Utilization of Biomass to Ash: An Overview of the Potential Resources for Alternative Energy.

Climate change and the potential depletion of fossil fuels have increased international demand for alternative and renewable energy sources. In terms of the energy sector, for example, most of the South-East Asian countries (SACs) have a large number of biomass sources due to their vast forest resources and agriculture-based economies. Thus, the critical review was aimed at highlighting the overview of biomass energy in South-East Asia as a dynamically developing region, in order to obtain economic and environmental benefits from the existing sources of biomass in the world. The current review analyzed the sources of biomass, as well as their energy potential, use, and management, based on reports from different countries, published studies, and scientific articles. In SAC, the main sources of biomass were found to be coconut residues, oil palm residues, sugar cane residues, rice straw, rice husks, wood waste, and firewood. The combined annual biomass potentials in the forestry and agricultural sectors in South-East Asia were approximately over 500 million tons per year and more than 8 gigajoule of total energy potentials. The study identified the challenges and barriers to using biomass in these countries to achieve sustainable use of biomass sources and recommended sustainable approaches to using biomass energy by comparing traditional uses of biomass. Smart grid technologies have ways for solutions for better electric power production and efficient ways for distribution and transmission of electricity. Smart grids require less space and can be more easily installed when compared to traditional grids because of their versatilities. Upcoming challenges include technology optimization for the following uses of biomass energy: direct combustion of woody biomass; pyrolysis and gasification of biomass; anaerobic digestion of organic waste to produce biogas; landfill gas production direct incineration of organic waste. The barriers in this technology are emissions of carbon and nitrogen oxides, unpleasant odors, as well as the uncontrolled harvesting of biomass, which can harm nature.

Influence of Ground Calcium Carbonate Waste on the Properties of Green Self-Consolidating Concrete Prepared by Low-Quality Bagasse Ash and Rice Husk Ash.

Bagasse ash (BA) and rice husk ash (RHA) are by-products from electricity power plants. Ground calcium carbonate waste (GCW) is the by-product of the mining of calcium carbonate (CaCO3) in the color pigment manufacturing industry. Both BA and RHA are classified as low-quality pozzolanic materials, differing from GCW, which contains a high calcium oxide (CaO) content that leads to products equivalent to the hydration reaction. Therefore, GCW is likely able to improve the properties of self-consolidating concrete (SCC) incorporating BA and RHA. This paper discusses the production of green self-consolidating concrete (gSCC) and identifies the benefit of using GCW in gSCC prepared by triple combined GCW (10 and 20 wt%), BA (10, 20, and 30 wt%), and RHA (20 wt%). The results indicate that the majority of the gSCC retain acceptable flowability. The differences in the levels of gSCC substitution and the V-funnel flow results show general correlations with the increase in GCW. The gSCC prepared by 10 wt% GCW associated with 10 wt% BA and 20 wt% RHA was improved significantly. The filling and passing abilities of the gSCC were improved by using GCW. In addition, gSCC achieved mechanical property development and was able to minimize the consumption of OPC by up to 40%.

Cost-benefit analysis of the production of ready-mixed high-performance concrete made with recycled concrete aggregate: A case study in Thailand.

In the current green concrete structures, recycled concrete aggregate is used as recycled concrete waste. In this process, concrete waste is collected and crushed using a recycling procedure in order to produce crushed concrete which is then used in structural concrete where it replaces natural aggregate which is coarse. The recycled aggregate concrete is a sustainable concrete waste which in the long term can replace the demand for natural aggregate, a process which would, in turn, lead to its preservation. However, most concrete industries have been observed to be reluctant in the production of recycled aggregate concrete and utilization in its maximum potential. Industries are yet to embrace it not only due to its uncertain material performance but also due to its unexplored manufacturing plant operations which are yet to be established. This research aims to use of a cost-benefit analysis model of the production of ready-mixed high-performance concrete made with recycled concrete aggregate in Thailand. The model focuses on the evaluation of the financial effects which favor the recycled aggregate concrete manufacturing operations instead of the ordinary concrete. Research findings indicate that regardless of the manufacturing plant used, the price of recycled concrete aggregate cannot decrease below the price of natural aggregate concrete. The key result of this research is that recycled concrete aggregate manufacturing set-ups can be used in the industrial-scale manufacture of recycled concrete and at low prices. In addition, overhead bin type and front-end loader type of plants can be used to lower the incremental costs of recycled concrete aggregate. However, the demand and supply factors and the pricing effects of recycled concrete pose various difficulties which are hardly accounted for.

Production of high-early-compressive-strength Portland cement paste using low-pressure microwave-accelerated heating and curing: processing characteristics and factors affected.

The use of low-pressure microwave (MW)-accelerated heating and curing in the production of high-early-strength Portland cement paste (CP) in relation to the processing characteristics and factors affected is investigated. The effects of the pressure in the MW cavity, the feed direction of the MW, and the number of CP specimens per MW curing batch on the temperature increase and moisture content (i.e., the water-cement ratio (w/c)) of the CP and its compressive strength after MW-curing CP are considered. A double-feed MW-vacuum system is used to generate MW by applying 800 W (1 magnetron) or 1,600 W (2 magnetrons) and to convey MW to the CP specimens. The CP pastes are designed and mixed at specific initial w/c ratios of 0.25, 0.35, and 0.45. The CP specimens are cured using a low-pressure MW cavity at 30 and 50 kPa and fed in symmetrically or asymmetrically perpendicular directions of the CP specimens in batches of 12 (3.95% of the volume of microwave cavity) and 24 specimens (7.90% of the volume of the microwave cavity) per MW-curing batch with the following dimensions: 5 cm long × 5 cm wide × 10 cm thick. The experimental results show that with the maximum MW curing temperature of 70 °C from the initial stage (approximately the first 30 min of applying low-pressure MW curing) until 100 min, the temperature of the CP increases continuously at a high rate; then, the rate at which the temperature increases decreases slightly, which is consistent with the remaining w/c of the CP. The pressure in the MW has a slightly different temperature increase and remaining CP. A perpendicular symmetric magnetron placement in respect to the horizontal position of the specimens can lead to a steady increase in the strength development of all the CP specimens. Further, over the course of 28 days, compared with the water-cured CP, the MW-cured CP develops more compressive strength.

Use of limestone powder during incorporation of Pb-containing cathode ray tube waste in self-compacting concrete.

For several decades, cathode ray tubes (CRTs) were the primary display component of televisions and computers. The CRT glass envelope contains sufficient levels of lead oxide (PbO) to be considered hazardous, and there is a need for effective methods of permanently encapsulating this material during waste disposal. We examined the effect of adding limestone powder (LS) on the fresh and cured properties of self-compacting concrete (SCC) mixtures containing waste CRT glass. The SCC mixtures were prepared using Type 1 Portland cement at a constant cement content of 600 kg/m(3) and a water-to-cement ratio (w/c) of 0.38. CRT glass waste cullet was blended with river sand in proportions of 20 or 40% by weight. To suppress potential viscosity effects limestone powder was added at levels of 5, 10, or 15% by weight. The slump flow time, slump flow diameter, V-funnel flow time, Marsh cone flow time, and setting time of the fresh concrete were tested, as well as the compressive strength and ultrasonic pulse velocity of the hardened concrete. Addition of limestone powder improved the fresh and hardened properties. Pb leaching levels from the cured concrete were within US EPA allowable limits.

Utilization of cathode ray tube waste: encapsulation of PbO-containing funnel glass in Portland cement clinker.

The disposal of cathode ray tube (CRT) generates large quantities of leaded glass waste. The encapsulation of glass from the funnel portion of CRT in cement clinker was investigated. Samples of cement raw material containing 0 (control), 0.1, 0.2, 0.3, 0.4, or 0.5 wt% of CRT funnel glass ground to less than 75 µm were heated to 1480 °C in an electric furnace for 1.5 h at a heating rate of 5 °C/min to produce cement clinker. The Pb encapsulation and chemical composition of the clinkers were analysed using X-ray techniques and atomic absorption spectroscopy (AAS). The maximum PbO encapsulation occurred in mixtures containing 0.1 wt% funnel glass.

Utilization of ground waste seashells in cement mortars for masonry and plastering.

In this research, four types of waste seashells, including short-necked clam, green mussel, oyster, and cockle, were investigated experimentally to develop a cement product for masonry and plastering. The parameters studied included water demand, setting time, compressive strength, drying shrinkage and thermal conductivity of the mortars. These properties were compared with those of a control mortar that was made of a conventional Portland cement. The main parameter of this study was the proportion of ground seashells used as cement replacement (5%, 10%, 15%, or 20% by weight). Incorporation of ground seashells resulted in reduced water demand and extended setting times of the mortars, which are advantages for rendering and plastering in hot climates. All mortars containing ground seashells yielded adequate strength, less shrinkage with drying and lower thermal conductivity compared to the conventional cement. The results indicate that ground seashells can be applied as a cement replacement in mortar mixes and may improve the workability of rendering and plastering mortar.