How to Tell If You Have Concrete Cancer: Signs, Causes, and What to Do Next
Concrete is often seen as an indestructible building material, but like anything else, it can deteriorate over time. Concrete cancer, a serious structural issue caused by internal chemical reactions and moisture exposure, can lead to cracking, spalling, and ultimately, major structural failures.
If you’re noticing cracks in your foundation, pool, driveway, or walls, you might be wondering: Is this normal wear and tear, or do I have concrete cancer? This guide will help you recognize the warning signs, understand the causes, and take action before the damage worsens.
What Is Concrete Cancer?
Concrete cancer refers to progressive deterioration caused by internal chemical reactions that weaken the material over time. The most common cause of concrete cancer is Alkali-Silica Reaction (ASR)—a process where certain minerals in concrete react with moisture and create an expanding gel. As this gel swells, it forces cracks to develop, allowing more water to seep in and accelerating the damage.
Another common cause is corrosion of reinforcement bars (rebar) inside the concrete. When moisture reaches the rebar, it rusts and expands, putting pressure on the surrounding concrete, which leads to cracks and spalling.
Warning Signs of Concrete Cancer
If you suspect concrete cancer, look for these key warning signs:
1. Cracks in the Concrete
Fine, spiderweb-like cracks (map cracking)—Common with ASR-related concrete cancer.
Vertical or diagonal cracks—Often seen in foundations, walls, and pool shells.
Cracks near joints or edges—These can indicate underlying expansion due to ASR.
2. Flaking, Chipping, or Spalling
Concrete breaking off in chunks—This happens when ASR or rusting rebar causes the concrete to push outward.
Pitted or uneven surfaces—Especially on driveways, pool decks, or patios.
3. White Residue or Oozing Gel
White, chalky stains (efflorescence)—Indicates that moisture is moving through the concrete, dissolving minerals.
Sticky or crystallized gel leaking from cracks—A clear sign of ASR expansion.
4. Rust Stains on the Surface
Brown or orange streaks—Appear when rusting rebar starts to stain the surrounding concrete.
Stains forming around cracks—Often means moisture has reached the reinforcement inside.
5. Water Seepage or Persistent Dampness
Wet patches that don’t dry—A sign that water is trapped inside deteriorating concrete.
Leaks in pools or basements—Cracks caused by concrete cancer often lead to water loss.
6. Hollow or Weak Spots
Tapping on the concrete produces a hollow sound—This suggests internal cracking and loss of integrity.
Sections of the concrete feel loose or unstable—Common on pool decks, stairs, and balconies.
If you’re seeing one or more of these symptoms, it’s important to take action quickly before the damage spreads.
What Causes Concrete Cancer?
Several factors contribute to concrete cancer, including:
Alkali-Silica Reaction (ASR) – The primary cause of concrete cancer, ASR happens when reactive silica in aggregates interacts with alkalis in cement and water, forming an expansive gel.
Rebar Corrosion – When moisture and oxygen reach the steel reinforcement inside concrete, rust forms and expands, cracking the surrounding material.
Moisture Exposure – Poor drainage, leaks, or high humidity can accelerate ASR and rusting of rebar.
Poor-Quality Concrete Mix – Using low-grade cement or omitting key additives like fly ash increases the risk of ASR.
Extreme Weather Conditions – Repeated freezing and thawing cycles, intense heat, and heavy rain all contribute to concrete deterioration.
Austin homeowners, in particular, should be on high alert—Texas’ humid climate and seasonal rainfall create the perfect conditions for ASR to thrive.
How to Confirm If You Have Concrete Cancer
1. Visual Inspection
Look for the warning signs mentioned above—especially cracking, spalling, and discoloration.
2. The Tap Test
Lightly tap the concrete with a hammer or solid object:
A solid "thud" means the concrete is intact.
A hollow or echoing sound may indicate internal damage.
3. Professional Testing
Petrographic Analysis – A lab test that examines concrete composition under a microscope.
Core Sample Testing – Involves extracting a piece of concrete to assess ASR damage.
Moisture and Expansion Monitoring – Determines how much water is being absorbed and how the concrete is shifting.
If your concrete fails any of these tests, it’s time to consider repairs or remediation options.
What to Do If You Have Concrete Cancer
Once concrete cancer starts, it won’t stop on its own—but the damage can be managed if caught early.
Repair Options:
Crack Sealing – Applying epoxy or polyurethane to seal cracks and prevent further moisture infiltration.
Surface Coatings – Specialized coatings that slow down ASR progression and protect the surface.
Rebar Treatment – Removing or treating corroded rebar to prevent further expansion and cracking.
Concrete Replacement – In severe cases, damaged sections must be removed and replaced.
A Better Alternative : RENOLIT’s Waterproofing Solution
If traditional repairs aren’t enough—or if you want a long-term, cost-effective solution—consider RENOLIT’s advanced waterproofing membranes.
Stops Moisture Infiltration – RENOLIT’s high-performance membranes completely seal concrete surfaces, preventing water from triggering ASR and rebar corrosion.
Extends Concrete Lifespan – Unlike temporary fixes, RENOLIT provides permanent protection, saving you from costly repairs down the road.
Eco-Friendly & Cost-Effective – Reduces the need for demolition and replacement, lowering costs and minimizing environmental impact.
When to Consider RENOLIT:
If crack repairs aren’t working and the problem keeps coming back.
If legal action isn’t an option, and you need a practical fix.
If you want a solution that prevents future damage.
RENOLIT has helped thousands of homeowners protect their concrete structures—and it could be the perfect solution for you, too.
Final Thoughts: Don’t Ignore the Signs
Concrete cancer is a progressive issue that will only get worse over time. If you’re seeing cracks, flaking, leaks, or discoloration, act now before it leads to costly structural failures.
✔ Inspect your concrete regularly for signs of deterioration.
✔ Consult a professional if you suspect ASR or rebar corrosion.
✔ Consider RENOLIT’s waterproofing technology for a long-term solution.
Your home, pool, and foundation are major investments—protect them before it’s too late!
