TECHNICAL | BTS/CONCRETE
GEOPOLYMER CONCRETE IN TUNNELLING
At the monthly BTS meeting at the Institution of Civil Engineers, in London, in March 2023, John Day, Chief Technical Officer of Wagners EFC Pty Ltd, Charles Allen, Director of OTB Concrete, and Richard Sutherden, Engineering Director with Murphy for the HMJV (Hochtief- Murphy Joint Venture) provided perspectives on the use and future potential of geopolymer concretes, and the Earth Friendly Concrete in particular, in underground applications
INTRODUCTION
What are geopolymer concretes and AACM? Geopolymer concretes are considered a subset of alkali activated cementitious materials (AACM) containing Pulverised Fuel Ash (PFA) and Ground Granulated Blastfurnace Slag (GGBS). Unlike Ordinary Portland Cement (OPC), which is a
hydraulic binder that hydrates with water in standard concrete mixes, AACM requires the chemical inputs of a precursor plus an alkali activator that generally has a silicate or hydroxl basis.
Why do we need alternatives to OPC? Production of OPC is estimated to contribute 8% of the world’s total CO2
area of focus to reduce carbon on construction projects.
Wagners EFC A geopolymer concrete called Earth Friendly Concrete® (EFC) has been developed by Australian building materials manufacturer/supplier Wagners EFC Pty Ltd over the past decade; it is effectively concrete as we know it, but without OPC. The EFC binder content comprises approximately 75%
GGBS and 25% fly ash, which are mixed with an alkali activator system that initiates the chemical reaction between the binder components. Other constituents such as aggregates, sand, and water are added in the same proportions as standard OPC-based concretes. This provides extremely low CO2
emissions and embodied energy as the binder has 80% less CO2 than emissions, equating to 3 billion
tonnes of CO2/year (2016 figures), with 1 tonne of OPC resulting in 1 tonne of CO2. As such, it is a significant
an OPC binder. So, 1m3
of the EFC is calculated to save around 200kg of CO2 compared to producing concrete with the
conventional cementitious mixes. EFC has no calcium and, as this is what is attacked by sulphates (sulphate
Left, figure 1:
from different concrete binders
Comparative analysis of CO2
1,200 1,000 800 600 400 200 0
117.59 Wagner EFC®
1150.00
598.95 AUS Ave (OPC) AUS 50% GGBS
1040.00 US (OPC)
912.00 UK (OPC)
475.00 UK 50% GGBS
Sources: Australian OPC and 50% GGBS; are averages of Aus LCI and EpiC Database / US OPC – American Cement Manufactures EPD, 2016 / UK OPC and 50% GGBS – ICE DBE v3.0 2019
16 | July 2023
kg C02
e/1 tonne of product
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53
