Does Stamped Concrete Crack? Best Kept Secrets Revealed!

drivewaygeek.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com

Does Stamped Concrete Crack?

Yes, stamped concrete does crack, just like any standard concrete slab on grade. Shrinkage cracks are an intrinsic part of the concrete curing process and you do not need to worry about them too much.

Does stamped concrete crack in other ways? Stamped concrete driveways can also develop structural cracks. These you need to worry about. Clean and fill them up with a flexible sealer, as soon as possible. When done carefully the repair process can be made to blend with the stamped pattern.

Moisture and water will get into the concrete substrate through the cracks. Water within the concrete slab is damaging as it corrodes both the concrete and the reinforcement. 

“The most destructive agent of concrete structures and components is probably water”.

Quote from Wikipedia

The cracks will grow and propagate, unless repaired and sealed.. 

Is Stamped Concrete Less Likely to Crack?

Stamped concrete driveway is as likely to crack as concrete driveway. Why? Simply because the difference between a stamped concrete driveway and a standard concrete driveway is only superficial. Structurally they are the same.

The entire process of preparing the soil support system, pouring and reinforcing concrete, is exactly the same in both types of driveways. The stamping process only affects the top layer of the concrete which is mostly cement and sand.

The advantage of stamped concrete over normal concrete is that cracks are less visible. The cracks will often blend in with the stamp pattern, color and texture.

Why Does New Stamped Concrete Crack?

New stamped concrete develops shrinkage cracks as soon as it starts curing. The development of shrinkage cracks is an intrinsic part of the curing process.

Concrete cures by a process called hydration. Water reacts with cement to form a crystalline structure that enmeshes the aggregates. 

Excess water evaporates creating pores, causing the concrete to shrink. The shrinkage stress results in hairline shrinkage cracks.

The shrinkage cracks in concrete slabs, typically less than 1/16 th an inch wide, are a perfectly normal occurrence. Shrinkage cracks start to become visible as soon as the curing process begins.

Shrinkage cracks have no adverse effect on the structural integrity of the stamped concrete driveway. Control joints are sawed into the concrete slab to encourage the cracks to stay within the joints.

How Do You Keep Stamped Concrete from Cracking?

You can never eliminate shrinkage cracks from a stamped concrete driveway as they are intrinsic to the curing process. However, they can be made less visible by the use of Control Joints.

Structural cracks, on the other hand, are caused by stresses such as ground movement, expansion & contraction with temperature changes, freeze thaw cycles and of course vehicle load. 

You can mitigate the effect of such stress by using high quality materials and construction practices. Some key elements to focus on are:

Soil Support System

The soil support system is important for any concrete slab-on-grade. The importance increases substantially for a driveway because of much higher load from cars and trucks.

There are 5 steps involved in building up a good soil support system.

STEP 1 – Subgrade:  is native soil tamped to a firm finish. In case the quality of the native soil is not very good, improve it by adding a couple of inches of good quality top soil or treating it with cement or lime.

STEP 2 – Geotextile: prevents the migration of crushed stone or gravel from the sub-base into the subgrade.

RECOMMENDED PRODUCT

---

The Best Geotextile Driveway Fabric for Your Driveway & Patio Base

Geotextile driveway fabric is a supportive layer that is laid between the compacted subgrade and the sub-base aggregates to prevent the migration and loss of the aggregates in to the subgrade. It helps stabilize the ground, permit drainage and prevent weed growth.

Here is the Geotextile Driveway Fabric I recommend.

---

STEP 3 – Sub-base: should be 4” – 6” thick and made up of several layers of compacted crushed stone or angular gravel. 

STEP 4 – Base: should be 2” thick and made up of a layer of pea gravel topped by a layer of coarse sand.

STEP 5 – Vapor Retarder: prevents ground moisture from permeating into the concrete.

For more information on soil support system preparation for a concrete driveway check out my article Best Base for Concrete Driveway? (A Quick Look!).

RECOMMENDED PRODUCT

---

The Best Vapor Barrier for Under Concrete Slab such as Driveways, Garage Floors & Patios

A concrete vapor barrier is a material that prevents moisture from entering a concrete slab from the grade below. This helps in controlling the concrete curing conditions in the initial stages. Subsequently it prevents the wicking of moisture into the concrete slab from the damp earth.

Here is the Vapor Barrier I recommend.

---

Concrete Mix Composition

Do not compromise on the compressive strength of the concrete mix. Quite often, 3000 psi concrete is considered adequate for a concrete driveway. Lower strength concrete is more likely to crack under heavy loads and ground movement.

Use concrete with a compressive strength of 3500 psi in warm climates and 4000 psi in cold climates. Higher strength is required to deal with stress caused by freeze thaw cycles.

A water to cement ratio of 0.50 or slightly less is required for achieving required compressive strength. The compressive strength also depends on the cement to aggregate ratio. A higher ratio typically means higher strength concrete.

Check out my post How Long Does an Exposed Aggregate Driveway Last? (Effective Tips!) for a table that gives the indicative cement to aggregate ratio for different compressive strength levels.

Slab Thickness & Reinforcement

The strength of a stamped concrete driveway is proportional to the slab thickness and the type of reinforcement used. 

Concrete driveways are often 4” thick with welded wire mesh reinforcement. This is OK for a standard concrete driveway. It will bear the load of standard passenger cars. You can expect it to crack, sink or heave due to ground movement.

In my opinion, a stamped concrete driveway should be 6” thick, reinforced with steel rebars. This will make it fairly crack resistant.

Do You Need Control Joints in Stamped Concrete?

Yes. You do need control joints in a stamped concrete driveway. If anything, they are even more important for stamped concrete as you do not want its beauty to be marred by random cracks.

The indentations created by the stamping process are superficial and are not a substitute for control joints. So, what are control joints anyway?

Control Joints (aka Contraction Joints) are either indented in fresh concrete (or cut with a saw the next day) to encourage shrinkage cracks to stay within the joint and not spread randomly, all over the slab surface. 

Concrete develops shrinkage cracks as it cures. The water and cement in the concrete mix react to form a web-like crystalline structure that binds the aggregates. The concrete shrinks when water exits and the stress causes the concrete to crack.

Control joints create a fault line. The concrete slab thickness at the joint is less than the slab thickness. The concrete is therefore more likely to crack at the control joint when it shrinks.

Sawing control joints in a stamped concrete surface can be a bit tricky. You can let the control joints destroy the beauty of a stamped pattern or you can choose patterns that incorporate the control joints.

Using patterns that recreate cobblestone streets or natural stone tiles are a great way of blending beauty and function.

Thank you very much for reading this post. I do hope you found it informative and helpful.