Lime Testing Unit

Lime and lime mortar, stucco and relief have been used since a long time in the history of civilization. Traces of lime have been found in some early Egyptian buildings mainly in monuments. The ancient Greeks commonly used lime stucco as external covering for the temple.

Lime has been used in India as construction material from ancient times however, the application has been found to be very limited. A scientific study has been done on Karvan, a well known place of pilgrimage in Gujarat in Western India by R. V. Karanth’, K. Krishnan” and K. T. M. Hegde” in 1986. The site dates to 2nd to 3rd centaury AD, the evidence of lime plaster used, however has been found of 7th centaury AD. There are not many references to lime plastered structures of ancient India in stratified excavations. G. R. Sharma (Sharma, 1969: 29) recorded the occurrence of brick walls “painted with lime” at Kausambi. He also states that the use of lime as a building material at Kausambi was rare. John Marshall recorded the use of gypsum at Mohenjo-Daro as a mortar and also as a plaster medium (Marshall, 193 1: 269), but the plaster samples from these structures were not examined to evaluate their quality or analysed scientifically to determine their composition. In Islamic architecture hydraulic lime as mortar and plaster has been used extensively.

In traditional Indian buildings ‘surkhi’ or burnt clay and ‘bajri’ (sand) was added with hydraulic lime. In some places hydraulic lime was made by burning argillaceous limestone or ‘Kankar’.

After the development of Portland cement, a new material as a binder in India, decline in the use of lime as a building material started. Over a period of time, many historic and traditional buildings of stone and bricks, which were set in lime based mortar have been repaired with cement which gives disastrous effects on the buildings. Since both materials are chemically different and incompatible.

Before invention of cement, lime mortar was used for building construction material; the properties of lime depend on raw material of lime, burning temperature and slaking process.

Now days heritage conservation professionals are facing problems for selection of lime; the knowledge of preparation of mortar and slaking process to get good results during conservation and restoration of historic buildings and wall painting is lacking. Keeping the above points in view a Lime Testing Unit has been established at INTACH Conservation Institute, Lucknow.

Intach lime testing centre, over a period of two years, has developed many tests for scientific examination of lime, lime mortar, mural paintings, etc. Presently lime testing centre is working on 21 tests related to historic lime and mortar. The centre has adopted BIS standards as well as some other international standards. The Centre is committed to provide unmatched services in heritage conservation. Soon the centre will also start training course for architects, conservators, archaeological engineers, and heritage contractors.

People can approach the lime testing unit for getting sample tested by writing to us –

MR ASHOK KUMAR PANDEY
INTACH CONSERVATION INSTITUTE
B-42 NIRALA NAGAR
LUCKNOW -226020
Email- limeresearchcentre@gmail.com
Contact No – O –   +91-522-2787159
M –    +91-9415552737

TESTS CARRIED OUT AT LIME TESTING CENTRE, LUCKNOW

Tests of Quick Lime

SL.NO. TYPE OF TEST OUT COME USEFULNESS
1 Visual examination Color of lime and state of Lime-like lumpy, powdery, soft and hard is tested. Purity of quick lime
2 Hydrochloric acid test Gradation test of Quick Lime before slaking. To know the class of Quick lime as A,B,C,D,E,F etc.
3 Ball test Class of Lime after slaking. To know the class of Quick lime as A,B,C,D,E,F etc.
4 Impurity test Quick Lime/ Impurity in lime The presence of pure Calcitic lime( Cao) or Dolomitic lime( Cao & Mgo)
5 Plasticity test Quick Lime/Lump formation Plasticity of lime is carried out to know the workability

Tests of Lime Plaster/Mortar

SL. NO. TYPE OF TEST OUT COME USEFULNESS
1 Sampling Samples collection from site,Photograph of building feature with a record shot.Photograph the mortar in situ before sampling.Note and record the color, texture of the plaster/mortar.Collection of at least two samples of the same type of mortar from different nearby locations, each between 25 and 50 grams. Get samples from correct location like

  • walls – outer, inner all the three layers as rough and fine plasters
  • Ceiling
  • Roof top
  • Floor from corners and middle area
  • Samples from salt efflorescence area
2 Study of Physical properties Documentation & photographic study of Plaster sample Detail photo documentation during and after sampling in laboratory while understanding analysis
3 Elastic properties or strength of plaster surface, hardness and penetration resistance Schmidt hammer, also known as a Swiss hammer or a rebound hammer. This instrument is used at site. Results are obtain in graphic form. To study the nature of plaster in respect to good or dead plaster
4 Hardness of plaster by compression testing method Fully computerized method for testing of new plaster samples used during restoration To study the compression strength of new admixture used during / for restoration
5 Composition of plaster/mortar Percentage of Lime and aggregate Useful to know the percentage of slaked lime and type of aggregates during the preparation of admixture
6 Microscopic study Different type of aggregates in plaster Get idea about the aggregate type and pozzolanes.
7 Granulometry test Particle size distribution bySieve analysis method Different size of aggregates which play vital role in preparation of admixture
8 Study of soluble salt Presence of different soluble salt deteriorating the plaster To check the points of capillary action by providing barrier of damp proofing material
9 Vicat apparatus test Setting property of Plaster Get approx. timing of setting of plaster although the complete hardness comes due to evaporation of water and carbonation from plaster after long duration may be after many days, month or years depending on the thickness of plaster and the surrounding atmospheric condition of the building.
10 Carbonation test Setting of lime mortar, plaster /Carbonation status of newly applied lime plaster This tells about the completion of hardness which may occur after years; as per literature available complete carbonation takes many years.
11 Absorption test by Karsten Tube method Absorption of any liquid on stone and lime plaster surface It detects absorption level of water, solvent etc on stone surface/brick or lime plaster surface. Data can be calculated in relation of time.
12 Water absorption

  • Total immersion
  • Capillary action
Absorption of any liquid on stone and lime plaster surface It detects absorption level of water
13 Water vapour Permeability Evaporation rate Indirect study of porosity in plaster
14 Artificial weathering Artificial ageing effect Half-life period of plaster
15 Natural weathering Natural ageing effect Half-life period of plaster
16 Slaking of lime in field and preparation of Putty Slaking technique of quick lime Get best quality slaked lime