Enhanced Portland Cement Concrete Fatigue Model for StreetPave

2005 ◽  
Vol 1919 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Leslie Titus-Glover ◽  
Jagannath Mallela ◽  
Michael I. Darter ◽  
Gerald Voigt ◽  
Steve Waalkes
Keyword(s):  
Portland Cement ◽  
Stress Ratio ◽  
Design Method ◽  
High Volume ◽  
Fatigue Tests ◽  
Slab Thickness ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Fatigue Model ◽  
Pavement Thickness

The Portland Cement Association (PCA) pavement thickness design method for jointed concrete pavements is mechanistically based and consists of both fatigue and erosion analyses. It determines the minimum slab thickness required for a given set of site and design conditions on the basis of both fatigue and erosion criteria. At the heart of the fatigue analysis is the fatigue model, which establishes the number of allowable load repetitions for a given stress ratio [ratio of flexural edge stress caused by the application of wheel loads to the portland cement concrete (PCC) slab flexural strength]. The PCA fatigue model is based on data derived from beam fatigue tests conducted in the early 1950s and 1960s. The model estimates the conservative lower-bound estimate of the allowable number of load applications at a given stress ratio (i.e., it incorporates a high degree of reliability–-approximately 90% or higher). Although this may be desirable for high-volume, high-traffic pavements, it is too conservative for low-volume roads or street pavements. The PCA pavement thickness design method currently is being used in the American Concrete Pavement Association (ACPA) pavement design software, StreetPave. StreetPave incorporates the PCA's pavement thickness design methodology in a Windows-based user platform. ACPA commissioned a study to expand, improve, and broaden the current PCA fatigue model by including reliability as a parameter for predicting PCC fatigue damage and by calibrating the enhanced model with additional fatigue data from recently completed studies. An enhanced fatigue model was then developed.

High-Volume Fly Ash Concrete for Sustainable Construction

2012 ◽  
Vol 512-515 ◽  
pp. 2976-2981 ◽  
Author(s):  
Jeffery S. Volz
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
High Volume ◽  
Sustainable Construction ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Fly Ash Concrete ◽  
Worldwide Production ◽  
High Volume Fly Ash ◽  
Green Solution

With worldwide production of fly ash approaching 800 million tonnes annually, increasing the amount of fly ash used in concrete will remove more material from the solid waste stream and reduce the amount ending up in landfills. However, most specifications limit the amount of cement replacement with fly ash to less than 25 or 30%. Concrete with fly ash replacement levels of at least 50% – referred to as high-volume fly ash (HVFA) concrete – offers a potential green solution. The following study investigated the structural performance of HVFA concrete compared to conventional portland-cement concrete. Specifically, the research examined both the bond strength of reinforcing steel in HVFA concrete as well as the shear behavior of HVFA reinforced concrete. The results indicate that HVFA concrete performs as well or better than conventional portland-cement concrete.

Study on Chloride Penetration Resistance of High Volume Slag Powder Concrete

2014 ◽  
Vol 584-586 ◽  
pp. 1005-1010
Author(s):  
Hong Xia Ding ◽  
Chun Tao Wang ◽  
Bin Ge ◽  
Yun Sheng Li
Keyword(s):  
Portland Cement ◽  
Chloride Ion ◽  
High Volume ◽  
Penetration Resistance ◽  
Chloride Penetration ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Slag Powder ◽  
Chloride Penetration Resistance ◽  
Electric Flux

The influences of Portland cement substituted by slag powder in a high proportion (50% and 70%) on the chloride penetration resistance of concrete were studied. The results show that: the penetrability of Portland cement concrete reduced by one grade if 0.5% water reducer is added, but the water binder ratio is not the decisive factor for the permeability. There is a negative correlation between 6h electric flux and compressive strength only when concrete with same cementing materials. High volume slag powder concrete has excellent resistance to chloride ion permeability, which declines further with the increment of slag powder quantity added, the permeability coefficient of the concrete with 50% and 70% content of slag powder is as low as 27.8%~32.3% that of Portland cement concrete.

Development of a Capacitor Probe to Detect Subsurface Deterioration in Concrete

1997 ◽  
Vol 503 ◽  
Author(s):  
B. K. Diefenderfer ◽  
I. L. Al-Qadi ◽  
J. J. Yoho ◽  
S. M. Riad ◽  
A. Loulizi
Keyword(s):  
Dielectric Constant ◽  
Portland Cement ◽  
Electromagnetic Waves ◽  
Low Cost ◽  
Complex Dielectric Constant ◽  
Life Cycle Costs ◽  
Parallel Plates ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Set Up

ABSTRACTPortland cement concrete (PCC) structures deteriorate with age and need to be maintained or replaced. Early detection of deterioration in PCC (e.g., alkali-silica reaction, freeze/thaw damage, or chloride presence) can lead to significant reductions in maintenance costs. However, it is often too late to perform low-cost preventative maintenance by the time deterioration becomes evident. By developing techniques that would enable civil engineers to evaluate PCC structures and detect deterioration at early stages (without causing further damage), optimization of life-cycle costs of the constructed facility and minimization of disturbance to the facility users can be achieved.Nondestructive evaluation (NDE) methods are potentially one of the most useful techniques ever developed for assessing constructed facilities. They are noninvasive and can be performed rapidly. Portland cement concrete can be nondestructively evaluated by electrically characterizing its complex dielectric constant. The real part of the dielectric constant depicts the velocity of electromagnetic waves in PCC. The imaginary part, termed the “loss factor,” describes the conductivity of PCC and the attenuation of electromagnetic waves.Dielectric properties of PCC have been investigated in a laboratory setting using a parallel plate capacitor operating in the frequency range of 0.1 to 40.1MIHz. This capacitor set-up consists of two horizontal-parallel plates with an adjustable separation for insertion of a dielectric specimen (PCC). While useful in research, this approach is not practical for field implementation. A new capacitor probe has been developed which consists of two plates, located within the same horizontal plane, for placement upon the specimen to be tested. Preliminary results show that this technique is feasible and results are promising; further testing and evaluation is currently underway.

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