Type I/II Cement Is Coming Back. Did Concrete Learn Anything?

What was in this mix? 

Type I/II cement is making a comeback.

At least that is what the market is asking for.

Contractors want it.

Ready-mix producers want it.

Owners want concrete to act like concrete again.

After years of frustration with Type IL cement, the industry seems to be saying, “Enough. Give us the old cement back.”

Fair enough.

But here is the question nobody wants to answer.

If Type I/II cement comes back, did we actually learn anything?

Because blaming Type IL for every concrete problem is too easy. Concrete had issues before Portland-limestone cement showed up. We had scaling. Dusting. Cracking. Curling. Bad curing. Too much water. Poor finishing practices. Mix designs built around passing a 28-day strength test instead of creating durable concrete.

Type IL may have exposed those problems faster.

It may have made the margin for error smaller.

It may have removed some of the cushion the industry had been leaning on.

But Type IL did not invent bad concrete.

It exposed the bad habits we were already tolerating.

The Problem Was Bigger Than Type IL Cement

For years, the industry treated Type IL cement as a one-for-one swap with Type I/II.

That was the first mistake.

The second mistake was pretending the only thing that changed was the label on the silo.

Concrete Bob Higgins made a point in this week’s episode that should make everyone in the industry uncomfortable. A lot of the standards and assumptions we use today were built around concrete we do not really place anymore.

The cement changed.

The grind changed.

The chemistry changed.

The additives changed.

The performance changed.

But somehow the field was expected to keep doing the same thing and get the same result.

That is not how concrete works.

If the material changes and nobody clearly tells the contractor, producer, finisher, specifier, or owner what changed, then the field becomes the testing lab.

And when problems show up, who gets blamed?

The contractor.

The finisher.

The ready-mix producer.

The guy on the slab.

Some of that blame may be earned. Let’s not pretend every jobsite is a monument to best practices.

But the industry also needs to be honest. If we keep changing cement behind the curtain, we cannot act shocked when the folks placing it in the field are confused by the results.

We Chased Speed and Strength

Concrete used to be slower.

That is not always a bad thing.

In the 1920s, cement was much coarser. Concrete developed strength slower, but it was durable. According to Bob, even concrete from the 1950s showed very little deterioration in many cases.

Then the industry got impatient.

We wanted faster set.

Earlier strength.

More production.

More concrete with less cement.

So cement got ground finer.

Finer cement reacts faster. It can help reach early strength. It can make the 3-day, 7-day, or 28-day number look good.

But there is a trade-off.

Finer cement can generate more heat. It can increase water demand. It can contribute to cracking, curling, and durability issues if the rest of the system does not adjust.

That is the part we do not talk about enough.

We did not just improve cement.

We changed the behavior of concrete.

Then we kept measuring success with the same old ruler.

Did it hit 4,000 psi at 28 days?

Great. Ship it.

But what about the surface?

What about permeability?

What about long-term durability?

What about the top inch of concrete that gets abused by water, chlorides, carbonation, freeze-thaw cycles, heat, finishing practices, curing failures, and everything else Mother Nature and the jobsite throw at it?

That surface is the first line of defense.

And too often, we treat it like an afterthought.

The 28-Day Strength Test Is Not Enough

This is where the industry needs a gut check.

We have built a massive amount of confidence around compressive strength.

Break the cylinders.

Hit the number.

Move on.

But a cylinder break does not tell the whole story.

It does not tell you if the surface is durable.

It does not tell you if the top inch is weak.

It does not tell you if the concrete is more permeable than it should be.

It does not tell you if the curing process actually helped the part of the concrete that matters most in service.

Bob mentioned research where 4,000 psi concrete was tested with no cure and with a seven-day water cure. When the top inch was isolated, the seven-day water-cured concrete was still significantly lower in compressive value than the rest of the concrete.

Think about that.

You could pass the strength test and still have a weaker surface.

That is a problem hiding in plain sight.

And it matters because most durability problems do not start in the middle of the slab.

They start at the surface.

That is where water enters.

That is where chemicals enter.

That is where freeze-thaw damage starts.

That is where scaling, dusting, and surface failures show up.

If the surface is weak, the concrete is already compromised, even if the cylinder breaks look fine.

Self-Desiccation Is Concrete Running Out of Gas

One of the more important parts of this episode was the discussion around self-desiccation.

Put simply, self-desiccation means the concrete is using up or losing available water internally before the cement has fully done its job.

The relative humidity inside the concrete drops.

Cement formation slows down.

At a certain point, it can basically stop.

That means you may have cement in the mix that never fully becomes useful cement paste.

So when everyone screams for a lower water-cement ratio, we need to ask a better question.

Is the cement actually hydrating?

Because if the cement is not forming properly, then some of that cement becomes expensive filler.

That is not durability.

That is not sustainability.

That is not performance.

That is just checking boxes.

The scary part is that Bob talked about field studies where the top inch of concrete self-desiccated within two to three weeks, even when water curing and curing compounds were used.

That should get our attention.

Because if we think curing is handled just because we sprayed something on the slab or kept water on it for a prescribed period, we may be fooling ourselves.

The question is not, “Did we cure it?”

The question is, “Did the curing work?”

Going Back to Type I/II Is Not a Free Pass

The return of Type I/II cement may help.

It may give contractors and producers back some consistency.

It may provide more forgiveness.

It may reduce some of the frustrating behavior many have seen with Type IL.

But going back to Type I/II does not automatically fix concrete.

If we return to Type I/II and keep the same bad habits, we will end up right back where we started.

Too much water will still be too much water.

Poor curing will still be poor curing.

Bad finishing timing will still be bad finishing timing.

Specs obsessed with 28-day strength will still ignore durability.

Material inconsistency will still create jobsite chaos.

And contractors will still get blamed for problems they did not fully create.

So yes, bring back Type I/II where the market demands it.

But do not waste the opportunity.

Ask better questions.

What cement are we actually getting?

What are the proportions?

Is the Type I/II from one supplier behaving the same as the Type I/II from another?

Are we being told what has changed?

Are the specs responding to the cement being used?

Are curing procedures actually producing a durable surface?

Are we designing concrete for long-term performance, or just for a cylinder break?

Those questions matter.

Concrete Needs Transparency

Ready-mix producers are expected to disclose what they put in concrete.

Admixtures.

Additives.

Adjustments.

Anything beyond the basic ingredients needs to be accounted for.

But cement manufacturing does not always get the same level of scrutiny from the people downstream who are expected to live with the results.

That needs to change.

If the cement changes, the field needs to know.

If limestone content changes, the field needs to know.

If the grind changes, the field needs to know.

If the material behaves differently, the field needs to know.

You cannot ask a contractor to adjust methods for a material he does not understand and was never told changed.

You also cannot ask a ready-mix producer to deliver consistency when the upstream material is inconsistent.

Concrete is hard enough when everyone knows what they are dealing with.

It becomes a mess when nobody does.

The Industry Has a Chance Here

This moment could be good for concrete.

Not because Type I/II cement is magic.

It is not.

But because the Type IL fight forced the industry to have a conversation it should have had years ago.

What changed in our cement?

What changed in our concrete?

What changed in our expectations?

What are we measuring?

What are we ignoring?

Who gets blamed when the system fails?

The easy move is to say, “Type IL was the problem. Type I/II is the solution.”

That is too simple.

The better answer is this:

Type IL exposed how little margin for error we had left.

The concrete industry had already been pushing speed, early strength, lower cement contents, finer grinds, tighter schedules, and weaker curing discipline.

Type IL just made the consequences harder to ignore.

Now the market is pushing back.

Good.

But if we are going back to Type I/II cement, let’s not go back to sleep.

Let’s use this moment to fix the real problem.

Concrete should not be designed only to pass a 28-day strength test.

It should be designed to last.

Let’s keep it concrete.