MXPA96005755A - Concrete and mortar resistant to sulphates and aci - Google Patents

Abstract

The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and volatile ash for use in construction and other applications, said hardenable mixtures show significant levels of sulfate and acid resistance while maintaining acceptable compressive strength properties; sulfide-resistant hardeners of the invention containing volatile ash comprise cementitious materials and a fine aggregate, the cementitious materials may comprise volatile ash as well as cement, the fine aggregate may comprise volatile ash as well as sand, the total amount of volatile ash in the hardenable mixture. it varies from about 60% to about 120% of the total amount of cement, ie, whether the volatile ash is included as a cementitious material, a fine aggregate or an additive or any combination of the above, in the specific examples , the mortar containing 50% ash vol til and 50% of cement in cementitious materials demostrópropiedades of higher corrosion resistance

Description

CONCRETE AND RESISTANT MORTARS THE SULFARTS AND ACIDS The invest _ < jac? ón that leads to the present mvencLÓn was directed with the collaboration of the Government under Contract No.DE-FG22-90PC_029. granted by the Department of Energy. The Government has certain rights over this invention.

FIELD OF Lft INVENTION The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and volatile ash for use in construction and other applications, said hardenable mixtures show significant levels of resistance to sulfates and acids while maintaining acceptable compressive strength properties.

BACKGROUND OF THE INVENTION Concrete Corrosion v Mortar caused by acid v Sulfate The concrete and the mixture contain hydroxyl or calcium (Ca (0H) a), which reacts easily with acids or sulfates to form ettringite. This results in reduced strength of the concrete and the mixture, which manifests itself in surface damage and eventually leads to complete structural deterioration. Nowhere are these problems as acute as in our cities, where buildings and roads deteriorate slowly under the onslaught of acid rain and other pollutants. Corrosion of conventional concrete due to chemical attack of both concrete and steel reinforcement costs a huge amount of money annually to repair and maintain the structures. The attack for his. Tato and acid are a major problem with the durability of concrete. For pH values between 3 and 6, acid attack progresses at a rate proportional to the square root of time (Neville, 1983, Properties of Concrete, 3rd Ed., Pitrnan Publishing Inc., London). In the concrete pipes in the sewer systems, severe damage is caused by the action of the Thiobacillus concrete vor bacteria. especially in hot climates. Sulfur-reducing bacteria reduce the sulfate present in natural water to produce hydrogen sulfide as a waste product. Another group of bacteria i reduced sulfur and oxidized it back to sulfuric acid (Thorton, 1978, ftCl 3, Procedures 75: 577-584). Therefore sulfuric acid attack occurs, dissolving and gradually deteriorating the concrete surfaces. This process is commonly referred to as "corona corrosion" in wastewater collector systems. In cement formulations, one way of minimizing the damage caused by acid or sulfate attack is to reduce the amount of C3ñ (tricalcium alkyl, 3Ca0.ftl_, 0a) present in the concrete. This frost-resistant cement is known as type V normal portland cement. Type V portland cement specifies a C3fi content not greater than 5%. Typically, however, the cost of port i and normal type V cement is higher than that of standard portland type I cement. Other strategies to increase the resistance of concrete to corrosion, such as polymer concrete, are also extremely expensive. Unfortunately, the expense,. Making acid-resistant concrete can outweigh the benefit of using such concrete. Another possible way to increase the resistance to acids is to introduce volcanic ash to the concrete or to the mortar. Nasser and Lai (1990, Proceedings of the First Material Enorneepna Conores, Denver, Colorado, pp.688-97) and Trassar and Batic (1989, Res. Of Concrete and Concrete 19: 194-202) reported that Class F volcanic ash It is a good supply of ozone, which can improve the concrete's resistance to sulphate attack. Data on the corrosion resistance of the monitored concrete samples for more than three years indicated that concrete samples with 20% cement replaced by volatile ash protected the reinforcing rods from corrosion better than simple concrete (Maslehuddin et al., 1987, ACI 3, Procedures 84: 42-50). The results of another study suggested that volatile ash with a finer particle size showed greater resistance to sulfate attack (Sheu et al., 1990, Svtnpos? Um z-oceeding, E_li? Osti _-__ d Cofll Conversion BV- Produces; C aractßrization. Ut.il i? At? On ¿_nd. DÍ.SPQ_a_ _LL, Soc. De Material Investigation 178: 159-166). However, studies reported to date have not clearly revealed the degree of corrosion resistance or indicated the exact characteristics of the cement or mortar containing volatile ash. In part, this is due to the use of generic volatile ash that tends to be of a "true" quality from one lot to another. Without determining these characteristics, it is impossible to form any definitive conclusion t the usefulness of the concrete or mortar, much less the risk using unpredictable materials on a construction project.

Volatile Ash Volatile ash, a by-product of coal-burning power plants, is produced worldwide in large quantities every year. In 1988, t 84 million tons of coal ash were produced in the U.S. in the form of volatile ash (60.7%), bottom ash (16.7%), slag heater (5.9%) and deeulfurization of flue gas (16.7%) (Tyson, 1990, Coa! Combus ion Bv-Product tttii. 7 * tior, Pitsburg, 15 pp.). Of the approximately 50 million tons of volatile ash produced annually, only t 10% is used in the _ncrete (Committee ftCI 226, 1987, "Use of Flv ftSh In Concrete." P.CI 226.3R-87 PCI 3. Procedures 84 : 381-409). The remaining portion is discarded mainly as waste in landfills. It is generally beneficial for a utility to sell the ashes, even at low or subsidized prices, than to dispose of it in a sanitary landfill. Sales not only generate certain income, but also, more importantly, * / itan waste costs. In the 1960s and 1970s the cost of discarding ash was typically less than $ 1.00 per ton. However, due to stricter environmental regulations that began in the late 1970s, the cost of disposing of ash has risen rapidly from $ 2.00 to $ 5.00 per tonne and continues to rise (Bahor and Golden, 1984, Proceedings, 2nd International Conference on £ ___ TechnolQqv and Mar tinq. London, pp.133-136). The * '"" - Landfill utility due to concerns t the environment has additionally raised the cost of disposal. The Environmental Protection Agency (EPFI) calculated in 1987 that the total cost of waste disposal at coal-fired power plants ranged from $ 11.00 to $ 20.00 per ton of volatile ash and bottom ash (Courst, 1991, Proceedings: 9th International Symposium on the Use of Ashes, 1: 21-1 to 21-10). This growing trend in the cost of waste has raised many concerns and researchers are urgently looking for ways to better utilize volatile ash. A potential outlet for volatile ash is incorporation into concrete and mortar mixtures. Volatile ash is used in concrete in two different ways, one as cement replacement and the other as filling. The first use takes advantage of the pozzolan properties of volatile ash, which, when reacted with lime or calcium hydroxide, can improve the strength of cementitious mixed rpos. However, volatile ash is relatively inert and the increase in compressive strength can take from 90 to 180 days to materialize. In addition, because volatile ash is only a by-product, the quality of volatile ash has always been a major concern for end users in the concrete industry. The incorporation of volatile ash into concrete is more manageable and thus reduces water requirements compared to conventional concrete. This is very beneficial when the concrete is pumped in place. Among numerous beneficial effects are reduced outcrop, reduced segregation, reduced permeability, increased plasticity, reduced heat of hydration, and increased setting times (ACI Committee 226, 1987, previously mentioned). The settlement is higher when volatile ash is used (U Ita et al., 1989, SP-114, American Concrete Institute, Pitsburg, pp.219-240). However, the use of volatile ash in concrete has many disadvantages. For example, the addition of zen. ' Voltage to concrete results in a product with low air drag and early resistance development. Therefore, in the art there is a concrete need and mortar resistant to sulfates and acids. There is a more urgent need for concrete and mortar resistant to sulphates and acids at a reasonable cost, without sacrificing the regime of strength gain specifications required in construction. There is also a need in the art to find economic uses for the volatile ash produced during the combustion of mineral coal. The present invention addresses these and other needs. The citation or identification of any reference in the application should not be construed as an admission that such a reference is available as a prior art to the present invention.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a hardenable mixture comprising volatile ash with improved resistance to sulfate and acid attack. The hardenable mixture of the present invention comprises cementitious materials and a fine aggregate and may further comprise a coarse aggregate. The cementitious materials may comprise volatile ash as well as cement. The fine aggregate comprises sand and may comprise volatile ash. The total amount of volatile ash in the hardenable mixture ranges from about 60% to about 120% of the total amount of cement, by weight, preferably from about 70% to about 120%, and most preferably about 100%. According to the invention, volatile ash is fractionated by size or volume into fractions having a narrower regimen of particle sizes and volumes; preferably fractions having finer particle sizes and volumes are used. Preferably the mixtures of the invention are prepared with cementitious materials comprising from about 5% to about 35% volatile ash, very likely from about 10% to about 25% volatile ash, and the fine aggregate comprising sand and ash. volatile, so that the total amount of the volatile ash present in the hardened mixture is from about 60% to about 120% by weight of the total amount of cement in the cementitious materials in the mortar. invention, the volatile ash has a fineness defined by a fineness modulus of less than about 600, wherein the module is calculated as the sum of the percentage of volatile ash retained by sieves of O, 1, 1.5, 2, 3, 5, 10, 20, 45, 75, 150 and 300 microns Most preferably volatile ash is a finer fraction of volatile ash having a fineness modulus of about 350. The role of fineness of the ash Volatile iza in the increase of the compressive strength of hardenable mixtures is more extensively elaborated in the Co-pending Application of E.U.A. Series No.08 / 246,875, filed on May 20, 1994, Proxy Case Number. "'5-035, entitled" IMPROVED COMPRESSIVE STRENGTH OF CONCRETE AND MORTAR C0NTAININ6 FLY ASH "(" Improved resistance to concrete compression and mortar containing volatile ash ") of the same authors mentioned herein, which is incorporated by reference in its entirety The use of finer volatile ash fractions is critical to prepare hardenable mixtures that provide maximum protection against attack of acids and sulfates, and demonstrate satisfactory pressure-resistant properties for use in construction and other applications In a further aspect, the total amount of volatile ash present in the mixture is from about 70% to about 110% by weight. weight of the total amount of cement in the cementitious materials in the mixture Very preferably, the total amount of volatile ash present in the mixture is approximately the same (110%) by weight c omo the total amount of cement present in the cementitious materials in the mixture.

In one aspect, the hardenable mixture is concrete. For example, the invention is directed to a concrete comprising about 1 part by weight of cementitious materials, about 1 to about 3 parts by weight of fine aggregate, about 1 to about 5 parts by weight of coarse aggregate, and about 0.28 to about 0.6 parts by weight of water, where the cementitious materials may comprise may comprise volatile ash as well as cement, where the total amount of volatile ash in the mixture varies from about 60% to about 120% of the amount total cement. Preferably, the volatile ash has a fineness as defined above. In another aspect, the hardenable mixture is mixture. Accordingly, the invention is directed to mixing comprising about 1 part by weight of cementitious mates, about 1 to about 3 parts by weight of fine aggregate and about 0.28 to about 0.6 (* Vtes by weight of water, where the cementitious materials may comprise may comprise volatile ash as well as cement, where the total amount of volatile ash in the mixture it varies from about 60% to about 120% of the total amount of cement Preferably, the volatile ash has a fineness as defined above The present invention contemplates achieving the objectives of resistance to acids and sulfates and maximum strength In one aspect, the invention provides hardenable mixtures containing ash, in particular concrete or mortar, with superior compressive strength greater than that of the cement or mortar equivalent composition, ie , with the same amount of cement, lacking volatile ash, this can be achieved by adding volatile ash as an additive or adding Substitute fine, or both, to a conventional mix, without reducing the amount of cement. Therefore, the pozzolan activity of the volatile ash will increase the strength of the "hardenable" mixture beyond what is possible with the cement alone. In addition, the regimen of resistance increase will be very fast, since the previous increase in strength is provided by the cement, and the subsequent resistance comes with the pozzolan activity of the volatile ash. Preferably, the total amount of volatile ash used as an additive is approximately equal to the total amount of cement, by weight. This embodiment of the invention is preferred "? > to construction projects where the increase in compressive strength is critical to maintaining a construction program and where protection against corrosion is desired. Although this embodiment of the invention is more expensive, for about the same prices as conventional hardenable mixtures, ie, cement-only mixture and concrete, the present invention advantageously provides a much stronger product that is resistant to acids and acids. sulfates.

In another embodiment, a hard mixture containing volatile ash can be prepared and shows a rate of increase in compressive strength equal to that of the same mixture without volatile ash, but with cost savings. Volatile ash can be used as a partial replacement of cement in cementitious materials, that is, to replace about 5% to about 35% cement. In this modality, the degree to which volcanic ash can replace cement without decreasing the rate of increase of, depends on the fineness of the volatile ash; the greater the fineness of the volatile ash, the greater the amount of volatile ash that can be used to replace the cement in the cementitious materials. More volatile ash or fine aggregate or additive may be included (although volatile ash presents pozzolanic activity whether introduced as a cementitious material, a fine aggregate or an additive). Preferably, the total amount of volatile ash * "equal to the total amount of cement." In yet another embodiment, the present invention provides a hardenable, inexpensive mixture, in which about 50% cement in the cementitious fabric is replaced. with volatile ash, preferably the volatile ash has a high degree of fineness.Although the rate of increase in compressive strength of this mixture was too slow in construction, after about 180 days the compressive strength of said mixture is approximately the same as that of a mixture without volatile ash, therefore, concrete oducts, such as concrete sewer pipes, which do not require immediate use can be prepared at a very low cost. The inventors for the purpose of the invention use volatile ash as a replacement for 25% cement in cementitious materials in a hardened mixture. it, that is, concrete or mortar. More volatile ash is used as an additive, or a replacement for fine watering, or both, so that the total amount of volatile ash present in the hardenable mixture is approximately equal to the total amount of cement present in the hardenable mixture. Said mixture provides all the advantages of resistance to the sulfates and acids conferred by the present invention, with satisfactory properties of resistance to compression. Consequently, an objective of this "Vention is to provide hardenable mixtures that are highly resistant to sulphates and acids and that exhibit superior compressive strength." Another object of the present invention is to provide hardenable mixtures that are resistant to sulfates and acids and less expensive, but that show the same compressive strength properties Still another objective of the present invention is to provide hardenable mixtures which are resistant to sulfates and acids, very cheap, and which achieve the required resistance to compression. of the invention is to use volatile ash These and other objects of the present invention can easily be appreciated with reference to the following figures and detailed description of the invention.

BRIEF DESCRIPTION PE LQS DRAWINGS Figure 1 shows graphs showing the size distribution of the fractionated particles of volatile ash and cement particles (inverted triangles, 98% of which have a diameter of 75 microns or less). (A) volatile ash from dry bottom heater (solid frames, in which 92% of the particles have a diameter of 75 microns or less) and fractions 1C (solid triangles, 95% less than 0 microns), IIF (diamond) solid, 96% less than 30 microns), 10F (open squares, 94% less than 20 micras), 6F (open diamonds, 99% less than 15 micras), 5F (X, 98% less than 10 micras) and 3F (open triangles, 90% than 5 micras). (B) Volatile ash from humid bottom heater (open boxes, 95% less than 75 microns) and fractions 18C (open triangles, 90.2% less than 75 microns), 18F (X, 100% less than 30 microns), 16F (open diary, 99% less than 20 microns), 15F (99% less than 15 microns), 14F (solid diamonds, 100% less than 10 microns) and 13F (open boxes, 93% than 5 microns). Volatile ash was collected from dry or wet bottom heaters and fractionated into six different size distribution fractions, as described in the Examples below. Figure 2 is a graph showing the relationship between the weight of the volatile ash mixture samples and the immersion time in a lOOml / HcsSO * bath for samples containing 25% volatile ash in cementitious materials. Also sign-volatile ash of dry bottom heater not r / driven; open diamond-volatile ash of unfractionated wet bottom heater; 6F open-sample triangle of volatile ash from unfractionated dry bottom heater; open box-control sample (not volatile ash); X-sample 16F25 of volatile ash of unfractionated dry bottom heater. Figure 3 is a graph showing the relationship between the weight of the volatile ash mixture samples and the immersion rate in a 100 l HzSO bath for samples containing 50% volatile ash in cementitious materials. The symbols used are the same as those of Figure 3. Figure 4 is a photograph of samples that had been immersed in a bath of 100ml / HaSO_, for 30 days. It is evident that the control (CF) and 20% of the volatile ash replacement samples (16F25, 6F25, M025 and H025) suffered severe corrosion by the treatment, however 50% of the replacement samples (16F50, 6F50 , M050 and HO50) were relatively unaffected. Figure 5 is a graph showing the loss of weight and the loss of compressive strength of the mixture samples containing varying percentages of volatile ash as cementitious materials after acid bath treatment for 28 days. The data shows that the optimum ratio of volatile ash to cement for acid and sulfate resistance is 1: 1. This ratio had the least weight loss and loss of resistance to the ojmpresión of all the samples tested.

DESCRIPTION PETLLñDñ PE Lfl INVENTION As described above, the present invention relates to curable mixtures resistant to acid and sulfate that comprise volatile ash. Preferably, the volatile ash used is of a defined degree of fineness. Through this specification, where specific relationships, percentages or proportions are mentioned, they are determined by weight and not by volume. The present invention is based, in part, on the observation that despite the supply and chemical composition of the volatile ash, the pozzolanic properties of the volatile ash depend on the degree of fineness of the volatile ash. Surprisingly, it has been found that the fractionation of the volatile ash to fractions of defined modulus modules as defined herein provides a high degree of control, despite the combustion conditions and the classification of the volatile ash. In the specific modalities, the corrosion resistance of the volatile ash mixture was investigated using volatile ash with well defined physical and chemical characteristics. The volatile ash was introduced as a pozzolan in the mixture to react with calcium hydroxide in the mixture, thereby reducing the reactivity of the mixture with acid. Specimens of volatile ash mixture made from different percentages of fractionated volatile ash, but containing a normal amount of cement, were immersed in a bath of concentrated sulfuric acid to evaluate their resistance to acid attack. The loss of resistance and weight due to the attack of acids was monitored. The invention is therefore based, in part, on the observation that the mixture containing volatile ash was H.ho more resistant to degradation by a bath of sulfuric acid. It was found that the optimum concentration of volatile ash for maximum resistance to acids is equal to the amount of cement, ie, equal amounts of cement and volatile ash in the mixture provide maximum resistance to acids. As used herein, the term "volatile ash" refers to a solid material having a chemical composition equal to or similar to the composition of the material that is produced during the combustion of mineral coal or powder. In a specific aspect, the solid material is the material that remains after the combustion of powdered mineral coal. ACI Committee 116 (1990, ACI 116-85, ACI Concrete Practice Handbook, Part I, American Concrete Institute, Detroit) defines volatile ash as "the finely divided residue resulting from the combustion of ground or powdered coal. which is transported from the furnace through the combustion gases ", and the term" ash, /? l? l "as used herein comprises this definition. Generally, the volatile ash derived from different carbons has differences in the chemical composition, however the main components of the volatile ash are S? 02 (25% to 60%), Al_.Oa (10% to 30%) and Fe20a ( 5% to 25%). The MgO content of the volatile ash is generally not greater than 5%. Therefore, the term volatile ash generally refers to solid powders comprising about 25% about 60% silica, about 10% to about 30% Als »Oa, of about 5% to about 25% of FeaOa, from about 0% to about 20% CaO, from about 0% to about 5% MgO. The term "volatile ash" also contemplates synthetic volatile ash, which can be prepared to have the same performance characteristics as the volatile ash described herein.

Currently, volatile ash ^ .e is classified primarily into two groups: Class C and Class F, in accordance with ASTM C 618 (1990, supra). Class F is usually produced by burning anthracite or bituminous mineral coal, and Class C results from sub-bituminous or 1-inite mineral coal. Generally, volatile ash from the combustion of subbituninous coal contains more CaO and less Fe_.Oa than volatile ash from bituminous coal (Bery and Malhotra, 1980. ACI 3 Procedures 77: 59-73). For < Therefore, the CaO content of volatile ash Class F is usually greater than 10%, the sum of the oxides S 02, AlaOa and FeaOa being not less than 50%. For Class F volatile ash the CaO content is usually less than 10% and the sum of the aforementioned oxides is not less than 70%. The vitreous phase of the volatile ash depends essentially on the combustion conditions and the type of heating. It has been found that non-driven volatile ash obtained from different heaters, such as dry bottom heaters or wet bottom heaters, behaves differently. Heaters that achieve higher temperature performance produce volatile ash with a more developed or pronounced vitreous phase. Alternatively, combustion in the presence of a fluidizing agent, which reduces the melting temperature of the volatile ash, may also increase the vitreous phase of the volatile ash produced by combustion in the lower temperature heaters. The compressive strength of a hardenable mixture containing volatile ash may depend in part on the vitreous phase of the volatile ash, so that volatile ash produced by higher temperature heaters, or produced in the presence of a fluidizing agent, or both. However, as demonstrated herein, the fineness module is the most important parameter for compressive strength, and fractional volatile ash from any supply, with a defined fineness modulus, can be used in accordance with the invention. Although volatile ash is generally in a dry and finely divided form, in many cases, due to the processes of heating and transportation, the volatile ash is moistened and often forms lumps. Said volatile ash may also be less reactive at times when the lumps may disperse to fine particles. Pozzolan, as defined by ASTM C 593 (1990, ASTM C 593-89, nnua BOOK f ASTM Stan ards, Vol.04, 02), is "a siliceous material or alurninosiliceo that itself does not possess or possess little cement value , but in a finely divided form and in the presence of moisture, it reacts chemically with alkaline earth or alkali metal hydroxides at ordinary temperatures to form or help form compounds that have cementitious properties. " The rate of increase in compressive strength of concrete or mixture containing volatile ash depends on the modulus of fineness of the fractionated volatile ash. As used herein, the term "fineness modulus" refers to a measure of volatile ash particle volume distribution or volatile ash particle size distribution. According to the present invention, the fineness module is a distribution analysis that is much more informative than a determination of average diameter or determination of the total surface area. Preferably the fineness modulus is determined as the sum of the percentage of the ash. volatile that remains in each of the series of sieves of different sizes. Consequently, the term "fineness module" refers to a relative value, which may vary depending on the number of screens selected. Because, in accordance with the present invention, volatile ash particles of smaller size or diameter are preferred for use in mixtures • Ureable, the most accurate determinations of the fineness modules are possible if smaller series of sieves are chosen. Preferably, the size of the screens is predominantly below 10 microns, that is, the screens can be 0.5, 1, 2, 3, 4, 5, 6, 7, 8 and 10 microns. In this case, the preferred fineness module will be a larger absolute number, reflecting the higher degree of accuracy of determining this value for the volatile ash particles of smaller diameter or size.

The pozzolanic reaction of the volatile ash in the hardenable mixtures comprising cement is the reaction between the constituents of the volatile ash and calcium hydroxide. It is generally assumed that it is carried out on the surface of the volatile ash particles, between silicates and aluninates from the vitreous phase of the volatile ash and the hydroxide ion in the solution within the pores (Plowrnan, 1984, Procedures, 2üÚ In ern ^ -JOnal Conf9renco op Ash Technology and Marketing London, pp.437-443). However, _ < srno was shown in Co-pending Application Sene No.08 / 246, 875, filed on May 20, 1994, Proxy Case Number 715-035, the pozzolanic reactions of volatile ash depend on the volume of the volatile ash particles: the smaller the volume of the particle, the faster it completes its reaction with the cement to contribute to the compressive strength. The solubility and reactivity regime of these vitreous phases in different types of volatile heat depends on the vitreous phase of the volatile ash, which in turn depends on the combustion temperature of the heater produced by the volatile ash. of the combustion conditions in the vitreous phase of the volatile ash, different volatile ash of a kind may behave differently, depending on the content of SiO_ », A1_, 03 and Fe_.03, and other factors such as the particle size distribution and the storage conditions of volatile ash (see Altcin et al., 1986. "Comparative study of the cementitious properties of different volatile ashes", in rv-fls., Silica Fu e. Slag and Naturia Pozzolans in Concrete.

SP-91, American Concrete Institute, Detroit, pp.91-113; Lisko itz et al., 1983, Final Report. Vol I, Department of E.U.A. of Energy, Technology and Energy Center Morganto n, August, 211pp. ). During hydration, portland cement produces an excess of lime (CaO) that is released into the pore spaces. It is the presence of this lime that allows the reaction between the silica components in the volatile ash and the calcium hydroxide to form additional hydrated calcium silicate [C-S-H_. He et al (1984, Cement and Concrete Research 14: 505-511) showed that the content of crystalline calcium hydroxide in portland-volatile cement pastes decreases as a result of the addition of volatile ash, most likely as a result of a reaction of calcium with alumina and volatile ash ash to form additional CSH. This, "Ocedirniento stabilizes the concrete, reduces the permeability and increases the resistance to chemical attacks." Although without intending to be limited by any particular theory or hypothesis, it is believed that the capicity of the volatile ash particles to be located in the pore spaces of A hardenable mixture such as concrete or mixture determines how effective the particles are in contributing to the compressive strength or reacting with reactive components in cement.Therefore, it is preferable to use finer fractions of volatile ash, since the space of pore is more accessible for particles having smaller volume, however, the invention contemplates optimizing the fineness of a volatile ash fraction for a particular application and contemplates using volatile ash fractions having a value regime of fineness modules. The fraction of the volatile ash can be achieved by any means known in the art. technique, preferably, fractionation procedures with a «asthenia air classifier. In a specific embodiment, which is described below, a Micro-Sizer air sorting system was used to fractionate volatile ash at six different particle size scales. In another embodiment, the volatile ash can be fractionated by sieving. For example, a sieve of 4.5 microns or smaller can be used to select particles of a defined maximum size. In another embodiment, the volatile ash can be ground to a desired size. This method can increase the performance of volatile ash; preferably, the grinding process produces acceptably uniform particles and does not introduce metallic debris or other impurities from the grinding apparatus. The term "cement" as used herein, refers to a powder comprising alumina, silica, lime, iron oxide and magnesia burned together in an oven and finely pulverized, which, when mixed with water, binds and binds to other materials present in the mixture in a hard mixture.

Therefore, the hardenable mixtures of the present invention include cement. Generally, cement refers to hydraulic cements such as, but not limited to, portland cement, in paticular portland cements of type I, II, III, IV and V. As used herein, "cementitious materials" are refers to a portion of a hardenable mixture that provides agglutination or binding of other materials present in the mixture, and therefore includes cement and pozzolanic volatile ash. The volatile ash may comprise from about 5% to about 60% cementitious materials in a hardenable mixture of the invention; preferably the volatile ash may comprise from about 10% to about 25% cementitious materials. The rest of the cementitious materials is generally cement, in particular portland cement. In a specific embodiment, described below, the hardenable mixtures of the invention comprise Portland portland cement.

It should be noted that when volatile ash is used to replace less than 50% cement as cementitious materials in a hardenable composition of the invention, additional volatile ash may be included in the composition in such a way that the amount of volatile ash be in the preferred regime of about 100% cement amount. In a specific embodiment, the volatile ash constitutes from about 10% to about 25% of the cementitious materials, and the volatile ash is used as an aggregate f in a ratio of about 4: 1 to about 1: 1 with respect to sand. Therefore, in this mode, volatile ash is an additive in addition to a cement replacement, or a replacement of cement and a fine aggregate, or both. The term "concrete" refers to a hardenable mixture comprising cementitious materials; a fine aggregate, such as sand; a coarse aggregate, such as, but without limiting itself to them, thick aggregate of grilled lime or grilled basalt; and water. The concrete of the invention further comprises volatile ash having a defined fineness; preferably the volatile ash is fractionated. In the specific embodiments, the concrete of the invention comprises about one part by weight of cementitious materials, about 1 to about 3 parts by weight of fine aggregate, from about 1 to about 5 parts by weight of coarse aggregate, and about 0.28 to about 0.6 parts by weight of water, such that the ratio of cementitious materials to water ranges from about 3: 1 to about 1.5: 1; preferably the ratio of cementitious materials to water is about 2.2: 1. In a specific modality, the concrete comprises 1 part of cementitious materials, 2 parts of siliceous sand or Ottawa sand, 3 parts of coarse aggregate of 0.95cm basalt and 0.5 parts of water. The term "mortar" refers to a hardenable mixture comprising cementitious materials, a fine aggregate, such as sand and / or volatile ash and water. The inventive mixture further comprises volatile ash, preferably ui > defined fineness. In a further aspect, volcanic ash is used as a fine aggregate in a ratio of about 4: 1 to about 1: 1 to sand. Still in another form, volatile ash is an additive in addition to a cement replacement, or a replacement of cement and a fine aggregate. In the specific embodiments, the mixture of the invention comprises one part by weight of cementitious materials, about 1 to about 3 parts by weight of aggregate, and from about 0.28 to about 0.6 parts by weight of water, so that the ratio of cementitious materials to water varies from about 3: 1 to about 1.5: 1. In a specific embodiment, the mixture comprises 1 part of cementitious materials, 2.75 parts of Otta sand sand, and 0.5 parts of water. As previously noted, volatile ash can be used as a fine aggregate in mortar or concrete resistant to eVc? Do and sulfate, in addition to or instead of a cement replacement. In each case, the pozzolanic activity of the volatile ash contributes to the cementitious properties of the mixture. It has been found that substituting volatile ash for a conventional fine aggregate, such as sand, provides the advantages of acid and sulfate resistance with increased compressive strength of concrete or mortar. When volatile ash is used as a partial replacement for cement and added with a fine aggregate, the resultant hardenable mixture has comparable or superior compressive strength properties to those of cement alone due to the pozzolanic activity of the volatile ash. When volatile ash is used solely as an additive, a hardenable mixture results with highly increased compressive strength properties. In accordance with the invention, finer fractions of volcanic ash are preferably used. According to the present invention, the hardenable mixture may further comprise one or more of the following: glass fiber, fumed silica, which is a by-product of the silicon metal industry which usually consists of about 96% -98% SiO_ . reagent, and that is generally in very fine particle sizes less than 1 miera; and a superplasticizer, an expensive but common additive for concrete used to lower the requirement for water to mix the concrete, such as Daracem-100 (W.R. Grace). The addition of fumed silica may improve the early rate of increase in strength of the hardenable mixture, and therefore may be a desirable component of the hardenable mixtures of the present invention. Smoked silica, which is reactive, can also restrict reactive materials to acid and sulfate in cement. In a specific embodiment, the hardenable mixture of the invention may also comprise glass fibers for reinforcement. The use of glass fibers in the hardenable mixes of the invention for reinforcement can be effected because the volatile ash, particularly the fine fractions of volatile ash, reacts more easily than the glass fibers with reactive components of the cement, i.e. Ca (OH) a, thus preventing the long-term reaction of the glass fibers with these reactive components, which otherwise degrade the glass fibers. Therefore, the present invention advantageously provides concrete and mortar resistant to acid and sulfate, which have significantly improved tensile strength because the glass fibers can also be protected. As discussed above, the most inert hardenable mixtures are those that contain approximately equal amounts of volatile ash, or volatile ash and fumed silica (as discussed below), and cement. In another specific embodiment, the hardenable mixture of the invention also comprises glass fibers and fumed silica. The fumed silica reacts more easily with the reactive components of the cement than the glass fibers and therefore can provide desirable early protection of the glass fibers against degradation as well as provide early increases in compressive strength. Subsequently, the volatile ash will react with said reactive components of the cement, preventing the anticipated and subsequent reactivity of the glass fibers. As noted above, the reaction of the glass fibers with alkaline earth or alkali metal compounds can lead to degradation of the glass fibers and loss of insistence to the tension of the hardened mixture. concrete beams of the invention with dimensions of 7.68cm x 15.24cm x 68.58crn to evaluate the flexural strength of volatile ash concrete, that is, using simple beams with three-point load. Preferably said test procedures are in accordance with ASTM C 78 (1990, ASTM C 78-84, Annual Tide of ASTM Standards, Vol. 04.02) Chemical Composition Chemical Composition < _e Fractionated Volatile Ash The chemical composition of the fractionated fly ash is shown in Table 1. The CEM sample is the cement sample used in this study. The SECO and the HUMID samples are the volatile ashes coming from the ashes v. olatiies of dry and moist non-fractionated bottom, respectively. 3F is the finest volatile ash sample of the dry bottom ash and 13F is the finest volatile ash sample of the wet bottom ash. The thickest volatile ash samples of dry and wet bottom ash are 1C and 18C respectively. Both the dry and wet bottom volatile ash used in the present were classified as ash from Class F in accordance with ASTM C-618 (1990, SU ra). Most »fractionated volatile ashes vary slightly in the oxide composition with changes in particle size. It has been reported that the separation of Class F volatile ash (high calcium content) to size fractions does not result in a significant chemical, morphological or mineralogical specification between the particles (Hemrnmg and Berry, 1QB6) and Posiurn Proceedings. and Coal Conversion By-Products: C rac enza -on, u-.il iza on _u__. Devices and TT.

Material Research Society 65: 91: 130). The content of S? Oa. Has to be smaller when the particle size is larger. The differences in the chemical composition of the two volatile ashes in the contents of S? O_, FeaOa, and CaO were observed. Samples of volatile dry bottom ash were 10% richer in S? O_. that the samples of the volatile bottom ash wet. The CaO content of dry bottom volatile ash varied from 1.90% to 2.99%, while for volatile wet bottom ash, CaO ranged from 6.55% to 7.38%. Content _ __. 03 of the volatile wet bottom ash was approximately twice as high as that of the dry bottom volatile ash. The highest concentration of FeßOa of each type of volatile ash was observed in the thickest particle sizes, namely 1C and 18C. The chemical composition of the fractionated fly ash is shown in Table 1.

CUflPRQ 1 Chemical Composition of Fractionated Flying Ash and Cement It is interesting to note that after the volatile ash was fractionated to different sizes, the ignition loss (LOI) of the finer particle was greater than for the larger particles. In other words, the LOI content gradually decreased as the particle grew. Ravma (1980, Cement and Concrete Research 10: 573-80) also reported that the finest particle of fly ash has the highest 1.01 values. Ukita et al. (1989, in Flv Ash, Silica Fume, Slag, and Natural Pozzolans In Concrete, SP-114, American Concrete Institute, Pitsburg, pp.219-240) also showed that although the chemical composition does not change when the average diameter of the volatile ash decreased from 17.6 microns to 3.3 microns, LOI increased from 2.78 to 4.37. Our observations and these previous reports are in conflict with the report of the ACI Committee 226 (1987, "Use of Fly Ash in Concrete" .. ACI 226.3R-87 ACI 1.

Methods 84: 381-409) and Sheu et al. (1990, Syrnposiurn .. ¿Ooe-ingS Eli. Q__b and oal Conversion By-Product: Charactgr za on. utilization _u___ Pisposal __L C? C. Material Research 178: 159-166) which states that the coarse-sized fraction of volatile ash usually has a LOI higher than the fine fraction.

Analysis of Particle Size of Fractionated Ashes The particle size distributions of fractionated ash from dry-bottomed and heated bottom heaters are shown in Figures IA and IB respectively. The curves for the original volatile feed ash are not as pronounced as the others because the original unfractionated feed ash includes the full size regime and therefore a larger size distribution regime than the fractionated samples. The percentage of volatile ash in each fraction that has a smaller size than a particle size is indicated in the parentheses in each curve. For example, in the case of 3F volatile ash, the finest of the dry bottom ash, 3F (90% ~ 5 microns) means that 90% of the volatile ash particles are smaller than 5 microns. From the original supply, each type of volatile ash was fractioned into six regimes. As shown in Figures IA and IB, the volatile ash particle size varied from 0-5.5 microns to 0-600 microns. The average diameters of - ,. and 13F were 2.11 and 1.84 microns, respectively, while the mean diameters of the thickest particle size, 1C and 18C, were 39.45 and 29.23 microns, respectively. For volatile wet bottom ash, 13F was the thinnest fraction and 18C was the thickest. It was found that the unfractionated wet bottom volatile ash is finer than the unfractionated dry bottom volatile ash. The particle sizes of the unfractionated dry bottom volatile ash ranged from about 1 miera to BflO daughters, with an average particle diameter of 13.73 microns. Particulate volatile ash with a non-fractionated moist bottom included particles up to 300 microns with an average diameter of 6.41 microns. Fragment particles of smaller size tended to have more spherical shapes (Hemming and Berry, 1986, ______L__.

Fineness of Fractionated Volatile Ash The traditional fineness values of the volatile ash were determined by both wet sieve analysis and Blame fineness together with the specific gravity of the fly ash, which are shown in table 1. The average diameter, of which 50 percent of particles are larger than this size, also presented in this table. In accordance with ASTM specifications C-618 (1990, suora). the volatile IC fractionated ash is ^ acceptable for use in concrete, since the percentage of volatile ash retained in the No.325 sieve is greater than 34%.

TABLE 2 Fineness of Cement and Fractionated Flying Ashes . / »Two methods are used to measure the fineness of the fractionated ash. The first method comprises determining the residue on a sieve of 45 microns (No.! 25). Using the No.325 sieve method, samples 3F, 5F, 6F, 10F, 13F, 14F, 1F, 16F and 18F fractionated volatile ash had the same fineness: all have zero retention. The second method was to measure the surface area by air permeability test. It can be noted from Table 3 that, while fine, is the particle size of the fractionated fly ash, the greater the specific gravity and Blaine's fineness. In general, volatile ash of higher fineness had higher specific gravity, according to the previous research (Hansson, 1989, Symposium Procedures, Conversion by-products of Volatile Ash and mineral coal: characterization, utilization and waste V, Soc. of Investigation of Material 136: 175-183). The density of the volatile ash coming from different power generation plants varies from 1.97 to 2.89 (g / cma), however it usually varies between about 2.2 to 2.7 (g / crna) (Lane and Best, 1982, suora) . The work done by McLaren and Digiolin (1990, Seminar on Combustion of Coal and Use of Subproducts, Pittsburgh, p.15) reported that Class F volatile ash had an average specific gravity value of 2.40. The specific gravity of the fractionated volatile ash varies & 2.28 for thicker volcanic ash at 2.54 for volatile ash fine volatile ash from dry bottom, and from 2.22 for coarse volatile ash at 2.75 for the finest volatile ash from bottom-heavy ash. The density differences between the dry bottom ash and the wet bottom ash suggest that the very fine particles of the wet bottom volatile ash are used to thick walls, are free of voids, or are composed of components crystalline or glass denser than volatile dry bottom ash (Hernrning and Berry, 1986, Symposium Proceedmgs, Fly Ash and Coal Conversion By-Products: Charactepzation, Utilization and Disposal II, Material Research Society 65: 91: 130).

Resistance to Corrosion of Volatile Ash Blend The 6F fractionated volatile ash was mixed, ^ jf, the original supply of dry bottom volatile ash (DRY), and wet bottom volatile ash (HUM) with cement to form volatile ash cement mortar. The ratios are shown in Table 3.

CUflPRQ 3 Proportion of Volatile Ash Blend Mortar to Resist Acid Acid Sample Ash Cement Are a U / C + F Type of Volatile Volatile Ash CF 1.00 - 2.75 0.50 Seca25 0.75 0.25 2.75 0.50 Not fractionated, b? Ca Wet 0.75 0.25 2.75 0.50 Not fractionated, wet 6 25 0.75 0.25 2.75 0.50 6F 16F25 0.75 0.25 2.75 0.50 16F SecaSO 0.50 0.50 2.75 0.50 Not fractionated, dry Wet 0.50 0.50 2.75 0.50 Unfractionated, 50 wet 6F50 0.50 0.50 2.75 0.50 6F 16F50 0.50 0.50 2.75 0.50 16F As can be seen in Table 3, the percentage of volatile ash used in the mixtures was 25 and 50 percent by weight of cementitious materials (cement and volatile ash). In other words, in this experiment the volatile ash replaced the cement in the cementitious materials. The ratio of water to cementitious materials of all the mixtures remained constant at 0.5. Two 5.08 cm containers were strained and cured in saturated lime water approximately 60 days before being placed in the acid bath. Each container was carefully weighed. Samples of volatile ash mixture and control samples (100% cement, > -> volatile ash, in cementitious materials) were then submerged in a 100 ml / 1 sulfuric acid bath. All samples were tested under the same corrosive environment until the date of the test. To evaluate the degree of damage caused by acid attack, samples were removed from the acid bath and washed with tap water. The samples were then weighed in the dry saturated surface condition. The weight loss was then determined by comparison of the original sample previously recorded.

Results and Discussion The sample designated "CF" is the control mixture that does not contain volatile ash in the mixture. The number "25" and "50" represents the percentage of cement replaced by the volatile ash. The weights of the samples at different times after being submerged in the concentrated HaS02 solution _- 100 rnl / 1 are recorded in Table 4. The compressive strength of the volatile ash mixtures before being submerged in the solution of H_.S0_¡ are also presented in the Table 4 s- CUflPRQ Effect of the Volatile Ash Mixture in H SQ._ of 100ml / l Question-Weight in different times (g) Comp Do not. day 0 day 1 day 3 dThe 7 day 14 day 21 day 30 k _? / em_.

CF 301.7 289.3 262.2 206.5 139.5 100.1 hg.g 701 SECA25 297.1 287.0 263.0 212.7 166.5 125.5 92.7 641. .2 HUM25 297.8 286.8 260.7 212.3 164.6 122.1 89.3 650. .3 6F25 299.6 287.6 260.3 208.6 153.4 110.6 79.2 661. .9 16F25 297.0 284.6 255.5 197.7 135.4 90.6 60.9 654. .6 CA50 295.8 295.4 293.6 289.5 280.1 276.8 257.8 382 HUM50 291.9 291.8 291.3 291.1 291.3 276.8 233.5 459. .4 6F50 294.8 297.7 294.8 293.6 294.3 292.6 287.2 390. .8 16F50 298.3 298.2 298.0 298.2 298.5 290.8 269.3 456 For the control sample that contains cement and does not contain volatile ash, corrosion due to acid attack is alarming. The weight loss of the control sample was 30% on the seventh day and 67% on the 21st day. Such rapid deterioration of the cement mixture is alarming. The data indicate that the , 1 free or calcium hydroxide in the cement control sample is extremely vulnerable to acid attack. The substitution of cement by volatile ash can "Restrict" free calcium hydroxide compounds and prevent them from suffering attack by sulfuric acid. The results presented in Table 4 indicate that 25% of the volatile ash mixture samples were vulnerable to acid degradation, but less than the control sample. Partial protection from acid attack was observed regardless of volatile ash ffl-Lpo or its particle size (Figure 2). When 50% cement is substiutuized with volatile ash in mixture, the weight loss is significantly reduced. After 7 days, there was no measurable weight loss, the weight loss was limited to 6% after 21 days. With this degree of replacement, the type of volatile ash and its particle size did not have a significant effect on the corrosion resistance of the volatile ash mixture (Figure 3). After 30 days, the particle size of the volatile ash shows an effect on the corrosion resistance (Figure 4). The unfractionated volatile ash sustains more damage than the fractionated 15-micron ash samples (6FC50 and 16FC50). Figure 4 shows the remains of the volatile ash mixture samples after being submerged in H_ >; S0 for 30 days. Samples of volatile ash mix with 25% replacement of cement with volatile ash in the mixture "Severe weight loss after treatment in the H ^ SO solution of I00rnl / 1. With 50 percent volatile ash in the mix, the control sample is much more resistant to acid attack than the control and 25 percent of the volatile ash cement samples. In terms of compressive strength, samples with 25% replacement provide a higher compressive strength than 50%. Based on the compressive strength, the samples can be divided into two groups. pl- first is the control and 25% volatile ash samples that demonstrate compressive strength values of more than 632.7 kg / crn_ > . The second group consists of the 50% volatile ash samples that demonstrate values of compressive strength between about 351.5 kg / crna at 456. 5 kg / cm_. manometric The weight loss and loss of compressive strength of the mixture samples containing variable quantities of volatile ash that replaces the cement are shown in Figure 5. This graph demonstrates a clear maximum of sulfuric acid attack protection when 50% of the cement is replaced with volatile ash, that is, when the amount of volatile ash present is approximately the same as the amount of cement in the mixture. The results also show that the maximum corrosion resistance is achieved when the ratio of cement to volatile ash is .1: 1 in a mixture, or cement composition. Higher amounts or • Low volatile ash leads to weight loss and loss of compressive strength increased by acid attack. Clearly, the compressive strength of a sample is not a precise determinant of acid resistance; but it is the amount of volatile ash in the ezzc that governs the resistance. These data indicate that the volatile ash content limit of cementitious materials, that is, the maximum replacement of cement with volatile ash, to provide corrosion resistance against acid attack while maintaining acceptable compressive strength is around- 35%. The scope of the present invention should not be limited by the embodiments described herein. In fact, various modifications of the invention, apart from those described herein, will be apparent to those skilled in the art from the foregoing description and the appended figures. Several publications are cited herein, whose descriptions are incorporated by reference in their entirety.

Claims (21)

NQVEPñP PE Lñ INVENCIÓN CLAIMS

1. - A hardenable mortar containing cementitious materials, volatile ash and a fine aggregate, where the cementitious materials may comprise volatile ash, thus cement characterized in that the total amount of volatile ash varies from about 60% to about 120% of the, total amount of cement in the hardenable mixture, by weight.

2. The hardenable mortar according to claim 1, further characterized in that the volatile ash has a fineness defined by a fineness modulus of less than about 600, wherein the fineness module is calculated as the sum of the percentage of ash volatile retained in sieves of 0, 1, 1.5, 2, 3, 5, 10, 20, 45, 75, 150 and 300 microns.

3. The hardenable mortar according to claim 1, further characterized in that the cementitious materials comprise from about 5% to about 35% volatile ash, and the fine aggregate comprises sand and volatile ash.

4. The hardenable mortar according to claim 3, further characterized in that the cementitious materials comprise about 25% volatile ash, and the total amount of volatile ash in the mixture is / approximately 100% of the total amount of cement in weight.

5. The hardenable mortar according to claim 1, further characterized in that the total amount of volatile ash present in the mixture is from about 70% to about 110% of the total amount of cement in the cementitious materials in the mixture, in weigh.

6. The hardenable mortar according to claim 5, further characterized in that the total amount of volatile ash present in the mixture is approximately equal to the total amount of cement in the cementitious materials in the mixture, by weight.

7. The hardenable mortar according to claim 1, further characterized in that the volatile ash is volatile wet bottom ash having a fineness modulus of less than about 350.

8.- A concrete comprising 1 part by weight of materials cementitious materials, from about 1 to about 3, "" parts by weight of a fine aggregate, about 1 to 5 parts by weight of a coarse aggregate, and about 0.28 to 0.5 parts by weight of water, where the cementitious materials they comprise from about 0% to about 60% by weight of volatile ash and from about 40% to about 100% by weight of cement, characterized in that the total amount of volatile ash varies from about 25% to about 150% by weight. the total amount of cement by weight.

9. The concrete according to claim f characterized further because the volatile ash has a fineness defined by a fineness modulus of less than about 600, wherein the fineness module is calculated as the sum of the percentage of volatile ash retained in sieves of 0, 1, 1.5, 2, 3, 5, 10, 20, 45, 75, 150 and 300 microns.

10. The concrete according to claim 8, further characterized in that the cementitious materials comprise from about 5% to about 35% volatile ash, and the fine aggregate comprises sand and volatile ash.

11.- The concrete in accordance with the claim 10, further characterized in that the cementitious materials comprise about 25% volatile ash, and the total amount of volatile ash in the mixture is approximately 100% of the total amount of cement, by weight.

12.- Concrete in accordance with the claim 8, further characterized because the total amount of ash The amount present in the mixture is from about 70% to about 110% of the total amount of cement in the cementitious materials in the concrete, by weight.

13.- The concrete in accordance with the claim 12, further characterized in that the total amount of volatile ash present in the concrete is approximately equal to the total amount of cement in the cementitious materials in the concrete, by weight.

14.- The concrete in accordance with the claim (&; - < further characterized in that the volatile ash is volatile wet bottom ash having a fineness modulus of less than about 350.

15. A mortar comprising 1 part by weight of cementitious materials, about 1 to about 3 parts by weight of a fine aggregate and about 0.28 to 0.5 parts by weight of water, wherein the cementitious materials comprise from about 0% to about 60% by weight of volatile ash and from about-40% to about 100% by weight of cement, characterized in that the total amount of volatile ash present in the mixture is from about 25% to about 150% by weight, of the total amount of cement by weight present in the mixture.

16. The mortar according to claim 15, further characterized in that the volatile ash has a fineness defined by a fineness modulus of less than about 600, wherein the fineness modulus is calculated co o _._. sum of the percentage of volatile ash retained in the sieves of 0, 1, 1.5, 2, 3, 5, 10, 20, 45, 75, 150 and 300 microns.

17. The mortar according to claim 16, further characterized in that the cementitious materials comprise from about 5% to approximately 35% volatile ash, and the fine aggregate comprises sand and volatile ash.

18. The hardenable mortar according to claim 17, further characterized in that the materials Tinen bears comprise about 25% volatile ash, and the total amount of volatile ash in the mixture is approximately 100% by weight, of the amount total cement.

19. The mortar according to claim 15, further characterized in that the total amount of volatile ash present in the mixture is from about 70% to about 110% by weight, of the total amount of cement in the cementitious materials. in the mix.

20. - The mortar according to claim 19, further characterized in that the total amount of volatile ash present in the mixture is approximately equal to the total amount of cement in the cementitious materials in the mixture, by weight.

21. The hardenable mortar according to claim 15, further characterized in that the volatile ash is volatile wet bottom ash having a modulus * fineness of less than about 350. RFSUMFN FROM I TO INVENTION The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and volatile ash for use in construction and other applications, said hardenable mixtures show significant levels of resistance to sulfate and acid while maintaining acceptable compressive strength properties; the hardenable sulfate and acid resistant mixtures of the invention containing volatile ash comprise cementitious materials and a fine aggregate; the cementitious materials may comprise volatile ash as well as cement; the fine aggregate may comprise volatile ash as well as sand; the total amount of volatile ash in the hardenable mixture ranges from about 60% to about 120% of the total amount of cement, by weight, whether the volatile ash is included as a cementitious material, a fine aggregate or an additive or any cobination, "_ the above; In specific examples, the mortar containing 50% volatile ash and 50% cement in the cementitious materials demonstrated superior corrosion resistance properties. MK / crrn * P96 / 889F