creamy texture isproduced. It is called lime putty.

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The effect of extended exposure of lime puttyto water indicates that portlandite crystals, Ca(OH)2, undergo both animportant size reduction and a shape change from prism to plate like crystals agglomeratedas aggregates.15        Types of Lime Following are the types of lime on the bases of the hydration·        Hydraulic lime (HL)·        Ariel lime (Non hydraulic lime)·        Dolomitic lime ·        Micronized quick lime5.1       HydraulicLimeHydraulic lime (HL) is a general term forvarieties of lime (calcium oxide), or slaked lime (calciumhydroxide), used to make lime mortarwhich set through hydration. Hydraulic limeprovides a faster initial set and higher compressive strength than air limeand eminently hydraulic lime will set in more extreme conditions includingunder water.4There are two basic types of hydraulic limes:5.1.

1       Natural Hydraulic Lime (NHL)Natural hydraulic lime (NHL) is produced by heating (calcining)limestone thatnaturally contains clay andother impurities: no materials may be added to create the hydraulicity. This isalso known as calcitic lime or white lime. 12 Natural hydraulic limes (NHL) are binders inconformity with the EN 459-1:2010. This type of binder is obtained by firingmarly limestone at a temperature similar to the one used to produce air lime,and consists of calcium silicates, calcium aluminates and calcium hydroxide. It is classified as a binder with hydraulic properties,having not only a hydraulic curing but also an aerial curing obtained bycarbonation with atmospheric carbon dioxide. This double type of curing can bevery beneficial for a variety of applications, particularly in conservation orrehabilitation interventions of existent and historic buildings.5.

1.2       Artificial Hydraulic Lime (AHL)Artificial hydraulic lime (AHL) or artificial lime(AL) becomes hydraulic when hydraulic and/or pozzolan materialsare added either before or after burning in a lime kiln. Artificial limes aremore specifically identified as hydraulic lime (HL), as defined European Norm 459(EN-459), “Consists of lime and other materials such as Portland cement, blast furnace slag, fly ash,limestone filler and other suitable materials”5.2       ArialLime Aerial lime is softer and sets much more slowly. Thecarbonation process is very slow and the material remains soft and flexible. 2Aerial lime hardens slowly due to the atmosphericCO2.

Hydraulic lime (HL) or natural hydraulic lime (NHL), composed by calciumsilicates, calcium aluminates, and calcium hydroxide can harden under water andalso the atmospheric CO2 contributes to its hardening process. The usage ofpure aerial lime binders reduces the water resistance and mechanic durabilityof the material.25.

3       DolomiticLime Whenever dolomitic or magnezian limestone iscalcined instread of pure caciltic limestone the lime we obtain is dolomiticlime. The calcination of dolomitic lime, using CaMg(CO3)2  as a raw material, occurs at low temperatureas compare to calcitic lime stone that is about 725oC versus 900oC. This produces magnesia that is MgO and quick lime that is CaO. MgOslakes slower than CaO and produce brucite which is Mg(OH)2.

Thereaction of conversion of magnesia into brucite is less exothermic. Hardeningprocess is more complex than that of calcitic lime and by readction with carbondioxide produces MgCO3. Other magnesium carbonates can be formeddepending upon the conditions such as humidity, temperature and ph etc.

12 Dolomiticlime is an attractive rock which is calcium magnesium carbonate. It consistof about 50% calcium carbonate and 40% magnesium carbonate, which giveapproximately 22% calcium and at least 11% magnesium. 2 Limestone was calcined using traditional furnacesadapted to the characteristics of each region. In the same way, lime slakingwas diverse and led to lime putties with different properties.

In particular,in the North of Italy rich in dolomitic stone the use of lime was highlyextended and during years was one of the main materials in local architecture.Although its use has declined due to the introduction and to the fastimplementation of cements in the mid XIX Century, lime is still one of themajor materials to be considered in restoration works.25.4       Micronizedquick limeCaO after grinding andscreening is called micronized quicklime.6        List of Tests on Limeo   Test on freshmortar§  Consistency test by flow table§  Bulk density testo   Tests onhardened mortar§  Tensile test·        By UTM·        Pull offadhesion test§  Compression test§  Flexural test§  Capillary water absorption test§  Water vapor permeability test§  Measuring modulus of elasticity By resonantfrequency§  Dimensional variation due to shrinkage measured withvernier calipers §  Mercury intrusion porosimetry§  Measuring the extent of carbonation·        X-RayFlourescence spectroscopy- XRF·        Thermogravimetricanalysis (TGA)/ Thermal diffraction analysis (DTA)·        X-raydiffraction (XRD)·        Phenolphthaleinindication test§  Mineralogicalphases6.

1       Testfor water absorptionThereare the following test for water absorption. 6.1.1       Capillary water absorption testInthis test the hardened mortar is kept in contact with water 5mm from base inaccordance with EN 1015-18: 2002 and then graph is plotted b/w mass of waterabsorbed by specimen and contact area of specimen with water.

The specimen iskept in contact with water until the saturation i.e the difference b/w toweights is less than 1%. 11 6.2       Bondstrength test6.2.

1       Tensile bond testMortarof thickness 20±2mm was applied b/w two tile slab. The procedure is to applythe mortar on one tile slab then the other tile slab is pressed against themortar with thumb and rubber mallet as the traditional procedure adopted now adays in such kind of works. The tile slab is pressed with uniform pressureagainst mortar. Then after curing two metal pieces are glued with both tilesand now can be fixed in UTM to apply the tensile load of 5N/s until rupture.The rupture may be classified as the cohesive or adhesive. The rupture will beadhesive if the failure is in tile mortar interface and will cohesive iffailure is in core of mortar.

116.3       Measuringthe extent of carbonation6.3.

1       Thermogravimetric analysis (TGA)/ Thermaldiffraction analysisForit the powdered sample <106µm is dried at 60oC and analyzed inthermal analysis equipment (TGA-DTA) in an argon atmosphere 3L/h. The heating rateis 10 oC/min from room temperature to 1000 oC. With thistemperature change there is physical and chemical change in test specimen. Eachconstituent has its own temperature range of decomposition and a specific massloss such as de-hydroxylation of portlandite occure in the temperature range of350-550 oC and calcite decompose in the temperature range of 550-850oC. By the results obtain from TGA-DTA we can have knowledge of extent ofcarbonation.136.3.

2       X-ray diffraction (XRD)Extentof carbonation can also be measured by using XRD apparatus. Lime in powder formis placed in XRD apparatus and after analysis peaks for various compounds areobtained giving information about its composition.13 6.

3.3       Phenolphthalein indication test Fractured surface of lime is sprayed with 1%Phenolphthalein solution to give the indication of carbonation as the result ofcuring. Absence of pink color on surface indicates the specimen is fullycarbonated. 14Phenolphthaleinindication analysis is also used to measure the depth of carbonation.176.

4       Testsgiving the mineralogical information6.4.1       Scanning electron microscopic analysis (SEM) By using scanning electron microscopemineralogical and microstructure data can be achieve and we can also check thecorrespondence of these results with the results of other mechanical tests.15 6.4.2       Field Emission Scanning electron microscopicanalysis (SEM)Thetextural study, mortars fragments were metalized with a carbon layer and themicrostructure analysed by using a Carl Zeiss Leo-Gemini 1530 fieldemission  scanning electron microscope(FESEM). 86.4.

3       Thermogravimetry (TGA) and X-ray diffraction(XRD)Themineralogical phases of both internal and external zones of mortar samples canbe determined by thermogravimetry (TGA) and X-ray diffraction (XRD). In TGA, itwas employed a Shimadzu TGA-50H thermogravimetric analyser, working in air in atemperature range of 25–950oC, with a heating speed of 5oC/min. For the XRDanalysis, it was used a Panalytical X’Pert PRO MPD diffractometer, withautomatic loader and X’Celerator detector, 4–70o  2? explored area. 86.

4.4       X-Powder Software PackageTheidentification of the mineral phases was performed by using the X-Powdersoftware package.86.5       Poresize distribution test 6.

5.1       Micrometics Autopore III 9410 Porosimeter(Mercury Injection Porosimetry, MIP)Open porosity (Po, %)and pore size distribution (PSD, in a range of 0.002 < r < 200 ?m) weredetermined using a Micrometics Autopore III 9410 porosimeter (mercury injectionporosimetry, MIP). Mortar fragments of ca.

1 cm3 were oven-dried for24 h at 60 oC before the analysis. 86.6       Flexuraland compressive strength test6.6.1       Hydraulic press or Universal testing machine Flexural andcompressive strength were measured by means of a hydraulic pressINCOTECNIC-Matest.

According to the EN 1015-11 standard, flexural assays werecarried out on three samples per mortar (of 4 x 4 _x16 cm). The six samplesobtained after the flexural rupture were used for the compressive assays.87        Additives for Lime In modern era different organic and inorganicmaterial is adding to improve the lime characteristic. These materials aredivided in to two types: 3,61.     Minerals2.

     Organicadditives·        Minerals (i.e. Pozzolans, mineralfillers, ceramic powder, microsilica,fillers etc) that are used in lime based mortars with the aimto improve certain properties or obtain special performances mainly related tothe increase of mortar strength, 6·        Organic (Admixtures), added in lowamounts (i.e. Not higher than a 5% of the total mass) in order to produce apermanent modification in the fresh or hardened mortar, such as densitydecrease, workability improvement or waterproofing. And it includes water retention, water repellant plastifier agents,organic fiber etc.

126·        Natural hydraulic lime mortar withgraphene oxide(GO)5 By these additivescharacteristics of lime may be changed and as the result the performance anddurability can be improved. Pozzolanic ensure hydraulicity and increase theresistance of water action. Nanosilica and zeolites helps to gain strength.

Fibers help to reduce the risk of cracking. Plastiszers reduces the need ofwater. Some water repellant additives may improve not only the water absorptioncharacteristics but also the freeze and thaw. In some cases it also improvesthe mechanical properties. Water retention additives control the risk ofdesiccation.12Additions of organicsin lime matrix enhance its strength due to reaction b/w polymer from naturalorganic and portlandite of lime that forms calcium oxalate monohydrate.

Formation of this new complex compound enhance the strength of mortar byincreasing the binding strength b/w consecutive lime partials and reducesstress concentration during loading. 18 

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