Exploring optimum percentage of fly-ash as a replacement of cement for enhancement of concrete properties

2020 ◽  
Vol 11 (1) ◽  
pp. 16
Author(s):  
Sarvat Gull ◽  
Shoib B. Wani ◽  
Ishfaq Amin
Keyword(s):  
Fly Ash ◽  
Progressive Increase ◽  
Decision Makers ◽  
Partial Replacement ◽  
General Increase ◽  
Normal Concrete ◽  
Fly Ash Concrete ◽  
Optimum Quantity ◽  
Lab Experiments ◽  
Management Scheme

Researchers and decision makers are continuously looking out to determine the potential and effectiveness of fly-ash as a partial replacement of cement in concrete. The current study is carried out to check the optimum or nearly optimum quantity of fly-ash with which cement should be replaced to get most of the properties of concrete enhanced and to give the idea about the quantities of fly-ash that can be used in a better way and better cause so that a proper management scheme of its usage and disposal can be implied. Further, a comparison is given between normal concrete and fly-ash concrete to show the properties which can be enhanced by proper utilization of fly-ash as a partial replacement of cement. After carrying out the lab experiments, it has been seen that the replacement of fly-ash in concrete has resulted in general increase in compressive strength, flexural strength and splitting tensile strength up to 15% replacement and after then the strength is decreased considerably than that of normal concrete. Addition of fly-ash in concrete has resulted in decrease in the water absorption of concrete and hence decreases in permeability of concrete. There is a progressive increase in workability with increase in percentage of fly-ash in concrete. The current study has led to a conclusion that in order to achieve best results in use of fly-ash concrete, the fly-ash used for replacing cement in concrete should have the required properties as specified by the standards and proper techniques of processing fly-ash as well as mixing of fly-ash with cement must be employed.

scholarly journals CORROSION BEHAVIOR OF REINFORCING STEEL IN RC SLAB CONTAINING CHLORIDES WITH PARTIAL REPLACEMENT OF CEMENT AS FLY ASH

2019 ◽  
Vol 31 (3) ◽  
Author(s):  
Sristi Das Gupta ◽  
Takafumi Sugiyama ◽  
Md Shafiqul Islam
Keyword(s):  
Reinforced Concrete ◽  
Fly Ash ◽  
Current Density ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Concrete Cover ◽  
Partial Replacement ◽  
Normal Concrete ◽  
Fly Ash Concrete ◽  
Rc Slab

Steel reinforcement in concrete containing fly ash has been practically employed to RC structures in snowy cold region and coastal areas so that the durability of the structures against corrosion can be enhanced. In this research to make the compatibility with RC slab bridge sodium chloride solution of 10[WU1] % in concentration was applied on RC slab and corrosion development was monitored by electrochemical method. Applying fly ash in RC slab at two replacement levels of 15[WU2] % (F15) and 30% (F30) of cement the specimens were observed. The observation result verified that fly ash concrete showed longer period of corrosion initiation (ASTM C876) than normal reinforced concrete. The initiation period of corrosion was 4.5 and 6 times longer for F15 and F30 concrete than normal concrete, as well as 91 days strength of F30 concrete was about 14% higher that of norma concrete. Test result showed that fly ash has better influence on steel corrosion reduction than concrete cover increment. It was observed that fly ash concrete (F15 and F30) with 3 cm concrete cover has better corrosion resistivity than using 4 cm cover of non-fly ash concrete. Furthermore, using the same concrete cover (3 cm) it was found that the actual corrosion rate was decreased about 68 to 82% by adding fly ash 15 to 30% respectively compared to normal reinforced concrete. In addition, a significant attenuation in corrosion area in rebar between fly ash concrete and normal concrete was found. Based on actual corrosion area on rebar surface, actual corrosion current density was larger than corrosion current density found from non-destructive way. Moreover, further analysis was conducted for characterization of different corrosion products using Raman spectroscopy with 532 nm wave length. It revealed that the corrosion product (Oxides and Oxyhydroxides compound) were less in F15 and F30 concrete compared to normal concrete. Considering these results, the possibility of reduction of chloride induced corrosion in reinforced concrete structure using fly ash has confirmed. 

Experimental Study on Sustainable Concrete with the Mixture of Low Calcium Fly Ash and Lime as a Partial Replacement of Cement

2011 ◽  
Vol 250-253 ◽  
pp. 307-312 ◽  
Author(s):  
Muthuramalingam Jayakumar ◽  
M. Salman Abdullahi
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Water Absorption ◽  
Chloride Ion ◽  
Apparent Volume ◽  
Partial Replacement ◽  
Fly Ash Concrete ◽  
Low Calcium ◽  
Chloride Ion Penetration ◽  
Ion Penetration

Even though the use of fly ash in concrete is nowadays a common practice, its relatively slow pozzolanic reactivity hinders its greater utilization; hence efficient methods of activation are on demand. This study was carried out to evaluate the influence of lime as a chemical activator on the mechanical and durability properties of high strength fly ash concrete. Mixtures were made with 0, 30, 40, and 50% of cement replaced by low calcium fly ash. Corresponding mixtures were also made with the same amount of fly ash and addition of 10% of lime to each mixture. For each concrete mixture, slump, compressive strength, water absorption, sorptivity, apparent volume of permeable voids, and resistance to chloride-ion penetration were measured. The results obtained showed that addition of lime improved the compressive strength significantly at all ages. The strength of all the fly ash mixtures containing lime surpassed that of the corresponding Portland cement mix at 60 days. Addition of lime also improved the sorptivity and resistance to chloride-ion penetration of the fly ash concrete. It however increases the water absorption and the volume of permeable voids of the fly ash concrete.

scholarly journals Hardened Behavior of Fly Ash Incorporated Concrete with Bottom Ash (FACB) as Partial Replacement of Fine Aggregate

2020 ◽  
Vol 9 (4) ◽  
pp. 2898-2907 ◽  
Keyword(s):  
Fly Ash ◽  
Thermal Power ◽  
Bottom Ash ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Experimental Scheme ◽  
Fly Ash Concrete ◽  
Wide Range ◽  
Binder Ratio ◽  
User Friendly

The utilization of thermal power plant waste ashes (fly ash and bottom ash) in concrete as partial replacement of cement and sand could be an important step toward development of sustainable, user-friendly and economical infrastructure. For this purpose, different concrete mixes were considered at constant binder content of 300kg/m3 and differ water-to-binder ratio (w / (c + f) mainly as 0.5 , 0.55 and 0.6. Also six wide range of fly ash replacement levels (f/c ratio) namely 0, 0.11, 0.25, 0.43, 0.67 and 1.0 were introduced in the experimental scheme. The 3-days to 180 days compressive strengths of FACB was measured at interval of 3, 7, 28, 56 and 90 days. This study also presents a relationship between the ratios of split tensile (ft) strength to compressive strength (fc). It is applicable to lean concrete having consideration of curing period at early age (3day) to long term (180days). The results of this investigation are principally important, because the comprehensive information on the dependability of the relationships has not been available for (w/c+f) and bottom ash combination. The investigational results of this work are indicated that waste-Bottom ash with the regular sizes can be used successfully as a fine aggregate in fly ash concrete (FAC). The Study also reflected in finding constant “k” by ACI code equation for fly ash and bottom ash mix concrete. It has obtained between 0.337 - 0.504. This could be useful in finding splitting tensile strength when concrete carrying fly ash and bottom ash.

scholarly journals Effect of Vietnamese Fly Ash on Selected Physical Properties, Durability and Probability of Corrosion of Steel in Concrete

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 593 ◽  
Author(s):  
Chinh Van Nguyen ◽  
Paul Lambert ◽  
Quang Hung Tran
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Acid Resistance ◽  
Steel Corrosion ◽  
Strength Loss ◽  
Reinforced Concrete Beams ◽  
Partial Replacement ◽  
Nacl Solution ◽  
Fly Ash Concrete ◽  
Corrosion Of Steel

Vietnamese fly ash was used as a partial replacement for ordinary Portland cement in the proportions of 10%, 20% and 40%, while the water to cementitious ratios were kept constant at 0.42, 0.5 and 0.55, respectively, for three groups. The compressive strengths of all mixes were determined up to 90 days. The acid resistance of fly ash concrete was examined by the mass loss and compressive strength loss of 100 × 100 × 100 mm3 cubes immersed in a 10% H2SO4 solution. The probability of steel corrosion in the fly ash concrete was assessed by measuring the half-cell potentials of steel bars within beams dimensions of 100 × 100 × 500 mm3, and the flexural strengths of these beams after 300 days of immersion in a 5% NaCl solution were determined. The results demonstrate that the compressive strength of fly ash concrete is reduced at an early age but increases as the concrete continues to hydrate. The fly ash increases the sulfuric acid resistance of concrete. Fly ash additions have only a limited effect on reducing the risk of probability of corrosion of steel in the concrete. The load capacities of 10% and 20% fly ash reinforced concrete beams are higher than that of the control beams after 300 days immersed in a 5% NaCl solution.

ESTIMATION OF DEFORMABILITY OF FRESH CONCRETE MIXED WITH FLY ASH FLOWING THROUGH TAPERED PIPE USING PUMPING TESTER

2011 ◽  
Vol 25 (31) ◽  
pp. 4299-4302
Author(s):  
NORITSUGU YAMAJI ◽  
CHIKANORI HASHIMOTO ◽  
TAKESHI WATANABE ◽  
KEISUKE ISHIMARU
Keyword(s):  
Fly Ash ◽  
Coefficient Of Variation ◽  
Fresh Concrete ◽  
High Viscosity ◽  
Normal Concrete ◽  
Fly Ash Concrete

In study, we quantitatively evaluate and compare high-viscosity concrete with type fourth fly ash and normal concrete. We estimate the deformability of fresh concrete using a pumping tester and investigate the pumpability of concrete. In this study, the range of stable pumping is evaluated by having the average pump oil pressure and the coefficient of variation of the oil pressure. At an average pump oil pressure of less than 0.50 MPa and coefficient of variation of less than 15 %, the range of steady pumping of fly ash concrete and normal concrete are different. Concrete with type fourth fly ash significantly decreases the coefficient of variation of the oil pressure and prevents the stoppage of fresh concrete flowing in pipe.

High Dosage Type-C Fly Ash and Limestone in Sand-Gravel Concrete

1996 ◽  
Vol 1532 (1) ◽  
pp. 36-43
Author(s):  
Mohamed Nagib Abou-Zeid ◽  
John B. Wojakowski ◽  
Stephen A. Cross
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Concrete Beams ◽  
Partial Replacement ◽  
Equal Weight ◽  
Department Of Transportation ◽  
Fly Ash Concrete ◽  
Freeze And Thaw ◽  
Concrete Mixtures ◽  
Type C

Alkali-silica reactions are a major cause of concrete deterioration. The reactions can lead to severe damage that may ultimately endanger the performance and safety of concrete structures. The use of fly ash as partial replacement of Portland cement and the use of some limestone in concrete mixtures were considered as two potential approaches to minimize the severity of the problem. Sand-gravel concrete mixtures were prepared by replacing 15, 25, and 35 percent, by weight of Portland cement, with an equal weight of ASTM Type C fly ash. In those mixtures, either 30 percent or 50 percent of the total aggregate was limestone. Concrete beams were prepared and the wetting-and-drying test was performed in accordance with Kansas Department of Transportation (KDOT) specifications. Also, freeze-and-thaw testing of concrete beams were performed on some selected mixtures. Results indicate that most of the fly ash concrete mixtures with 30 percent limestone do not fulfill the requirements of the KDOT specifications. The fly ash mixtures with 50 percent limestone yield better results; most of them meet the specifications. Results also show that increasing the fly ash dosage does not seem as effective as introducing limestone for alleviating alkali-silica reaction problems.

scholarly journals A Review on Early Age and Long-term Compressive Strength of High-volume Fly Ash Concrete

2018 ◽  
Vol 207 ◽  
pp. 01004
Author(s):  
Mu Li
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Volume ◽  
Partial Replacement ◽  
Early Age ◽  
Fly Ash Concrete ◽  
Power Stations ◽  
High Volume Fly Ash ◽  
Curing Age

Fly ash is a by-product of the combustion of the coal-fired electric power stations, and disposal of fly ash has been one of the environmental challenges. Much of the studies have been focused on the mechanical property of fly ash concrete. It is no doubt that the use of high-volume fly ash as a partial replacement of cement is also one of the effect way to utilize fly ash. It is known that the compressive strength of fly ash concrete is lower than that of ordinary concrete at early age, especially for high-volume fly ash concrete. It is urgent for engineers to consider the compressive strength of high-volume fly ash concrete at different curing age. In this review, the compressive strength of high-volume fly ash concrete in various literature was reported and then analyzed. Furthermore, the proposal of the utilization of high-volume fly ash concrete is provided.

scholarly journals Interlocking Pavement Tiles using RCA with Industrial Waste as Admixtures

2021 ◽  
Author(s):  
Anjana S ◽  
Diya Elizabeth Isaac ◽  
Neelanjana S ◽  
Aswathy G
Keyword(s):  
Fly Ash ◽  
Industrial Waste ◽  
Recycled Concrete ◽  
Partial Replacement ◽  
Normal Concrete ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Coarse Aggregates ◽  
Loss Of Strength ◽  
Enormous Quantity

The unprecedented increase in construction and developmental activities in the current era brings with it many irreversible impacts on the environment. The major impacts being the depletion of natural resources and generation of an enormous quantity of Construction and Demolition (C&D) wastes. Hence it has become important to reuse and recycle C & D wastes generated. These wastes can be processed to obtain Recycled Concrete Aggregates (RCA), which can be used for producing recycled concrete. It was found that the strength of Recycled concrete matches with that of paver quality concrete. Therefore, the study aims at producing interlocking paver blocks by replacing the normal coarse aggregates in pavers by RCA along with fly ash as admixture, an industrial waste. Fly ash being a pozzolanic admixture is used in order to overcome the loss of strength due to the addition of RCA. In the present study, a 30% replacement of normal aggregates with RCA and 15% replacement of cement with fly ash in the mix was used as it was found to provide the optimum strength. A comparison of the important properties of paver blocks were conducted between normal concrete pavers, pavers with RCA replacement and pavers with RCA replacement and fly ash. It was found out from the study that Interlocking pavers with partial replacement of normal aggregates with RCA and fly ash obtained strength comparable to that of normal paver blocks. Hence these paver blocks can be used for laying of roads and can contribute towards a sustainable development.

scholarly journals Wood ashes from electrostatic filter as a replacement for the fly ashes in concrete

2021 ◽  
Vol 2 (2) ◽  
Author(s):  
Piotr-Robert Lazik ◽  
◽  
Harald Garrecht ◽  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Coal Fly Ash ◽  
Wood Ash ◽  
Fly Ashes ◽  
Normal Concrete ◽  
Cement Production ◽  
Fly Ash Concrete ◽  
Electrostatic Filter ◽  
Laboratory Investigations

Many concrete technologists are looking for a solution to replace Fly Ashes that would be unavailable in a few years as an element that occurs as a major component of many types of concrete. The importance of such component is clear - it saves cement and reduces the amount of CO2 in the atmosphere that occurs during cement production. Wood Ashes from electrostatic filter can be used as a valuable substitute in concrete. The laboratory investigations showed that the wood ash concrete had a compressive strength comparable to coal fly ash concrete. These results indicate that wood ash can be used to manufacture normal concrete.

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