Construction Materials Labs
The Cementitious Materials and Construction Materials Testing Laboratories have numerous cement and concrete testing features. Standard cement tests include fineness, strength, and time of set; and aggregate testing includes complete gradation analysis, impurities and deleterious materials, absorption, specific gravity, and voids analysis. Cement analysis capabilities include tests based on X-ray fluorescence and diffraction (XRF, XRD), atomic absorption spectrophotometry (AA), and colorimetric analysis conducted in the EGRC. Chemical analysis by ion-specific electrode, with either water-soluble or acid-soluble techniques, can also be conducted.
These labs have equipment to mix batches of various sizes up to 16 cubic feet in volume and can provide all standard tests of fresh concrete such as slump, flow, air content (pressure and volume method), unit weight, and bleeding. Other equipment includes a 3-ton overhead crane. Moist room facilities and controlled humidity and temperature facilities are also available. Shrinkage and creep testing may be conducted for concrete strengths up to approximately 140 MPa (20,000 psi). In addition, computer-monitored maturity and heat of hydration testing is available.
Durability testing is an important aspect of these labs, and they contain a variety of equipment for this purpose. For example, standard half-cell potential tests for corrosion may be conducted, and a variety of "lollipop" type potential corrosion comparisons with several impressed current options are available. Tests of concrete permeability such as rapid chloride permeability, AC impedance testing, and AC impedance spectroscopy are routinely conducted. Also, the potential for alkali silica reactivity can be determined by numerous methods.
Researchers in these labs frequently use a state-of-the-art freeze-thaw chamber with computer-controlled and programmable temperature cycles. Standard frost-scaling testing is also conducted. This device is frequently used to conduct rapid freezing and thawing but can be configured to conduct a wide range of cold temperature investigations. Computer-based determination of the mass-adjusted dynamic modulus from resonant frequency analysis tracks deterioration.
Test equipment is also available for nondestructive evaluation of construction materials and structures with wave propagation methods, including fundamental frequency devices, pulse velocity, oscilloscopes, transducers, and various impact instruments. The Stress Wave Analysis Program (SWAP) provides unique graphics-controlled capabilities of collecting wave signals, performing various signal processing techniques, and evaluating the processed signals using pattern recognition techniques. Other CFL labs also have this kind of equipment.