Diagnosis and Control of Alkali-Aggregate Reactions in Concrete
Aggregates containing certain constituents can react with alkali hydroxides in concrete. The reactivity is potentially harmful only when it produces significant expansion.(1)** This alkali-aggregate reactivity (AAR) has two forms—alkali-silica reaction (ASR) and alkali-carbonate reaction (ACR, sometimes called alkali-carbonate rock reaction, or ACRR). ASR is of more concern than ACR because the occurrence of aggregates containing reactive silica minerals is more common. Alkali-reactive carbonate aggregates have a specific composition that is not very common. Alkali-silica reactivity has been recognized as a potential source of distress in concrete since the late 1930s.(2,3) Even though potentially reactive aggregates exist throughout North America, ASR distress in structural concrete is not common. There are a number of reasons for this:
Recycling wind turbine blade composite material as aggregate in concrete
............................................................................................................................. v CHAPTER 1: INTRODUCTION ............................................................................................. 1 1.1 Literature Review ........................................................................................................ 3 CHAPTER 2: EXPERIMENTATION ..................................................................................... 9 2.1 Methodology ................................................................................................................ 9 2.2 Phase 1 ....................................................................................................................... 13 2.3 Phase 2 ....................................................................................................................... 15 2.4 Results ....................................................................................................................... 17 2.5 Discussion .................................................................................................................. 23 CHAPTER 3: ECONOMIC ANALYSIS ............................................................................... 33 3.1 Assumptions .............................................................................................................. 34 3.2 Cost avoidance for sending wind turbines to landfill ................................................ 35 3.3 Cost avoidance for obtaining limestone course aggregate ........................................ 36 3.4 Cost avoidance for transporting aggregate ................................................................ 37 Cost of producing composite aggregate from wind turbines ........................................... 38 CHAPTER 4: ENVIRONMENTAL IMPACT ...................................................................... 40 4.1 Recycling vs landfilling vs incineration of composite material ................................ 40 4.2 Life Cycle Analysis ................................................................................................... 41
Novel method for the determination of the methoxyl content in lignin by headspace gas chromatography.
The paper reports on a headspace gas chromatographic (HS-GC) method for the determination of methoxyl in lignin. The method involves the quantitive cleavage of methoxyl with hydroiodic acid (HI) to form methyl iodide in a closed headspace sample vial at 130 °C for 30 min. After HI has been added, the sample is neutralized by injecting a sodium hydroxide solution; the methyl iodide in the vial was determined by HS-GC using a flame ionization detector. The results showed that the method has an excellent measurement precision (RSD < 0.69%) and accuracy (RSD < 3.5%) for the quantification of methoxyl content in lignin. The present method is simple and accurate and can be used for the efficient determination of methoxy1 content in lignin and related materials.