SEACON – A NEW RESEARCH PROJECT TOWARDS THE SUSTAINABILITY OF CONCRETE

Antonio Nanni (presenter) and Seyedmorteza Khatibmasjedi

University of Miami, Coral Gables, FL

2016 ICSC + SCC 2016

Washington, DC, May 15-18, 2016

• BACKGROUND• CRITICAL ISSUES• CONCEPT• GOAL• OBJECTIVES• CONSORTIUM • WORK PACKAGES (WPs)• CONCLUSIONS• ACKNOWLEDGEMENTS

TABLE OF CONTENTS

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SEACON project - Background

On October 1, 2015, a consortium of six partners and threecollaborators led by the University of Miami started a 2.5-year research project

This project titled “Sustainable concrete using seawater, salt-contaminated aggregates, and non-corrosive reinforcement”or SEACON was funded under the aegis of the Europeanresearch program called Infravation

(http://www.infravation.net/)

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SEACON

SEACON: Sustainable concrete using seawater, salt-contaminated

aggregate and non-corrosive reinforcement

(http://www.infravation.net/projects/SEACON)

• More than half of the world’s population will lack sufficient drinking water by 2025

• The construction industry uses several billion tons of freshwater annually to wash aggregates and mix/cure concrete

• The potential use of recycled raw materials (fuels, aggregates, SCMs) in cement and concrete production is limited by the chloride content

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http://www.water.ca.gov/

SEACON project – Critical issues

• The use of seawater and salt- contaminated aggregates is prohibited by standards and codes due to associated risks of corrosion of steel reinforcement

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SEACON is not an attempt to develop a new technology or a new chemistry of cement, but rather to contribute to a change in culture that will allow cement and concrete manufacturers to be responsive to emerging societal needs pointing to a wiser use of natural resources

There is the perception that sustainability has a negative impact on economics and makes the production of goods more expensive and more regulated

SEACON is an attempt to pursue the goals of SUSTAINABILITYby removing unnecessary regulations that prevent a better exploitation of byproducts, recycled materials and, where appropriate, saltwater without affecting the quality and durability of the final product

SEACON project - Concept

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SEACON outcomes are intended for the concrete industry but also the general public as a demonstration of the commitment of this industry to be a significant player and partner in addressing global challenges associated with preserving quality of life and environment

This presentation provides a summary of the technical tasks and expectation of this research program in addition to some preliminary experimental results related to Work Package 2

SEACON project – Concept (Cont.)

SEACON project - Goal

This goals translates in the safe utilization of seawater and salt-contaminated aggregates (natural or recycled) for a sustainable concrete production when combined with non-corrosive reinforcement

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SEACON’s aim is to advance the position of the concrete

industry as a whole by making its product more

economical, more durable and more environmentally-

benign. This is accomplished by addressing the following

two challenges:

a) resource and energy efficiency in road construction

and maintenance (Eco-design); and

b) virgin material reduction by substitution or recycling

SEACON project - Objectives

• Assess through LCA and LCC durability performance and economical impact resulting from use of chloride contaminated aggregates, high chloride content cement and seawater in structural concrete

• Validate suitable reinforcement alternatives (i.e., improved SSRand GFRP)

• Demonstrate technology by means of two real-size field prototypes in two countries (Italy and Florida, USA)

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• Make it clear that chlorides are harmful to “black” carbon steel reinforcement, but do not damage the concrete’s characteristics (i.e., workability, strength development, durability)

Partners• University of Miami (UM)

• ATP srl (ATP)

• Politecnico di Milano (POLIMI)

• Owens Corning (OC)

• Buzzi Unicem (BUZZI)

• Acciaierie Valbruna (AV)

Collaborators• Florida DOT (FDOT)

• Pavimental (PV)

• Titan America (TT)

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SEACON Project - Consortium

SEACON Project – Work Packages (WPs) Tasks and relationships

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Work Package 1

• Production of cement with high chloride content (> 0.1%, i.e., out of EN 197-1 Standard!)

• Recovery of artificial aggregate with high chloride content

• Concrete mix-design optimization

• Characterization of hardened concrete

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Work started in 2014 and continuing

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• Concrete specimens from three different mixes: i. Mix A: a benchmark regular concrete mix

ii. Mix B: proportions identical to mix A, except for the substitution of tap water with seawater from Key Biscayne Bay (Florida)

iii. Mix C: contains seawater from Key Biscayne Bay and the natural-coarse-aggregates is substituted with RCA

• Fresh concrete characterization

0

5

10

15

20

25

mix A mix B mix C

Slu

mp

(cm

)

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

mix A mix B mix C

Air

co

nte

nt

Durability results

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Work started in 2014 and continuing - cont.

0

10

20

30

40

50

60

70

0 28 56 84 112 140 168 196 224 252 280 308 336 364 392

Co

mp

ress

ive

Stre

ngt

h (

MP

a)

Age (days)

Mix A

Mix B

Mix C

0

1

2

3

4

5

6

7

0 28 56 84 112 140 168 196 224 252 280 308 336 364 392

Ten

sile

Str

engt

h (

MP

a)

Age (days)

Mix A

Mix B

Mix C

Outdoor

Seawater

Outdoor

Seawater

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• Based on previous work, Mix A and B were selected for future work. The mix proportions are in compliance with FDOT for the Halls River Bridge plan (WP4)

• Fresh concrete characterization

• 132 cylinders (100x200 mm) cast to obtain compressive and tensile splitting strength at 3, 7, and 28 days of moist curing and 0.5, 1, 1.5, and 2 years of exposure to standard and aggressive conditioning

Work started in 2015

Mixture

type

Slump Density Air Content

(%)

Concrete

temperature

in. mm lb/ft3 kg/m3 °F °C

Mix A 4 100 146.8 2349.9 1.3 80 26

Mix B 3.75 95 147.2 2358.6 1 80 26

Work started in 2015 – cont.

• Hardened concrete characterization

• 8 cylinders cast to study chloride penetration, salt crystallization, and carbonation using SEM at 0.5, 1, 1.5, and 2 years of exposure to aggressive conditioning

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0

10

20

30

40

50

60

70

0 3 6 9 12 15 18 21 24 27 30

Co

mp

ress

ive

Stre

ngt

h M

Pa

Age (days)

Mix A

Mix B

0

1

2

3

4

5

0 3 6 9 12 15 18 21 24 27 30

Ten

sile

Str

engt

hM

Pa

Age (days)

Mix A

Mix B

Work started in 2015 – cont.

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• 6 prisms (100x100x285 mm) cast for ASR monitoring by modified concrete prism test or CPT (ASTM C1293)

• 48 cubes (200 mm) cast and exposed to standard ambient and accelerated conditioning to study the GFRP bond to concrete properties after 0.5, 1, 1.5, and 2 years per the ACI440.3R, B.3

• GFRP bars embedded in concrete beams with cross section replicating the test blocks from bulkhead cap of Halls River Bridge (WP4). Each specimen was reinforced with four #5 GFRP bars which will be extracted from the concrete at 6 months, 1, 1.5, and 2 years of exposure to accelerated conditioning (seawater at 60°C (140°F) ) and tested for tensile properties, transverse and horizontal shear strength, and microstructure properties

Work started in 2015 – cont.Summary

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Specimen type (in mm)

(100 mm = 3.94 in.)

MixTotal

A B

150x190x1420 mm beam with #5 GFRP bars 4 4 8

200 mm cubes with #3 GFRP bars 24 24 48

100x100x285 mm prisms 3 3 6

100x200 mm cylinders 70 70 140

Total 101 101 202

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Work Package 3

Based on work in WP1, appropriate stainless steel (SSR) bars selected and characterized as reinforcement to concrete (according to the chloride limits determined by the initial contamination of raw materials and further expected penetration from the environment)

Output: evaluation of expected life of SSR bars embedded in chloride contaminated concrete and recommendation for demo projects

Work Package 4

Field demonstration projects and long-term on-site monitoring

• Bridge substructure and superstructure in Florida (USA). Halls River Bridge to use GFRP reinforcement

• Reinforced concrete retaining walls in Italy to use SSR and GFRP reinforcement

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WP4- Demo in Citrus County, Florida

New bridge total length is 56.5 m consisting of five 11.3 m simply supported spans (two 3.6-m traffic lanes with 2.4 m outside shoulders, 1.5-m wide sidewalk with standard traffic barrier and bridge pedestrian/bicycle railing on each side)

Replace functionally obsolete Halls River Bridge to increase capacity and improve safety

Halls River

Bridge

Replacement

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Halls River Bridge Replacement

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Halls River Bridge Replacement

Super- and sub-structure classified as extremely aggressive due to chloride concentrations in water and close proximity of superstructure to water

Provisions being made for collection of samples from the bulkhead cap over time as shown in figure

Non-corrosive bars and stirrups address long-term durability of cast-in-place concrete bulkhead caps, pile caps, wing-walls, back-walls, deck and approach slabs

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WP4- Proposed Demo in Italy

Wall exposed to harsh environmental conditions (including artificial addition of chlorides), ideal challenge to longevity of the structure

Project consists of a reinforced concrete retaining wall:

Work Package 5

• LCA to calculate the environmental impact

• LCC to do the economic optimization

Output: to ensure and prove feasibility and sustainability of SEACON-technology

• Alignment to R&D conducted by LCE4ROADS (formerly ECOLABEL) EU project for:

omaterials

o processes selection

o design

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Work Package 6 and Work Package 7

• Dissemination

• Exploitation

• Standardization

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Management

organization chart

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CONCLUSIONS

The possibility of using seawater in place of freshwater and recycled concrete aggregate in substitution of natural aggregate will be investigated

At this time, it is possible to state that mechanical behavior of concrete produced with seawater from Key Biscayne Bay and the selected proportions of components can be considered comparable to the one obtained with freshwater

Compressive strength development results confirm previous studies, showing an initially higher strength for the mix containing seawater followed by lower, but comparable, values at longer ages

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CONCLUSIONS – cont.

Fresh concrete properties (i.e., slump, air content and temperature) seem not influenced by the presence of seawater

Plans for two field demo projects in place. Halls River Bridge scheduled for construction in fall 2016

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ACKNOWLEDGEMENTS

Infravation and all partners in SEACON are acknowledged for the support provided.

The authors wish to gratefully acknowledge the contributions of the personnel at the Pennsuco Plant of Titan Cement Groupfor the advice, cooperation and permission to use their facilities.

THANK YOU

Questions?