Eco-Friendly Practices in Concrete Block Construction

27th May 2024 -

The concrete block sector has embraced eco-friendly approaches to minimise its carbon footprint. For this feature, we explore the innovative processes in eco-friendly concrete block construction, highlighting their environmental benefits.

Are concrete blocks sustainable?

While concrete itself has a significant carbon footprint because of cement production, concrete blocks are considered sustainable building materials. The sustainability lies in their durability, longevity and the potential for introducing sustainable practices throughout their lifecycle. 

1. Use of recycled materials

Some concrete block manufacturers incorporate recycled materials. For example, a mortar mix for concrete blocks can include fly ash, slag cement and recycled concrete aggregates. These recycled materials partially replace newer materials like cement and aggregates. This reduces the demand for natural resources and diverts waste from landfills.

2. Energy-efficient production

Manufacturers have implemented energy-efficient production methods to reduce their carbon footprint. This includes the use of alternative fuels like biomass or waste-derived fuels to power kilns. Plus, heat recovery systems capture and reuse thermal energy from the production process, reducing overall energy consumption.

3. Water conservation

Advanced concrete block production uses water recycling and management systems to minimise water usage and reduce wastewater discharge. This includes capturing and treating water for reuse, as well as using efficient curing methods requiring less water.

4. Emissions reduction

Efforts are being made to reduce emissions associated with concrete block production. These methods include optimising kiln operations, dust control measures and exploring alternative cement formulations that have lower carbon footprints. For example, calcined clays or limestone are potential replacements for traditional Portland cement. 

5 types of sustainable concrete blocks

The choice of concrete blocks is crucial in minimising the environmental impact while ensuring structural integrity and long-term performance. Several types of concrete blocks have emerged as preferable options.

1. Insulated concrete blocks (ICBs)

Also known as concrete masonry units (CMUs), Insulated concrete blocks, are highly recommended for sustainable construction. These blocks feature 2 concrete layers separated by a rigid insulating material. Typically, the insulation used is either expanded polystyrene (EPS) or extruded polystyrene (XPS). 

The insulating core enhances the thermal performance of the blocks, which creates reduced heating and cooling demands. Also, many ICB manufacturers incorporate recycled materials like fly ash, slag cement and recycled aggregates into the concrete mix. 

2. Aerated concrete blocks

Aerated blocks are lightweight, precast concrete blocks made from a mixture of cement, lime, gypsum and an expansive agent. The structure provides excellent thermal insulation properties. Furthermore, aerated blocks are highly durable and fire resistant. They can be produced using recycled materials which reduces their carbon footprint.

3. Recycled concrete blocks

As the name suggests, recycled concrete blocks are manufactured using crushed and recycled concrete from demolition waste. These blocks divert waste from landfills and limit the demand for newer materials, resulting in a lower environmental impact. Recycled concrete blocks can be reinforced with steel or fibres to enhance their strength. This makes them suitable for a wide range of construction applications.

4. Hollow concrete blocks

Hollow concrete blocks are designed with hollow cores or cavities within their structure, lowering the amount of concrete required for production. This design saves on materials and offers great thermal insulation properties. Also, you can fill the cavities with insulating materials like mineral wool or foam, further boosting its thermal performance.

5. Interlocking concrete blocks

Commonly known as permeable pavers, interlocking concrete blocks are designed to fit together like puzzle pieces. They create a strong and stable surface without the need for conventional mortar. These blocks are often made with recycled materials and can be designed to be permeable, allowing stormwater to enter the ground. 

They are versatile and can be used for various applications, such as driveways, patios and pathways. 

What are the benefits of eco-friendly concrete blocks?

The sustainable practices employed in the production of concrete blocks reduce their environmental impact and enhance structural properties. Below, we outline the pros that make them a compelling choice for sustainable construction projects.

Enhanced durability

The incorporation of recycled materials improves the durability and longevity of concrete blocks. These materials often have pozzolanic properties, which react with calcium hydroxide to form additional cementitious compounds. It increases concrete block density and strength over time. This extended durability reduces the need for frequent repairs or replacements. 

Improved thermal performance

Sustainable concrete blocks can be designed with insulating materials or cavities filled with insulation, improving thermal performance. This enhanced thermal efficiency results in reduced energy consumption for heating and cooling, lowering the building's operational carbon footprint. Plus, the high thermal mass of concrete blocks helps regulate indoor temperatures. 

Increased fire resistance

The use of recycled materials like fly ash and slag cement can boost fire resistance. These materials improve the concrete's ability to withstand high temperatures and prevent spalling (the breaking off of surface material). It provides an additional layer of safety and protection. 

Superior acoustic insulation

Dense concrete blocks combined with recycled materials may also improve acoustic insulation properties. This enhanced sound insulation reduces noise transmission between spaces, creating a more comfortable indoor environment. 

Versatile design opportunities

Sustainable concrete blocks can be manufactured in a variety of shapes, sizes and textures, allowing for flexibility and creative design. The versatility allows the integration of eco-friendly features like green roofs, rainwater harvesting systems or passive solar design. 

Resilience to extreme weather

The durability and moisture resistance contribute to their resilience against extreme weather conditions. This resilience helps protect the building, reducing the need for repairs or replacements and minimises the environmental impact of reconstruction.

Can you build greener with blocks?

Both concrete blocks and bricks have their pros and cons. Weighing up the environmental impact and performance characteristics is important in making informed decisions. Here, detail the sustainable comparisons between the 2 materials.

Aspect	Concrete Blocks	Bricks
Recycled content	Can incorporate high levels of recycled materials like fly ash, slag cement, and recycled aggregates.	Limited availability of recycled or reclaimed bricks.
Manufacturing process	Potential for energy-efficient production with alternative fuels, heat recovery systems and water conservation measures.	Traditional clay brick manufacturing is energy-intensive and has higher emissions.
Thermal performance	Insulated and hollow concrete blocks with insulating materials offer excellent thermal insulation properties.	Traditional clay bricks have moderate thermal mass but poor insulation, leading to higher energy usage.
Durability	Exceptional durability, resistance to weathering, fire and moisture damage.	High-quality clay bricks can be durable but more susceptible to freeze-thaw cycles and moisture damage.
Design flexibility	Available in various sizes, shapes and textures for structural and aesthetic purposes.	Wide range of colours, textures, and patterns for architectural styles but less structural versatility.
Embodied energy	Lower embodied energy because of the potential for recycled content and energy-efficient manufacturing.	Higher embodied energy because of the energy-intensive firing process.
Maintenance	The modular nature allows for easy repairs and replacements, reducing waste.	May require more frequent maintenance or replacement due to potential damage.
Water management	Permeable concrete blocks can aid in sustainable water management.	Limited water management capabilities.

How to achieve sustainable construction standards

Certifications like the Building Research Establishment Environmental Assessment Method (BREEAM) provide a framework for recognising the environmental performance of buildings. Eco-friendly and sustainable high density concrete blocks are an important factor in achieving green construction standards. 

• Material selection: Whether you build a concrete block wall or lay a foundation, a key aspect of BREEAM is responsible material sourcing. Eco-friendly concrete blocks manufactured using recycled materials contribute significantly to this requirement. Selecting manufacturers that prioritise sustainable practices and have a certified environmental management system boosts your project credentials.
• Energy efficiency: By incorporating eco-friendly blocks into the building envelope, projects minimise energy consumption for heating and cooling. This lowers their operational carbon footprint and meets energy efficiency targets.
• Waste management: Eco-friendly concrete blocks contribute to resource efficiency by utilising recycled materials and minimising waste generation during production and construction. Also, the modular nature of concrete blocks allows for precise measurements and cutting, reducing on-site waste. These practices align with waste management and resource efficiency criteria.
• Indoor environmental quality: Certain types such as aerated blocks contribute to improved indoor air quality. This aspect is important for achieving credits related to indoor environmental quality in green building standards like BREEAM.
• Life cycle assessment (LCA): Green building certifications encourage a life cycle assessment (LCA) to evaluate the environmental impact of building materials and processes. Manufacturers can provide LCA data to demonstrate the sustainability credentials of their products. This helps with the certification process.

What is the future of sustainable concrete blocks?

Concrete blocks are set to undergo significant advancements in the pursuit of eco-friendly solutions. The future of sustainable concrete blocks promises innovative materials that will further reduce their environmental impact.

Carbon capture

A promising development is the integration of carbon capture and utilisation (CCU) technologies. They have the potential to capture carbon dioxide emissions from cement production and incorporate them into the concrete mix. This will effectively reduce the carbon footprint of concrete blocks.

Alternative binders and cementitious materials

While traditional Portland cement remains a crucial component of concrete wall blocks, alternative binders and cementitious materials could replace it. These alternatives include geopolymers, alkali-activated materials and calcium sulfoaluminate cement. They have lower embodied carbon footprints and may reduce the environmental impact of concrete block production.

Advanced recycling and waste utilisation

The future of sustainable concrete blocks will likely involve more sophisticated recycling and waste utilisation methods. This may include the introduction of recycled plastics, glass or even biomass materials into the concrete mix. Also, advanced sorting and processing technologies could allow the use of a wider range of recycled materials in concrete blocks.

Nanotechnology and self-healing concrete

Nanotechnology has the potential to revolutionise the properties of solid concrete blocks. The use of nanoparticles and nanomaterials may enhance the strength, durability and self-healing properties of concrete. Self-healing concrete can independently seal and repair crack damage, extending the lifespan of concrete structures. 

Digital fabrication and optimisation

Integrating digital technologies like 3D printing may enable the production of highly customised and optimised concrete blocks. These blocks could be tailored to specific project requirements, reducing waste and boosting energy efficiency. Plus, digital fabrication could help with the introduction of innovative designs that are challenging to achieve with traditional manufacturing methods.