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Svnopsis:--This paper presents information on the leachability of trace metal elements from a number of fly ashes from Canadian and the U.S. sources, and from the concrete incorporating the fly ashes. The concentrations of all regulated elements Ag, As, B, Ba, Cd, Cr, Cu, Hg, Pb, and Se in the leachates from the nine fly ashes tested were within the limits of the United States Environment Protection Agency and the Transportation of Dangerous Goods Act Regulations of Canada. The leaching of As, B, Ni, and Se from the fly ashes appeared to increase with an increase in their content in the fly ash; however, there were some exceptions. In general, the concentration of As leached from the fly ashes derived from the bituminous coals was much higher than that from the lignite or sub-bituminous coals. Regardless of the type and percentage of the fly ash used, w/cm of the concrete, and curing condition, none of the trace metals in the leachates from the fly ash concrete samples exceeded the regulated concentration limits by the United States Environment Protection Agency and the Transportation of Dangerous Goods Act regulations of Canada. The concrete incorporating the fly ashes is, therefore, considered environmentally stable.

The Japan Industrial Standard (JIS) of “Fly Ash for Use in Concrete, JIS A 620 1 ” was revised in 1999 in order to widen the utilizable amount of fly ash as a mineral admixture. The featured points in this revision were that; [l] fly ash with high loss on ignition (LOI) ranging from 5.0% to 8.0% is specified as Class-III, [2] fly ash with low Blaine fineness ranging from 15OOcm’/g to 2500cm’ig is specified as Class-IV, [3] high quality fly ash with LO1 less than 3.0% and Blaine fineness more than 5000cm2/g was specified as Class-I. Most of the fly ash qualified in JIS A 6201-1996 would be specified as Class-II. Class-III and Class-IV fly ash wouldn’t meet the requirement of JIS A 6201-1996. This paper describes the background and the contents of the revision of JIS A 6201.

In the process of a long-term study of fine cementless mortar from wastes of thermal power plants (TPP) and other industries, aspects of its tech-nology were determined which were as follows: power 1. Processing slag (also known as bottom plant to sand of 0 to 5 mm size fraction. ash) from the Abakan thermal 2. Grinding fly ash to a fineness of 700 to 750 m2/kg with the use of mechanochemical activation process. 3. Using two - stage thermal treatment of cementless mortar mixture and determining optimal regimes for secondary thermal treatment. 4. Using a model method for concrete development. The application of cementless ash slag mortars non- load - bearing concrete profitability respectively. to load - bearing and

This paper describes the process technology of the production of rice husk ash (RHA) as a supplementary cementing material. The incinerating tests of rice husks were carried out by changing the temperature and duration of incineration using a rotary kiln. From the incineration tests, it was concluded that the incinerating temperature should be lower than 550°C to obtain RHA with specific surface area larger than 50 m2/g, and the duration of incineration should be long enough to obtain RHA with ignition loss less than 3%. Based on the incineration test results with the rotary kiln, a new stirring type furnace is introduced in the present paper for the production of RHA with large specific surface area. An applicability of the stirring furnace is examined by changing the feeding rate of rice husks and rotation speed of stirrer. The RHA having specific surface area larger than 50 m2/g and ignition loss less than 3%, can be produced using the new stirring furnace at a temperature below than 5 0 0C. Using this high specific surface RHA, strength development properties of mortar were examined and compared to the mortar incorporating a lower specific surface RHA and silica fume. The compressive strength of mortar incorporating the high specific surface RHA was increased remarkably, and was higher than that of the lower specific surface RHA and silica fume. Furthermore, unlike other pozzolanic materials, mortar incorporating the higher specific surface RHA showed excellent early strength development.

This paper reports the results of an investigation of the sorptivity of mortar that contains varying amounts of ground brick from different European bricks. Waste clay brick deriving from four European countries was ground to roughly cement fineness and used to partially replace cement in quantities of 0, 10, 20 and 30% in mortars. The sorptivity and water absorption of these mortars were tested for curing periods of up to one year. The presence of ground brick does not have a significant effect on the water absorption of mortar. Sorptivity however, is affected considerably by not only the presence of ground brick but also by brick composition. Initially, the presence of ground brick in mortar increases its sorptivity. As curing periods increase, the sorptivity values for ground brick mortars decrease at a rate that is greater than that seen in mortars whose binder is 100% portland cement. This indicates that the ground brick decreases the capillarity of the mortar and this is attributed to the production of additional C-S-H gel. The additional C-S-H gel, in effect, refines the pore structure of the mortar and this is reflected in the increase in the compressive strength obtained for these mixes.