Current Search: Aggregates Building materials -- Recycling (x)
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(1 - 2 of 2)
- Title
- An Experimental Evaluation of High Volume Fly Ash Structural Concrete made from Recycled Aggregate.
- Creator
- Theodorou, Anthony Lloyd, Sobhan, Khaled, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
- Abstract/Description
-
Three vital factors, namely environmental protection, savings in costs, and strength/durability benefits, make it advantageous to incorporate fly ash of controlled quality and composition in all concrete made from construction demolition (C&D) recycled aggregate. The specific objective of this research was to compare the performance characteristics of High-Volume-Fly-Ash (HVFA) structural concrete containing C&D aggregate with that of normal recycled aggregate concrete containing no fly ash....
Show moreThree vital factors, namely environmental protection, savings in costs, and strength/durability benefits, make it advantageous to incorporate fly ash of controlled quality and composition in all concrete made from construction demolition (C&D) recycled aggregate. The specific objective of this research was to compare the performance characteristics of High-Volume-Fly-Ash (HVFA) structural concrete containing C&D aggregate with that of normal recycled aggregate concrete containing no fly ash. A coordinated experimental program was undertaken which comprised of ( 1) Compressive and Split Tensile strength tests; (2) ASTM durability tests by measuring resistance to chloride-ion penetration; and (3) Flexural strength tests on reinforced concrete beam specimens. Three mix designs were used, all of which had the same water/cement ratio of 0.45 and the same amount of recycled aggregate/yd^3. Mix 1 contained cement and no fly ash, Mix 2 contained 16% replacement of cement by weight, and Mix 3 contained 40% replacement of cement, called a HVF A mix. Results indicate that fly ash increases compressive strength, improves both moment carrying capacity and tension resistance, and increases resistance to chloride-ion attack.
Show less - Date Issued
- 2008
- PURL
- http://purl.flvc.org/fau/fd/FA00012563
- Subject Headings
- Aggregates (Building materials)--Recycling, Fly ash--Recycling, Concrete--Additives--Evaluation, Concrete--Permeability, Industrial minerals--Evaluation
- 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)
