Strength Enhancer admixture

[Rhuynh]

Curious to see what real engineers would do with an strength enhancing agent.

If it were possible to effectively increase the overall compressive strength on concrete by 20%-30%, how would you use the concrete? What changes would you make to your concrete designs?

To better illustrate what i mean:
Say your normal concrete with a 0.35 w/c yields 50 MPa.
With a strength enhancer the same mix yields 60MPa concrete.
What could you design with 60 MPa concrete?

Or better yet, You produce a 40 MPa concrete with a w/c ratio of 0.45, add the strength enhancer and get 50 MPa concrete, you effectively save money on cement content. Which is more Green in an environment point of view.

What other possibilities are there for a strength enhancer?

 

[Ron]

w/c ratio is the primary predictor of strength. A "strength enhancer" for concrete would likely be something that would lower the w/c ratio. What is the principle behind this "enhancer"? Sounds like snake oil.

 

[Rhuynh]

Ron you are absolutely right. One way to increase strength is to reduce water to cement ratio.

However going for a 0.45 ratio to a 0.35 ratio, is to increase cement content by roughly 25% (by mass). It may be more economical to produce the same strength using a chemical admixture.

 

[Rhuynh]

i'm not sure of the principle of this enhancer, i do not know why this agent increase strength. Im just wondering whether industry professional could benefit from strength enhancers. (i have left the undesired side effects out)

 

[JedClampett]

IMHO strength is an overrated property of concrete. Shear capacity is based on the square of the strength. Bending is only slightly impacted by increased strength. Only in columns is the increase in strength proportional to capacity.
So basically you're adding a fancy and expensive admixture to only marginally reduce material.

 

[hokie66]

I imagine a "strength enhancer" is a water reducing agent. 60 MPa to 100 MPa concrete is now commonly used in columns to reduce the area the columns deduct from the floor plate.

 

[Ron]

hokie66...that was my thought as well...a water reducer, whether high range or normal. No big deal...they're used everyday.

JC...good points. If you design concrete for durability, strength is just a by-product. Strength is just easier to quantify than durability.

 

[JAE]

Are you talking about Viagra?

 

[pwht1]

Are you talking about flyash or another pozzolan? Not something I'd consider a 'strength enhancer' (whatever the hell that would be) but it reduces the cement content.

 

[Ron]

JAE...Viagra for concrete...you'll make a mint!

pwht1...fly ash only reduces the amount of portland cement...it doesn't affect the w/c ratio except in certain instances where it can actually increase the ratio, which in turn, will decrease the strength.

 

[TDAA]

JAE and Ron:

The problem with that admixture is that you do not want to have the strength last for more than 4 hours. Otherwise you should seek help.

 

[Ron]

TDAA...problem is that when it gets hard is always cracks....painful!

 

[JAE]

I love these technical discussions!