Conservation – Restoration of Exposed Concrete Façade of Heritage Buildings in City Centre, Sector-17, Chandigarh

CHANDIGARH UT ADMINISTRATION HERITAGE CONSERVATION COMMITTEE

4th Meeting: 22nd May, 2014

Agenda Item No. 1

Conservation – Restoration of

Exposed Concrete Façade of Heritage Buildings in City Centre, Sector-17, Chandigarh

Presentation of HCC Sub-Committee Report by

CCA Research Cell Team Chandigarh

UNESCO: WORLD HERITAGE OVERVIEW

The International Charter for the conservation and restoration of monuments and sites (The Venice Charter 1964) adapted by ICOMOS (Intentional Council on Monuments and Sites) resolved to uphold age-old traditions-cultures to bring “unity in human values”, regard ancient monuments and safeguard its heritage for future generations.

It enlarges the scope, concept and definition of historic monuments to include the more modest works of arts which have acquired cultural significance and values in the fold of conservation and restoration of sites and heritage buildings.

It lays recourse to all sciences and techniques to safeguard its legacy and architectural heritage buildings, streets in the city landscape.

The UNESCO World Heritage Convention (Paris, 28th-29th October, 1999) resolution adopted by the 12th General Assembly of the State Parties, DOC: 14GA-WHC-03/14.GA/INF.8 dated: 16th July, 2003, highlights:

“The cultural and natural heritage is a function in the life of the community and to integrate-protect its heritage

in comprehensive planning programmes”.

Glossary of Words

Archaeological site and remains: As defined u/s 2(d) of the Act 1958, means any area which contains or is reasonably believed to contain “Ruins or Relics of Historical or Archaeological Importance” which have been in existence for not less than one hundred years, and includes

i. Such portion of land adjoining the area as may be required for fencing or covering in or otherwise preserving it, and

ii. The means of access to, and convenient inspection of the area;

Natural -Building Structure: A composite free standing natural or manmade structure, a rock or geological formation, building or other object (e.g. a bridge or a dam across a river), comprising of several parts and components made of different building material e.g. earth soil (mud), lime or cement, wood, brick, stone, steel or glass, including cement concrete, or Reinforced Cement Concrete (RCC) or other natural building material.

Culture/Cultural:

The arts, customs and institutions, related to ancient or modern intellectual achievements of a society or a nation. The structured way of life and living conditions of the people in a city, including heritage buildings, streets in the city landscape.

Conservation: Careful use of man-made or natural resource, art, architecture or cultural heritage, to preserve, restore or repair a piece of art or culture, archaeological or historical or heritage sites, monuments, and buildings, or the natural environment. This includes, truthfulness of building material used in the city development process.

City Structure/Landscape: Refer to the structured shape, size or composition, of a city landscape, optimum utilisations of land, space or buildings in an urban settlement, equitable distribution of various city functions and activities or building structures in a healthy living environment.

Heritage: Refer to events, activities or a legacy the citizen inherit, places and objects we want to protect as our historic culture / cultural identity for future generations. Moveable e.g. piece of art or custom or tradition, or Immovable e.g. natural heritage sites, monuments or buildings inherited or passed down from earlier generations and includes a street / buildings in the city landscape.

Habitable Building: A structure built as a place of work or living, fit safe & suitable for habitation i.e. such portion of a building in direct contact or used as a place of work or living. It also include such fixtures and infrastructure i.e. water supply, drainage or solid waste etc.

Insects & Mites: Insects are any of the numerous usually small arthropods, creatures in the class “Insecta” that live & survive on the exposed surface of buildings. In adult stage the insects or mites are characterized by three or more pairs of legs and a body. Mites are any of the various small or minute arachnids in the class of “Acarina”, parasitic on animals and plants or exposed concrete surfaces, a serious health hazard-transmit diseases.

Modern Concrete: Made of gravel (crushed stone/pebbles), sand, and modern cement, mixed with water as slurry, laid or cast in a mould forming a stone like mass when dry, a physical form or structure.

Microbial Agents: A minute life form; a microorganism, especially a bacterium that live & survive in moist exposed surfaces in buildings. Generally, these are formed on moist / damp or fissured concrete surfaces and are also a health hazard and cause infective diseases. These also act as food for growth of insects and mites.

Surface Texture: The word texture means: what things are made of and how they feel. Textures can be described as “rough”, “smooth”, “hard”, “soft”, “liquid”, “solid”, “lumpy”, “gritty” etc. The word “texture”, here includes the physical form, shape, size or composition of building material, colour, or healthy finish of exposed cement concrete surfaces in heritage buildings.

CHANDIGARH: CITY LEGACY OVERVIEW Chandigarh City is a symbol of India’s freedom, an expression of citizen’s faith in its development, i.e. Architecture, Urban Form, City Landscape.

It Nurtures a Way of Life for the people in the machine age civilisation, unfettered by the traditions of the past and the citizen’s faith to sustain its legacy for the future.

The Chandigarh City Charter – Edict, enlightens the citizens on its basic urban design concepts and architecture with a view to protect its legacy / inheritance, namely; i. “The Age of Statues is Gone”, commemoration of events to be confined to suitably

placed bronze plaques. ii. Protect and conserve its “Modern Age Architecture” and “Truthfulness of

Building Material” in the city landscape.

The presentation aims to protect / restore its architectural heritage, Conserve / Restore the Exposed Concrete Façade of City Centre Heritage Buildings in, Sector-17, Chandigarh

.

CHANDIGARH HERITAGE SUB-COMMITTEE: TERMS OF REF. The Chandigarh Heritage Conservation Committee (CHCC) in its meeting held on 14th Jan, 2013, constituted sub-committees i) to study / prepare draft on enabling Heritage Laws-Regulations, ii) study and formulate a plan for action to conserve-restore exposed heritage concrete structures / buildings in the Chandigarh City Landscape.

The sub-committee in its meetings in Nov / Dec, 2013 with the CCA Conservation Team, chalked-out a course of action and prepare a report on conservation-restoration of the Façade of Heritage Buildings / Precincts in City Centre (Jagat Cinema Site-TDI Mall), Sector-17, Chandigarh i.e. i. Undertake detail study of altered / damaged exposed brick / concrete surfaces of

heritage buildings / precincts jointly with CCA Conservation Team. ii. Accept / protect and preserve the Chandigarh City Heritage Legacy on

“Truthfulness of Building Material” in restoration of heritage buildings / precincts. iii. Create awareness, identify viable natural building material, skills / techniques and

train skilled / unskilled workers in conservation / restoration of heritage buildings. iv. Evolve norms, standards and specifications for treatment / restoration of exposed

concrete surface textures of heritage buildings in City Centre, Sec-17, Chandigarh. Evolve a strategy for a suitable / cost-effective future course of action for

citizen participation to sustain the City Landscape in Sec-17, Chandigarh.

The Draft Master Plan 2031, enlists buildings in Capitol Complex, CCA in PEC Campus, Sector-12 etc. and the City Centre / Jagat Cinema and other buildings in Sector-17 in the “Heritage Zone” Grade-I i.e. of historic importance, excellence in architectural style, design and use of natural building material. It does not permit intervention / alteration of the concrete façade / surface textures of concrete structures in the city landscape.

Chd Adm. Engg. Deptt. tests of structural stability of concrete structures in Capitol Complex, show that they are safe for habitation purposes.

HERITAGE BUILDINGS SECTOR-17 CHANDIGARH

Census 2011 Area of Chandigarh City (UT) - 114 km2 Elevation above MSL - 350 m (1,150 ft) Population Metro - 1,025,682 persons Density - 8,400/km2 (22,000/sq mi)

Le Corbusier’s Chandigarh: Capitol Complex

Siting of the Capitol Complex in the Chandigarh City Landscape

A View of the Jan Marg Looking Towards the Shivalik Hills: the seven-storey blocks add a touch of

urban habitat in a City Landscape

Chd. Adm. Planning Deppt. / CCA Research Cell study of the structures in the City Centre, show that 80840.31 m2 i.e. 3.80%, constitute “altered / damaged concrete structures” due to human intervention i.e. alteration of the exposed concrete surface with cement plaster / paint / hoardings etc., which require repair and restoration.

The entire external or internal exposed concrete surface i.e. 2127376.52 m2, constitute “damaged surface textures” due to effects of air pollution / carbonation / algae / microbial action which require restoration, sustainable treatment and regular maintenance.

Physical Survey of Heritage Buildings / Precincts

Of the total 500 public / privately owned heritage buildings, 23.40% are structurally safe i.e. telephone exchange, GPO, banks, cinemas, SCOs. The original architectural building façade, shuttering pattern-formwork is visible. 49.60% have altered / damaged exposed concrete façade due to painted surface (cement plaster or enamel oil paint). 22.80% show signs of weathering action carbonated / blackened surface, 0.40% show signs of alteration / damage due to microbial action or green algae on surface. 3.80% have developed visible cracks and are structurally damaged, which require structural restoration, see table below:

Sr. No.

Description of Heritage Buildings No.of Bldg.

Percentage

1. Stipulated exposed concrete building façade: visible shuttering pattern / formwork. Surface texture show signs of carbonation / black streaks

117

117/500 x 100 = 23.40 %

2. Stipulated exposed concrete building façade: altered / damaged surface due to high carbonation / blackening

114

114/500 x 100 = 22.80 %

3. Stipulated exposed concrete building façade: altered / damaged due to cement plaster or painted surface

248

248/500 x 100 = 49.60 %

4. Stipulated exposed concrete building façade: altered / damaged due to microbial action / green algae surface

2

2/500 x 100 = 0.40 %

5. Stipulated exposed concrete building façade: structurally damaged due to spalling / cracks and exposed reinforced steel bars

19

19/500 x 100 = 3.80 %

Total No. of Buildings Surveyed including Telephone Exchange / GPO, 17 Bay Off., Additional Town Hall and Jagat Cinema Bldg.

500 100%

Agents of Change: Altered / Damaged Heritage Building Façade

Conservative assessment carried-out by the CCA Conservation Team show that 60% to 65% of the altered / damaged concrete façade has been done by banking institutions or public / private corporates. The break-up of the agents of change, effecting the altered or damaged exposed concrete façade or the concrete surface texture, either intentional or incidental due to absence of awareness of the heritage status of the City Centre Landscape.

Sr. No.

Description of Heritage Buildings Agents of Change / Ownership

Percentage

1. Stipulated exposed concrete building façade i.e. concrete columns / architrave / parapets: altered / damaged due to cement plaster or painted surface which require restoration by sand / shot blasting, use of proportionate mix of natural building material.

Govt. / public or private owned bank corporate buildings, e.g. bank square, GPO / telephone exchange and 17 bay office building

60 to 65 %

2. Stipulated exposed concrete building façade i.e. concrete columns / architrave / parapets: altered / damaged due to cement plaster or painted surface which require restoration by sand / shot blasting, use of proportionate mix of natural building material.

Private / individual or joint ownership small holdings, i.e. cinema, SCOs, retail, shop / commercial buildings

40 to 35 %

The HCC Sub-Committee report focuses on cleaning / restoring the façade of heritage buildings / precincts by active participation of the private sector / shopkeepers / owners of the properties. It also focuses on the need to accord priority to protect and conserve the Government owned Public Buildings Bank Square etc. as a demonstration exercise and thereafter take-up the Private Commercial Buildings in City Centre, Sector-17, Chandigarh. The study of the physical condition of building structures related to conservation of the City Centre, Sector-17 are highlighted as follows:

•Poor construction of RCC structures in the private sector with alterations and changes made by human interventions, damaging the exposed concrete surface building façade. •Pitting / spalling, cracks and fissures in exposed concrete surfaces, RCC column. •Carbonation / blackening of building architrave, parapet facia due to dampness and deposit of salts and fungus on its surface. •Some of the parapets partly broken, damage concrete cover, exposing steel reinforcement at many places. •Vegetation growth, algae, microbial growth, carbonation etc, on exposed concrete surfaces of building architraves and on roof top. •Concrete surface façade painted with variety of cement / oil based applicants damaging the exposed concrete surface building façade. •Structural changes in use of natural building material, making it unsafe for pedestrian movement in front covered / paved corridors.

Damaged concrete façade: Heritage Building Central

Plaza, Sector-17, Chandigarh

Damaged roof top architrave: SCO Concrete Building, Central Plaza, Sector-17, Chandigarh

Altered / damaged concrete façade: Heritage Building Central Plaza, Sector-17, Chandigarh

Altered / damaged concrete façade: Unauthorised covered

verandah in Heritage Building, Sector-17

Damaged concrete façade of Cinema

Building along newly constructed Fly Over: Sector-17, Chandigarh

Altered / damaged concrete façade /

verandah flooring: Heritage Buildings,

Sector-17, Chandigarh

Altered / damaged concrete façade of

Bank Square Heritage Buildings: poor or

unhealthy street City Landscape,

Altered / damaged concrete façade of

Heritage Buildings: poor or unhealthy

street City Landscape, Sector-17,

Chandigarh

Altered / damaged concrete façade of

Heritage Buildings: poor or unhealthy City

Landscape, Sector-17, Chandigarh

Altered / damaged concrete façade of

Heritage Buildings: poor or unhealthy City Landscape, Sector-17, Chandigarh

Altered / damaged concrete façade of Heritage Hotel

Buildings: poor or unhealthy City Landscape, Sector-17,

Chandigarh

A View of the Jan Marg Looking Towards the

Shivalik Hills: the seven-storey blocks add a touch of urban

habitat in a City Landscape

RESTORATION OF JAGAT CINEMA / TDI MALL HERITAGE BUILDING: DEMONSTRATION EXERCISE

Pursuant to the CHC meeting held on 24th Jan, 2013, the Chief Architect Urban Planning Deptt. followed-up action in the Sub-Committee meeting held on 24th Dec, 2013 for feedback from conservation experts i.e. the architect members of the CHCC – Sh. SD Sharma, Prof. Rajnish Wattas, the CCA Conservation Team comprising of Prof. Jagjit Singh Ghuman and Prof. Prafulla Janbade.

It was also noted that the case of TDI Mall falls in the Chandigarh Heritage Zone V and a detail case study / demonstration exercise taken-up by and the CCA Conservation Experts and TDI Mall Representatives.

Aerial View of Jagat Cinema Site and N-E

Facing Front Exposed CC Façade of Heritage Building

before its Re-construction and old

Jagat Cinema Exposed CC Façade / TDI Mall, Sector-

17 Chandigarh.

It is noted that, the ICS Hotels Pvt. Ltd. revised building plans / application to erect / re-erect / add to / alter the Jagat Cinema Site / Building in Plot No. 32, Sector 17-A, Chandigarh u/r 5 of the Punjab Capital (Dev. & Reg.) Building Rules 1952 were sanctioned vide Memo No. 52713/SDO(B)/CP-949 dt. 25th April, 2011.

In the course of its re-construction the stipulated exposed cc façade was altered i.e. RCC walls with steel shuttering pattern façade has been constructed in cement / brick work, exposed surface cement plastered and further coated with acrylic off-white colour paint.

The proposal to regularise it was not accepted and TDI Mall representative submitted details of alterations in the exposed concrete façade as follows: • The surface has been thoroughly cleaned, by removing all motor droppings, algae,

fungus, greens and all other foreign matters. • Base preparation has been done by cleaning the surface with sand paper. • Pitting of surfaces have been filled with cement putty and rubbed with sand paper

to make the surface clean and level (smooth). • Coat of water proof cement paint @ 3.84 Kg./sq. mtr. has been applied. • Exterior grade primer, make Berger applied @ 2.2 Kg./10 sq. mtr. • Finish with Acrylic smooth exterior paint, make Berger @ 1.67 Ltr./10 sq. mtr. external building surface.

N-E Facing Front Exposed CC Façade of

TDI Mall Heritage

Building after its Re-

construction with Altered /

Painted Exposed CC

Façade, Sector-17 Chandigarh.

Efforts made by TDI Mall representatives from Oct’2013 to Jan’2014 to restore the stipulated concrete façade comprising of the GF cc columns-architrave, side walls , front and rear parabolic façade by i.e. 7 samples for columns-architrave and 3 samples with cement plaster and use of synthetic colours / paints to restore the texture / colour of the concrete façade were examined at site and discussed in the Heritage Sub-Committee meetings.

The samples were not approved / accepted / un-satisfactory due to mismatch in use of restoration material, application technique, texture / colour

i. Sand / shot blasting, dry process cleaning / restoration of altered / damaged concrete surfaces.

ii. After (i) above, wet process cleaning with sponge and clean portable water. iii. Restoration / treatment of exposed concrete with a workable mix of concrete

i.e. cement, sand and grit for walls and cement-putty mix for exposed columns.

The TDI proposal / paint work was not acceptable as it did not meet the conservation / restoration techniques i.e. satisfactory cleaning / removal of paint work from concrete surfaces etc. The CCA Conservation Multi-Disciplinary Team recommended,

1. Chief Architect UT Chanidgarh with Heritage Committee Members, CCa Conservation Team and TDI Mall Representatives.

2. Members inspecting the sand blasted column surface with partially treated concrete mix.

3. Sand blasted column exposed concrete surface.

Different restoration techniques for concrete columns and walls have to be used i) workable mix of OPC grey / white cement, sand, grit is suitable for restoration of concrete walls only, and ii) the circular surface for the columns suitably restored with OPC grey / white cement-wall putty mix only.

1 sample of the exposed concrete wall surface and 1 sample of the exposed concrete column surface was accepted and approved by the Heritage Sub-Committee / CCA Conservation / TDI Teams on their joint visit / meeting on 21st Feb, 2014.

Area a) Surface area of 39 columns @ 5.15 m2 /

column = 201 m2 b) Surface area of architrave – Length

202.5 m x surface parameter 1.075 m = 217.68 m2

c) Total stipulated concrete surface area for columns and architrave=418.68 m2 .

Cost Effective Restoration: Column / Architrave Concrete Surface

Cost a) Dry process cleaning: sand blasting 10 Kg. psi, including sand, labour

etc. Rs. 250 / m2 i.e. Rs. 23.23 / ft2 b) Restoration: OPC grey / white cement with white cement based putty

mix, labour etc. Rs. 301.22 / m2 i.e. Rs. 27.98 / ft2. c) Silicon surface protective coating, Rs. 120.00 / m2 i.e. Rs. 11.15 / ft2. d) Misc. expenses: scaffolding, taxes etc., Rs. 177.60 / m2 i.e. Rs. 16.50 / ft2. e) Total Effective Cost is Rs. 848.82 / m2 i.e. Rs.78.86 / ft2

Area a) Side walls surface area FF = 1508.12 m2 b) Front / rear parabolic surface area =

366.66 m2 . c) Total area for walls and parabolic

surfaces = 1874.78 m2

Cost Effective Restoration: Wall Concrete Surface

Cost a) Dry process cleaning: sand blasting 10 Kg. psi, including sand, labour

etc. Rs. 250 / m2 i.e. Rs. 23.23 / ft2 b) Restoration: OPC grey / white cement with sand / grit concrete mix,

labour etc. Rs. 712.23 / m2 i.e. Rs. 66.17 / ft2. c) Silicon protective surface coating, Rs. 120.00 / m2 i.e. Rs. 11.15 / ft2. d) Misc. expenses: scaffolding, taxes etc., Rs. 861.18 / m2 i.e. Rs. 80.01 / ft2. e) Total Effective Cost is Rs. 1943.41 / m2 i.e. Rs.180.55 / ft2

RESTORATION: NORMS / STANDARDS / SPECIFICATIONS

There are no norms, standards or specifications to grade concrete surface textures in heritage buildings. It is also noted that the stipulated exposed concrete surfaces of TDI Mall Heritage Building has been altered / damaged in the construction process. Its effective cost for a) columns-architrave and b) side walls-parabolic front & rear façade given by TDI Mall Representatives are at page no. 20 & 21 of the Report. The norms, standards and specifications for restoration of altered / damaged concrete surfaces are as follows:

1.Dry Process Cleaning: This refers to cleaning of the exposed concrete surface with a piece of cloth, coir / nylon soft brush, for smooth concrete textures, steel wire brush or sand / shot blasting for rough concrete textures, altered / damaged concrete surfaces, see IS Code: 4988 (Part IV). NB: Sand / shot blasting cleaning process on unaltered / undamaged concrete surfaces invariably damages the fine surface texture.

2.Wet Process Cleaning: This refers to cleaning of the exposed concrete carbonated surface with clean portable water, scrubbed with a sponge / bucket or gently washed with water hose pipe. NB: Do not use any detergents / corrosive additives with water in wet process cleaning of concrete surfaces.

3. Restoration of concrete wall surface texture: Truthfulness of material; • Grey Ordinary Portland Cement (GOPC), 43 Grade, IS Code : 8112-2013, initial

setting time 30 minutes. Do not use Portland Pozzolon Cement (PPC) due to fly ash and other additives / ingredients.

• White Ordinary Portland Cement (WOPC), IS Code : 8042-1989, surface fineness IS : 4031 Pt 2: 1999, initial setting time 80 minutes.

• Washed River-bed Sand (medium grains), IS Code : 383. • Coarse River-Bed Grit 2 to 4 mm for restoration for concrete mix, IS Code : 383.

4. Restoration of concrete wall surface texture: Composition of concrete mix; • Grey Ordinary Portland Cement (GOPC) 1 part • White Ordinary Portland Cement (WOPC) 1 ½ part • Washed River-bed Sand 2 part • Coarse River-Bed Grit 2 to 4 mm 3 part

5. Restoration of concrete column surface texture: Truthfulness of material; • Grey Ordinary Portland Cement (GOPC), 43 Grade, IS Code : 8112-2013, initial

setting time 30 minutes. Do not use Portland Pozzolona Cement (PPC) due to fly ash.

• White Ordinary Portland Cement (WOPC), IS Code : 8042-1989, surface fineness IS : 4031 Pt 2: 1999, initial setting time 80 minutes.

• White Wall Putty (cementing agent), IS Code : 63 , initial setting time ≥100 minutes, tensile adhesion >1.0.

6. Restoration of cc column surface texture: Composition of concrete mix; • Grey Ordinary Portland Cement (GOPC) 1 part • White Ordinary Portland Cement (WOPC) ½ part • White Wall Putty 3 part

7. Formwork: No formwork required for restoration of concrete columns-architrave with cement / putty mix. Restoration of wall and parabolic concrete surface shall ensure shuttering pattern 10 mm joints in flat steel frames 10 mm x 32 mm.

8. Placing of concrete: Concrete mix to be securely placed on suitably treated exposed concrete surface of the wall with formwork of flat steel frame (without steel plate).

9. Grouting of joints: The 10 mm x 32 mm steel frame joints to be grouted with the concrete mix and ensure uniform concrete texture / colour.

10. Workability: Use of natural building material shall ensure workability. Control water content, IS Code : 456 for workability of concrete mix for wall / parabolic surfaces.

11. Workmanship: Trained, skilled, dedicated workman engaged in conservation / restoration process shall ensure uniform concrete surface texture / colour.

12. Surface Texture: Smooth / soft concrete surface texture for columns, architrave ensured by 2 coat process application / cleaning of cement-putty mix with 80 to 120 grade sand paper 2 coat silicon based sealant / water repellent. The side walls, front-rear parabolic surfaces laid / finished with concrete mix in shuttering pattern, grouting of the joints and protected with 2 coat silicon based sealant / water repellent.

13. Colour: Uniformity of natural colours for standard grey / white cement concrete or putty mix shall be ensured for all restored surfaces i.e. sustain truthfulness of building material.

14. Curing: The restored concrete mix wall surfaces in concrete mix only require curing with clean portable water as per IS Code : 456. The concrete columns and architrave restored with cement and putty do not require curing with water and will require 24 hours for its setting before the next coat is applied.

15. Durability: Restored exposed concrete wall surfaces with concrete mix of cement, sand and grit, enhances the stability and durability of the concrete structure. Similarly the cement-putty mix restored columns also ensures uniform surface texture and colour of the concrete façade. The concrete surface of heritage buildings is also improved with application of silicon based

sealant / water repellent protective coating.

FINDINGS / CONCLUSIONS Detail study of exposed concrete surface structures require periodic examination of its structural stability, assessment of the extent of structural alteration / damage and exposed corroded steel bars treated with protective anti-corrosive agents. The study also assess available options in the cleaning / removal of carbonation by dry / wet process, repair or restoration of altered / damaged concrete surfaces. Removal of cement mortar plaster or paints or other synthetic agents on concrete surfaces, which permanently alter / damage the “texture of exposed concrete surfaces”. All such alterations or damage need to be stopped / totally prohibited and timely efforts made to protect / conserve the concrete surface texture of heritage buildings in the Chandigarh City Landscape.

It is noted that the City Centre is regulated by specific zoning and architectural controls for concrete and brick structures. There are two types of controls, a) shop cum office buildings i.e. brick façade on the V4 road and b) the rest of the banking / commercial privately owned properties in the City Centre are in exposed concrete façade. As per Edict of Chandigarh, any form of alteration / change in its façade is not permitted and “Truthfulness of the Building Material” is to be maintained.

(NB. Use of detergents, chlorine, caustic soda or other corrosive agents in the dry or wet process cleaning is totally prohibited).

Of the total 500 public / privately owned heritage buildings surveyed, only 23.40% are maintain the original architectural building façade (shuttering pattern-formwork). The concrete surface texture however show signs of weathering action / carbonation / black streaks. 49.60% have altered / damaged exposed concrete façade due to painted surface (cement plaster or enamel oil paint). 22.80% show signs of weathering action carbonated / blackened surface, 0.40% show signs of alteration / damage due to algae, microbial action. 3.80% have developed visible cracks and are structurally damaged, which require restoration.

Conservation of cement concrete façades in heritage buildings begin with the assessment of the extent of structural damage or alteration of exposed concrete surfaces by paint, plaster, effects of carbonation, algae, microbial action etc. in buildings. Findings of the study on use of “Truthfulness of Material” help build the use of skills and techniques in the Restoration Process. The conservation of cement concrete structures and its relationship with structural damage vis-à-vis surface texture damage is given below:

Dry or wet process cleaning without sand / shot blasting and application of petroleum mix on concrete surface is simple and cost-effective. This is possible with periodic cleaning of outdoor or indoor concrete surfaces damaged due to weathering action or effect of carbonation.

The process of conservation / restoration of the exposed concrete façade carried-out with natural building material namely; cement, sand, grit or white cement based putty has been successfully achieved to restore truthfulness of concrete surface texture / colour, of concrete heritage public / private buildings in Sector-17, Chandigarh. The accepted cost effective sustainable conservation / restoration technique for sustaining a healthy City Centre Landscape is given below:

i. Sand / shot blasting, dry process cleaning IS Code: 4988 (Part IV).

ii. Wet process cleaning with clean portable water with hose pipe or bucket-sponge.

iii. Restoration / treatment of exposed concrete with natural building material only, i.e. a workable mix of concrete i.e. cement, sand, grit or putty (white cement based filling agent).

iv. Application of protective coating with silicon, polymer or petroleum based mix on concrete / putty mix.

Repair or restoration of altered or damaged concrete surfaces require careful handling by a multi-disciplinary conservation team.

THANK YOU