Cor-Tuf Screed

Leveling UHPC with a Standard Power Screed

Construction crews know how to get a batch of concrete mixed, poured, and leveled. At job sites around the country (and the world), construction professionals use standard machines and well-known techniques to do the job right. We, like most construction professionals, believe that any new concrete technology should be mixed, transported, poured, and leveled these standard machines and techniques.  Concrete construction—including leveling—shouldn’t need an overhaul.

As you know, concrete screeds come in a few main types, in order to handle the scale and nature of a project. For small residential sites, you’re probably using a hand-held vibratory screed and some floats. For a bridge or paving project, a truss or roller screed is the equipment of choice. These are nice improvements over the old days of having a whole crew use 2×4’s to level out every concrete pour, and the technology advancements to the modern power screeds have done a lot for project productivity.

UHPC is definitely an improvement over old-fashioned concrete, but if it requires massive increases in additional “expert” manpower, complex equipment, and a steep learning curve, it’s not a viable option for budget-conscious contractors. Instead, it should be cost-effective, using standard machines and material specifications—so that it can be seamlessly incorporated into a contractor’s normal workflow.

That’s why we level Cor-Tuf Ultra-high Performance Concrete (UHPC) with a typical power screed, after mixing and pouring from a standard ready-mix truck. Easy mobilization and integration into fleet-wide project planning means minimal training and no special equipment rentals. You don’t need to bring in a specialist for every UHPC job, or purchase a proprietary applicator.

This is an improvement over the UHPC  stuck in the days of a gimmicky subscription model, demanding special project oversight and an all-in-one machine that mixes special sand and cement, pours the mix, and levels it using hydraulic levelers. 

Salesmen might make this sound great, but it doesn’t make sense for a typical contractor. In practice, this arrangement means a giant machine needs to be delivered, with extra lead time, added overhead costs, and scrutiny on local workers who are there to level the concrete. 

Why do these vendors use this burdensome approach? Other UHPC mixes may not be able to achieve the desired consistency, workability or results without special mixing programs. They need to have long mixing times with expensive, single-use equipment to pass slump and cylinder tests. In-house supervisors and operators may need to perform the installation with an experimental machine because it doesn’t level out easily with a typical screed, from a stand-off dragon model to a cheap handheld model. The result may be a decent UHPC product, but the process upends the façade of competitive parity with efficient construction. 

Bridge overlays using the simplified UHPC method

Contrast this with our approach to recent bridge overlays. Ready-mix gets delivered in a standard ready-mix truck. With our fibers integrated, the crew spreads as they usually would, and a truss power screed levels the poured material. The screed is installed on tracks with hand cranks, and only needs a minor PVC attachment to get the job done. In, out, and onto the next job with minimal opportunity for incidents or change orders. The contractor uses the same sand and cement as they usually would, and techniques similar to all their jobs that use traditional concrete.

The benefits of integrating Cor-Tuf UHPC seamlessly means you gain from the advancement of high-strength and long-performing UHPC without significantly altering the way in which you work with concrete. Contractors need to be trusted to do their jobs, especially when it comes to tried-and-true techniques such as screed leveling. They should not be burdened with unnecessary costs and methods simply because they want to start taking advantage of state-of-the-art material. 

The bottom line for any construction project is time and money. The cost of new machinery often outweighs its benefits in modern construction. Standard techniques and equipment, such as ready-mix trucks and power screeds, should be the foundation of applications such as UHPC. New solutions must always factor in real-world applications that contractors use.

By achieving a UHPC product that joins local supply chains with classic techniques to achieve next-generation results, Cor-Tuf has found the sweet spot. Stay tuned for more updates on our ongoing projects demonstrating seamless integration with methods that work. Your sand, your cement, our Cor-Tuf UHPC.

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PRODUCT DATA SHEET

CTL Group Material Testing Results*


Concrete Performance
Test MethodCuring Conditions at CTL Group AgeTest Results
Compressive StrengthASTM C 3973°F/100% RHat 1 day9,050 psi
Compressive StrengthASTM C 3973°F/100% RHat 3 days11,140 psi
Compressive StrengthASTM C 3973°F/100% RHat 14 days16,000 psi
Compressive StrengthASTM C 3973°F/100% RHat 28 days21,000 psi
Compressive StrengthASTM C 3973°F/100% RHat 56 days23,000 psi
Compressive StrengthASTM C 1856Controlled Curingat 28 days25,500 psi
Length Change of HHCASTM C 15773°F/50% RH28 days
(26 days Dry)
-0.033%
Chloride PenetrabilityASTM C 1202
AASHTO T277
73°F Limewater
190°F water 5 days;
190°F air 2 days;
73°F water until testing
28 days
28 days
≤100 (Negligible)
≤100 (Negligible)
** Flexural StrengthASTM C 160973°F Limewater28 daysL/600 = 2800 psi or better
** Flexural StrengthASTM C 160973°F Limewater28 daysL/150 = 1500 psi or better
Direct Tensile StrengthAASHTO T39773°F Limewater28 days1000 psi or better
Modulus of ElasticityASTM C 46973°F Limewater28 days6800 ksi
Abrasion Resistance, Ave LossASTM C94473°F Limewater58 days0.016 oz
Freeze Thaw Resistance RDMASTM A 66673°F Limewater28 days600 cycles, 96%

Notes:
*Testing results confirmed by independent laboratory CTL
Group. Results are based on laboratory mixes.
**Data per UCF Material Study 5/10/2022
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Client: Cor-Tuf UHPC CTL Project No: 059330
Date: 1/20/2020

What Makes UHPC Ultra-High Performance

UHPC achieves its superior performance through a dense nano-scale matrix that is far less permeable than conventional concrete. This matrix is combined with steel fiber reinforcement, which provides exceptional ductility and crack resistance.

Though exact formulations and results vary by producer, UHPC generally incorporates a blend of Portland cement, sand, supplementary cementitious materials, chemical admixtures, and fibers – resulting in a material dramatically stronger, tougher, and longer lasting than traditional concrete.

Cor-Tuf Outperforms Conventional Concrete and Other UHPCs

Feature Cor-Tuf UHPC Conventional Concrete Other UHPCs
Compressive Strength 25,000+ psi 4,000–6,000 psi 18,000–22,000 psi
Ease of Placement ✅ Standard Equipment ✅ Standard Equipment ❌ Specialized Tools
Bonding & Ductility Extreme Low Moderate
Freeze-Thaw Resistance 1000+ Cycles 20–80 Cycles 300 Cycles
Chloride Permeability Near Zero High Low
Lifespan 100+ Years 25–30 Years 50–60 Years

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