SPA Application: Quality Management of PCC Structures and Pavements
Quality management of portland cement concrete ( PCC ) with beams and cylinders are well documented and fairly sufficient. Since the concrete is sampled before it is placed, and cured under laboratory conditions, test results reflect more information about the mix design, than in situ results. The maturity test method is founded on these traditional tests regarding the quality and strength of concrete, but is nondestructive and allows for in situ testing. The maturity method ensures the quality of concrete in place and under the actual environmental condition, but does not provide any information about the quality of construction. Since the PSPA is portable, seismic tests can be readily combined with the maturity concept for comprehensive quality management.
Some of the practical uses consist of quality management of concrete members, timing the opening of roads to traffic and optimizing the time for removing formwork.
Case Studies for Quality Management: PCC Structures and Pavements
Impact of Environmental Parameters
on Strength Gain of Concrete Estimated with
Maturity and Seismic Methods
D. Yuan, S. Nazarian and A. Medichetti
Center for Highway Materials Research
The University of Texas at El Paso
El Paso, TX 79968
A paper for possible inclusion in Session
Development in Field Monitoring of Properties of Concrete
Sponsored by Committee A2E03
2004 Annual TRB Meeting
Two nondestructive testing techniques for monitoring and predicting the strength gain of Portland cement concrete are maturity and seismic methods. In these methods, either the timetemperature history or the seismic (dynamic) modulus of concrete is related to the strength parameters through standard tests on concrete specimens. These relationships are then used on actual construction sites usually with virtually no consideration given to the environmental conditions at which the concrete is poured and the curing regime implemented. Through an extensive lab and field testing program, the impacts of the environmental and curing parameters on the accuracy of the relationships developed for estimating strength are investigated. The strength-maturity relationships obtained from standard-cured cylinders may not accurately estimate the in situ strengths when the moisture, temperature or curing regimes are vastly different. The strength-modulus relationships seem to be less sensitive to these environmental and curing factors.
Use of Stress Wave Techniques
to Monitor and Predict Concrete Strength
Deren Yuan, Soheil Nazarian and Dong Zhang
Center for Highway Materials Research
University of Texas at El Paso
500W. University Ave, TX 79968
The feasibility of using stress wave technique, a nondestructive testing technique, to monitor and predict the strength and modulus development of Portland cement concrete was investigated. The measured quantity of this technique is the dynamic modulus of elasticity. The dynamic modulus can then be related to the strength parameters and static modulus obtained from conventional testing on the molded specimens or drilled cores. In this investigation, the laboratory tests on molded concrete specimens and cores were carried out with the simplified free- free resonant column method and the field or in-place tests on concrete elements were conducted with a hand- held device called the Portable Seismic Pavement Analyzer. In all instances, the maturity of the concrete as a function of time (time-temperature factor) was measured.
A database, containing results from about 1000 specimens made from low, medium and high-strength concrete mixes, has been developed. Preliminary relationships between the dynamic modulus and the strength and static modulus parameters are proposed in the basis of the type of coarse aggregate. Unlike a strength-maturity relationship that is usually very specific to a particular mix under a particular curing condition, a dynamic modulus-based relationship is mainly affected by the nature of the coarse aggregate and, to a lesser extent, by other parameters such as curing condition, admixture, and water-cement ratio.
The technique used in this study has shown to be a rapid, simple and very economic means for estimating the strength and modulus development of concrete and determining the time required to open a repaired or newly constructed concrete pavement to traffic.
Geomedia SPA Application: Quality Management of PCC Structures and Pavements