Why Are Concrete Mix Studies Necessary for Construction?

Be it a bridge, highway, or roadway, construction doesn’t start until the materials and mixes are cleared for use. 

In order to optimize mixes to meet agency and project standards, project owners will consult a materials testing laboratory, such as G3 Quality, who employ experienced technical staff who design mixes for numerous specifying agencies. G3’s technical staff will ensure that the mixes meet the required design criteria for the agency the mix is being used for. 

This introduces two challenges for project owners: knowing these specific agency standards and getting the mix right. 

At G3 Quality, we’ve been supporting construction projects with concrete mix studies for the past decade. From concrete trial batching and field qualifications to soil-cement and more, we’ve done it all. 

Discover why concrete mix studies are crucial before construction paving/placement starts, and how G3 has delivered these services for past projects.

The Importance of Concrete Mix Studies 

Before a construction project kicks off, extensive testing and analysis, or mix design studies, are carried out on concrete materials that will be used. It’s a crucial step to take in order to meet specific agency standards as well as regulatory and safety benchmarks.

“No construction paving or placement project can begin without first completing the required mix studies; it’s the foundation which quality construction is built upon.”

Marc Robert, G3 Quality Technical Services Director

In order to meet those standards and specific project requirements, material designers and testers will take samples, break-test them for compressive and flexural strength, and use their findings to optimize mixes. The testing process is a bit complex, such as determining the different sizes of aggregate to use and whether the water-to-cement ratio meets separate requirements of the specifying agency.

Optimizing Mix Designs

The mix designs for concrete contain a combination of aggregates, cementitious materials, admixtures, and water. The ultimate goal is to find the optimal blend that meets the requirements of the project and to do so in a cost-effective manner. 

Mix studies allow G3 Quality to find the optimal blend through experimentation until the mix is perfected. Material samples are prepared using different combinations and ratios of ingredients, before being tested in the lab for compressive strength, flexural strength, unit weight, workability, and other design criteria.  All of which we touched on in a previous blog about How to Measure Concrete Strength.

The resulting test data is then used to adjust the concrete mix design until the optimal formula is reached. It’s a rigorous process of understanding the material properties, and finding the best formula for the project needs. It also provides valuable data to inform quality control throughout the construction process.

Meeting Agency & Engineering Requirements

All major infrastructure projects must adhere to construction guidelines and material standards set forth by regulatory agencies and engineering communities, such as the standard for water-to-cement ratio (W/C) for concrete. 

While projects with Caltrans have no specific W/C requirements, military construction projects won’t allow any higher than 0.45 W/C. For reference, higher W/C ratios  may lead to weaker concrete and surfaces, while lower W/C ratios signal a need for stronger materials.

At G3 Quality, we understand how difficult it can be to keep up with differing agency requirements and ensure your mixes are just right. You may not be familiar with other caveats as well, such as how many specimens are needed for FAA versus military and Caltrans. That’s why we’re here – to ensure your mix designs meet all standards and perform for the long term.

Concrete Mix Case Study: LAWA LAX Runway 24R Exits

This FAA project has several challenges for a concrete pavement mixture. LAWA places a high emphasis on strength, good placement practices, and long life durability of the concrete pavement. We started this process with Granite Construction 6 months prior to their concrete plant being erected on-site. The first part of the process is testing the aggregate materials. Granite Construction went with the Vulcan Material Orca aggregate source in British Columbia. G3 started testing for gradation combinations to establish the Coarse Factor and Workability factor (CF/WF), testing for any deleterious materials, and  Alkali/Silica reactivity. 

Once the testing of the aggregate was completed, G3 moved to the second step and brought all the materials into our Cerritos laboratory to start work on the mix study. The requirements were to provide a dense concrete for the durability aspect through a water/cementitious (w/c) ratio curve. This w/c curve gave Granite Construction the most efficient cementitious content for early strength requirement at 3 to 5 days and the ultimate strength requirement of 650 psi flexural at 28 days. The mix study also provides a chance to investigate the workability and cohesive nature of the mixture. All this information was made available to the client on how their expectations of the concrete mixture will perform in the field.  Once completed, the submittal package was checked against the FAA LAWA requirements for acceptance. After 40 days of work on the mix study, G3 submitted the final submittal package to Granite Construction in March 2023 and the approval went through with no comments or revisions. 

In partnering with Granite Construction, we were able to work together closely to provide a cost-effective mix that meets all the project specifications. From the aggregate, batching, workability in placement, and the strengths needed to meet the project specifications, it all started with the mix study process and partnering with the client to work out any issues prior to batching a single yard of concrete.   

Get Your Mix Approved with G3 Quality

G3 Quality has been carrying out mix studies and material design services for the past decade and many large-scale projects up and down the state of California. Thanks to our testing facilities in Cerritos, Redlands, Bakersfield and Sacramento along with our mobile testing labs, we can support your project with several materials design services, from HMA and soil-cement to cement-treated base designs and more. Consult G3 Quality to ensure your materials are ASTM C33-qualified and meet specific agency standards.

Fill out a form on our Contact page to keep your materials in line with project and safety requirements.