Carbonation of autoclaved aerated concrete containing fly ash

ce/papers ◽  
2018 ◽  
Vol 2 (4) ◽  
pp. 47-51 ◽  
Author(s):  
Bernd Winkels ◽  
Holger Nebel ◽  
Michael Raupach
2013 ◽  
Vol 357-360 ◽  
pp. 949-954
Author(s):  
Ye Zhang ◽  
Peng Xuan Duan ◽  
Bao Sheng Jia ◽  
Lei Li

In this paper, the low-silicon coal gangue fly ash is used to produce autoclaved aerated concrete. The influences of water binder ratio, coal gangue fly ash content, calcareous content and conditioning agents on the compressive strength of the autoclaved aerated concrete are investigated. Optimal raw material formulation and procedure are determined for the autoclaved aerated concrete. The compressive strength and frost resistance of autoclaved aerated concrete made by the optimal raw material formulation and procedure meet with the requirements of autoclaved aerated concretes of B05 grade, and its thermal conductivity, drying shrinkage reach the requirements of the relevant national standards of China.


2014 ◽  
Vol 29 (4) ◽  
pp. 726-732 ◽  
Author(s):  
Zhonghe Shui ◽  
Jianxin Lu ◽  
Sufang Tian ◽  
Peiliang Shen ◽  
Sha Ding

2014 ◽  
Vol 899 ◽  
pp. 409-414 ◽  
Author(s):  
Alena Struhárová ◽  
Stanislav Unčík ◽  
Svetozár Balkovic ◽  
Mária Hlavinková

Fluidized fly ash has different physical and chemical properties compared to fly ash emerging from classic combustion. It contains amorphous phases resulting from a dehydration of clay minerals as well as unreacted sorbent of CaCO3, free CaO and anhydrite (CaSO4). Work targets the possibilities of production of an autoclaved aerated concrete (AAC) from fluidized fly ash, and its influence on particular physical-mechanical properties of autoclaved aerated concrete.


2014 ◽  
Vol 599 ◽  
pp. 302-309 ◽  
Author(s):  
Bao Guo Ma ◽  
Li Xiong Cai ◽  
Shou Wei Jian ◽  
Lei Su

This article discussed the influence of FA fineness on the production performance and usability through the autoclaved aerated concrete slurry gas foaming curve and basic physical properties of blocks; meanwhile, studied the influence of different fineness FA on the composition and morphology of hydration products through X-ray diffraction analysis and scanning electron microscopic analysis, The results show that in the cement-fly ash-lime system autoclaved aerated concrete, the higher fineness of FA, the more water it need, and more sensitive the slurry presents; when the FA residue decrease from 17.8% to 8% through a 0.045mm square hole sieve screen, its specific surface area enlarge from 325m2/Kg to 388m2/Kg, the autoclaved aerated concrete specific strength increase by 53.24% and 40.96% in the case of the same ratio of water and resemble extended degree, respectively. Keep on increasing FA fineness does harm to its specific strength. The crystallinity of tobermorite, which is the main hydration products of autoclaved aerated concrete decreases with the increasing of FA fineness, however, crystallite size become larger.


2013 ◽  
Vol 395-396 ◽  
pp. 433-438 ◽  
Author(s):  
Ye Zhang ◽  
Peng Xuan Duan ◽  
Bao Sheng Jia ◽  
Lei Li

In this paper, compared with common fly ash, the low-silicon coal gangue fly ash is used to produce fly ash autoclaved aerated concrete. The influences of water binder ratio, coal gangue fly ash content, calcareous content and conditioning agents on the compressive strength of the autoclaved aerated concrete are investigated. The results indicate the coal gangue fly ash has different properties from the common fly ash such as its granule appearance and the activity as AAC siliceous raw material. It is noting that the coal gangue fly ash can also be used to prepare AAC blocks by optimizing the raw material formulation and procedure and its B05 product can reach the China top industrial standard.


2018 ◽  
Vol 276 ◽  
pp. 148-153
Author(s):  
Matěj Lédl ◽  
Lucie Galvánková ◽  
Rostislav Drochytka

After introducing SNCR in coal combustion process in power plants, the valuable by-product such as fly ash remains contaminated with amount of ammonia in form of NH4HSO4, (NH4)2SO4 respectively, which became undesirable in AAC technology because the toxic ammonia is released in the air during the mixing process. This paper deals with the effect of varying ammonia content in fly ash after selective non-catalytic reduction (SNCR) on the physical-mechanical properties of the fly ash based autoclaved aerated concrete (AAC) with the main focus on determination of the impact of the various content of ammonium ion in fly ash on the initial consistency of fresh slurry, the residual content of ammonium ion in hardened aerated matrix and also the impact on the bulk density, compressive strength and tobermorite formation after hydrothermal treatment. Seven batches of AAC, made out of fly ash with rising content of ammonium ion from 0 ppm to 250 ppm, were tested and based on the results obtained it was found out that ammonia is released during the mixing process entirely and doesn‘t remain in AAC after autoclaving, moreover it doesn‘t affect the properties of both fresh slurry (no apparent foaming effect noticed) and thermally treated samples of AAC. Formation of tobermorite wasn’t negatively affected.


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