® Concrete Developments to Improve the Environment David Hocking, Technical Manager Boral Concrete 26 August 2014 Topics 1. Background/History of sustainability in concrete supply 2. Innovation 3. Challenges 4. Cement/Binder response 5. Concrete Properties 6. Projects/Case studies 7. Port Botany – High SCM Precast (high durability) 8. Admixtures 9. Strength assessment by Concrete Maturity ® Is the concrete industry innovative? ® Wholly Australian owned, Boral is the only Company to maintain a comprehensive construction materials testing and research facility. - Over 50 people capable of performing over 440 different tests in aggregates, concrete - Performed creep testing on the Burj Khalifa in Dubai and many other international projects Some of the construction industry firsts associated with sustainability include: - 1966-68: The development and use of flyash in concrete - 1970-72: The development and use of Ground Granulated Blast Furnace Slag as a cement replacement - 1995-present: Development of "Green Concrete"--now sold as "Envirocrete" with use of recycled raw materials contributing up to 42% potential reduction in Greenhouse Gas Emissions - 2008 Introduction of PCE based slump retention precast concrete products at Baulderstone Port Botany Project - 2008/10: Introduction of remote computer based temperature matched curing at Baulderstone Port Botany Project to enable early stripping without cylinder testing - 2009-present: Development of Envisia™ low carbon footprint concrete Background Innovative concrete technology such as new binders, admixtures, aggregates, testing and analysis ensures the concrete industry is far from a mature state. Explore developments in binder and concrete technology using such cements as activated slag systems. In recent times Geopolymers have undergone a rapid increase in awareness. Boral has developed a hybrid type hydraulic/activated cement with structural and durability properties that are superior as a low carbon concrete product. ® 4 The Challenge? Create a lower carbon concrete WITH high performance LOWER CARBON HIGH EARLY STRENGTH LOW-SHRINK & CREEP HIGH DURABILITY ® 5 ® Cement is the major contributor to carbon emissions in concrete production FINAL EMISSION FACTORS ACTIVITY EMISSION FACTOR Coarse Aggregates – Granite/Hornfels 0.0459 tCO2-e/tonne Coarse Aggregates – Basalt 0.0357 tCO2-e/tonne Fine Aggregates 0.0139 tCO2-e/tonne 0.8200 tCO2-e/tonne Fly Ash (F-type) 0.0270 tCO2-e/tonne GGBFS 0.1430 tCO2-e/tonne Concrete Batching 0.0033 tCO2-e/m3 Concrete Transport 0.0094 tCO2-e/m3 On Site Construction Activities 0.0090 tCO2-e/m3 Cement SOURCE: Summary of CO2 Emissions From Concrete—Monash University (Flowers and Sanjayan, 2007) 6 Boral’s Response - ENVISIA® Technology ® Portland cement has a high carbon content and is the primary contributor to carbon emissions from concrete production. Boral is committed to creating “sustainable solutions for a world-wide building and construction industry”. Activated binder systems such as ENVISIA® technology is one of Boral’s key responses to the supply of low-CO2-e concrete. 7 Activated Slag cement (ZEP used in ENVISIA® Concrete) ® Replaces Portland cement’s higher carbon component. Contains significantly less OPC than a typical concrete. Offers a lower carbon concrete with excellent shrinkage & durability performance characteristics. Complies with Australian standards. Demonstrates plastic, placement and finishing properties that are consistent with conventional concrete. No additional safety requirements. 8 Drying Shrinkage - Applications ® 2011 Barangaroo South Project 50MPa Diaphragm Wall panels, 150-270uS April 2013 Barangaroo Prototype – Ropes Crossing 50MPa Post Tensioned (25@3d), ~300uS 2013-2014 Barangaroo Civil Works – Batch Plant commissioning, Working Platform for Basement of Towers, ~300-400uS 2013-2014 Cantilever 60MPa beam – Mosman Residential project, ~440uS April 2014 City of Sydney – Foot path Newtown 32MPa, 320uS April 2014 George St Sydney 40MPa, 300uS May 2014 North Bondi 50MPa Decorative suspended slab, 300-360uS 9 Green Star Requirements ® To achieve 3 points – 40% cement and specified recycled water and aggregate components reduction + potential innovation points 10 ® Significantly Lower Carbon, Without the Usual Compromise New technology, used in the manufacturing process, means less carbon-intensive Portland cement is required to achieve the same strength outcomes as conventional concretes. The lower Portland cement content, means lower embedded carbon levels. 11 ® Early Strength Performance is comparative Suited to applications where early strength performance of concrete is paramount. The key benefit of using Activated cements is that a lower shrink-lower Carbon result is achieved without undue compromise in strength performance and stressing cycle times. Performance is approximately in line with other conventional concretes so the usual trade-offs are not necessary to achieve a lower Carbon result. Trade-offs are not necessary to achieve a lower Carbon result. 12 ® Low Shrinkage Advantage Outperforms conventional concretes by offering up to a 50% reduction in shrinkage. Typical shrinkage performance is demonstrated in Graph at right. May enable design of large slabs with fewer or no joints using a lower Carbon concrete. Permits larger joint spacings, less curing time, less shrinkage and less cracking, without compromising sustainability goals. Up to a 50% reduction in shrinkage 13 ® Lower Creep Creep strain may be reduced by 40% over conventional concrete of similar characteristic strength & modulus of elasticity. When combining the reduced creep and shrinkage properties the structural designer may be able to gain benefit from: Reduced volume of concrete needed. Reduced reinforcement ratio. Reduced pre-stressing losses. Reduce creep strain by 40% 14 ® High Durability ENVISIA® concrete maintains the well known durability advantages of slag blended cements. Exceeds the durability performance of mixes designed for the Port Botany Expansion Project which required a 100 year design life. 50 MPa - high slump - high durability mixes Grade Cement Replacement Slump Drying Shrinkage Chloride Diffusion (NT443 test, 35 days) Standard Port Botany Expansion ENVISIA® 50 MPa 50 MPa 50 MPa 33% 57% 65% 200mm@3hrs 200mm@3hrs 200mm@3hrs 650μs 450μs 300μs 3.7x10-12 m2/s 2.8x10-12 m2/s 1.4x10-12 m2/s *Comparison using Sydney based materials Sulphate resistance & chloride diffusion are superior to current durable concrete mixes 15 ® High Durability ENVISIA® provides lower chloride diffusion, water absorption & permeability compared to an equivalent grade of conventional concrete. ENVISIA® can therefore be used in demanding applications where chloride resistance and sulphate expansion characteristics are important. CHLORIDE MIGRATION COEFFICIENT WATER PERMEABILITY RATE OF WATER ABSORPTION 16 ® Behaviour that is consistent with standard concrete Mirrors the performance of Portland cement concrete– rheology, placing, setting time & strength development Delivery, pumping and placing for a suspended concrete slab at Ropes Crossing – April 2013 Placing 32 MPa ENVISIA® concrete Delivered by agitator and pump - May 2010 Normal handling and finishing 17 Post-tensioned 32 MPa slab - June 2010 ENVISIA® Activated cement concrete has been trialled with industry partners in a range of projects Warehouse floor - May 2011 Pavement produced to RMS specification - April 2011 Hume Hwy, Woomargama - September 2011 High strength pavement - September 2012 ® Barangaroo South Project ® concrete is an exciting product innovation helping us achieve “ ENVISIA our vision for Barangaroo South. Lend Lease is committed to delivering ® a climate positive and lower carbon outcome for the entire Barangaroo precinct, pioneering a new era in sustainability and setting new engineering benchmarks for others to follow. ” Tom Waters, Lend Lease Construction Manager for Tower 2 of International Towers Sydney at Barangaroo South. 19 ® Summary of Benefits Challenges Lower Carbon Green Star MAT-4 requires 40% reduction in cement across the whole of a project ENVISIA® technology Significantly exceeds current Green Star cement reduction requirements Cycle times are paramount - traditional Green Star concrete elongates cycle times Achieves early age requirements for PT consistent with commercial Portland cement concrete Low Shrink & Creep Modern building designs requires low shrinkage & creep concrete. 3 Green Star concrete exhibits 100 to 150µm higher shrinkage Has a typical shrinkage of less than 300us (50% lower than conventional concrete and 60% lower than normal green star concrete) and up to 40% lower creep. High Durability Durability is critical for many developments on prime sites Delivers up to 60% reduction in chloride ion diffusion (NT443 test, 35 days) compared to a conventional high durability concrete mix High Early Strength Consistent Behaviour Fully Compliant Delivers plastic, placement and finishing properties that mirror Portland cement based conventional products. Ease of use on site! Fully compliant with AS 1379, from cement that complies with Australian Standard AS3972. 20 Behaviour / Software inputs ® 21 High Performance low carbon technology has been used in a range of projects Port Botany Sea Wall Warehouse floor - May 2011 Hume Hwy, Woomargama - September 2011 High strength pavement - September 2012 ® ® Plastic Properties require as much consideration as hardened properties – Slump retention with Lower carbon concrete Slump Retention of Conventional Super plasticiser versus Precast Super Plast./Slump retention 250 200 20mm Offsite Precast mix Pre cast S/Plast plus slump rete ntion 150 Slump 20mm Onsite Precast mix Precast S/Plast plus slump retention Warehouse floor - May 2011 100 10mm Tre mie mix Conv entional piling mix 20mm Conve ntional S/Plast 50 20mm Onsite Pre cast mix Precast S/Plast 0 At batching 30 Minutes Hume Hwy, Woomargama - September 2011 60 Minutes 90 Minutes 120 Minutes 150 Minutes High strength pavement - September 2012 Other Initiatives to support sustainable concrete Concrete Maturity and Temperature monitoring What is Concrete Maturity? The maturity method is a technique to account for the combined effects of time and temperature on the compressive strength development of concrete. The maturity method relies on the measured temperature history of the concrete during the curing period to estimate its compressive strength. Able to assist with cycle times, as per contribution to *34% reduction in PBT3 total construction times. Source: D Packer 21/4/2010 ® Other Initiatives to support sustainable concrete Concrete Maturity and Temperature monitoring New Equipment/Technology Mobile secure stand alone units Battery back up for 6 days to cover full monitoring cycle Solar panel battery recharge potential Wind turbine battery recharge potential ® Conclusion ® The design, construction and supply of concrete continues to demonstrate innovative products and processes to improve sustainability. Binder, admixtures, aggregates and supporting activities, such as research and development is not only reducing carbon intensity but importantly meeting or exceeding performance requirements. Whilst not limiting where new developments may originate from, cements including nanotechnology, admixtures and concrete assessment/testing improvements would be deemed to be the near term focus areas for further improving the environment. 26 ® Thank you
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