Developing new building materials and construction technologies

Development of Durable Concretes using High Volumes of Cement    Replacement    Materials (HV-CRMs)

• Explored the utilization of HV-CRMs to extend the gains of cement reduction, enhanced durability, conservation natural resources & mitigation of  damage to ecology.
• Mixes with 1)same binder content (constant w/b) or 2)increased binder (reduced w/b) developed- upto 70% GGBS or 50% FA for M30- M40 grades.
• 10 to 15% of SF boosts the properties in case of HV- FA (- Triple blends).
• Benefits- Drastic modification of micro structure, reduced H2O absorption, cl- ingress, H2O permeability sulphate attack & Corrosion.
• Effectiveness of ground and ultra fine FA

Assessment of Early Age Stiffening and  Strength of Concrete Mixtures

• Very important for deciding de-shuttering schedule in modern fast-track constructions -problems with interaction & in-compatibility of multi-ingredient mixtures
• Techniques – Pin penetration, strength tests, US signature analysis & Maturity.
• US Pulse captured using a Digital Oscilloscope & analyzed wrt peak amplitude, wave energy, and attenuation (FFT)
• Peak amplitude & attenuation showed higher correlation & better depicted the growth of strength with age
• Maturity approach used for varying temperature histories
• The Hansen and Kim theory, yielded the best prediction
• Formulated an approach for strength prediction at different ages and temperature histories using attenuation and maturity measurement

High Performance Concrete for Construction of Pavements

• M40, M50 and M60 mixes with 50% FA & Fiber (steel/polymer) developed
• Flexural strengths up to 9 MPa suitable for ultra-thin white topping (<100mm) obtained.
• Toughness index (I30) – 21 – 30 for SFRC and 7 – 20 for Polymer fibers.
• Transport properties- Water absorption and Cl- diffusion substantially reduced(nearly one order less).
• Incorporation of Polymer fibers substantially reduced plastic, drying and restrained shrinkage.
• Considerable delay in development and widening of cracks & their width, Increased no of well behaved cracks.
• Improved wear resistance and improved riding comfort.

Drying Shrinkage                                                   Ring Shrinkage              Plastic Shrinkage Test on Panels

Precast FACC Piles Driving and Testing

Investigations on Effect of Silica Fume in Concrete

• Evaluated the effectiveness of densified and undensified SF on concretes with/ without FA.
• Parameters : Cement grade, SF dosage, workability & curing protocols.
• Assessed- strength at different ages & transport corrosion resistance & pore refinement.
• Significant improvement by addition of SF, USF – better performance.
• Evaluated autogenous & drying shrinkage of pastes. Careful curing emphasised.
• Triple blend advantages brought out- effective utilization of HVCRMs- use of SF in a prestigious construction (parliamentary library).

Development of Structural Concretes with Fly Ash Aggregates

• Angle of Inclination-30°,  Revolution Speed-32 RPM
• Aggregate size –  5-20 mm
• Shape- Spherical
• Specific Gravity – 1.4-1.6
• Bulk Density (kg/m3)- 600-1000
• Water Absorption- 14-19%

•  Density –  1700-1900kg/m3
• Light weight Concretes
• Structural grade concrete up to M40

Durability

• FAAs intact after 2 years, pH sufficient for corrosion resistance
• Increased Acid resistance
• RCPT-Moderate-Very low
• Corrosion rate & Resistivity – Improved presence of fly ash

Achievements

• Technology for the production of FAAs
• Alternative to natural gravel/crushed stone aggregate
• Usable upto M40 grade structural concretes
• Light weight Concretes
• Modified Bolomey Equation-Comp.Strength.
•    fc = K* [cw-0.5](1-a)

Conservation of  natural resources & ecological balance

Studies on precast structural system under seismic loading

Precast Structural Systems under Seismic Loading

Earthquake resistant building with precast concrete elements needs special attention to joints

• Grid system with light weight infill
• Reinforcement detailing ensures large ductility with retention of strength
• Reduction in dead weight of structure
• Improper compaction of concrete eliminated

• Size of assemblage : 2590*2300*2640 mm
• Interior joint assembly comprising two floor slab  units & two wall  panel units
• Equivalent moment cyclically applied on  wall panel
• Joints withstood service and ultimate load

Outcome of the study

• Novel prefabricated light weight system developed utilises new materials and sustains cyclic loads besides regular loads

Development of Advanced Composite Construction Materials and Methodologies for Assessment of Durability Related Parameters

Devlopment of Ultra high Performance Concrete

• Development of Mix design with optimal curing regime and steel fiber volume to attain compressive strength of more than 200 MPa for  UHPC
• Experimental studies to characterize and develop analytical models for UHPC to study its properties under uniaxial loading, tension, compression bending, and impact.
• Development of structural sections with UHPC

Devlopment of Ultra high Performance Concrete as a retrofitting material

• Design of precast UHPC strips and methodology to adhere these strips with pre-damaged reinforced beams.
• Flexural testing of damaged reinforced beams strengthened with UHPC strip of different thickness
• Monolithic failure of composite strengthened beams
• Application of Acoustic emission to understand damage and crack propagation at different loading levels for undamaged and retrofitted beams.
• Crack classification and damage quantification by suggesting damage zones using AE parameters.
• A new recommendation for probabilistic based crack classification using AE parameters for RC beams

Development  of Geopolymeric   Cement Concrete

• Embodied energy of PCC>600 KWh/m3
• 1 ton Cement =   1 ton CO2
• Need for alternate Binder

• No Portland Cement
• Eco-friendly (low ‘embodied energy’, low ‘embodied CO2’)
• High strength
• Fast setting
• Turnover time-1day
• No water curing
• Highly durable

Outcome

• Development of non Portland cement concrete
• Fly ash as sand replacement in concrete

Development of Geopolymer Cement  Concrete

• No OPC low embodied energy,; co-friendly  low CO2  emission
•  Alkali activation of industrial wastes; High strength, Highly durable
•  Ambient/heat curing, No water curing; Fast setting, Turnover-1day,
• Investigations on the Behaviour of Reinforced GPCC under Flexure, shear, compression and bond

Studies on Geopolymer Concrete Structural Elements

Failure Modes of Geopolymer Concrete Compression Members

Shear Performance of Geopolymer Concrete T- Beams  Geopolymer Concrete Beam under flexural loading

Synthesis of Alternative Binder and Aggregate/Filler/Fibre from Waste Materials

Development/synthesis of alternative binder and aggregate/filler/fibre for concrete

Materials -Alternate binder

• Fly ash (FA)
• Ground granulated blast furnace slag (GGBS)
• Silica fume (SF),
• Micronised biomass silica (MBS)

Materials -Alternate aggregate

• Copper slag
• Manufactured sand
• Recycled aggregate

Studies on Ultra High Performance Geopolymer Concrete

To develop an ultra high performance geopolymer concrete (UHPGPC) the following principles were adopted:

• Elimination of ordinary Portland cement by geopolymer binder (activation of GGBS and SF by hydroxides and silicates).
• Enhancing the homogeneity of the matrix by limiting the maximum size of the aggregates up to 2.36 mm.
• Improving the compacted density by optimising the granular mix (particle packing).
• Increase the mechanical property of the matrix by incorporating appropriate amount of steel fibres.
• Curing at ambient temperature conditions.

Materials Used

• Fly ash
• GGBS
• Silica fume
• Standard sand
• Grade I (G1)
• Grade III (G3)
• Quartz sand (Qs)
• Steel fibres (6 mm and 13 mm)

Alkaline activator solution: Commercial grade sodium hydroxide/potassium hydroxide flakes and sodium silicate/potassium silicate solution was used as activators.

UHPGPC mix with flowable consistency Failure of Cube Specimen with and without fibre

Test set up for determination of flexural strength

Design of Sifcon / Alternative Material for use in Underground Reinforced Hardened Shelters

The underground shelters which are subjected to heavy transient blast loading requires suitable material of construction which should possess higher tensile strains, higher energy absorption and better ductility characteristics. To achieve the above requirement, the conventional concrete requires large thickness and heavy reinforcement, which will lead to increased weight and other problems related to handling and erection. This has been overcome by use of SIFCON material and the study has been successfully demonstrated at laboratory level.

Slurry Infiltrated Fibrous Concrete (SIFCON) structural elements possess better properties as compared to their counterparts built using conventional reinforced concrete. The main focus of the study is to throw more light on the design and construction aspects of underground reinforced hardened shelters, using SIFCON. Construction of underground hardened shelter requires prefabrication of various structural components at factory for better quality control. For transporting these structural components to the required site, weight of each element is a major concern.

• Use of SIFCON resulted in complete elimination of reinforcement  and also in significant reduction in the thickness of the shell.
• Special test instrumentation and loading arrangements have been designed and used for testing circular and hairpin geometry.
• The innovative idea of using SIFCON has resulted in better performance against blast loading and increased ductile behaviour.
• Even though initial costs may be higher for SIFCON, owing to its better structural performance, reduced handling and erection cost, its cost/benefit ratio is higher.
• Circular SIFCON specimens showed higher post peak response when compared to hairpin SIFCON specimens hence was recommended.
• The under ground shelters designed using the proposed SIFCON technology are better suitable for housing control & command facilities near airports and for other strategic defense institutions.