CONCRETE ACTION 2014

Prof. Er. Jagjit Singh Ghuman

Coordinator and Principal Investigator, CCA Conservation Research Project

Formerly Chief Town Planner and Head T&CP Dept., Govt. of Punjab

Conservation of Modern ArchitectureRestoration of Cement Concrete Structures

Truthfulness of Material and Construction CodeGrading and Restoration of Surface TexturesExposed Concrete Façade of Heritage Building

Prof. Prafulla T. Janbade

Asst. Prof. Architecture and Principal Investigator,

CCA Research CellChandigarh College of Architecture

CITY LEGACY / OVERVIEW

Chandigarh City is a symbol of India’s freedom, an expression of citizen’s faith in its development, i.e. “Urban Form, Architecture, City Landscape”, to sustain its legacy / heritage buildings for the future generations.

The study “Truthfulness of Material and Construction Code”, quantify and qualify norms, standards, code of practices for concrete structures in the construction industry.

The study of Corbusier’s Concrete, “Grading and Restoration of Surface Textures” covers the demonstration exercise undertaken for conservation and effective treatment of exposed concrete surface texture of a roof in a faculty room in CCA Building Chandigarh.

The study / demonstration exercise on conservation, repair, restoration of “altered or damaged concrete façade of Heritage Buildings” in the City Centre / CCA Building in Chandigarh.

The study / demonstration exercise aim to protect / restore its architectural heritage sustain a healthy work-living environment and ensure a distinct quality of life to its citizen.

Ancient or pre-historic concrete used a) Pozzolan, a siliceous aluminous material from volcanic ash, b) quicklime obtained by heating limestone, mixed with sand and grit / gravel.

Modern Cement Concrete in the construction industry was revived by James Parker, a clergyman in 1780’s and developed as Portland Cement by Joseph Aspdin (1779-1855) of UK in 1824.

Portland Cement gets the name from its resemblance (on hardening) to the famous limestone, obtained from quarries on the Isle of Portland in UK.

It is made from finely pulverized alumina (form of aluminum oxide occurring naturally), limestone, iron oxide, magnesia, and silica burnt together in a kiln.

TRUTHFULNESS OF MATERIAL AND CONSTRUCTION CODE

or cement mortar for stone or brick laying

TYPE-PROPERTIES OF MODERN CEMENT

“Portland Cement” is by far the most common type of cement, generally used around the world, often referred to as OPC used as mortar in masonry or cement concrete in the construction industry.•Natural or Geo-polymer Cement•Energetically Modified Cement (EMC)

Portland Cement Blends, these are available as inter-ground mixtures of Portland Cement with similar formulation with different ingredients at the concrete mixing plant, namely;

Non-Portland Hydraulic Cements, ground granulated blast furnace slag is not hydraulic on its own, but is "activated" by addition of alkalis, most economically using lime.•Slag-Lime Cement•Super Sulfated Cement•Calcium Sulfoaluminate Cement

• Portland Blast Furnace Cement• Portland Pozzolan Cement• Portland Silica Fume Cement

• Expansive Cement • White Blended Cement• Finely Ground Cement

GRADING OF CEMENT AND CONCRETE

Indian Standard Code for grading of cement and concrete in the construction industry is given for:•Type and Properties of cement, sand and gravel•Design , composition and proportioning mix•Compressive strength for structural stability•Workability of graded cement concrete, laying and formwork•Structural’s durability Compaction by use of vibrators•Time schedule for curing and removal of formwork

DETERIORATION OF CEMENT CONCRETE STRUCTURES

Damage of exposed cement concrete due to environmental changes, its scanning-mapping to maintain permanent record / data, its restoration, maintenance and upkeep is a major concern of physical planners, architects and engineers.•Environmental causes, climate and weathering action, air and water pollution, effect of pH value, carbonation, corrosion of reinforced steel.

SCANNING, MAPPING OF DAMAGED CONCRETE STRUCTURES

Diagnosis of deterioration / damage, required for assessing the quantum of repair / rehabilitation necessary, is made by the following methods:• Identifying symptoms by visual observations, The symptoms which indicate active corrosion of the embedded steel include appearance of red stains on the surface; splitting and spalling of concrete cover exposing reinforcement; appearance of parallel cracks along the reinforcement, embedded pipe fitting etc. and, cleavage planes showing the separation of concrete from the bars.• Damage can also be assessed by non-destructive methods, The Non-destructive Evaluation Testing Methods now available include the Ultrasonic pulse velocity test; Rebound hammer test; Half-cell potential mapping method; Electrical resistivity measuring method; permeability test; chloride test; water test; petrography and carbonation test.•Scanning and mapping techniques, CorroMap and Core Test

Conservation of cement concrete begins with the assessment of the extent of structural damage in buildings. Findings of the study of “Truthfulness of material and construction code” helps to build this relationship.

Patch work repair of exposed concrete surfaces, invariably do not match with the surface texture. Changes effected due to faulty repair and treatment of exposed concrete surface texture need to be restored.

Avoid mismatch of exposed concrete surface texture of buildings in the city landscape.

CONSERVATION OF CEMENT CONCRETE STRUCTURES

GRADING AND RESTORATION OF SURFACE TEXTURES

The CCA Research Cell study covers, in-depth investigation of the exposed cement concrete structures and surfaces in buildings. It also aims to identify options-alternatives for preventive treatment of the controlled building façade and the exposed cement concrete roof surface of the CCA Building to restore its healthy texture, namely:• Truthfulness of material and construction code• Grading-Restoration of Corbusier’s Concrete: Demonstration Exercise,i.Study the CCA building structure, develop skills & techniques for conservation of exposed cc surface texture.ii.Application of silicon, polymer or petroleum based products to ensure sustainable maintenance of the concrete surface texture.

GRADING AND RESTORATION OF SURFACE TEXTURES

The physical condition and characteristics of exposed cement concrete structure and surface texture was carried out for the listed heritage buildings in Chandigarh.

Cement Concrete Building Structure and Architectural

Controlled Façade

(Exposed Concrete Surface Texture)

External

Exp. c.c.

Facade

Internal

Exposed

Concrete

Gross

Exposed

Concrete

Damaged

Concrete

Structure

(in m2)

Damaged Untreated

Surface Texture

(in m2)

(m2) (m2) (m2) Area % age Area % age

Capitol Complex 158938.93 635755.73 794694.67 8025.00 1.01% 794694.67 100%

Assembly Building 34690.20 138760.80 173451.00 2601.77 1.50% 173451.00 100%

Secretariat Building 40471.90 161887.60 202359.50 2428.31 1.20% 202359.50 100%

High Court Building 25439.48 101757.92 127197.40 1526.37 1.20% 127197.40 100%

Hall of Shadows Building 289.09 1156.34 1445.43 17.35 1.20% 1445.43 100%

Geometric Hill 231.27 925.07 1156.34 5.78 0.50% 1156.34 100%

Open Concrete Pavement 57817.00 231268.00 289085.00 1445.43 0.50% 289085.00 100%

City Centre, Sector-17 92507.20 370028.80 462536.00 11346.59 2.45% 462536.00 100%

SCO Concrete Façade 52035.30 208141.20 260176.50 7805.30 3.00% 260176.50 100%

Govt. Buildings Concrete Façade 11563.40 46253.60 57817.00 1734.51 3.00% 57817.00 100%

Office and Hotel Complex 28908.50 115634.00 144542.50 1806.78 1.25% 144542.50 100%

Museum and Arts College, Sector-10 40471.90 161887.60 202359.50 3237.75 1.60% 202359.50 100%

College of Architecture, Sector-12 1156.34 4625.36 5781.7 109.85 1.90% 5781.7 100%

PGI Campus, Sector-12 46253.60 185014.40 231268.00 3700.29 1.60% 231268.00 100%

Punjab University Campus, Sector-12 2890.85 11563.40 14454.25 231.27 1.60% 14454.25 100%

Administrative Block 2312.68 9250.72 11563.40 185.01 1.60% 11563.40 100%

Gandhi Bhawan 578.17 2312.68 2890.85 46.25 1.60% 2890.85 100%

Punjab, UT and other Govt. Off. Bldg. Façade, Sector-10 46253.60 185014.40 231268.00 3700.29 1.60% 231268.00 100%

SCO Bldg. Concrete Façade, MM, Sector-9 37002.88 148011.52 185014.40 4255.33 2.30% 185014.40 100%Physical assessment of the area of external exposed façade and the concrete surface texture of cement

concrete building structures in Chandigarh City Landscape.

Physical assessment and grading of exposed cement concrete surface texture (Table 1) show that the damage of concrete structures in the Capitol Complex is approximately 1.62% as compared to private owned concrete buildings in Sector-17 (2.04%) and along Madhya Marg Sector-9 (2.3%).

The damage of exposed concrete surface texture is predominantly due to structural alterations and faulty repair of the building façade.

Grading of surface texture for sustainable restoration of concrete structures is as follows:

ST 1: Glossy shiny, lustrous bright silver grey or beige colour.

ST 2: Soft, fine to touch in silver grey colour partial change in colour of concrete surface texture due to carbonation etc.

ST 3: Smooth free from irregular surface particles, in steel or processed wood shuttering or moulding with carbonation and change in concrete surface texture colour.

ST 4: Coarse medium or small granular surface, with surface voids, carbonation, change in concrete surface colour.

ST 5: Course rough or large granular surface, generally seen in rough wood shuttering, carbonation and total change in concrete surface texture colour.

RESTORATION OF CONCRETE SURFACE TEXTURES

The restoration, maintenance and upkeep of exposed concrete surface is generally carried-out by;• Dry or Wet Process: cleaning the Cement Concrete surface infested with dust and cobwebs, etc. with water and brush.• Optional, use mechanical or manual dry or wet process i.e. air or sand blasting, or steel or coir fibre brush for cleaning the concrete surface to remove carbonation.• Mechanical or manual process i.e. compressed air pump with a spray gun to dry and clean the Concrete Surface.• Protect & treat: all concrete surfaces with silicon or polymer based product or petroleum based product i.e. a mixture of sulphur free Diesel (low lubricant) 50% + Kerosene (absence of olefin lubricant) 40% + 10% household insecticide-disinfectant (by volume) with a 4” paint brush or a compressed air pump spray gun.• Ensure fire and other safety requirements: including use of silicone hand gloves, face mask, protective glasses etc. when treating or applying the aforesaid indigenously prepared mixture.• Allow free flow of air & ventilation: in the room or interior portion of the building before occupying it

CONSERVATION OF CCA BUILDING:DEMONSTRATION EXERCISE

Graded Surface Texture

Recommended Cleaning Process

Surface Treatment

ST 1: Glossy, lustrous silver grey or beige colour.

Dusting , cleaning with soft cotton fibre dry mopper and clean portable water without any additives

Clear wax or petroleum jell, polish mix with diesel or kerosene

ST 2: Soft, fine to touch in silver grey colour

Coir or soft brush dry process with nylon sponge and water without any additives

Petroleum base proportionate mix with insecticide

ST 3: Smooth free from irregular surface voids or particles

Coir or soft brush dry process with nylon sponge and water without any additives

Petroleum base proportionate mix with insecticide

ST 4: Coarse medium or small granular surface, with surface voids

Wire brush, low pressure sand or water blasting mechanical process or wet process

Petroleum base proportionate mix with insecticide

ST 5: Course rough or large granular surface voids

Wire brush, low pressure sand or water blasting mechanical process or wet process

Petroleum base proportionate mix with insecticide

Recommended effective cleaning and treatment process for exposed cement concrete graded surface texture.

HERITAGE BUILDINGS: SEC-17, CHANDIGARH

Physical condition of exposed concrete surfaces of heritage buildings in Sector-17, Chandigarh show distinct or marked alteration or damage of stipulated exposed concrete surfaces.

Conservative assessment of the heritage buildings show that; 11346.59 m2 i.e. 2.45% is altered or damaged due to human intervention i.e. alteration of the exposed concrete surface with cement plaster / paint / hoardings etc., which require repair and restoration.

The total exposed concrete surface of 462536.00 m2 is damaged due to effects of air pollution / carbonation / algae / microbial action and requires restoration, sustainable treatment and regular maintenance.

Altered / damaged concrete façade of Bank Square Heritage Buildings, Sec-17, Chandigarh

Altered / damaged concrete façade of Heritage Buildings: poor or unhealthy City Landscape

CCA HERITAGE BUILDING FACADE

Chandigarh College of Architecture: Heritage Building façade concrete surface texture damaged due to effects of weathering, carbonation, algae /

microbial action

Exposed concrete façade sunshade partially damaged due to weathering / air-pollution /

carbonation action before sand blasting

Heavy duty 10 Kg. psi. sand blasting machine at the CCA New Library Building Block Façade

CCA Conservation Team interacting / assessing the effect of sand blasting on exposed concrete surface

with Er. Ravinder Chadha of M/S Prime Engineers

FINDINGS AND CONCLUSIONS

Dry process cleaning with sand / shot blasting is not desirable as it damages its sensitive / fragile concrete surface texture. Alternately, wet process cleaning of the carbonated concrete surface with with water hose pipe, soft brush or bucket-sponge with potable water before, so as not to damage the surface texture of the concrete façade. It is also noted that the entire CCA Library Block exposed concrete surface façade will require repair / restoration. So as to ensure cost effective restoration of the exposed concrete façade CCA Heritage Building without damaging the concrete / brick surfaces, the following alternative is recommended:• Wet process cleaning with water hose pipe, soft brush or bucket-sponge with potable water before, so as not to damage the surface texture of the concrete façade.• Restoration / treatment of exposed concrete with natural building material only, i.e. a workable mix of concrete (cement, sand, grit) for repair of structural damage or cement-putty mix (white cement based filling agent) for restoration of concrete surface textures.• Application of protective coating with petroleum based insecticide mix on interior concrete surfaces or silicon, polymer protective coating on concrete / putty mix on exterior exposed concrete surfaces.

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