Concrete Materials

Both concrete materials and concrete construction work have been focal points in CIVE at Oklahoma State University. The research team at OSU have focused on solving real-world problems through using real equipment.  As shown in Figure 1, OSU has both a concrete paver and a concrete pump.  They also have a temperature-controlled mixing, curing, and nine environmentally controlled chambers where they can simulate different weather conditions.

Further, concrete mixing can be completed in a temperature and dust controlled mixing room at the BCEL.  Some of the fresh properties testing for concrete include: Slump, temperature, Unit Weight, Type B air meter, six super air meters, and the Box Test. Isothermal calorimetry testing can also be measured. Multiple hydraulic presses can be used for compressive, tension, and flexural testing. Most concrete durability testing can be completed such as hardened air void analysis, bulk freeze-thaw, alkali silica reaction, sulfate attack, and carbonation. For example, with freeze-thaw durability, Figure 2 (a) through (d) show the sample preparation process from cut with a concrete saw, polished on multiple automated polishers, coloring prepared with a stereomicroscope, and scanned with an automated hardened air-void analysis (Rapid Air 457). Also, bulk freeze-thaw testing can be completed using one of the five freeze-thaw chambers (see Figure 2e). In addition, physical and chemical testing of cement, fly ash, and slag can also be conducted.

The team also has expertise in instrumentation, app development, programming, advanced testing methods, optical microscopy, electron microscopy, and X-ray microscopy all applied to construction materials.  This equipment will be discussed later in the document.

Aggregate

Most of the typical aggregate testing can be completed such as gradation, LA abrasion, potential ASR reactivity, freeze-thaw durability, flat and elongation, absorption, specific gravity, voids content, and unit weight. The BCEL has a designated aggregate room for sieving and LA abrasion. Chemical testing can also be conducted on the aggregate. The OSU CIVE research team also has the abilities to test aggregates for mechanical responses such as California Bearing Ratio (CBR), Triaxial Shear Strength, Resilient Modulus (M_R­) and Permanent Deformation Accumulation under Repeated loading. The team can test cylindrical triaxial specimens with a diameter of 152 mm (6 in.) and a height of 305 mm (12 in.). These triaxial tests can be conducted with complete pore-water pressure control. Moreover, the set-up can also measure the permeability during the triaxial testing.

Numerical Modeling Capabilities

The OSU CIVE team has expertise in the use of several state-of-the art numerical modeling software packages. Some of the most commonly used software packages include:

• ABAQUS for Finite Element Modeling of structures, embankments, pavements, and railroad tracks
• Particle Flow Code (PFC) for Discrete Element (DE) Modeling of coarse-grained geomaterial behavior. Example applications include: (a) interaction between aggregates and geogrids in pavement and railroad applications; (2) studying the mechanism of particle breakage under repeated loading, etc.;
• Fast Lagrangian Analysis of Continua (FLAC; both 2D and 3D versions) for geotechnical analysis of soils, rocks, groundwater, and construction processes such as excavation.

Nondestructive Testing

For many construction materials there has been extensive nondestructive testing capabilities for both laboratory and field application. This nondestructive testing can be found in many forms throughout the laboratory depending on the research project. While NDT strength testing capabilities of rebound test, penetration test, pull-out test, and break-off test can be found in many material laboratories, the BCEL also has ultrasonic pulse velocity devices with 54 kHz and 150 kHz P-wave transducers and 250 kHz S-wave transducers to enable estimation of dynamic modulus of elasticity of materials. These ultrasonic pulse velocity devices have been used to not only determine the uniformity of a concrete structure, but monitor the crack development with a concrete sample being loaded. The BCEL also has the ability to complete acoustic emission testing.  This is where high resolution microphones are used to detect cracks within materials as they occur.

Bridges and Structures

The capabilities of Oklahoma State University with regards to bridges and structures has a very extensive compared to many others. As shown in Figure 3, the BCEL has a 6,000 ft² strong floor is supported by 90 gallons per minute hydraulic pump that can provide hydraulic power for both large-scale static and fatigue testing. Large objects such as full-scale bridges or columns can be constructed and load tested to failure.  A 20-ton overhead crane with a 30 feet hook height can assist in the testing process of full sized frames and structures for testing. There is structural measurement and monitoring equipment for use during the testing. Also for small sample compressive strengths, flexural strength, or tension strength testing, a hydraulic machine with the capabilities of 330,000 psi.

Bert Cooper Engineering Laboratory

The Bert Cooper Engineering Laboratory opened in 2015 the Bert Cooper Engineering Laboratory (BCEL) (figure 4) is a 33,000 ft² state-of-the-art structural engineering and materials engineering research laboratory on the campus at Oklahoma State University (OSU).  BCEL houses a variety of high-performance equipment to conduct multi-scale research activities, from durability and mechanical micro-characterization to full-scale serviceability and integrity testing. The capabilities of this lab can be described as uniquely broad-ranging for structural and materials engineering compared to another university structural and materials engineering facilities. The laboratory has a fully equipped fabrication shop, concrete mixing and curing rooms, concrete pump truck, slip formed paver, concrete durability testing, environmental chambers, aggregate sieving room, nondestructive evaluation room with extensive laboratory and field NDT equipment, structural measurement and monitoring equipment, a 6,000 ft² strong floor, and a 20-ton overhead crane with a 30 feet hook height.  Compressed air power is provided throughout the laboratory and both Wi-Fi and Ethernet connections make data transmissions readily accessible.  Camera technologies, and our broadband capability make remote monitoring and remote management of research a reality. At the front of BCEL, a considerable amount of space has been provided for student workspace, faculty offices, and even a conference room suitable for meetings, workshops, and guest speaker presentations.

The BCEL has multiple strength testing machines. Figure 5a shows a typical compressive machine of 160,000 lbs., which has the capacity of breaking a 4x8 inch concrete cylinder up to 12,500 psi. For higher compressive strengths, flexural strength, or tension strength testing, Figure 5b shows a hydraulic machine with the capabilities of 330,000 psi. If larger testing samples or higher possible testing of a material may be required, the BCEL has a 6,000 ft² strong floor strong floor is supported by 90 gallons per minute hydraulic pump that can provide hydraulic power for both large scale static and fatigue testing. Large objects for testing such as a full-size bridge beam can be moved into the laboratory using one of four large overhead doors. A 20-ton overhead crane with a 30 feet hook height can assist in the testing process of full-sized frames and structures.

The BCEL also contains a temperature and dust controlled concrete mixing room, vented aggregate sieve room, nine environmentally controlled chambers, and a moisture curing room. Figure 6 (a) shows the concrete mixing room, which is equipped with a paste and mortar mixers, a ¼ CY concrete drum mixer, and ¾ CY concrete drum mixer.  The aggregate sieve room contains a large Gilson sieve machine and a smaller sieve shaker machine, and a LA abrasion machine. Figure 6 (c) and 6 (d) show two walk-in temperature and humidity controlled environmental chambers. One room close to 150 ft³ has been designed for moisture curing concrete cylinders and the other room with more than 300 ft³ room has been designed at a significantly lower moisture content for testing such as drying shrinkage testing.