scholarly journals Durability of Cement and Ash Mortars with Fluidized and Siliceous Fly Ashes Exposed to HCl Acid Environment over a Period of 2 Years

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3229
Author(s):  
Elżbieta Janowska-Renkas ◽  
Agnieszka Kaliciak ◽  
Grzegorz Janus ◽  
Jolanta Kowalska

The paper presents results of research on the impact of fly ash from fluidized bed combustion (FBC) of lignite, used in quantities of 30 and 45% by mass, and the mixture of FBC and silicious fly ash in amount of 45% by mass, on properties of cement–ash mortars. Mortars were exposed to aggressive environment of 1, 3, and 5% HCl solutions for 2 years. Mortars containing 45% FBC exposed to 1% HCl solution (pH = 2) showed the highest durability from among other mortars. The growth of their strength observed after 90 days of testing in 1% HCl environment, as well as the lowest drop of strength after 730 days of exposure to this environment, resulted from the reduced amount of large pores from 20 to 200 nm in mortars containing fly ash, with simultaneous growth of smaller pores of <20 nm during testing. A beneficial effect has been demonstrated of FBC addition to cement on properties of cement–ash mortars exposed to the aggressive impact of the HCl. Mortars with FBC fly-ash content increased to 45% by mass showed higher strength values, smaller differences in linear and mass changes, and increased durability in an aggressive environment observed during 730 days of testing.

2016 ◽  
Vol 722 ◽  
pp. 168-172
Author(s):  
Karel Kulísek ◽  
Dominik Gazdič ◽  
Karel Dvořák ◽  
Marcela Fridrichová

The present work focuses on the use of fluid fly ash for Portland clinker burning. Fluid ashes are carriers of all basic oxides represented in the cement raw meal. However, while the share of hydraulic oxides is in ashes sufficient, there is a significant deficiency in calcium oxide content. Preliminary studies have shown that the combination thereof with calcite as the second essential component of the fluid fly-ashes for the raw material based on Portland clinker burning application, it is necessary to solve a problematic issues. The first one concerns the potential leakage SOx resulting from decomposition of CaSO4 ash into the atmosphere. The second circumstance is the correction tracks raw meal in order to redistribute in the samples prepared under the initial studies, the obtained clinker minerals content in favor of calcium silicate, of them further in favor of alite. The last issue is the evaluation of the impact of fluid utilization of fly ash as a partial raw material bases for reducing CO2 emissions in the Portland clinker burning.


2021 ◽  
Vol 1205 (1) ◽  
pp. 012004
Author(s):  
Vít Šmilauer ◽  
Radoslav Sovják ◽  
Šárka Pešková ◽  
Rostislav Šulc ◽  
František Škvára ◽  
...  

Abstract The paper presents a ternary binder development and its utilization in shotcrete. The binder is made from fluidized bed combustion (FBC) fly ash, siliceous fly ash, and Ca(OH)2 addition, now available under the name Sorfix. XRD and TGA identified ettringite and C-S-H as two main hydration products. In addition, thermodynamic modeling verified robustness in terms of space-filling capabilities when varying input oxide composition. Since alkali-free accelerators produce mostly ettringite in Portland-based systems, a fraction of Portland cement was advantageously replaced with the ternary binder, forming early ettringite as well. Extensive testing led to 45% replacement of Portland cement, following J2 curve for early strength gain used commonly in shotcrete tunnel linings. The shotcrete was successfully tested in a mock-up experiment in a 2 m3 Prague served for the full-scale application, utilizing over 1000 tons of Sorfix and saving over 700 tons of CO2


2018 ◽  
Vol 276 ◽  
pp. 160-166
Author(s):  
Tomáš Žlebek ◽  
Jakub Hodul ◽  
Rostislav Drochytka

This paper focuses on the possible use of fly ash contaminated by denitrification process as filler for special grouts based on epoxy resin. This fly ash is contaminated by combined ammonia ions as a consequence of flue gas denitrification. When mixing this fly ash with water and silica materials, ammonia (NH3) is released, therefore its application in these materials is inappropriate. The use of such fly ash as filler in polymeric substances, e.g. epoxy, polyester or vinyl ester resin, seems to be appropriate. When mixing fly ash with these materials, fly ash particles become coated with a polymeric substance, therefore no toxic ammonia is released. In the experiment, the impact of two kinds of contaminated fly ashes (FA-1, FA-2) and different percentages of filler in a polymer grout was examined on the resulting physical and mechanical properties. It was found that the best properties were by the grout with fly ash from circulating fluidized bed combustion from the Kladno thermal power plant (FA-1) under 45% of filling. This material showed high compressive and three-point bending strength and the flexural modulus was even higher than in the case of the reference material, which contained reference silica sand with optimal round grain shape as filler. Furthermore, chemical resistance of these materials against aggressive liquid solutions used in industrial operations were examined. An ideal grout formula was checked in a cut of an embedded steel element under optical microscope. A pull-out strength test was also performed in the case of the best formulas to determine the anchoring rate of embedded steel rod.


2014 ◽  
Vol 548-549 ◽  
pp. 228-232 ◽  
Author(s):  
Xiao Chen ◽  
Ji Wei Liu ◽  
Ming Kai Zhou

To improve the impact of fly ash on the properties of cement-fly ash stabilized crushed stone, and promote it popularize and apply better. This paper investigated the effect of fly ash content on unconfined compressive strength, cleavage strength and resilient modulus of cement-fly ash stabilized crushed stones, and those relationships between mechanical parameters. The results showed that with increasing of the fly ash content, the unconfined compressive strength and cleavage strength increased at first, then decreased, the resilient modulus decreased, and The brittleness index increased. We can conclude that the optimal fly ash content is between 10% and 15%, and increment of fly ash content can improve its crack-resistance.


2018 ◽  
Vol 174 ◽  
pp. 02006 ◽  
Author(s):  
Elżbieta Janowska-Renkas ◽  
Jolanta Kowalska ◽  
Grzegorz Janus ◽  
Agnieszka Kaliciak

The study shows results of research on the aggressive environment impact (1, 3 and 5% HCl solution) on durability of cement mortars with fraction from 30 to 45% by mass of fly ashes from the fluidized bed combustion (FBC fly ash) and conventional fly ashes used separately and in the form of a mixture. The impact of aggressive environments on durability of cement and ash mortars was tested for aperiod of 365 days, by testing the compressive strength, linear changes, mass loss and porosity. It was demonstrated that mortars with the content of FBC fly ashes, after 365 days of tests showed the higher resistance to aggressive environment impact. It is confirmed by e.g. their higher compressive strength, and thus the reduced total porosity. Reduction of total porosity content (<50 nm) was accompanied by the increased compressive strength, which in the aqueous environment was in favour of cement mortars, and in the aggressive environment in favour of cement and ash mortars. It was demonstrated that the content of pores < 200 nm was lower for mortars with FBC fly ashes and mixtures of ashes regardless of environment the mortars were stored in. A beneficial impact of FBC fly ashes was found on physical properties of mortars, i.e. reduction of the shrinkage, lower mass loss and reduced destruction of mortars in the acid corrosion environment. That effect was especially beneficial for the mortar with higher (45% by mass) content of FBC fly ashes, regardless of aggressive character of the environment.


2002 ◽  
Vol 21 (7) ◽  
pp. 763-771 ◽  
Author(s):  
Kishore ◽  
S.M. Kulkarni ◽  
S. Sharathchandra ◽  
D. Sunil

Author(s):  
Nevin Selc¸uk ◽  
Yusuf Gogebakan ◽  
Zuhal Gogebakan

The behavior of 20 trace elements (As, B, Ba, Cd, Co, Cr, Cu, Hg, Li, Mn, Mo, Ni, P, Pb, Sb, Se, Sn, Tl, V, Zn) and 8 major and minor elements (Al, Ca, Fe, K, Mg, Na, Si, Ti) during the combustion of high ash content lignite with and without limestone addition have been investigated in the 0.3 MWt Middle East Technical University (METU) Atmospheric Bubbling Fluidized Bed Combustor (ABFBC) Test Rig. Experiments were performed without fines recycle. Inert bed material utilized in the experiments was bed ash obtained previously from the combustion of the same lignite without limestone addition in the same test rig. Concentrations of trace elements in coal, limestone, bottom ash, cyclone ash and filter ash were determined by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Measurements show that the distribution of major and minor elements follows the ash split between the bottom ash and fly ash and that the major proportion of most of the trace elements (As, Ba, Cr, Hg, Li, Mo, Ni, Sn, V, Zn) are recovered in fly ash. Comparisons between the trace element partitioning of the runs with and without limestone addition reveal that addition of limestone shifts the partitioning of Ba, Cr, Hg, Mo, Ni, Sn, V, Zn from bottom ash to fly ash.


2013 ◽  
Vol 357-360 ◽  
pp. 671-675
Author(s):  
Zhong Dong Liu ◽  
Wen Juan Zhao

In this paper the molding mechanisms of mibration compaction for concrete bricks is explained. A lot of concrete bricks with different ash content were by a vibration compaction machines produced. The characteristics of the concrete bricks are investigated. The experiments showed that the starting hardness of the concrete bricks at the separation from molding tools is sufficient for brick stacking.


Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2527
Author(s):  
Natalia Wielgus ◽  
Jan Kubica ◽  
Marcin Górski

This paper presents novel research on a fluidized bed combustion (FBC) fly ash-based geopolymer as a contribution to the problem of FBC fly ash disposal, and a proposal for a new geopolymer composition—an environmentally friendly material that is possible to use in construction. Geopolymer samples of various composition (containing FBC fly ash as the main raw material, metakaolin and CRT glass as additional components, and sodium silicate and sodium hydroxide as activators) were subjected to flexural and compressive strength tests. An investigation on the effect of the demolding time was carried out on one selected mixture. The test showed that both the composition and the demolding time have a decisive influence on the basic mechanical properties. A mixture containing FBC fly ash to metakaolin in a mass ratio of 3:1, removed from the mold after 14 days, was found to be the best in terms of the mechanical parameters expected from a material that could be used in construction, e.g., for the production of precast elements. According to the results obtained, FBC fly ash is a promising and environmentally friendly raw material for the production of geopolymer, with good mechanical properties and low density. Moreover, a high compressive strength can be obtained by curing the geopolymer at ambient temperature.


2014 ◽  
Vol 1054 ◽  
pp. 148-153
Author(s):  
Tereza Otcovská ◽  
Pavel Padevět

Fly ash is a waste product produced during combustion of coal. There are two basic types of fly ash. According to the type of combustion, there is produces pulverised coal combustion (PCC) fly ash or fluidized bed combustion (FBC) fly ash. Use of fly ash additives influences moisture properties of binder gels (cement paste). The particular object of interest of this post is capillary action of water in the binder gels with different concentration of fly ash in the mixture. There are substantial differences among moisture properties of binder gels with FBC fly ash additives compared with the binder gels with PCC fly ash additives.


Sign in / Sign up

Export Citation Format

Share Document