scholarly journals Use of Off-ASTM Class F Fly Ash and Waste Limestone Powder in Mortar Mixtures Containing Waste Glass Sand

2021 ◽  
Vol 14 (1) ◽  
pp. 75
Author(s):  
Chang-Seon Shon ◽  
Aidyn Tugelbayev ◽  
Ramazan Shaimakhanov ◽  
Nariman Karatay ◽  
Dichuan Zhang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Waste Glass ◽  
Recycled Concrete ◽  
Limestone Powder ◽  
River Sand ◽  
Single Use ◽  
Glass Sand ◽  
Class F Fly Ash ◽  
Class F

Developing sustainable concrete with less ordinary Portland cement is a growing issue in the construction industry. Incorporating industrial by-products (such as fly ash or slag) or municipal solid wastes (such as waste glass or recycled concrete aggregate) into the concrete becomes an effective way to reduce the consumption of natural sources and carbon dioxide emission if a proper mix design is provided. The present study examines the influence of the combined use of off-ASTM Class F fly ash (FFA) and waste limestone powder (LSP) on flowability, compressive strength, and expansion characteristics of mortar mixtures containing waste glass sand (WGS). FFA and LSP were used as cement replacement while WGS was used as partial reactive siliceous river sand replacement. Material variables included different WGS replacement ratios (25%, 50%, and 75%) with river sand, LSP contents (25%, 50%, and 75%), FFA contents (15%, 30%, and 45%), and different combinations of FFA-LSP (15–10%, 15–15%, 15–30%, and 15–35%). It is shown that the single use of FFA or LSP reduces both compressive strength and flowability of mortar mixture as its replacement level increases. However, mixtures combined with FFA and LSP provide higher or comparable strength to the single LSP or FFA mixture. For the expansion characteristics due to alkali-silica reaction, the single-use of more than 30% FFA or 75% LSP has less than 0.1% expansion, which is a non-reactive aggregate criterion based on the C1260/C1567 when the test period is extended to 56 days. Moreover, the combination of FFA and LSP has a considerable reduction in expansion rate compared to the single FFA or LSP mixture.

scholarly journals Influence of the Nature and Rate of Alkaline Activator on the Physicochemical Properties of Fly Ash-Based Geopolymers

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Marouane EL Alouani ◽  
Saliha Alehyen ◽  
Mohammed EL Achouri ◽  
Abdelowahed Hajjaji ◽  
Chouaib Ennawaoui ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Physicochemical Properties ◽  
Fire Resistance ◽  
Electrical Performance ◽  
Infrared Spectrometry ◽  
X Ray ◽  
Alkaline Activator ◽  
Class F Fly Ash ◽  
Class F

The influence of alkali cations on mix design of geopolymers is essential for their mechanical, thermal, and electrical performance. This research investigated the influence of alkali cation type on microscale characteristics and mechanical, dielectric, and thermal properties of fly ash-based geopolymer matrices. The geopolymers were elaborated via class F fly ash from the thermal plant Jorf Lasfar, El Jadida (Morocco), and several alkaline solutions. Morphological, structural, mechanical, dielectric, and thermal characteristics of materials synthesized via fly ash with different proportions of KOH and NaOH aged 28 days were evaluated. The physicochemical properties of class F fly ash-based geopolymers were assessed using X-ray diffraction (XRD), Fourier-transform infrared spectrometry (FTIR), and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX) analyses. Based on readings of the results obtained, XRD and FTIR analysis detected the creation of semicrystalline potassium/sodium aluminate-silicate hydrate (KASH/NASH) gel in the elaborated matrices after the geopolymerization reaction. The SEM analysis proved the formation of alkali alumina-silicate hydrate gel in the raw material particles after the polycondensation stage. Experimental compressive strength data indicated that the highest compressive strength (39 MPa) was produced by the alkaline activator (75% KOH/25% NaOH). The dielectric parameters values of the elaborated materials changed depending of the mass ratios KOH/NaOH. Dielectric findings demonstrated that geopolymers containing 100% NaOH have better dielectric performances. The fire resistance study revealed that the geopolymer binders induced by KOH are stable up to 600°C. Based on these results, it can be deduced that the formulated geopolymer concrete possesses good mechanical, dielectric, and fire resistance properties.

Hydroceramic-Concrete Designed for a Project Material of Soil Stabilization

2012 ◽  
Vol 450-451 ◽  
pp. 756-763
Author(s):  
Ri Gao Chen ◽  
Yi Lan Chen ◽  
Xin Yue Zhao ◽  
Michael W Grutzeck
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Room Temperature ◽  
Soil Stabilization ◽  
Coagulation Time ◽  
Conventional Concrete ◽  
Good For ◽  
Class F Fly Ash ◽  
Cementing Material ◽  
Class F

As the traditional material commonly used, cement has its own limitation such as limited solidifying objects, bad stability in water, high cost and uneasy adjustment in coagulation time, not good for solidifying the waste etc.. The succeed in developing a hydroceramic-concrete for soil stabilization can take place of traditional cementing material such as conventional concrete applying and avoid the shortage of them. Here we show that a mixture of Class F fly ash, metakaolin and 8M NaOH (hydroceramic) will harden at room temperature, attaining 9.2 MPa compressive strength at 90 days, It is suggested that a hydroceramic-concrete may be used as a project material of soil stabilization as it has similar or even better compressive strength than conventional concrete.

scholarly journals Experimental and Statistical Study on Mechanical Characteristics of Geopolymer Concrete

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1651 ◽  
Author(s):  
Yifei Cui ◽  
Kaikai Gao ◽  
Peng Zhang
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Fly Ash ◽  
Mechanical Characteristics ◽  
Statistical Hypothesis ◽  
Geopolymer Concrete ◽  
Empirical Equations ◽  
Class F Fly Ash ◽  
Class F

This paper studies the statistical correlation in mechanical characteristics of class F fly ash based geopolymer concrete (CFGPC). Experimentally measured values of the compressive strength, elastic modulus and indirect tensile strength of CFGPC specimens made from class F fly ash (CFA) were presented and analyzed. The results were compared with those of corresponding ordinary Portland cement concrete (OPCC) using statistical hypothesis tests. Results illustrated that when possessing similar compressive and tensile strength, the elastic modulus for CFGPC is significantly lower than that of OPCC. The corresponding expressions recommended by standards for the case of OPCC is proved to be inaccurate when applied in the case of CFGPC. Statistical regression was used to identify tendencies and correlations within the mechanical characteristics of CFGPC, as well as the empirical equations for predicting tensile strength and elastic modulus of CFGPC from its compressive strength values. In conclusion, CFGPC and OPCC has significant differences in terms of the correlations between mechanical properties. The empirical equations obtained in this study could provide relatively accurate predictions on the mechanical behavior of CFGPC.

scholarly journals Development of Sustainable Eco-friendly Geopolymer Composites for Construction Applications

2020 ◽  
Author(s):  
Mohamed Rabie ◽  
Mohammad Irshidat ◽  
Nasser Al-Nuaimi
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Power Plants ◽  
Sodium Hydroxide Solution ◽  
Testing Machine ◽  
Heat Curing ◽  
Alkali Solutions ◽  
Binder Ratio ◽  
Class F Fly Ash ◽  
Class F

Geopolymerization is a process where silica and alumina rich source materials turns into excellent binding materials by the aid of alkali solutions. Materials such as fly ash are by-products in energy power plants. Fly ash is classified based on its constituent materials. Fly ash class F mainly consists of alumina and silica. Compressive strength of class F fly ash geopolymer mortar is influenced by many factors such as the molarity of sodium hydroxide solution, fluid to binder ratio, Na2SiO3/NaOH ratio, curing duration and curing temperatures. The present study investigates the effect of these factors on the compressive strength of geopolymer mortar. For each combination, three cubes with dimensions of 50 x 50 x 50 mm were casted. After heat curing in the laboratory oven, the samples were tested on a universal testing machine for the compressive strength. The results showed very high early compressive strength of 63.9 MPa for samples cured at 80 °C and for a duration of 24 hr.

Sign in / Sign up

Export Citation Format

Share Document