U.S. Concrete National Laboratory

Welcome to our virtual tour of U.S. Concrete's National Research Laboratory. The Laboratory, through its groundbreaking research, has significantly advanced the performance of concrete and driven the creation of new, innovative, and cost-effective solutions – real products that are making an impact today.

 

U.S. Concrete's National Research Laboratory was founded in 2009 as the research and development division of U.S. Concrete. During this time, we have engineered superior concrete mixes using alternative cement materials. These new mixes not only outperform traditional concrete mixes relative to set times and early strength, but significantly reduce the products carbon footprint. Many of these products have sprung from our Environmentally-Friendly (EF) Technology™ Initiative. We have also developed and brought to market U.S. Concrete's Aridus® an innovative product that addresses Rapid Drying Concrete. This proprietary mix dries faster than conventional mixes, allowing flooring materials to be installed faster and more effectively – avoiding costly flooring failures.

Our mission at U.S. Concrete's National Research Laboratory is to initiate and work with partners on fundamental research and then pursue and develop commercially viable solutions that address the needs of owners, developers, architects, and engineers. We are proud to have established an academic-industrial partnership with research teams at the University of California, Los Angeles (UCLA) and Arizona State University (ASU), along with other institutions worldwide, to develop alternative supplementary cementitious materials (SCMs). These efforts will focus on identifying and developing alternative supplemental materials that can be used to replace cement in concrete.

As noted by Ryan Henkensiefken, business development engineer, Central Concrete, "Cement production is responsible for 5% of man-made CO2 emission. For every ton of cement clinker manufactured, about one ton of CO2 is released into the atmosphere. To combat these environmental effects, our team will be aggressively pursuing solutions that reduce the use of cement, and thus the GHG footprint of concrete."

 

Researching Environmental Conditions: Temperature & Humidity

Highlights:
Our Batch Room is temperature and humidity controlled. It can operate from 50 degrees Fahrenheit to 100 degrees Fahrenheit and from roughly 30% relative humidity to 100% relative humidity.

Having the ability to control temperature and humidity in the Batch Room allows us to experiment with different environmental conditions and see how those conditions affect the performance of concrete. We are constantly testing our concrete mixes and working to optimize such properties as workability, set time and early strength, evaluating these under diverse environmental conditions. This has been extremely beneficial in making significant strides in our EF Technology™ Initiative – an initiative that led us develop to develop a stronger, more durable and greener concrete mix, over traditional concrete.

 

Data on our Low-CO2, EF-Based Concrete

Environmental Condition: 50 degrees

 

Proper Sample Storage

Often you will see concrete samples stored in troughs filled with water. If they are not properly maintained, they can actually leach vital components and hydration products out of the concrete. To eliminate this issue, we store all of our concrete samples in a temperature and humidity controlled "moist room".

 

Computer-Controlled Environmental Chambers

All three of our environmental chambers are controlled from a web-based application. This application will alert us if any chamber is operating outside of the temperature or humidity tolerances that were set. We can dial-in remotely and solve the problem if a chamber should move out of tolerance.

 

Investigating Unique Local Challenges: Materials and Environment

Though concrete is being poured throughout the country every day, the construction industry is far from monolithic. Each area of the country has unique challenges, which makes a one-size-fits-all product very rare.

To ensure that we are meeting the unique needs of each local market, we begin our investigations using mortar. This gives us a great deal of flexibility -- allowing us to look at several multiple material combinations (such as different water/cement ratios, cementitious combinations and admixture combinations) under various environmental conditions.

 

Environmental Testing

We conduct moisture, shrinkage and evaporation testing in our Environmental Test Room.

Similar to our Batch Room, we can establish temperature ranges from 50 to 100 degrees Fahrenheit and relative humidity ranges from 30% to 100. Within those ranges, we set even tighter controls, eliminating environmental variations within our testing.

Our Environmental test room was critical in our fundamental research, exploring slab warping – the foundation for our work when developing U.S. Concrete's Aridus® Rapid Drying Concrete.

 

Simulating Truck Mixing Action

Often times when concrete is tested in a laboratory it is mixed for a few minutes, dumped into a wheel barrow, tested for fresh properties, and then samples are made. Unfortunately that does not accurately simulate the real environment.

In reality, concrete is mixed at the plant for a short period of time and is dumped into a ready-mix truck where it will slowly churn for 60 minutes or more before it is placed. How the concrete behaves after all this time is often quite different than how it behaves in the first minutes.

To achieve greater accuracy, our laboratory utilizes a concrete mixer designed to mimic the mixing action that you will find in our ready-mix trucks, or in a centrally mixed ready-mix plant.

Again, this was beneficial as we pursued our development of U.S. Concrete's Aridus ® Rapid Drying Concrete. Our Aridus solution is a low water/cement mixture. Slump loss and early setting can plague mixtures of this type. Our research efforts revealed that to avoid this issue, we needed to leave the concrete in the mixer for two hours at "transit" speed. The result: we optimized the admixtures to hold slump for two hours and achieve a normal set time.

 

A Closer Look: Mixing Time

Our laboratory concrete mixer is set up on a timer and a rheostat. The timer allows us to secure a precise mixing time, while the rheostat allows us to achieve a full range of mixing speeds – simulating the ready-mix plant environment and their ready-mix trucks.

This has proved to be very useful when looking at the effectiveness of different chemical admixtures, primarily high-range water reducers. We have shown that concrete can be mixed for several hours and still get the desired slump, set time, strength and durability properties if properly designed.

 

Thermal Signature Analysis

Our Thermal Signature Box allows us to look at the heat signature of our concrete samples, providing us valuable insight on the chemical reactions taking place.

Because the reaction that takes place in concrete is an exothermic reaction, we can look at the interactions of different cementitious and various chemical admixtures and see how well they are performing, just by looking at the temperature rise.

We discussed earlier how concrete mixing time could affect concrete performance, but these issues can be avoided when the concrete is properly designed. Chemical admixtures are effective tools to control the set time and slump life of concrete, and we have used our thermal signature box to determine the proper dose of the admixtures for different conditions.

 

Aggregate Quality Classification: Optimizing Aggregates Use

Just like baking a cake, when we design concrete the ingredients and portions are critical. Since nearly 70% of the volume of a concrete mixture is aggregates, knowing the exact properties of those aggregates is very important.

In our Aggregate Room we are constantly testing and qualifying materials that we can use in concrete. Recently, through rigorous testing, we were able to utilize a new aggregate, once thought of as waste, in our concrete. Not only were we able to find a new use for this product, eliminating its unnecessary waste, but its addition delivered a stronger, more durable product.

We are currently preparing to classify different grades of crushed returned concrete, in an effort to engineer many more environmentally-friendly concrete mixes, while diverting all this waste from landfills.

 

Ball Mill

In partnership with UCLA and the ASU, we are researching new materials to integrate into our concrete designs -- materials that will result in a superior product and lower the overall environmental impact. Some of these materials come in raw form, and therefore, need to be ground into a size suitable to be used as a cement replacement. Our Ball Mill is used for this purpose. After grinding the alternative cement materials, we perform numerous test, such as Blaine fineness and air sieve tests, to determine relative fineness of the material. Once the material is classified, we can test the mortar fraction under numerous conditions.

 

Rapid-Chloride Permeability/Durability Testing

While strength is a critical attribute to evaluate, so is durability. We want to ensure that the concrete will last the design life of the structure. To determine how durable the concrete is, we conduct Rapid Chloride Permeability testing – or RCP testing. Saturated samples of concrete are epoxied into the holders, and chambers on the end of the holders are filled with a salt solution. We then pass electricity through the sample and amount of electrical charge passed can give us an indication of the porosity that can be related to how durable the concrete will be.

Industry-wide, it is now recognized that incorporating supplemental cementitious materials into concrete can dramatically improve the durability properties of concrete.

 

We thank you for attending this Virtual Tour of our 3,500 square foot research facility. As you have seen, it is unlike any other research laboratory in the ready-mix industry.

We are committed to pursuing ground-breaking, fundamental research and developing and bringing to market real solutions to our customers that will meet their goals. By reducing the Portland cement content with cement replacement materials, we have engineering higher performing products that significantly reduce their impact on the environment.

We invite you to learn more about the advantages our products deliver over traditional concrete – from high early-strength, low shrinkage and superior permeability – all while reducing the project's carbon footprint.

To learn more about US Concrete’s National Research Laboratory contact:
Alana Guzzetta
Laboratory Manger
U.S. Concrete National Research Laboratory
Email

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