How to Reduce Concrete Waste, Re-use it, and Improve the Performance of Low-Carbon Concrete – Mapei

The Australian concrete industry faces significant environmental challenges as it strives to meet the growing demand for sustainable construction practices. While concrete is the most widely used and versatile building material, it is notorious for its environmental impact.

The disposal of waste concrete in landfill poses a threat to the environment. Similarly, the high consumption of natural sand, aggregates, and cement has raised concerns about their environmental impact, prompting a revaluation of traditional practices. As the industry strives to reduce its reliance on virgin resources and minimise its ecological footprint, innovative approaches are being sought to ensure long-term sustainability.

Transforming concrete waste into a resource

It is estimated that 3% of produced concrete gets returned and disposed of, translating to approximately 900 million tons per year of concrete waste.1 If expressed in terms of “equivalent” CO2, it affects 267 kg of CO2 for every cubic metre of returned concrete.2 We must remember that around 60-70% of the volume of concrete is made up of coarse and fine aggregates (Sand and Gravel).

The Recon Line

Re-Con Zero Evo is a two-component powder product made from a unique formula developed by MAPEI research laboratories, which allows returned concrete to be ultimately and quickly recovered directly from mixer trucks turning the waste concrete into recyclable aggregate. This eliminates the need to send waste concrete to treatment plants or landfill and the requirement for any additional treatment equipment.

The aggregates formed with Re-Con Zero Evo on waste concrete can partially replace natural aggregates when mixing new concrete. With assistance from MAPEI technical expertise to evaluate the performance of the concrete mix, up to 20% replacement of natural aggregate may be made possible. Re-con Zero Evo transforming the linear economy to the in-demand “Circular economy” in the construction world essentially solves two problems with one ‘stone’.

• Reduces the depletion and decline of natural resources.
• Reduces waste and the use of landfill sites.

Read more about the Re-Con Line by Mapei.

1. Mapei-GBCA Transform 2021 – Principle of Circular Economy – Lifecycle of Concrete
2. Realtà Mapei International n° 76 – 10/29/2019 Re-Con Zero Evo: sustainable concrete with recycled aggregates

Solution to tackle the challenges of Concrete mixes using SCMs and recycled aggregates

When using SCMs (Supplementary Cementitious Material) and recycled aggregates, concrete mixes will generally demand increased water content, encounter challenges in achieving optimal rheological properties, and develop a slow mechanical strength at both early and late stage.

The Cube System

The CUBE system is an integrated approach that helps the concrete industry overcome the difficulties of reduced clinker cements and quality variances of recycled aggregates. CUBE system actively helps the industry maintain its high standards whilst reducing the climatic impact.

This system comprises products that can aid the different challenges of concrete mixes using recycles and waste material, and these products include:

• Particular absorption inhibitor (RE-CON AGG Technology)
• Specific gradual-release polymers
• Strength enhances for the low carbon concrete

Read more about the Mapei CUBE system.