scholarly journals Pozzolanic Effect on the Hydration Heat of Cements Incorporating Fly Ash, Obsidian, and Slag Additives

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Ilker Ustabas ◽  
Sakir Erdogdu ◽  
Ihsan Omur ◽  
Erol Yilmaz
Keyword(s):  
Fly Ash ◽  
Cementitious Materials ◽  
Climate Impact ◽  
Hydration Heat ◽  
Replacement Rate ◽  
Blended Cements ◽  
Pozzolanic Material ◽  
Durable Products ◽  
Chloride Sulfate

Made up of an engineered mix of ordinary Portland cement (OPC) with artificial pozzolans such as trass, fly ash, and slag, the blended cements have been intensely employed within cementitious materials. The main reasons behind this intensive use can be clarified by enhanced workability/strength, the high resistance to chloride/sulfate, reduced permeability/alkali-silica reaction, and a drop in the heat generated by cement’s hydration. The use of cementitious blends within concrete not only offers durable products but also cuts climate impact by energy saving and falling CO2 emissions. This study presents pozzolanic effect on the hydration heat of cements incorporating fly ash, obsidian, and slag additives. The blended cements were manufactured by three different replacement ratios of 20%, 30%, and 50%. The change in the hydration heat of obsidian-, fly ash-, and slag-based cements was observed by several Turkish standards (TS EN 196-8 and TS EN 196-9). Mortars were used for determining the uniaxial strengths of obsidian-, fly ash-, and slag-based cements. The results show that cement’s hydration heat decreases as the rate of additives (e.g., obsidian) increases from 20% to 50%. The cement’s fineness greatly affects its hydration heat. Increasing the refinement of pozzolanic material to a certain level (30%) leads to an increase in the hydration temperature. After reaching this level, there is no clear relation between the fineness and the replacement rate of pozzolans. As a result, the findings of this work will provide a good understanding of artificial pozzolans on performance and quality of obsidian-, fly ash-, and slag-based cements.

scholarly journals Effect of Bogue Potential Phases of Clinker on the Mechanical Strength of Fly ash-Limestone Based Portland Composite Cement

2021 ◽  
Vol 2 (2) ◽  
pp. 1-6
Author(s):  
B N Mohapatra
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Natural Resources ◽  
Mechanical Strength ◽  
Cementitious Materials ◽  
Strength Development ◽  
Blended Cements ◽  
Current Production ◽  
Increasing Demand

Continuous rise in population coupled with infrastructural requirements leads to increasing demand of cement which is projected to be around 4.8 billion tons by 2030 and 6.0 billion tons annually by 2050 from current production level of more than 4.2 billion tons [1], and this further requires judicious use of natural resources, particularly limestone on one side and to mitigate carbon and energy footprints on other for sustainable development. Therefore, to bring down environmental impact during cement production, cement industries have been engaged over the years to substitute Portland cement with alternative cementitious materials; fly ash, granulated blast furnace slag, limestone etc individually or in combination of two-three mineral constituents in the manufacture of blended cements, which showed better durability characteristics in comparison to ordinary Portland cement. The formulation and commercialisation of these cements largely depends on the quality of Portland clinkers in terms of oxide constituents, potential as well as actual phase composition, morphology and granulometry of alite and belite grains, along with availability and quality of the cementing materials, prevalent standard norms and regulations. In view of above, present paper highlights the effect of different clinkers in terms of potential minerals as per Bogue calculations (CL-1:C3S-48.20%, C3A-6.30%; CL-2:C3S-54.20%, C3A-9.30% and CL-3: C3S-60.05%, C3A-9.0%) on mechanical strength of fly ash-limestone based ternary cement blends, Portland composite cements, similar to CEM-II/A, B-M as per EN-197-1, prepared with 15, 20, 25, 30 and 35% by weight fly ash and 5 & 10% by weight limestone, by inter-grinding of all cement constituents process, maintaining Blaine’s fineness at 370±10m2/kg, and the results of compressive strength at different curing ages showed optimum strength development in case of clinker CL-2 with potential phases, C3S-54.20% and C3A-9.30%, thus leading to better management of natural resources and extended mine life.

Effects of Mineral Admixtures and Superplasticizer on Controlling Hydration Heat of Cementitious Materials

2013 ◽  
Vol 639-640 ◽  
pp. 368-371
Author(s):  
Qing Huang ◽  
Jian Yin ◽  
Wei Min Song
Keyword(s):  
Fly Ash ◽  
Release Rate ◽  
Early Stage ◽  
Cementitious Materials ◽  
Heat Evolution ◽  
Hydration Heat ◽  
Mineral Admixtures ◽  
Evolution Rate ◽  
Two Parameters ◽  
Peak Value

The effects of mineral admixtures and superplasticizer on reducing the hydration heat of cementitious material were evaluated in this study, and the heat evolution rate and hydration heat were tested as the two parameters to evaluate the effect of improvement. The results showed that the cement partly-replaced with fly ash (FA) and slag (SG) could significantly decrease the release rate of hydration heat on the early stage of hydration, and lower the peak value of the heat evolution rate. The superplasticizer (TJ-Ⅲ) could reduce the hydration heat mainly on the early stage of hydration, and extended the induction period. In comparison with slag, the fly ash had more active effects on reducing the peak value and release rate of hydration heat.

Pulse Velocity Measurements in Fly Ash Blended Cementitious Systems Containing 43 Grade Cement

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
V. M. Sounthararajan ◽  
A. Sivakumar
Keyword(s):  
Fly Ash ◽  
Cost Savings ◽  
Ultrasonic Pulse Velocity ◽  
Cementitious Materials ◽  
Ultrasonic Pulse ◽  
Pozzolanic Reaction ◽  
Pulse Velocity ◽  
Supplementary Cementitious Materials ◽  
Pozzolanic Material ◽  
Cementitious Systems

Investigations on the different supplementary cementitious materials based on the hardening properties and the optimized dosage in cementitious systems find the right choice of pozzolanic material. It is essential to combine various additive/admixtures in concrete in proper proportions to maximize the benefits resulting in cost savings in construction. In the recent years, production technology and composition of hydraulic cements affect the setting and early age behavior of cementitious material. The addition of fly ash in cement is one viable technology to derive maximum benefits in terms of the economy and improved pozzolanic reaction. Ultrasonic pulse velocity testing is a feasible method for evaluating the hardening properties of cementitious materials. In this study, an attempt was made to derive the engineering basis for understanding the development of hardness during hydration of fly ash (FA) based cementitious systems. The tests conducted using pulse velocity technique proved to be an effective method for characterizing the early strength gain properties of different cementitious systems.

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.

scholarly journals The Influence of Supplementary Cementitious Materials on Climate Impact of Concrete Structures Exposed to Chlorides

2018 ◽  
Vol 58 (1) ◽  
pp. 77-93 ◽  
Author(s):  
Nadia Al-Ayish ◽  
Otto During ◽  
Katarina Malaga ◽  
Nelson Silva ◽  
Kjartan Gudmundsson
Keyword(s):  
Fly Ash ◽  
Service Life ◽  
Concrete Structures ◽  
Cementitious Materials ◽  
Climate Impact ◽  
Design Approach ◽  
Supplementary Cementitious Materials ◽  
Minimum Cover ◽  
Chloride Environment ◽  
Cover Thickness

Abstract Addition of fly ash or GGBS in concrete has shown to increase the durability and thus the service life of concrete structures exposed to chlorides. Currently, the durability relies on regulations, which beside a minimum cover thickness also put constraint on amount and type of SCM in different environments. Swedish regulations do not, however, consider the actual durability of different binders. As a consequence, a LCA might be misleading. This paper investigates the climate impact of concrete with SCM in chloride environment. Current prescriptive design approach is compared with a performance based service life approach and applied to bridge parts.

scholarly journals MECHANICAL AND WATER TRANSPORT PERFORMANCE OF SUSTAINABLE GEOPOLYMER COMPOSITE USING BINARY BLENDS OF POZZOLANIC MATERIALS

2019 ◽  
Vol 81 (5) ◽  
Author(s):  
Khan Asudullah Khan ◽  
Ashwin Raut ◽  
C. Rama Chandrudu ◽  
C. Sashidhar
Keyword(s):  
Fly Ash ◽  
Water Transport ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Bottom Ash ◽  
Total Solid ◽  
Cementitious Materials ◽  
Binary Blend ◽  
Pozzolanic Material ◽  
Water Transport Properties

The focus of the researchers has now shifted towards the geopolymer based materials as it considered as sustainable alternative to the existing cementitious materials. This paper attempts to incorporate the binary blend of pozzolanic material to develop geopolymer composite and understand it’s mechanical and water transport performance as a building material. The combination of bottom ash and rice husk ash with fly ash as a common binder was used for development of geopolymer composite. Replacement levels of both bottom ash and rice husk ash was kept at 40%, 30% and 20% of total solid proportions. Also, the molarity of NaOH was provided at 12 M and 14 M levels respectively. The results showed that the blend of FA-BA blend to be better performed against the blend of FA-RHA blend for their mechanical and water transport properties. The compressive strength of the geopolymer composite having blend of fly ash and bottom ash reached to the value of 41.49 MPa due to its suitable Si/Al ratio for geopolymerization reaction, which is quite remarkable. Also, the results of water transport performance shows the blend of FA-BA to be 15-20% more resistant to percolation of water as compared to FA-RHA blended geopolymer composite, thus lowering the risk of damages to the structures.

scholarly journals Durability of Blended Cements Made with Reactive Aggregates

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2948
Author(s):  
Esperanza Menéndez ◽  
Miguel Ángel Sanjuán ◽  
Ricardo García-Roves ◽  
Cristina Argiz ◽  
Hairon Recino
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Coal Fly Ash ◽  
Alkali Silica Reaction ◽  
Hardened Concrete ◽  
Natural Pozzolan ◽  
Blended Cements ◽  
Pozzolanic Material ◽  
Level Ii ◽  
Points Of View

Alkali–silica reaction (ASR) is a swelling reaction that occurs in concrete structures over time between the reactive amorphous siliceous aggregate particles and the hydroxyl ions of the hardened concrete pore solution. The aim of this paper is to assess the effect of pozzolanic Portland cements on the alkali–silica reaction (ASR) evaluated from two different points of view: (i) alkali-silica reaction (ASR) abatement and (ii) climatic change mitigation by clinker reduction, i.e., by depleting its emissions. Open porosity, SEM microscopy, compressive strength and ASR-expansion measurements were performed in mortars made with silica fume, siliceous coal fly ash, natural pozzolan and blast-furnace slag. The main contributions are as follows: (i) the higher the content of reactive silica in the pozzolanic material, the greater the ASR inhibition level; (ii) silica fume and coal fly ash are the best Portland cement constituents for ASR mitigation.

scholarly journals Use of Potabilized Water Sludge in the Production of Low-Energy Blended Calcium Sulfoaluminate Cements

2021 ◽  
Vol 11 (4) ◽  
pp. 1679
Author(s):  
Antonio Telesca ◽  
Neluta Ibris ◽  
Milena Marroccoli
Keyword(s):  
Co2 Emissions ◽  
Carbon Footprint ◽  
Energy Demand ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
X Ray Diffraction ◽  
Hydration Properties ◽  
Blended Cements ◽  
Calcium Sulfoaluminate ◽  
Pozzolanic Material

Ordinary Portland cement (OPC) manufacture determines about 8% of the global anthropogenic CO2 emissions. This has led to both the cement producers and the scientific community to develop new cementitious materials with a reduced carbon footprint. Calcium sulfoaluminate (CSA) cements are special hydraulic binders from non-Portland clinkers; they represent an important alternative to OPC due to their peculiar composition and significantly lower impact on the environment. CSA cements contain less limestone and require lower synthesis temperatures, which means a reduced kiln thermal energy demand and lower CO2 emissions. CSA cements can also be mixed with supplementary cementitious materials (SCMs) which further reduce the carbon footprint. This article was aimed at evaluating the possibility of using different amounts (20 and 35% by mass) of water potabilization sludges (WPSs) as SCM in CSA-blended cements. WPSs were treated thermally (TT) at 700° in order to obtain an industrial pozzolanic material. The hydration properties and the technical behavior of two different CSA-blended cements were investigated using differential thermal–thermogravimetric and X-ray diffraction analyses, mercury intrusion porosimetry, shrinkage/expansion and compressive strength measurements. The results showed that CSA binders containing 20% by mass of TTWPSs exhibited technological properties similar to those relating to plain CSA cement and were characterized by more pronounced eco-friendly features.

Effect of ground granulated blast funrnace slag and fly ash on strength, permeability, and under-water abrasion of fine-grained concrete

2020 ◽  
Vol 71 (7) ◽  
pp. 775-788
Author(s):  
Quyet Truong Van ◽  
Sang Nguyen Thanh
Keyword(s):  
Fly Ash ◽  
Concrete Strength ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Chloride Permeability ◽  
Cement Replacement ◽  
Fine Grained ◽  
Granulated Blast Furnace Slag ◽  
Compressive Strength Test ◽  
Economic Ground

The utilisation of supplementary cementitious materials (SCMs) is widespread in the concrete industry because of the performance benefits and economic. Ground granulated blast furnace slag (GGBFS) and fly ash (FA) have been used as the SCMs in concrete for reducing the weight of cement and improving durability properties. In this study, GGBFS at different cement replacement ratios of 0%, 20%, 40% and 60% by weight were used in fine-grained concrete. The ternary binders containing GGBFS and FA at cement replacement ratio of 60% by weight have also evaluated. Flexural and compressive strength test, rapid chloride permeability test and under-water abrasion test were performed. Experimental results show that the increase in concrete strength with GGBFS contents from 20% to 40% but at a higher period of maturity (56 days and more). The chloride permeability the under-water abrasion reduced with the increasing cement replacement by GGBFS or a combination of GGBFS and FA

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