Effect of ceramic waste powder on alkali-activated slag pastes cured in hot weather after exposure to elevated temperature (original) (raw)
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Materials and Structures, 2010
The residual compressive strength behavior of alkali activated slag paste (AASP) after temperature exposures up to 1,200°C was investigated. Strength loss of approximately 60% occurred between 100 and 200°C and a further strength loss in the order of 30% at 800°C. Total loss of strength occurred at 1,200°C. Thermogravimetric studies (TGA/DTG) verified AASP contained no Ca(OH)2 which governs the chemical
Materiales de Construcción
This study assessed the mechanical properties, and structural changes induced by high temperature exposure, of alkali-silicate activated slag cements produced with sodium silicates derived from silica fume (SF) and rice husk ash (RHA). Similar reaction products were identified, independent of the type of silicate used, but with subtle differences in the composition of the C-S-H gels, leading to different strength losses after elevated temperature exposure. Cements produced with the alternative activators developed higher compressive strengths than those produced with commercial silicate. All samples retained strengths of more than 50 MPa after exposure to 600 °C, however, after exposure to 800 °C only the specimens produced with the RHA-based activator retained measurable strength. This study elucidated that silicate-activated slag binders, either activated with commercial silicate solutions or with sodium silicates based on SF or RHA, are stable up to 600 °C. Citation/Citar como: Bernal, S.A.; Rodríguez, E.D.; Mejía de Gutiérrez, R.; Provis, J.L. (2015) Performance at high temperature of alkali-activated slag pastes produced with silica fume and rice husk ash based activators. Mater. Construcc. 65 [318], e049 http://dx.doi.org/10.3989/mc.2015.03114.
INTERNATIONAL JOURNAL OF CIVIL …, 2010
The aim of this work is to investigate the influence of sodium oxide on properties of fresh and hardened paste of alkali-activated blast furnace slag from Isfahan steel plant. The silica modulus (SiO 2 /Na 2 O) of activator was adjusted at 0.6 and a number of mixes were designed in such a way to contain different levels of sodium oxide including 1, 2, 3, 4, 5, and 6% by weight of dry slag. The most important physico-mechanical properties of the pastes including workability, initial and final setting times, 28-day compressive strength and efflorescence severity were measured. Suitable mixes were chosen for more studies including compressive strength at different ages, 90-day autogenous and drying shrinkages. According to the results, increasing the sodium oxide content of the mixes results in increased workability, reduced setting times, and higher compressive strength. The results confirm the possibility of achieving 28-day compressive strengths up to 27.5, 50.0 and 70.0 MPa for mixes with sodium oxide content of 1, 2 and 3 wt% respectively. The measured values for autogenous shrinkage were all less than 0.1% and SEM studies showed a significant decrease in pore sizes with increasing sodium oxide concentration from 1 to 2%.
Acta Polytechnica CTU Proceedings, 2021
The usage of waste materials is a very important global topic. The large amount of waste everywhere in the world needs to be processed or disposed. Landfilling is not an option anymore, because of European legislation and restrictions. A lot of studies are trying to develop new options or possibilities of using waste materials. This research is trying to find a way to process blast furnace slag. A high-speed mill was used for the mechanical activation. Chemical activation was used as the next step of activation. There are many materials that could be used, but in this study we used slaked lime and water-glass. Slaked lime had a positive effect on mechanical properties. Samples had higher compressive strength but the effect was limited only for 5 wt. %. Another used material was water-glass, but in this case, there was a significant negative effect. Compressive strength and flexural strength were significantly reduced.
Alkali-Activated Slag Based Composites During Specimens Ageing
2020
The aim of the paper is to present the results of the experiment focused on the development of the mechanical fracture characteristics of alkali-activated slag (AAS) based composites within the time interval from 3 days to 2 years of ageing. Two AAS composites, which differed only in the presence of shrinkage reducing admixture (SRA), were prepared for the purpose of experiments. The composites were prepared using ground granulated blast furnace slag activated by water-glass with silicate modulus of 2.0, standardized quartzite sand with the particle grain size distribution of 0−2 mm, and water. Commercially produced SRA was added into the second mixture in an amount of 2 % by weight of slag. The test specimens were not protected from drying during the whole time interval and were stored in the laboratory at an ambient temperature of 21 ± 2 °C and relative humidity of 60 ± 10 %. The prism specimens made of the abovementioned composites with nominal dimensions of 40 × 40 × 160 mm with...
Influence of High Temperature on Non-Silicate Based Activated Blast Furnace Slag
Lecture Notes in Civil Engineering, 2019
The energy consumption and the greenhouse gases emission in order to manufacture Portland cement (PC) is very high. To find an alternative, the researchers initially replace the PC partially by Fly Ash. Later on, the researchers introduce a new binder which is being manufactured by the activation of ground granulated blast furnace slag (GGBFS). The paper presents the detail of the binder, manufactured by GGBFS and mild alkali as activator having the pH value of 10. The binder is manufactured by simple blending in which 85% is GGBFS, and 15% is the chemical activator. The test results of the alkali activated binder concrete (AABC) for compressive strength, splitting-tensile strength and flexural strength were found after exposure to elevated temperature 100 ℃, 200 ℃, 300 ℃, 400 ℃, 500 ℃, 600 ℃, 700 ℃ and 800 ℃. It has been observed that these results of the AABC at elevated temperature were very much comparable with that of the ordinary Portland cement concrete (OPCC). The deterioration in strength starts from 200 ℃ onwards. No spalling of the alkali activated binder concrete (AABC) has been observed at elevated temperature even at 800 ℃.
Materials, 2019
The effects of fines and chemical composition of three types of ground granulated blast furnace slag (GGBFS) on various concrete properties were studied. Those studied were alkali activated by liquid sodium silicate (SS) and sodium carbonate (SC). Flowability, setting times, compressive strength, efflorescence, and carbonation resistance and shrinkage were tested. The chemical composition and microstructure of the solidified matrixes were studied by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) coupled with EDX analyser. The results showed that the particle size distribution of the slags and the activator type had significantly stronger effects on all measured properties than their chemical composition. The highest compressive strength values were obtained for the finest slag, which having also the lowest MgO content. SC-activated mortar produced nearly the same compressive strength values independently of the used slag. The most intensive efflorescence and the lowest carbonation resistance developed on mortars based on slag containing 12% of MgO and the lowest fineness. The slag with the highest specific surface area and the lowest MgO content developed a homogenous microstructure, highest reaction temperature and lowest drying shrinkage. Thermogravimetric analysis indicated the presence of C-(A)-S-H, hydrotalcite HT, and carbonate like-phases in all studied mortars.