Current Search: Waste products as road materials (x)
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- Title
- Accelerated curing of concrete with high volume pozzolans - resistivity, diffusivity and compressive strength.
- Creator
- Liu, Yanbo., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
This investigation presents results of the temperature effect on durability properties (resistivity and diffusivity) and compressive strength of concrete with pozzolans, and the effect of pozzolanic admixtures on microstructure and chemical compositions of concrete pore solution. ... Temperature dependence of electrical resistivity and chloride diffusivity was studied by dynamic temperature tests. Accelerated curing regimes involving curing concrete specimens in 35À C lime water with...
Show moreThis investigation presents results of the temperature effect on durability properties (resistivity and diffusivity) and compressive strength of concrete with pozzolans, and the effect of pozzolanic admixtures on microstructure and chemical compositions of concrete pore solution. ... Temperature dependence of electrical resistivity and chloride diffusivity was studied by dynamic temperature tests. Accelerated curing regimes involving curing concrete specimens in 35À C lime water with different durations were tested. Compressive strength test, resisivity measurement and rapid chloride migration (RCM) tests were performed. A leaching method was used to measure pH and conductivity of concrete pore solution. ... The accelerated curing regimes were found to increase the compressive strength and resistance to chloride ion penetration at short-term and long-term. With the developed correlation between resistivity and migration coefficients, it is possible to employ the resistivity measurement as an alternative or replacement of the RCM test to evaluate resistance of chloride ion penetration of concrete. Pozzolanic admixtures were found to decrease both pH and conductivity of concrete pore solution as the replacement ratio increased. Moreover, the migration coefficients were found to be greatly correlated to the microstructure properties of concrete, such as porosity, formation factor and tortuosity.
Show less - Date Issued
- 2012
- PURL
- http://purl.flvc.org/FAU/3358603
- Subject Headings
- Pavements, Concrete, Additives, Quality control, Waste products as road materials, Reinforced concrete, Corrosion, Testing
- Format
- Document (PDF)
- Title
- Performance characteristics of coal fly ash and wood ash-modified asphalt binder.
- Creator
- Butul, Boris., Florida Atlantic University, Reddy, Dronnadula V.
- Abstract/Description
-
Coal fly ash and wood ash were added singly to asphalt mixes as partial replacements of the asphalt cement. Mechanical property testing and cost analysis were carried out with the following percentages: 0, 10, 15, 20, and 25. The objective of the investigation was to determine the changes in mechanical properties and cost-effectiveness of ash modification. The softening point, penetration, creep displacement, and modulus of elasticity indicated stiffening of the mix with increased ash...
Show moreCoal fly ash and wood ash were added singly to asphalt mixes as partial replacements of the asphalt cement. Mechanical property testing and cost analysis were carried out with the following percentages: 0, 10, 15, 20, and 25. The objective of the investigation was to determine the changes in mechanical properties and cost-effectiveness of ash modification. The softening point, penetration, creep displacement, and modulus of elasticity indicated stiffening of the mix with increased ash proportion. The indirect tensile and compression strengths reached peak values for the 10 and 15% mixes. The Marshall stability, the bulk density, and the maximum density, decreased with ash addition. The cost analysis indicated a saving of 6% for ash replacement of 15%. Therefore, the replacement of 10 to 15% of asphalt cement is an excellent solution to decrease the mix costs and to reduce the amount of ash in landfills without compromising the mechanical properties of the mix.
Show less - Date Issued
- 2000
- PURL
- http://purl.flvc.org/fcla/dt/12674
- Subject Headings
- Coal ash, Fly ash, Waste products as road materials, Asphalt cement--Additives
- Format
- Document (PDF)
- Title
- Durability of a recycled aggregate concrete base course material under coupled environmental exposure and cyclic.
- Creator
- Gonzalez, Lillian, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
- Abstract/Description
-
Long term durability is a major concern for wide-scale use of recycled aggregate materials in civil engineering construction. The purpose of this study is to provide an insight into the damaging effects of combined wet-dry cycles and repeated mechanical loading in a recycled aggregate concrete (RAC) base course material made from recycled crushed concrete aggregate and cement. A coordinated experimental program followed by a mechanistic pavement modeling and life cycle analysis was conducted...
Show moreLong term durability is a major concern for wide-scale use of recycled aggregate materials in civil engineering construction. The purpose of this study is to provide an insight into the damaging effects of combined wet-dry cycles and repeated mechanical loading in a recycled aggregate concrete (RAC) base course material made from recycled crushed concrete aggregate and cement. A coordinated experimental program followed by a mechanistic pavement modeling and life cycle analysis was conducted as part of this research study. This laboratory investigation was divided into three phases each consisting of both wet-dry exposed specimens (WD), and control or non wet-dry exposed specimens (NWD). Phase I experiments involved monotonic loading tests under compression and flexure to evaluate the strength properties. Phase II involved testing a total of 108 cylindrical specimens in cyclic compressive loading at three different stress ratios. After each regime of cyclic loading, residual compressive strengths were determined. In addition, the load-deformation hysteresis loops and the accumulated plastic deformation were continuously monitored through all loading cycles. Phase III included a flexural fatigue test program on 39 beam specimens, and fracture testing program on 6 notched beam specimens, each one having 19-mm initial notch. Traditional SR-N curves, relating the Stress Ratio (SR) with the number of cycles to failure (N or Nf), were developed. Fatigue crack growth rate and changes in Stress Intensity Factors were obtained to determine Paris Law constants and fracture toughness. A mechanistic analysis of a typical highway pavement incorporating RAC base was performed with KENPAVE program, followed by a Life Cycle Analysis (LCA) using the GaBi software. It was found that the specimens subjected to wet-dry cycles suffered significantly higher damage expressed in terms of accumulated plastic deformation, and loss of residual compressive strength, modulus, fatigue endurance limit, and design life, compared to specimens not exposed to wet-dry cycles. Although such degradation in material properties are important considerations in pavement design, a concurrent Life Cycle Analysis demonstrated that recycled aggregate concrete base course still holds promise as an alternative construction material from environmental stand point.
Show less - Date Issued
- 2014
- PURL
- http://purl.flvc.org/fau/fd/FA00004116, http://purl.flvc.org/fau/fd/FA00004116
- Subject Headings
- Aggregates (Building materials ) -- Recycling, Concrete -- Mechanical properties, Construction and demolition debris -- Recycling, Structural engineering, Sustainable construction, Waste products as road materials
- Format
- Document (PDF)