Chloride ingress through alkali-activated mortar samples was found to be moderate to high when fly ash content exceeded 20% of the slag and fly ash blended binder. Bondar et al. ( Bondar et al., 2019 ) described mortar with activated slag/fly ash binder with a ratio of 80/20 as having low chloride diffusivity, and mortar having a …
Low-temperature alkali-modified fly ash as an effective adsorbent for removal of ammonia nitrogen, phosphorus and COD from the wastewater. Ruihong Meng 1, Pengcheng Lv 2, ... Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain …
The alkali element content is second only to the sulfur content as the most important factor affecting dust-specific resistivity. Size sieving, soaking in distilled water, and ion migration at a high voltage are effective methods of changing the sodium and potassium contents in fly ash.
Sintered fly-ash based aggregate: Alkali-activated GGBFS: 20–30% replacement by volume: Decrease of flexural strength from 5.7 to 2.9 MPa and compressive strength from 42.5 to 15.2 MPa: This study: Sand: Alkali-activated fly ash/slag: 25, 50 and 75% replacement of sand by volume: Decrease from 52 to 28, 20 and 13 MPa [33]
When fly ash content is increased to 45%, UPV increases up to 4145 m/s or 1.17% more. The highest UPV of 4151 m/s was recorded in specimens containing 55% of fly ash, and this value is 1.32% higher compared to UPV in control specimens. When fly ash content is increased to 65%, UPV drops down to 4147 m/s.
The effect of alkali content of fly ash on ASR expansion was reported by several researchers. Schumacher & Ideker ... [103] found that low alkali fly ash was more effective than high alkali fly ash to reduce the ASR expansion after more than 10 years of testing period, as shown in Fig. 7. It can be seen that both low alkali and high alkali fly ...
Alkali-activation is effective municipal solid waste incineration fly ash (MSWIFA) solidification ... CFA is captured in the power plant, its water content is 0.72% and the D 50 is 3.29 μm. By the same methods in the tests of MSWIFA, its activity index and specific surface area are 762 m ... Municipal solid waste incineration fly ash (MSWI …
CaAl-LDH was the most effective in reducing the content of free Cl-. ... B. Sun, G. Ye, G. de Schutter, A review: Reaction mechanism and strength of slag and fly ash-based alkali-activated materials, Constr. Build. Mater. 326 …
It was reported that fly ash can be converted into zeolites in alkali solutions by hydrothermal reaction, which is an effective method to produce new values from fly ash and reduce the environmental pollution problem caused by a stack of fly ash [27]. During the hydrothermal reaction process of synthesizing zeolite, a kind of sodium silicate ...
To activate the binder components in fly ash/GGBS-based geopolymers, granular sodium metasilicate (Na 2 SiO 3) anhydrous (50% Na 2 O, 46% SiO 2, and 4% H 2 O) is often employed as a solid activator. Since, unlike two-part geopolymers, there is no need to create a NaOH solution before mixing, using granular alkaline activators in one …
The preferred production route involves hydrothermal treatment of coal fly ash in a strong alkali solution. The process involves several parameters, such as reaction temperature, time, the concentration and amount of alkali solution, and silica content in the fly ash, all of which strongly and non-monotonically affect the conversion.
To solve the problem of environmental pollution from stockpiling of solid waste and to achieve safe and efficient underground engineering, an environment-friendly waste-based ternary geopolymer grout was developed using blast furnace slag, sunflower stalk ash, and black rice hull ash. KOH-activated grouts were used as the controls. The …
Studies on Physio Chemical Properties of Fly Ash for their Effective Alkali Activation Revathi 1, Jeyalakshmi * Rajamane2, Sivasakthi, Dhinesh3 ... Amorphous content in the fly ash has notbeen quantified from XRD. The glassy phase content of fly ash was determined by ...
The Class F fly ash used in this experiment was obtained from the Huaneng Power Plant in Qingdao, Shandong Province, China. It has a specific surface area of 517 m 2 /kg and an apparent density of 2.12 g/cm 3.Its chemical composition is listed in Table 2.The total Si oxide and Al oxide content of the fly ash is 82.45 %.
The value for a 25% RL was interpolated to be 0.112%. The graph includes the expansion data provided by CTS laboratory. Concrete containing fly ash of alkali content >4.0% Na 2 O e are represented by the hollow markers while those containing fly ash of alkali content <4.0% Na 2 O e are represented by solid markers. Also, the Type of the …
Alkali activation became the most cost-effective solution to this problem and can be utilised in precast structures and concrete products that are resistant to heat and environmental decay. ... Fly ash has a …
Studies on Physio Chemical Properties of Fly Ash for . their Effective Alkali Activation. Revathi. 1, Jeyalakshmi * Rajamane. 2 ... Fly Ash; CTM: Compression Testing Machine; GSM: Geo polymer ...
The laboratory test program [11], which included, in addition to DX fly ash, a fly ash with 36.3% retained on the 45 μm sieve, indicated that fly ashes of varying fineness (up to the EN 450 limit) were equally effective in controlling expansion provided the alkali content of the fly ash was similar.
As a result, it can be concluded that the 1-month alkali solution injection was effective in accelerating the pozzolanic reaction of the cement paste with 40% replacement of fly ash. Previous article in issue; ... which had 2 times as high the fly ash content as FA20, was 2.6 and 4.5 times as much as that for FA20 in the case of the …
With a SiO 2 content above 50%, it is a high-silica fly ash, more suitable as a ... The sodium silicate solution made from roasted fly ash by acid dissolution-alkali leaching is used as the silicon source, and the sodium silicate solution is passed through a strongly acidic cation exchange resin to obtain a silicic acid solution with a pH of 2 ...
Mortar-bar expansion tests, conducted in accordance with Iowa DOT IM 491.17, did not …
This study aimed to develop a high-strength, cost-effective, and low-carbon alkali-activated slag/bagasse ash (AASL/BA) composites through multi-objective optimization (MOO) models. The results showed that increasing SCBA content reduced the compressive strength of AASL/BA, particularly beyond 50 %.
The chemical reaction between reactive silica or alumina in fly ash and calcium hydroxide (Ca(OH) 2 –CH) formed from hydration of cement at intermediate temperatures to form durable products such as calcium silicate hydrate or calcium aluminate hydrate is known as the pozzolanic reaction [].Because of its pozzolanic …
The XRD pattern for fly ash is shown in Fig. 2.Almost all crystalline peaks could be identified and were classified into either Mullite (Al 4.66 Si 1.39 O 9.75) or Quartz (SiO 2).The hump in the XRD pattern, in the 2theta range 17°–33°, is indicative of the amorphous phases which are considered as potential reactive components for alkaline …
This study uses fly ash to replace partial cement. NaOH is used to increase alkali content of cement to 1.0% Na 2 O eq.LiOH and LiNO 3 are added separately to obtain several Li/(Na + K) molar ratios to fabricate cement specimens cured at 38 °C in a relative humidity environment. This study aims to observe the diachronic changes …
The high content of Al 2 O 3 and SiO 2 in class F fly ash make it suitable for conversion to other substrates with high-capacity adsorption. Class F fly ash has been chemically altered into a substrate having a surface with high polarity by hydrothermal …
PDF | On Apr 23, 2018, Revathi and others published Studies on Physio Chemical Properties of Fly Ash for their Effective Alkali Activation | Find, read and cite all the research you need on ...
Alkali activation of fly ash with proper mix design and correct formulations can exhibit very good strength and chemical resistance and other potentially valuable characteristics similar or even ...
The effective thermal conductivity of ed concrete is influenced by the porosity, ... The mass content of fly ash in alkali-excited concrete should not surpass 20 %, and the mass content of the aerogel must be less than 8 % to circumvent material waste and substantial strength loss. While can considerably decrease the thermal ...
Two Portland cements (PC) with alkali contents, of 1.02% Na 2 O e (HAPC) and 0.60% Na 2 O e (LAPC) were used together with 18 fly ashes with a wide range of chemical composition. The chemical compositions of the PCs and fly ashes are presented in Table 1. Recently published changes in the Canadian specifications for …
Especially, in order to determine the effective alkali content for the detection of alkali activity of aggregate, ... New insights into the role of fly ash in mitigating alkali-silica reaction (ASR) in concrete. Cement and Concrete Research, 144 (2021), Article 106440. View PDF View article View in Scopus Google Scholar
Download scientific diagram | Alkali content in fly ash with different particle size. from publication: Mechanism of the effect of alkali metal on the electrostatic precipitability of fly ash ...
The decreased strength of ACC-20 compared to ACC-10 can be attributed …
The volume of gel pores gradually increased from 7 days (Fig. 8 a) to 90 days (Fig. 8 c) in all HVFA pastes regardless of alkali content. At the early stage of 7 days, the volume of gel pores was directly related to alkali content. This could be associated with the faster rate of hydration of the HVFA system at an early age.
However, Gao et al. [14] found that increasing SF content reduced the workability of alkali-activated slag-fly ash paste since more water was needed to wet particle surface. Moreover, SF exhibits potential as an activator due to its chemical reactivity, serving as a supplier of silicates in alkaline solutions [15], [16] .
