News

NCAB Decisions 2008

11/2008 | 09/2008 | 07/2008 | 03/2008

Decisions of the National Coal Ash Board (NCAB) 11/2008

At a meeting of the National Coal Ash Board held in November 2008, it was decided to continue to promote research and development on the following subjects:

  • Agriculture – Cherry tomatoes on a coal ash growth medium as compared to other growth media
  • Environment – Environmental criteria for fly ash in infrastructures
  • Infrastructures – Geographic records (GIS) of projects

These are the resolutions that were passed:

Cherry tomatoes on a coal ash growth medium compared to other growth media: Comparative observations of the cherry tomatoes raised on coal ash growth medium contrasted with those grown on tuff and perlite growth media.
 
Brief description
Plants are raised on artificial growth media in order to be able to provide their roots with an optimal balance of air and water, enhance the effectiveness of irrigation and fertilization regimes, improve the resistance of the plant to soil diseases and provide better and higher quality yields than those obtained using natural soil.In the context of the activities taken to expand the use of bottom ash technology for the growth media of crops, the use of Matza’it (a mixture of bottom ash sorted to a compatible size mixed with compost) was used in the feeding ditches in the context of a comparison with the most common other growth media (tuff in ditches and perlite in sleeves) and with the local sand.
Transition coefficients for pollutant values from the extraction of granular to monolithic ash Determining the transition coefficients from pollutant concentrations obtained from the examination of dry fly ash leachates to findings obtained in moistened ash leachates, compacted into a monolithic structure.
 
Brief description
From an environmental perspective, the behavior of fly ash that is applied as moistened (conditioned) filler compacted in road embankments and infrastructures is that of an inert monolith, in terms of the criteria posed by the European standards. Consequently, the environmental criterion for the use of fly ash in infrastructures should be based on the concentration of pollutants obtained in leachates using the monolith (solid matter) test method.The aim of this study is to produce a list of maximum values for fly ash leachates designated for use as fillers in infrastructure constructions, based on the transition coefficients from the laboratory test findings on granular ash leachates, which is the simplest method to perform such tests on an ongoing basis, to the tests of the monolithic ash leachates, which represents the engineering state in the infrastructure construction. This list of values can serve as a tool to monitor the applications of fly ash in infrastructures.
Geographic documentation of ash in infrastructures A geographic mapping (GIS – Geographic Information System) of all projects involving paving and infrastructure in which coal ash is used.
 
Brief description
Coal ash is used as a filler in infrastructure projects of varying scales, from very large projects involving hundreds of tons, to much smaller ones of just a few hundred tons. The application of the ash in these projects is conducted in the context of permits that are issued subject to the environmental conditions determined for the different applications.The National Coal Ash Board (NCAB) is required to maintain geographical records of all projects in which coal ash is applied as a paving and filler substance in infrastructures. It is especially important for the NCAB to document all the smaller projects, which cover a wide area, and to make sure that the permits for their implementation are provided in consideration of the geographic constraints determined for them.

Decisions of the National Coal Ash Board (NCAB) 09/2008

At a meeting of the National Coal Ash Board held in September 2008, it was decided to continue to promote research and development on the following subjects:

  • Agriculture – A coal ash medium on which to grow grapes for wine

These are the resolutions that were passed:

A coal ash medium on which to grow grapes for wine: Observations of the improvement of soil on which to raise grapes for wine in Sde Boker using a coal ash growth medium, compared with the local loess soil.
 
Brief description
Two types of grapes are grown in the Sde Boker vineyard – merlot and cabernet. The wine is produced in the Tishbi winery and is highly acclaimed both in Israel and abroad. However, the vines suffer due to the poor quality of the loess soil, reflected in low yields and high water costs.A nutrition growth medium based on sifted coarse bottom ash mixed with compost should improve the balance of air, water and fertilizer in the root area, contribute to the development of the vine, increase the yield and bring about more effective utilization of the water and fertilizer.

Decisions of the National Coal Ash Board (NCAB) 07/2008

At a meeting of the National Coal Ash Board held in July 2008, it was decided to continue to promote research and development on the following subjects:

  • Construction – Effectiveness of coal ash in concrete.

These are the resolutions that were passed:

Effectiveness of coal ash in concrete: An examination of the Pozzolan activity of ash from varied coal sources in the cement admixture, dependent on the type of cement.
 
Brief description
In the context of ongoing research at the Technion’s National Building Research Institute, tests are being conducted as to the effectiveness of coal ash as an alternative to cement, regarding its functioning, strength and durability (in terms of carbonation and permeability of chlorides). The aim of the research is to establish equivalent cement alternative coefficients in ash for concrete admixtures based on the most recent standards, in which quality demands (durability) are subordinate to environmental conditions and purpose.A comparative analysis of the study’s results shows that the effectiveness coefficients obtained in the admixtures of a one cycle of tests were consistently and considerably lower than for the other cycle, despite the fact that the ash used in that cycle was of a higher quality than in the other. The apparent reason for the reduced ash efficiency was the lower quality of the cement as a manipulator (as a trigger of hydration processes).

The test program will test this hypothesis against the effect of the quality of the cement on the function of the ash (coal) origin.

Decisions of the National Coal Ash Board (NCAB) 03/2008

At a meeting of the Coal Ash Board held on March 6, 2008, it was decided to continue to promote research and development on the following subjects:

  • Environment – Monitoring of the quality of runoff water from fly-ash road embankments

These are the resolutions that were passed:

Monitoring of the quality of runoff water from fly ash road embankments Assessment of concentrations of pollutant trace elements in rainwater leachates of fly ash in road embankment slopes, carried out by Dr. Meni Ben-Hur of the Soil, Water and Environmental Sciences Institute, Agricultural Research Organization, Volcani Research Center.
 
Brief description of work
Tests carried out on the fly ash embankment on the access road to the northern entrance to Jisr-el-Zarka, which was built ten years ago, show that after a relatively brief period of about two years, the surface of the coal ash becomes sealed due to the carbonization process that occurs when the coal ash comes in contact with the environment and is exposed to rainwater, which causes limestone to sediment in the cavities between the particles, to create a impermeable layer that does not allow infiltration of water.From this it may be concluded that the coal ash system in the road embankments has no active contact with the environment, with the exception of the coal ash surface on the embankment slopes. Although the concentrations of pollutants in the runoff leachates obtained from the interim surface situated between the coal ash and the natural layer of soil in the two years of monitoring did indicate low and decreasing values of pollutants over time, repeated observations are needed in order to conclusively establish these low values at negligible levels over time.