NCAB Decisions 2007
Decisions of the National Coal Ash Board (NCAB) 11/2007
At a meeting of the National Coal Ash Board held on November 22, 2007, it was decided to continue to promote research and development on the following subject:
- Environment – Fixation of radioactive waste with fly ash.
Details of the decision follow:
|Fixation of radioactive waste||A probe study under the supervision of Prof. Haim Cohen in the Ariel University Center to explore the possibility of exploiting the properties of fly ash as Pozzolan and filler for the fixation of radioactive waste, at low and medium radioactive levels, in solidified bodies.
Brief description of the work
Prof. Haim Cohen has been involved for many years in the development of the uses of fly ash as a neutralizing and fixating reagent for hazardous industrial sludge, based on the unique properties of the ash (alkaline reaction, large surface area, efficient adsorption properties). The objective of the development is to save on the high cost of treating these wastes using conventional methods (until now about $1,000 per ton sludge). The by-product of the fixation should meet the maximum concentration demands for leachates into the environment, and can be exploited, thanks to the ash properties, as a partial substitute for sand in concrete mixes.
Decisions of the National Coal Ash Board (NCAB) 09/2007
The meeting of the National Coal Ash Board held on September 6, 2007 resolved to continue to advance and promote research and development in the following areas:
- Agriculture – Lime- and fly-ash-stabilized sewage sludge for agricultural use
- Agriculture – Cultivating crops on a bottom-ash growth medium
- Environment – Characterization and definition of fly ash in accordance with accepted dust standards.
Details of the decision follow:
|Lime- and fly-ash-stabilized sewage sludge for agricultural use||An ongoing study to complete the licensing of sewage sludge stabilized with lime and fly ash and its application in field observations, to be carried out by Dr. Pinhas Fine and his colleagues of the Soil, Water and Environmental Sciences Institute, Agricultural Research Organization, Volcani Research Center.
The study will be carried out in the context of preparation for the operation of an experimental facility to manufacture lime- and fly-ash-stabilized sludge using the American N-Viro method in the Shafdan Water Reclamation Plant. In this context, the testing for pollutant trace elements in plants grown in soil enriched with lime- and fly-ash-stabilized sludge will be completed, and multi-annual field observations based on the conclusions drawn from the initial study carried out at the Volcani Research Center and in a number of agricultural plots will be begun.
|Raising crops on a bottom-ash growth medium||Field studies in the context of the increased exposure of farmers to the possibility of using bottom ash as a high-quality growth medium for crops.
In the Jordan Valley Research and Development Center – A multi-annual comparative experiment involving the raising of peppers on various growth media (ash, perlite, tuff) in various types of receptacles (sleeves, containers), further to the initial experiment, which pointed to a possible advantage to the use of sleeves over containers, and a certain advantage to the use of coal ash over other growth media.
In the Arava Research and Development Center -A comparative experiment involving the cultivation of peppers in a model farm involving different growth media (ash, perlite, tuff) in order to optimize savings and the more effective use of local saline water and fertilizers, under conditions of deficiency and sand to cover new agricultural areas.
In the Ein Shemer ecological hothouse – A comparative experiment involving the cultivation of anemones on ash and tuff growth media. The experiment is being carried out as part of the matriculation studies by students studying in the biology tracks in the high schools in the Hefer Valley area, under the supervision of counselors provided by the counseling services of the Ministry of Agriculture.
|Characterization and definition of fly ash in accordance with dust standards||The monitoring of fly ash by Teva and the analysis of free crystalline silica in dust samples in a specialized laboratory in the United States.
Fly ash is defined in Israel as “hazardous dust” due to its free crystalline silica (quartz) content. Based on studies carried out throughout the world, fly ash dust may be defined as nuisance dust or as unclassified particles. The fly ash will be monitored in order to examine the possibility of defining fly ash in Israel as harmless dust, in accordance with the accepted practice in the rest of the world.
Decisions of the National Coal Ash Board (NCAB) 05/2007
It was decided at the meeting of the National Coal Ash Board held on May 3, 2007 to continue to advance and promote research and development in the following areas:
- Construction – High volume fly-ash concrete.
- Environment – Infiltration of water in fly ash road embankments over time
These are the resolutions that were passed:
|High volume fly-ash concrete||A critical review of the research literature and documentation on the development of high volume fly ash concrete, carried out by researchers at the National Institute for the Research of Construction at the Technion.
Brief overview of the work
High proportions of coal ash in construction concrete were first introduced in the 1980s. Studies carried out in different places in the world clearly show that concrete that contains a high proportion of coal ash with certain properties excels in many aspects, both in its especially high compressive strength as well as in the prevention of the penetration of chlorides, enabling the replacement of a large proportion of the cement. This development is bolstered by the world trend in favor of penalizing industrial processes that cause CO2 emissions, raising the cost of cement and creating a business incentive to increase the proportion of fly ash as an alternative to the use of cement in concrete.
The goal of the critical literature survey is to prepare the knowledge base for research and to focus on the environmental conditions and raw materials in Israel. Based on the literature survey, a series of preliminary tests will be carried out to formulate detailed research questions and tests.
|The permeability of the road embankment to water||The double ring infiltrometer method is used to define the rate of hydraulic conductivity reduction over time of fly ash layer, exposed to the atmosphere, that used as structural filling in road paving.
Brief description of study
The environmental conditions for the use of fly ash in the paving of roads and similar uses have been determined assuming that the maximum mass of pollutants in the ash is leaching from the ash embankment, immediate passage through the ground and accumulation in the groundwater at the full quantitative potential of the ash found in the embankment. These assumptions, according to all of the experts, are manifestly unreasonable. However, they are unavoidable in the state of current knowledge and the absence of an understanding of the processes that take place in the fly-ash embankment and soils.
The early tests on the Jasr-a-Zarka embankment indicate the tendency of a tightly compressed fly-ash embankment to become sealed over time to the passage of water through it. In order to establish these findings and assess the sealing rate of the fly-ash embankment, infiltration tests through the fly-ash embankment will be conducted over a number of years from the earliest stages of its construction. This study evaluates the effect of the environmental conditions on the permeability of the fly-ash embankment and therefore, the discharge of the pollutants from the fly-ash.
Decisions of the National Coal Ash Board (NCAB) 03/2007
It was decided at the meeting of the National Coal Ash Board held on March 8, 2007 to continue to advance and promote research and development on the following subject:
- Industry – Fine bottom ash as a partial alternative to sand and as a filler in asphalt.
These are the resolutions that were passed:
|Bottom ash as a partial alternative to sand and as a filler in asphalt||In the context of the uses of fine bottom ash, which is obtained after separating the coarse particles intended for agriculture, the possibility of exploiting it as a partial alternative to natural aggregate and filler in hot asphalt mixes is being investigated.
A preliminary study commissioned by the National Coal Ash Board, and carried out by Prof. Ilan Ishai in the Technion Transportation Research Institute, included standard indicative tests and Marshall test systems of hot asphalt mixtures containing a portion of fine bottom ash. The ash mixtures were compared to a standard mixture containing regular mineral aggregates. The study showed that the bottom ash mixtures were similar in their properties to the control mixture, and although they were slightly inferior for some of the parameters, they excelled in the strength values and increased the asphalt’s durability.
In order to make the transition to the practical stages in the engineering application, these findings must be verified by a more complex study, in which the results will be examined for a broader area of materials and levels of experimentation. An effort should be made to test the increase of the proportion of the coal ash in the mixture as an alternative package both for sand and as filler. This will be done with a view to measuring the cost effectiveness of the use of coal ash in concrete plants located far away from active quarries.
Decisions of the National Coal Ash Board (NCAB) 01/2007
At a meeting of the Coal Ash Board held on January 4, 2007, it was decided to continue to promote research and development on the following subjects:
- Agriculture – Bottom ash as litter for chickens and to absorb contaminants in chicken droppings
- Infrastructures – Engineering/environmental specifications for the stabilization of dirt roads using bottom ash
- Environment – Content of natural radioactive elements in advanced concretes
These are the resolutions that were passed:
|Bottom ash used as litter for chickens and litter floors for laying hens||Field experiments in commercial chicken coops in Moledet and Bustan Hagalil
Brief description of experiments
Pursuant to the experiments carried out in the Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot and in a number of chicken coops, and based on the conclusions of these experiments, two experiments with different applications will be carried out: litter for heavy breeders in Moledet and contaminant-absorbent litter floors under the cages of light laying hens in Bustan Hagalil.
In a previous experiment carried out in Shavei Zion, certain problems came to light in the application of coal ash litter (initially dampness; dust later on), which were seen in the first half of the brooding period. The aim of the experiment in Moledet is to explore possible solutions to these problems. In the Bustan Hagalil experiment, evaluations for the environmental potential embodied in coal ash to prevent soil and groundwater pollution from hen droppings, which were seen in a limited previous experiment, will be corroborated.
|Engineering/ environmental specifications for the stabilization of dirt roads using bottom ash||The addition of an appropriate chapter in general binding specifications in applications using coal ash in infrastructures.
Brief description of work
Interest in the use of bottom ash as an aggregate in coal ash mixtures to stabilize dirt roads has been increasing. An examination of this application was done in the context of an experiment carried out in the Ayalon Park, in which a wide variety of mixtures composed of various materials was tested. The findings of the experiment pointed to a preference for the use of bottom ash.
As in all uses, specifications for environmental conditions should be prepared for this application too. Among other things, the specifications should ensure that the application of bottom ash using this technology on exposed paths and roads is conditional on the creation of tightly packed material that does not wear down to dust or scatter in the air.
|Content of natural radioactive elements in advanced concretes||A survey will be carried out to examine the radioactive content in common concretes made of local raw products, including coal ash, which represent the future of the concrete industry, based on the most recent construction standards.
Brief description of background of survey
The survey is intended to test the feasibility of the most recent version of IS 5098 – Content of Natural Radioactive Elements in Construction Materials. In accordance with the changes that have taken place in the construction industry in Israel, the survey will reflect concrete mixtures containing raw materials relatively rich in radioactive elements: gravel from the main dolomite quarries located in centers of principal demand in Israel; Rotem sand, which represents the most significant local alternative to traditional dune sand; cement manufactured from a broader basket of materials than in the past; coal ash as an alternative to both sand and cement.