Final Report April 2015
Excessive amounts of fly ash alkalis can cause efflorescence problems in concrete products and raise concern about the effectiveness of the fly ash to mitigate alkali-silica reaction (ASR). The available alkali test, which is commonly used to measure fly ash alkali, takes approximately 35 days for execution and reporting.
Optimising High Lime Fly Ash Content By Means of Silica Fume
- The fly ash with lower lime content reduced the 14-day ASR expansion more than that of fly ash with higher lime content. The opposite results were the case in 28-day ASR expansions. The ASR expansions of the fly ashbearing mixtures were significantly reduced by the introduction of the 5% silica fume. - Drying shrinkage of the mortars ...
Toughness study of polyacrylamide-modified slag/fly ash-based alkali
This study investigated the mechanical properties and toughness of slag/fly ash-based alkali-activated cementitious materials (AASF) by incorporating PAM with different molecular weights and dosages. ... the alkali content (Na 2 O as a percentage of the powder materials) was 8 %, and the activator modulus was 1.6. The PAM additive dosages were ...
Mechanisms of concentration control alkali activated fly ash …
The study investigates the impact of alkali content and FTs using various methods such as UCS tests, splitting experiments, FTs experiments, X-ray Diffraction (XRD), Scanning …
Addition of Class C Fly Ash To Control Expansions due to …
tors that influence the ability of fly ash to control ASR are the chem ical composition of fly ash, mixture proportions, type of reactive aggregates and amount of fly ash used. Some investigators, using low levels of fly ash replacement, have determined that the alkalies in fly ash participate in AS~ (3,4,18). OBJECTIVES
Effect of Fly Ash on Alkali-Silica Reactivity in Concrete
IP cement with a Class F fly ash that had an available alkali content of 0.50 percent. This investigation included fly ash from nine different sources. Five fly ashes were Class C and four were Class F as defined by ASTM C618. These fly ashes are presented in Table 2. Seven fly ash sources were selected on the basis of their clas
Effects of Fly Ash Inclusion and Alkali Activation on Physical
For example, when the fly ash content increased from 15% to 25%, the UCS of the soils stabilised with alkali-activated fly ash for the SM of 1.25 and M+ of 12% increased from …
Influence of the Fly Ash Content on the Fresh and Hardened …
Figure 1 shows the variation in initial and final setting times of alkali-activated slag/fly ash mixtures with variation in fly ash content and chemical admixture. The setting time of the BFS sample was an initial time of 9.8 h and a final time of 11.8 h, while those of the other samples were delayed: 10 h and 13.7 h for 85% BFS and 19 h ...
New insights into the role of fly ash in mitigating alkali-silica
The study was conducted to understand the effects of fly ash on alkali silica reaction (ASR) and specifically to investigate the role aluminum in fly ash in controlling the dissolution …
Alkaline Activation of Fly Ash: An Overview
Activation of fly ash enhance several properties of fly ash such as improvement in strength, shrinkage characteristics, acid and fire resistance, cold weather resistance, great workability …
What Is Fly Ash and How Is It Used in Concrete?
However, the danger to humans, wildlife, and the environment presented by fly ash production can be mitigated by using fly ash to improve the composition of concrete. Since fly ash contains aluminous and siliceous …
Effects of Fly Ash Inclusion and Alkali Activation on Physical
The UCS of the soil increased with the addition of alkali activators, fly ash content, and the curing time. The highest UCS result was found with 25% fly ash content, M+ of 16% and SM of 1.25 at 28 days of curing which can improve the …
Mechanisms of concentration control alkali activated fly ash …
In the framework of sustainable development and environmental preservation, this research aims to improve the stability and frost resistance of sulfate saline soil by utilizing industrial solid waste. Geopolymer materials containing fly ash (FA) activated by different NaOH concentrations were studied for study on stabilized soil with saline soil, with NaOH …
Alkali Content of Fly Ash
Sodium and potassium are the common alkalis present in fly ash. Excessive amounts of fly ash alkalis can cause efflorescence problems in concrete products and raise concern about the effectiveness of the fly ash to mitigate alkali-silica reaction (ASR). The available alkali test, which is commonly used to measure fly ash alkali, takes approximately 35 days for …
A multianalytical approach to understand the relationship …
2.1 Materials. The mortar bar specimens were prepared using ordinary ASTM C 150 Type I low alkali (Na 2 O eq = 0.26%) white portland cement (WPC) and a class F fly ash (chemical analysis provided in Table 1) with total alkali content of 1.75% Na 2 O eq.As in the case of the control system, the choice of WPC was to minimize problems due to fluorescence in the …
New insights into the role of fly ash in mitigating alkali-silica
Alkali-silica reaction (ASR) mitigation mechanisms of fly ash in concrete are still being debated and remain an interesting research topic. This study provides new insights into the role of ...
Addition of Class C Fly Ash To Control Expansions due to …
Fly ashes with high alkali contents (1.92 percent) were effective in inhibiting ex pansion related to ASR. Test results indicated that some Class C fly ashes at adequate replacement levels …
Role of High-Volume Fly Ash Concrete in Controlling Alkali …
The use of high-volume fly ash as a supplementary cementing material in controlling alkali-aggregate reactivity is an attractive solution. Fly ashes are often used in reducing the …
Influence of calcium oxide and sodium silicate on the setting
For the control group, as NaOH content increased from 5 % to 10 %, the drying shrinkage values at the same age gradually decreased. ... Shrinkage mitigation of alkali-activated fly ash/slag mortar by using phosphogypsum waste. Constr. Build. Mater., 375 (2023), 10.1016/j.conbuildmat.2023.130978. Google Scholar [46] T. Jiang, Y. Jin.
Fly ash sinking beads and
The most commonly used one-part AAC are GBFS and fly ash (FA). GBFS is the most commonly used raw material for AAC production. AAC derived from GBFS possess a dense microstructure and excellent mechanical properties [4], [5], but the disadvantage of using slag alone is that the setting time is too fast, which can narrow the application range of AAC [6].
Development of an eco-friendly geopolymer mortar using slag and fly ash
Hwang, C. L. & Huynh, T. P. Effect of alkali-activator and rice husk ash content on strength development of fly ash and residual rice husk ash-based geopolymers. Constr. Build.
Use and effect of fly ash in concrete: A literature review
A type of fly ash increasingly used for engineering purposes is Vietnamese fly ash, which is used in optimal dosages of 10% and 20%, where an improvement in its mechanical property of flexu ral
Assessing the effect of fly ash with a high SO3 content in hybrid
This requirement causes high energy consumption and makes it difficult to cure geopolymers on site. A way to avoid this problem is to use hybrid alkaline fly ash cement (HAFAC), which aims to maximize the use of fly ash (70 wt%–80 wt%) and minimize the use of OPC (20 wt%–30 wt%) in the binder through alkaline activation [8].
The effect of fly ash additive on the resistance of concrete to alkali
Fly ash additives increased concrete alkali silica reaction resistance. Fly ash additives can be used for modification of concrete. Concrete is the most widely used …
Using Class C Fly Ash to Mitigate Alkali Silica Reactions in …
mitigation when 25% of high-alkali cem ent was replaced with Class C fly ash. Lenke and Malvar 5 report that there are three characte ristics of a fly ash that determine its efficiency in …
How does fly ash mitigate alkali–silica reaction (ASR) in …
In the case of concrete using fly ash, under standard curing condition, the use of fly ash content from 15% to 25% replacement of OPC reduces significantly ASR [9, 10]. Effective content of fly as ...
EVALUATION AND BENEFICIATION OF HARVESTED AND …
the use of landfilled fly ash will hopefully encourage their use and ultimately increase the supply of fly ash available for producing high quality and green concrete. Additionally, the work done on high sulfur and/or high alkali fly ash will encourage …
Mechanisms of concentration control alkali activated fly ash …
Mechanisms of concentration control alkali activated fly ash stabilized saline soil in seasonally frozen regions. Sining Li; Yong Huang; Jian Sun; Qiushuang Cui; Rui Yu; Yubin Liu; Read the full article See related articles. Listed in This article is not in any list yet, why not save it to one of your lists.
(PDF) Synthesis and characterization of alkali-activated materials
Effects of the alkali content of biomass fly ash, after a washing pretreatment (WBFA), as well as the concentration of NaOH solution on the physical, mechanical and microstructural properties of ...
Rheology control and 3D concrete printing with fly ash
of using Bentonite clays in enhancing the yield stress and thixotropic buildup suitable for 3DCP is evalu-ated. The reduction in the requirement of clay by uti-lizing synergy with CMC is explored. 2 Materials and mehodst 2.1 Source materials Alkali activated pastes were prepared using y ash and slag as the binder materials. Class F or