Cement isn't just grey dust under our feet. It's the single most consumed material on Earth after water, responsible for around 8% of global carbon emissions. Every driveway, apartment block, bridge and sidewalk you walk past relies on this material, and most of us never stop to question if there's a better way. That's exactly why 9 Alternatives for Cement is one of the most important conversations in sustainable construction right now.

For decades, builders treated cement as an unavoidable default. It's cheap, widely available, and people understand how to work with it. But as climate deadlines get closer, and construction costs swing wildly, more homeowners, contractors and city planners are searching for replacements that don't sacrifice performance for cost. Many options already exist that match or beat cement on strength, durability and even long term cost.

In this guide, we'll break down every viable option, explain where each one works best, their real-world pros and cons, and help you decide which could replace traditional Portland cement on your next project. No industry jargon, no greenwashing, just practical facts you can use.

1. Hempcrete

Hempcrete is one of the most well-known 9 alternatives for cement, and for good reason. Made from the woody core of hemp plants mixed with lime binder and water, this material has been used in construction for over 2000 years, and modern testing has confirmed it outperforms traditional cement in many everyday use cases. Unlike cement, hempcrete is breathable, which means it regulates indoor humidity naturally and prevents mould growth inside walls.

Most people are surprised to learn hempcrete is not actually a structural material on its own. Instead, it works as infill between timber or steel framing, providing incredible insulation while adding very little weight to a building. A 200mm thick hempcrete wall has the same insulation value as 600mm of traditional concrete block, which cuts heating and cooling bills by almost 40% for most homes.

• Carbon negative: absorbs 1.6kg of CO2 for every kg of material produced
• Fire resistant up to 120 minutes of direct flame exposure
• Pest and rot resistant when properly cured
• Can be fully composted at the end of a building's life

The biggest downside right now is availability. Hemp cultivation is still restricted in many regions, which means material costs run 15-25% higher than standard cement for most projects. That gap shrinks every year however, as more countries legalize industrial hemp and local production scales up. It's currently best used for residential walls, garden retaining walls, and outbuildings.

2. Fly Ash Concrete

Fly ash concrete is by far the most widely adopted cement alternative in use today. A byproduct of coal power generation, this fine grey powder was once dumped in landfills by the millions of tonnes every year, until engineers discovered it makes an almost perfect replacement for Portland cement in concrete mixes.

When mixed with water, fly ash reacts chemically to create the same binding effect as cement, but with 80% less embodied carbon. Most highway departments across North America and Europe now use 20-30% fly ash replacement in all road concrete, and some have tested mixes with up to 70% replacement that still meet all strength standards.

Property	Standard Cement	30% Fly Ash Mix
28 Day Strength	32 MPa	35 MPa
Embodied CO2 per tonne	820 kg	570 kg
Cracking Resistance	Average	Excellent

Critics correctly point out that fly ash is still a fossil fuel byproduct, so it's not a permanent long term solution. But right now, there is enough unused fly ash in global stockpiles to build every new concrete structure for the next 12 years. For anyone looking to cut emissions on a project today without changing construction methods, this is the easiest swap you can make.

3. Rammed Earth

Rammed earth is the oldest building material on this list, used to build structures that have stood for over 7000 years. It is made simply by compacting layers of damp local dirt, sand and small gravel inside temporary formwork, with no added chemical binders at all. When done correctly, it produces solid, stone-hard walls that require almost no maintenance.

One of the biggest benefits of rammed earth is its thermal mass. It absorbs heat slowly during the day and releases it overnight, keeping indoor temperatures stable without mechanical heating or cooling. This makes it ideal for hot, sunny climates where air conditioning costs make up most of a home's energy bill.

1. Use local on-site dirt to eliminate transport emissions entirely
2. No processing required, just screening and compacting
3. Produces zero construction waste on site
4. Can be repaired with the same dirt it was built from

Rammed earth does require skilled labour to build correctly, and it is not suitable for very wet or flood prone regions. It also takes longer to construct than standard block work. But for custom residential builds, rammed earth walls will outlast cement structures by centuries while creating far healthier living spaces.

4. Mycelium Composites

Mycelium composites sound like science fiction, but they are already being used for commercial construction projects around the world. Made from the root network of mushrooms grown on agricultural waste, this lightweight material grows itself instead of being manufactured, using 99% less energy than cement production.

When grown in custom moulds, mycelium forms a rigid, fire resistant material that is lighter than styrofoam but stronger than many wood products. It is currently used for wall insulation, acoustic panels, and temporary event structures, with ongoing testing for load bearing applications.

• Grows to full strength in just 5 days
• Can be broken down and regrown at end of life
• Absorbs sound 3x better than cement board
• Produces zero toxic fumes when burned

Right now mycelium cannot replace cement for structural loads, so it works best as part of a mixed material build. It also needs to be sealed from direct moisture. But for any non-load bearing interior work, this is one of the lowest impact building materials that currently exists.

5. Recycled Plastic Aggregate Concrete

Instead of using sand and gravel for concrete aggregate, this alternative replaces 10-30% of the mineral aggregate with cleaned, shredded waste plastic. Not only does this keep plastic out of landfills and oceans, it produces concrete that is lighter and more crack resistant than standard mixes.

Testing has shown that plastic aggregate concrete has 20% better impact resistance than traditional concrete, making it ideal for sidewalks, car parks and road barriers. It also insulates better, so it does not crack from temperature changes as easily as standard cement.

Aggregate Mix	Weight per m3	Impact Resistance
100% Rock	2400 kg	100%
20% Plastic	2100 kg	121%

The primary downside is slightly lower compressive strength, so it is not recommended for foundation work or high load structures. But for every other common concrete application, this mix works perfectly, and every tonne produced removes 200kg of plastic waste from the environment.

6. Ferrock

Ferrock is a relatively new cement alternative made from waste steel dust and ground glass. Unlike cement, which releases carbon dioxide as it cures, Ferrock absorbs CO2 during the hardening process, making it carbon negative overall.

In independent strength tests, Ferrock outperforms Portland cement by 20% and is 5x more resistant to salt damage. This makes it ideal for coastal construction, road bridges and any structure exposed to harsh weather conditions.

1. Absorbs 1.5kg of CO2 for every kg of material produced
2. 100% made from industrial waste streams
3. Immune to rust and salt corrosion
4. Cures faster than standard cement

Ferrock is still produced at small scale, so supply is limited and costs are currently higher than cement. But production facilities are opening in three continents over the next two years, and prices are expected to drop below standard cement once mass production begins.

7. Timbercrete

Timbercrete mixes cement binder with sawdust and small wood waste particles to create a lightweight, insulating concrete block. It has been used in Australia and North America for over 30 years, and meets all international building codes for residential construction.

At half the weight of standard concrete blocks, Timbercrete reduces foundation load and cuts transport costs significantly. It also nails and cuts like wood, so builders can work with it using standard carpentry tools instead of heavy masonry equipment.

• 70% lower embodied carbon than standard concrete block
• Excellent sound and heat insulation
• No special tools required for installation
• Does not release toxic smoke in a fire

Timbercrete should not be used below ground level or for permanent water contact. It also requires a render or paint finish for external use. For above ground wall construction however, it is one of the most practical and cost effective cement alternatives available today.

8. Ashcrete

Ashcrete uses waste wood ash from sawmills and biomass power plants as a binding agent instead of Portland cement. Like fly ash, this material was once considered worthless waste, until testing confirmed it creates a strong, durable concrete mix.

Every tonne of Ashcrete produced prevents 750kg of carbon emissions compared to standard cement. It also has a smoother finish and less thermal expansion than cement, which means it rarely develops the fine surface cracks common on concrete slabs.

Material	Carbon Emissions per Tonne
Portland Cement	820 kg
Ashcrete Binder	70 kg

Ashcrete works best for footpaths, patio slabs, garden walls and non-structural work. It is not currently approved for high load structural use in most building codes, though ongoing testing is expected to change this within the next few years. For small residential projects, this is often the cheapest green alternative available.

9. Geopolymer Concrete

Geopolymer concrete is widely considered the most promising long term replacement for Portland cement. Made from activated natural clay and industrial waste, it produces 90% less carbon than standard cement while matching or exceeding all strength and durability standards.

Unlike many other alternatives, geopolymer concrete can be used for every application that traditional cement is used for, including high rise foundations, bridges, dams and roads. It has already been used for major public infrastructure projects in Europe, Asia and Australia.

1. Can be poured and finished using standard concrete equipment
2. Resists acid and chemical damage 10x better than cement
3. Reaches full strength in 24 hours instead of 28 days
4. Expected to match cement cost by 2027

Right now geopolymer concrete is about 10% more expensive than standard cement in most regions, and trained installers are still uncommon. But every major cement manufacturer is now investing in geopolymer production, and it is predicted to capture 30% of the global concrete market by 2030.

None of these 9 alternatives for cement are perfect one-for-one replacements for every single job. Traditional cement became the global standard for a reason: it's predictable, cheap, and works almost anywhere. But what this list makes clear is that we no longer have to default to it. For almost every common construction task, there is now an option that produces less carbon, lasts longer, or creates healthier indoor spaces.

Next time you're planning a patio, a wall, a renovation or a new build, don't just reach for the standard cement bag by default. Ask your supplier what alternatives they stock, run the numbers for your specific project, and test one small section first. Even swapping 20% of the cement on a single project adds up. Every builder, homeowner and handyman has the power to shift this industry one pour at a time.