Conventional concrete is not the most environmentally friendly building material, emitting ample carbon dioxide (CO2).

As such, Australia has sought ways to reduce its concrete carbon footprint to counter the warming planet. Here is a closer look at the CO₂ produced by concrete, ways to reduce its environmental impact, and current projects utilising low-carbon construction methods and materials.

Understanding Concrete’s Emissions Problem

Because Australia relies on concrete for its infrastructure, it is critical to reduce CO₂ emissions significantly to meet climate goals. From 2020–2021, Australia’s cement manufacturing emitted 4.7 metric tonnes of CO₂, 60% of which emanated from operational emissions.

The Cement Industry Federation says Australia’s cement production reached 5.26 million tonnes in 2020–2021 — a 2% year-over-year increase. Concrete production accounts for 8% of global CO₂ emissions — a dire outcome for warming, air pollution and climate-induced weather. Fortunately, not all hope is lost, as it is among the most straightforward materials to decarbonise.

Decarbonisation Solutions for Australia’s Concrete Sector

Australia has long set an example for decarbonising its concrete industry. However, there is still work to do. Here are five ways the country can continue making strides in its decarbonisation initiatives.

1.   Optimise Concrete Use

As one of the sturdiest building materials, it is little wonder why concrete is as widely utilised in construction as it is. However, optimising its use can significantly reduce carbon emissions.

Building experts must reconsider structural necessity before pouring concrete. For instance, can they utilise other load-bearing elements before turning to concrete? Design alternatives — arches, shells and vaults — use less concrete and add to the overall architectural interest.

2.   Explore Alternative Materials

Many material alternatives demonstrate comparable durability to conventional concrete. Geopolymer concrete, in particular, combines fine and coarse aggregates with fly ash or slag, applying a binding material to hold it together. Some studies indicate it decreases carbon emissions 65% more than standard concrete.

Asphalt is another environmentally friendly option due to its recyclability. In fact, most newly built roadways in the United States use asphalt made from 99% reclaimed materials, which also helps absorb transportation noise pollution.

3.   Precast Concrete for Less Waste

Prefabricated construction has become increasingly popular in recent years. With precast concrete, construction workers create the structure they need offsite and transport it to where they are building. This significantly reduces waste accumulation.

Because precast concrete manufacturing occurs in a controlled environment, workers can easily ensure quality control and consistent engineering outcomes. Offsite production also enables the recycling of concrete aggregate waste.

4.   Recycle Concrete Scraps

Concrete producers can reduce their product’s carbon footprint by giving it a second life. Crushing concrete with impactor equipment allows for greater reclamation. Other processes — such as removing dirt and contaminants from surfaces — ensure its reusability in other developments.

Concrete scraps pair well with raw materials in foundations for roads, parking lots and driveways. It may also apply to backfill for potholes, ecological fill and remediation projects.

5.   Implement New Policies

Australia has long implemented policies and regulations to decarbonise the cement sector. So far, it has decreased annual emissions by more than 20% since 2010 through improving energy efficiency, renewable energy and clinker alternatives.

Now, its government is considering imposing tariffs on imported concrete and steel from countries with less robust climate objectives. Australia must first mull over emissions from traded goods, international carbon costs, policy adaptations, and importer and exporter obligations.

Low-Carbon Concrete Projects Paving the Way

Experts have deemed several low-carbon projects champions of reducing concrete emissions in Australia, such as the following:

• Toowoomba Wellcamp Airport: Updates to Toowoomba Wellcamp Airport deployed Earth Friendly Concrete — a geopolymer foundation — with the ability to reduce carbon by 70% annually and conserve 250 kilogrammes of CO₂ per cubic metre poured.
• Pinkenba Wharf: Renovations at the wharf included precast EFC materials — the first and most extensive composites fibre project of its kind — with the ability to withstand 40,000 tonnes of clinker cargo weight.
• City of Sydney Concrete Road Test: In 2019, the City of Sydney replaced traditional concrete pavement leading to Sydney Airport with geopolymer concrete. As one of the most heavily travelled roads, experts have begun testing the geopolymer’s durability and performance for five years.

Giving the Greenlight to Decarbonised Concrete

Australia has not taken climate change lightly, making strides in decarbonising its concrete and cement sectors. Its many low-carbon construction projects have set an example for other nations to seek alternatives to reduce their concrete carbon footprints substantially.

Jane Marsh is Editor in Chief at Environment.co