SELF-CONSOLIDATING CONCRETE

Rico Fung, P.Eng., LEED®AP Director, Markets & Technical Affairs Cement Association of Canada Credit to Sherry Sullivan, CAC

Highly flowable, non-segregating concrete that can spread into place, fill the formwork, and encapsulate the reinforcement without any mechanical consolidation.

ACI International Committee 237 Self-Consolidating Concrete, July 2003

Self consolidating concrete, self placing concrete, or self leveling concrete. These concretes are highly flowable concrete that can spread into place under their own weight and achieve good consolidation without internal or external vibration and without exhibiting defects due to segregation and bleeding.

Kamal Khayat

NSERC Industrial Research Chair on High-Performance Flowable Concrete with Adapted Rheology

Département de génie civil - Université de Sherbrooke

Self-consolidating concrete (SCC), a highly flowable, yet stable concrete that can spread readily into place, fill the formwork, and encapsulate the reinforcement, if present, without any mechanical consolidation and without undergoing any significant separation of material constituents.

CSA A23.1

• SCC was developed in Japan in the mid 1980’s • Decrease in skilled labor • Heavily reinforced concrete structural design • Noise Pollution

• European countries adopted and advanced the development of SCC in Early 1990’s

• Coming to America, late 1990’s through University research

• SCC emerged into the forefront in North America at the start of the new Millennium mainly in precast/prestressed industry

• Commercialization into Ready Mixed Concrete began around 2001-2002

• Type GU/GUL/Type GUb-8SF/Type HE

• Slag / Fly Ash / Mineral Fillers

• 10/14mm stone (Gravel or Limestone)

• 50/50 blend of CA/FA

• Polycarboxylate High Range Superplasticizers

• Viscosity-modifying agent (VMA)

• Site Representation

High fluidity

Takes the shape of any formwork configuration

High resistance to segregation or bleeding

No honeycombing!

Reduce construction time

Maintain or Advance schedule

No vibrators Reduction of nerve and vascular damage

“white fingers”.

Smooth, Textured, or Patterned

A new way to think about concrete construction!

Horizontal SCC slabs, elevated decks, thin floors, radiant floors, repair

toppings, interior or exterior

Vertical SCC walls, columns, highly congested rebar, repairs, close

tolerances, smooth walls, form-liners, exposed columns, signs, architectural grade form finish, retrofitting.

Civil repair and rehabilitation of bridge piers and beams, water

tanks new construction – congested reinforcing, tight spaces

•Bar and Go finish •No trowel finishing required

SLU

MP

TES

T

SLU

MP

FLO

W

Fill slump cone mould, screed off excess concrete

Raise cone ~225 ± 75 mm above surface in 3 s ± 1s

Allow concrete to achieve max. spread, or until 2 minutes

have elapsed

Measure concrete spread at two perpendicular directions

(repeat test of diameters differ by more than 50 mm)

T50 time is the time it takes to reach a diameter of 50 cm

• L-Box • U-Flow • Column Segregation • J-Ring • V-Funnel

• Slump Flow • T50 / T40

• Visual Stability Index (VSB) • J Ring

• Compressive Strength • Hardened Air Void System (AVS) • Rapid Chloride Permeability (RCP) • Linear Shrinkage • Creep • Modulus of Elasticity

18 page guide

What is SCC

How to Utilize SCC Effectively

Engineering Properties

Test Methods

Production Requirements

Placing & Finishing

Toronto, Ontario

Designation: Class A office building

Height: 51 stories - 218m, with

3 levels of underground parking

Value: $300 million

Project Size: 1.2 million ft

Concrete: 50,000 m³

• SCC was not specified

• 16,000 m³ of Core Wall Concrete

• 340 m³ of concrete per wall pour

• 8 MPa in 12hrs / 60 MPa in 91Days

• Placement by bucket and pump

• Original mix met strength criteria however utilized conventional placement techniques

• R/M Producer proposed SCC to the contractor for the core wall application

• Will meet strength requirements

• Ease and speed of placement

• Noise reduction (no vibration)

• R & D

• w/cm 0.35 to 0.368

• Air content 1 to 3%

• Slump Flow 650 mm to 800 mm (T50 of 2 to 5 sec)

• Unit weight 2,375 to 2,425 kg/m³

• Compressive Strength 15 to 20MPa in 12Hrs (monitored on site by maturity meter) / 60 to 65MPa in 56-Days

• PUMP-A-BILITY

Pump distance ~300ft to core wall then 52 levels up (~800ft) ~Total 1100ft

Ministry of Transportation Ontario

St. Catharine's Ontario, July 2005

Rehabilitation and repair of bridge piers Removal and repair of deteriorated concrete and steel

reinforcing rebar

First project requiring pre-qualification of shrinkage to 0.06% maximum limit

350m3 , 3-5m3 per load First MTO project to specify SCC as repair material

Contractor:

Definite cost saving in labour: Reduced to 2 labourers.

50% less remedial work for patching and grinding. Impressed with ease of placing, filling and

consolidation in formwork.

Owner (MTO):

Considerable reduction in cracking. Superior finish, significant reduction of bug holes.

Toronto, Ontario September 2005, January 2006

• Phase 1 • 2,561m3

• Placed with 3 pumps • Pour completed in 12hrs

• Phase 2

• 3,145m3

• Placement completed in 10 hours • Placed with 2 pumps and 3 gravity fed chutes at an

average rate of 315 m3/hr.

University of Toronto

17 columns, 1m dia. x 19m height. 413 m3 of SCC Architectural P1 finish specified Colour consistency throughout

column and from column to column.

No lift lines or cold joints.

Pumped in one lift from bottom through a Guillotine valve.

Stripped 12-15 hrs the following day and re-formed and poured

Properly designed SCC can increase the light reflectance value of concrete

LEEDs points: Less lighting required with higher reflectivity of concrete on

exposed walls ceilings. SCM replacement

Light reflectivity Mix Design and form work quality Standard concrete: 35% Standard concrete with 50% slag: 38% SCC: up to 50%, will mirror any surface it comes into contact

with

Smoother surfaced and optimized mix designs.

Ministry of Transportation 2008 - 2009

SCC has been used to repair 11 bridges

SCC used for patching and refacing of piers,

abutment walls, deck soffits and girders.