scholarly journals The Effect of Calcium Formate, Sodium Sulfate, and Cement Clinker on Engineering Properties of Fly Ash-Based Cemented Tailings Backfill

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Wenbin Xu ◽  
Qianlong Li ◽  
Sada Haruna
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Sulfate ◽  
Setting Time ◽  
Practical Interest ◽  
Engineering Properties ◽  
Cement Clinker ◽  
Strength Development ◽  
Water Rate ◽  
Calcium Formate

The influence of admixtures on the engineering properties of fly ash-based cemented tailings backfill (CTB) is a topic of significant practical interest, as it affects the backfilling cost and the environmental effect of mining operation. This paper presents results of an experimental study on the influence of different activators on the engineering properties of the CTB containing fly ash. CTB samples are mixed with different contents of calcium formate, sodium sulfate, and cement clinker (4%, 8%, and 12% by mass of total binder) and cured in a cubic chamber (at 20°C and RH 90 ± 5%) for 3, 7, and 28 days. Specimen tests were performed to assess the slump height, setting time, leaching water rate, vertical settlement, and strength development. Furthermore, the XRD analyses were conducted on the hydration products of fly ash-based CTB mixtures. The results show that activators can cause decrease in the slump height, leaching water rate, and vertical settlement of fly ash-based CTB mixtures. However, inclusion of cement clinker ranging from 8%–12% of total binder can reduce the slump height, setting time, leaching water rate, and vertical settlement to an acceptable range. Addition of calcium formate in the fly ash-based CTB caused negligible change in compressive strength. The compressive strength improved with higher content of sodium sulfate and cement clinker at the age of 28 days. XRD analyses showed considerable intensity counts of C-S-H gel, calcium hydroxide, and ettringite, resulting from the addition of sodium sulfate and cement clinker. This study also shows that an understanding of the effect of activators on the engineering properties of fly ash-based CTB is crucial for designing a cost-effective and workable CTB with reduced environmental impact.

The Effect on Cement Mortar and Concrete by Admixture of Spray Drying Absorption Products

1989 ◽  
Vol 178 ◽  
Author(s):  
Kirsten G. Jeppesen
Keyword(s):  
Grain Size ◽  
Fly Ash ◽  
Cement Mortar ◽  
Setting Time ◽  
Mineralogical Composition ◽  
Cement Clinker ◽  
Strength Development ◽  
Fall Meeting ◽  
Freeze Thaw ◽  
Spray Dried

AbstractSpray dried absorption products (SDA) having special characteristics are used as substitutes for cement in the preparation of mortars; the qualities of the resulting mixed mortars are described. Conditions are described for mortar mixes, data for which were presented at the MRS Fall Meeting 1987.The influence of the composition of the SDA on water requirement and setting time has been studied. A full scale project involving 3 precast, reinforced concrete front-elements containing 20 and 30 wt.% SDA is described. Strength development, mineralogical composition and corrosion were monitored for two years.A non-standard freeze-thaw experiment was performed which compares mortars containing SDA and fly ash (FA) and also shows the effect of superplasticizer.The possibility of improving the SDA by grinding has been tested and a limited improvement has been found. The strength of the mixed mortars seems slightly influenced by the grain size of SDAGypsum (CaSO4·2H2O), synthetic calcium-sulphite (CaSO3·½H2O) and 2 SDAs have been used as retarders for cement clinker. Mortar test prisms have been cast and comparative strengths after curing for 3 years are reported

scholarly journals Influence of Mechanical and Mineralogical Activation of Biomass Fly Ash on the Compressive Strength Development of Cement Mortars

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6654
Author(s):  
Jakub Popławski ◽  
Małgorzata Lelusz
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Cement Mortar ◽  
Setting Time ◽  
Green Energy ◽  
Biomass Combustion ◽  
Strength Development ◽  
Compressive Strength Development ◽  
Biomass Fly Ash

Biomass combustion is a significant new source of green energy in the European Union. The adequate utilization of byproducts created during that process is a growing challenge for the energy industry. Biomass fly ash could be used in cement composite production after appropriate activation of that material. This study had been conducted to assess the usefulness of mechanical and physical activation methods (grinding and sieving), as well as activation through the addition of active silica in the form of silica fume, as potential methods with which to activate biomass fly ash. Setting time, compressive strength, water absorption and bulk density tests were performed on fresh and hardened mortar. While all activation methods influenced the compressive strength development of cement mortar with fly ash, sieving of the biomass fly ash enhanced the early compressive strength of cement mortar. The use of active silica in the form of silica fume ensured higher compressive strength results than those of control specimens throughout the entire measurement period.

scholarly journals Alkali-Activated Hybrid Concrete Based on Fly Ash and Its Application in the Production of High-Class Structural Blocks

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 946
Author(s):  
Oriana Rojas-Duque ◽  
Lina Marcela Espinosa ◽  
Rafael A. Robayo-Salazar ◽  
Ruby Mejía de Gutiérrez
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Modulus ◽  
Setting Time ◽  
Modulus Of Rupture ◽  
Strength Development ◽  
Block Type ◽  
High Class ◽  
Structural Blocks ◽  
Alkali Activated

This article reports the production and characterization of a hybrid concrete based on the alkaline activation of a fly ash (FA) of Colombian origin, which was added with 10% Portland cement (OPC) in order to promote the compressive strength development at room temperature. The alkali-activated hybrid cement FA/OPC 90/10 was classified as a low heat reaction cement (type LH), according to American Society of Testing Materials, ASTM C1157; the compressive strength was of 31.56 MPa and of 22.68 MPa (28 days) at the levels of paste and standard mortar, respectively, with an initial setting time of 93.3 min. From this binder, a hybrid concrete was produced and classified as a structural type, with a compressive strength of 23.16 MPa and a flexural modulus of rupture of 5.32 MPa, at 28 days of curing. The global warming potential index (GWP 100), based on life cycle analysis, was 35% lower than the reference concrete based on 100% OPC. Finally, its use was validated in the manufacture of a solid block-type construction element, which reached a compressive strength of 21.9 MPa at 28 days, exceeding by 40.6% the minimum strength value established by the Colombia Technical Standard, NTC 4026 (13 MPa) to be classified as high class structural blocks.

Interrelationship Analysis of Geopolymer Components Using Pearson Correlation Technique

2014 ◽  
Vol 567 ◽  
pp. 417-421 ◽  
Author(s):  
Andri Kusbiantoro ◽  
Norbaizurah Rahman ◽  
Noor Fifinatasha Shahedan
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Elemental Composition ◽  
Setting Time ◽  
Source Material ◽  
Curing Temperature ◽  
Strength Development ◽  
Correlation Technique ◽  
High Calcium ◽  
Geopolymer Binder

Performance of geopolymer based specimens is significantly affected by internal and external aspects. Curing temperature and air humidity are among the prominent external factors that contribute to the alteration of geopolymer properties. Nevertheless, internal component of geopolymer binder also carries essential effect to the hardened geopolymer binder produced. In this research, the study was concentrated on the elemental composition of source material components and their interrelation to the performance of geopolymer binder produced. Different types of fly ash were used as the source material in this research. Low calcium (class-F) fly ash was combined with high calcium (class-C) fly ash to determine the elemental composition effect, particularly SiO2, Al2O3, and CaO to the geopolymer properties. Analysis using SYSTAT statistical software indicated the importance of oxide composition of source material to the geopolymer specimens produced. Initial setting time of geopolymer paste was also possibly important to the compressive strength of geopolymer specimens produced. Nevertheless, final setting time indicated less importance to the compressive strength development of geopolymer binder.

scholarly journals Rapid Indicators in Detecting Variation of Fly Ash for Making HVFA Concrete

2015 ◽  
Vol 815 ◽  
pp. 153-157 ◽  
Author(s):  
Antoni ◽  
Rianto Gunawan ◽  
Djwantoro Hardjito
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Power Plants ◽  
Water Solution ◽  
Setting Time ◽  
Cementitious Materials ◽  
Strength Development ◽  
Quick Method ◽  
Alternative Material

The use of fly ash as an alternative material for cement substitute in concrete mix already a common practice nowadays. However, as a waste material, fly ash varies in quality and condition, as shown by variation of its fineness, specific gravity, Loss on Ignition (LOI) and also on its chemical composition. By measuring the acidity (pH) of the fly ash in water solution, percentage of mass retained on 45 μm sieve, and superplasticizer demand of the fly ash, we can develop a quick estimation of the quality of fly ash. This study aims to investigate a quick method to estimate the quality of fly ash by measuring the physical and chemical pointers, as indicator for its properties and the effect on the setting time and compressive strength of mortar. Fly ash content was varied from 0-70% of the total mass of cementitious materials to make HVFA mortar. Fly ashes were obtained from four power plants in Indonesia. Tests conducted were material characterization, setting time, temperature rise, and compressive strength of mortar at different ages. Different fly ash quality can be shown by the fast pointers; namely pH, superplasticizer demand and % retained on 45 μm sieve. Setting time and strength development were affected by the different properties of fly ash.

Engineering Properties of Controlled Low-Strength Material Made with Residual Soil and Class F Fly Ash

2014 ◽  
Vol 597 ◽  
pp. 345-348 ◽  
Author(s):  
Yeong Nain Sheen ◽  
Li Jeng Huang ◽  
Duc Hien Le
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Fly Ash ◽  
Setting Time ◽  
Engineering Properties ◽  
Residual Soil ◽  
Strength Material ◽  
Low Strength ◽  
Controlled Low Strength Material ◽  
Class F Fly Ash

This paper aims to employ combination of residual soil and Class F fly ash in developing a controlled low-strength material (CLSM), primarily used as backfilling material. In the mixture, surplus soil and concrete sand was blended well together with a given proportion of 6:4 by volume. Three levels of binder content (i.e. 80-, 100-and 130 kg/m3) and different percentages fly ash (i.e., 0%, 15%, 30%, and 45%) substituting to Portland cement were previously chosen for mix design. Several major engineering properties of the CLSM such as fresh density, flowability, setting time, water bleeding, unconfined compressive strength, and elastic modulus were investigated via a laboratory study. Testing results indicate that most of the proposed CLSM mixtures satisfy the requirements of excavatability as the 28-days compressive strength ranges from 0.3 to 1.4 MPa. In addition, increase in FA substituting to OPC resulted in workability improvement, setting time extension as well as compressive strength and elastic modulus reduction.

scholarly journals Setting and Hardening Behaviour of Alkali-Activated Landfilled Fly Ash–Slag Binder at Room Temperature

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3130
Author(s):  
Wei Liu ◽  
Lin Lin ◽  
Shuping Wang ◽  
Xiaoqin Peng ◽  
Bobo Wu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Room Temperature ◽  
Setting Time ◽  
Three Dimensional ◽  
Industrial Wastes ◽  
Dimensional Structure ◽  
Strength Development ◽  
Na2o Content ◽  
Solid Ratio

A geopolymer is normally considered an environmentally friendly binder due to the utilisation of industrial wastes. This study focusses on the potential of geopolymer preparation at room temperature from landfilled fly ash (LFA) which has been discharged to the land for more than three years. To accelerate the reaction process, 20–30 wt.% LFA was replaced by ground-granulated blast-furnace slag (GGBS). The effect of water glass modulus, Na2O content, water-to-solid ratio, and GGBS content on the setting time and strength development of the binder was discussed. Results showed that to activate LFA, the optimal value of the sodium silicate modulus for alkaline solution was 1.4–1.6 with a Na2O content of 10%, and the water-to-solid ratio was 0.4. In addition, the setting time of the binder reduced with increasing content of GGBS replacement, and the compressive strength increased due to the coexistence of C–(A)–S–H and zeolite-like phases. The maximum compressive strength of the binder was 29.2 MPa after 56 days of curing. The relatively low strength was likely due to the absence of the Q4 unit with a three-dimensional structure.

scholarly journals Study on Setting & Strength Characteristic of GGBS based Geopolymer Concrete by Blending of Fly Ash and Metakaoline

2020 ◽  
Vol 13 (1) ◽  
pp. 117-122
Author(s):  
Addepalli Mallinadh Kashyap ◽  
Tanimki Chandra Sekhar Rao ◽  
N.V. Ramana Rao
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Setting Time ◽  
Engineering Properties ◽  
Geopolymer Concrete ◽  
Conventional Concrete ◽  
New Material

Carbon dioxide is liberated in huge amounts by the manufacturing of Portland Pozzolana Cement. Normally, conventional concrete is manufactured with Portland cement, which acts as a binder. The production of cement emits CO2 into the atmosphere, which is a green house gas and causes the environmental pollution. Considering this as a serious environmental problem, there is a need to develop sustainable alternatives to Portland cement utilizing the industrial byproducts such as fly ash, ground granulated blast furnace slag and Metakaoline which are pozzolonic in nature. It has been established that fly ash can replace cement partially. In this context, a new material was developed known as ‖Geopolymer‖. In this study, the various parameters on the short term engineering properties of fresh and hardened properties of Geopolymer Mortar were studied. In the present investigation, cement is replaced by geopolymer source material and water is replaced by alkaline activator consisting of Sodium Silicate and Sodium Hydroxide of molarity (12M). The ratio of sodium silicate to sodium hydroxide adopted was 2.5. The test results showed that final setting time decreases as the GGBS content in the mix increases and also increase in compressive strength. Where as in the case of metakaoline, as the content increases, there is a decrease in compressive strength and setting times of the geopolymer concrete.

Development of Geopolymer Utilizing Inorganic Waste Materials

2014 ◽  
Vol 896 ◽  
pp. 553-556 ◽  
Author(s):  
Tjokorde Walmiki Samadhi ◽  
Pambudi Pajar Pratama ◽  
Nurhidayati Muan
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Setting Time ◽  
Factorial Experiment ◽  
Curing Temperature ◽  
Engineering Properties ◽  
Waste Materials ◽  
Setting Times ◽  
Wide Range ◽  
Inorganic Waste

Geopolymers, which are produced by the reaction between aluminosilicate solid precursors and concentrated alkali solutions, is an environmentally attractive construction material due to its much smaller carbon footprint compared to ordinary Portland cement (OPC), and its ability to consume a wide range of solid inorganic waste materials. This work describes the synthesis of geopolymers utilizing local aluminosilicate materials and the evaluation of several key engineering properties of the geopolymer product as a construction cement. A simple 22factorial experiment is undertaken to measure the effect of types aluminosilicate solids (metakaolin produced by calcining a Belitung kaolin at 750 °C, and coal fly ash from an East Java baseload powerplant) and alkali activators (NaOH and KOH solutions) on the initial and final setting time of the geopolymer cement mortar. All geopolymer mortar samples exhibit longer setting times compared to OPC mortars. Statistical analysis indicates that KOH produces faster initial setting than NaOH, while fly ash produces faster setting times compared to metakaolin. A 23factorial experiment is conducted subsequently, adding curing temperature (60 and 80 °C) to the experimental factors. The key engineering property measured in the second experiment is the compressive strength of geopolymer mortars. ANOVA treatment of the measured data indicates that all three experimental factors significantly impacts the compressive strength. Consistent with the preceding experiment, the use of fly ash and KOH significantly increases the strength of the geopolymer mortar. Higher curing temperature is also found to increase the strength. The use of metakaolin as geopolymer precursor produces compressive strength approximately 50% than that of the OPC mortar, while fly ash produces a geopolymer mortar strength that is at least as good as OPC.

Study on the Adaptability Between the Amount of C3S Mineral in Alite-Sulphoaluminate Cement Clinker and the Fly Ash

2011 ◽  
Vol 306-307 ◽  
pp. 975-979
Author(s):  
Yuan Chao Wu ◽  
Xiao Cun Liu ◽  
Bao Liang Li ◽  
Tong Liu ◽  
Wei Shan Wang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Setting Time ◽  
Cement Clinker ◽  
Sulphoaluminate Cement ◽  
Cement Clinkers ◽  
Addition Amount

The paper studied the adaptability between alite-sulphoaluminate cement clinkers with different amount of C3S and the fly ash admixture. The results showed that: with a fixed content of C3S, the setting time of the cement delayed, and the compressive strength of the cement decreased with increasing amount of fly ash admixture. With a fixed content of the fly ash admixture, the setting time of the cement delayed, the compressive strength of the cement increased with the increase amount of C3S, and the lowed percentage of the strength decrease at each ages; With addition of fly ash admixture, the early compressive strength of the cement decreased more, while the later compressive strength decreased less. Clinker with higher C3S content showed better adaptability with high addition amount of fly ash admixture.

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