Answer: Fly ash is a by-product from coal fired electric power generating plants The inorganic or inderal constituents of the coal, such as clay, quartz and shale, fuse and chemically recombine during burning to produce various crystalline and glassyphases of fly ash. The fly ash is entrained in the flue gas and cools into spherical, usually hollow shaped particles.

Fly Ash is a pozzolan. A pozzolan is a siliceous and/ or siliceous and aluminous material which in itself is not cementitious but will, in the presence of moisture and temperature > 40°F (> 5C), combine with calcium hydroxide to form cementitious compounds. The major use of fly ash is as a partial replacement for cement in concrete. The amount of cement replaced depends on the fly ash type, the fly ash quality, the application and the atmospheric conditions.

Answer: This is not true. In-fact the advantages of addition of fly ash are many, a few of which are listed below:

Fly ash is produced through the combustion of coal used to generate electricity. After coal is pulverized, it enters a boiler where flame temperatures reach up to 1500 degrees Celsius. Upon cooling, the inorganic matter transforms from a vapor state to a liquid and solid state. During this process individual, spherical particles are formed. This is fly ash. It is then collected by either using electrostatic precipitators, baghouses or a combination of both.

Typically, concrete designers use fly ash a partial replacement for portland cement at values up to 30 percent of the total cementitious composition. The use of high percentages (high volumes) of fly ash in concrete have been studied extensively over the last 15 years and the benefits have been well documented.

Fly ash is classified by the EPA as a non-hazardous product. As indicated by the MSDS, it is a relatively inert material. Fly ash is a product of coal combustion thus possesses no significant risk of fire or explosion. Fly ash is similar to sand in composition and consistency. When transporting and handling fly ash, the recommended precautions for safe handling as outlined on the product MSDS should be followed.

The impact of fly ash on air entraining admixture (AEA) is primarily due to the carbon, represented as loss-on-ignition (LOI), remaining in the fly ash after combustion of the coal fuel. Due to the high rate of absorption of surfactants such as air entrainment into carbon, the loss-on-ignition generally has a positive correlation with AEA dosage demand.

By reacting with free lime to form additional binder material, the permeability of concrete made with fly ash is lower than that made without it. Since virtually all durability aspects of concrete are improved with a reduction in permeability, the use of fly ash improves concrete durability. In addition, concrete water demand is typically reduced when using fly ash, leading to a lower water/cementitious ratio thus increasing strength.

Fly ash, particularly Class C, can effectively be used to stabilize soil for various types of construction. High calcium fly ash (Class C) acts as a good source of calcium hydroxide which "self activates", reacting with silica and alumina in the fly ash and soil to form a cementitious hydration product. In addition, C3A in fly ash (Class C) can react with sulfates to gain strength relatively quickly.

The primary difference between Class C and Class F fly ash is the chemical composition of the ash itself. While Class F fly ash is highly pozzolanic, meaning that it reacts with excess lime generated in the hydration of portland cement, Class C fly ash is pozzolanic and also can be self cementing. ASTM C618 requires that Class F fly ash contain at least 70% pozzolanic compounds (silica oxide, alumina oxide, and iron oxide), while Class C fly ashes have between 50% and 70% of these compounds.

For mix design purposes, fly ash itself should be considered like portland cement, except that the specific gravity for fly ash is different. The specific gravity of portland cement is typically 3.15, while the specific gravity of fly ash may range from 2.2 to 2.8, depending on fly ash composition. Therefore, if a certain percentage of cement is replaced with fly ash on a mass basis, simply multiply the initial portland cement quantity by the percent replacement.

The use of fly ash in concrete improves the environment in a variety of ways. By using fly ash as a partial replacement for portland cement, the production of carbon dioxide emissions is reduced. Every ton of portland cement produced creates approximately one ton of carbon dioxide emissions. Therefore, the use of 20 percent fly ash in a structure containing 500 cubic yards of concrete would reduce CO2 emissions by approximately 25 tons.

Sometimes. The primary ingredient in the chemical reaction needed for autoclaved aerated concrete production is silica. The silica and other raw materials combine to form Tobermorite, a manmade version of a naturally occurring mineral. This gives AAC its unique strength-producing crystalline structure. Silica is found in many sources, such as sand, copper mine tailings, volcanic ash, and fly ash.

Answer: Emerald ash borer, Agrilus planipennis, is an exotic, invasive beetle that belongs to the metallic wood-borer family (Buprestidae). It infests and destroys native North American ash trees.

Answer: Go to Link to access an Ohio State University Extension fact sheet that will help you identify ash trees.

Answer: Members of the OSU Extension Nursery, Landscape, and Turf Team have developed the following recommendation regarding the use of insecticides for controlling EAB in Ohio: "Ash trees within Ohio Department of Agriculture?s EAB quarantine, as well as those outside the quarantine but within the vicinity (i.e. 10-15 miles) of a known infestation, are considered to be at risk. Annual insecticide treatments should be considered by those in these areas who want to try to protect their ash trees.

Answer: Common signs of infestation include D-shaped exit holes through the bark about one-eighth of an inch wide, S-shaped larval galleries just beneath the bark, thinning canopy, vertical splits in the bark, and unusual shoots sprouting from the main trunk or base of the tree. To see pictures of these symptoms, go to Link.

Answer: First, take a look at the diagnostic check-off list available on this Web site at Link. If you find enough evidence of infestation, call the Ohio Department of Agriculture?s emerald ash borer hotline, (888) OHIO-EAB.

Answer: Ohio State University researchers are studying Asian trees ? in particular Manchurian ash, Fraxinus mandshurica ? as a possible source of resistance genes against emerald ash borer. For more information about this research, go to Link. Answer: Emerald ash borer has natural enemies: fungi, bacteria, parasitic wasps and woodpeckers, for example. But so far those enemies aren?t knocking them back.