Durability Properties Of Fly Ash Research Articles

Performance Evaluation of Mechanical and Durability Properties of Fly Ash and Silica Fume Based Concrete for Sustainable Building Material

he intensive use of cement in construction is a significant environmental concern. To reduce the use of cement for energy consumption, the use of supplementary cementitious materials (SCMs) like Fly ash (FA) and Silica fume (SF) in concrete is an interesting solution. FA and SF-based construction materials offer a lot of potential as alternatives to ordinary portland cement (OPC) because of their high performance and environmental friendliness. The level of replacement and the necessity for additional cementitious content are critical considerations when choosing the most sustainable material for concrete production. To achieve long-term sustainability, the use of FA and SF in the construction industry is essential. Therefore, the authors attempted to identify the preferred material between FA and SF for sustainability by conducting a performance evaluation on the mechanical and durability properties of two binary mixes, i.e., FA and SF-based concrete mixes. The first binary blended concrete mix is prepared by replacing cement with FA at 20%, 30%, and 40% by weight, and the second mix is prepared with SF at 5%, 7.5%, and 10% by weight. The compressive strength (CS), flexural strength (FS), water sorptivity (WS), and rate of chloride penetration (RCP) of these two binary blended concrete mixes were studied. The results show that the incorporation of SF and FA has a significant impact on workability. The use of SF considerably increased the early and long-term strength of concrete, whereas FA lowered early age strength; nevertheless, it enhanced long-term strength. It was concluded that the SF contributed to better durability properties than FA. FA at 30\% and SF at 10\% exhibited the desired strength and durability than OPC, which can be used as a sustainable building material.

Effect of granite industry waste addition on durability properties of fly ash blended self-compacting concrete

The continuous production of granite powder (GP) waste causes a deadly impact on environment and human life. This present study thus examines the impact of granite powder (GP) as substitute to natural fine aggregate (up to 60%) on compressive strength and durability properties of eco-friendly fly ash blended self-compacting concrete (SCC). Results revealed that strength enhanced on incorporation of up to 40% GP in concrete mixture than fly ash blended control mixture. Resistance against chloride, carbonation and corrosion improved for incorporation of up to 50% GP in concrete mixture than fly ash blended control mixture. Moreover, all the blended SCC mixtures, except SCC mixture containing 50% and 60% GP, showed higher compressive strength than ordinary Portland cement (OPC) based control SCC mixture at higher days of curing. Besides, all the blended SCC mixtures, except mixture containing 60% GP, showed better resistance against chloride, carbonation, drying shrinkage and corrosion than OPC based control SCC mixture. It was hence concluded that GP up to 50% as an alternative of fine aggregate could be positively incorporated in the production of eco-friendly fly ash blended SCC for the improvement of aforesaid durability properties (with little higher precaution against drying shrinkage).

Properties of Mortars Formulated from Self-Compacting High-Performance Concrete Containing Various Mineral Additions

The present study illustrates the fresh, mechanical, and durability properties of fly ash (FA)-based mortars formulated from self-compacting high-performance concrete (SCHPC). The control mixture (C) contained ordinary Portland cement (OPC) and fly ash (FA) as the binders, while the remaining mixtures were ternary cementitious blends of OPC, FA, silica fume (SF), metakaolin (MK), and limestone powder (LP). The effect of limestone powder (LP), metakaolin (MK), and silica fume (SF) as cement replacement on the V-funnel flow, slump flow, compressive strength, flexural strength, rapid chloride penetration (RCPT), ultrasonic pulse velocity (UPV), electric resistivity (ER), dynamic elastic modulus (DEM), and alkali-silica reaction (ASR) is comparatively assessed for SCHPC-based mortars. The results indicate better performance of ternary mixes of SF and MK in terms of strength- and durability-related properties for mortars formulated from SCHPC. The FTIR spectroscopy and SEM analyses confirmed the improved performance of mortars containing SF and MK against ASR.

Durability Performance of Fly Ash and Steatite Powder Based Geopolymer Concrete

This paper deals with the study of durability properties of fly ash and steatite powder based Geopolymer concrete. The activating alkali used was 10 M sodium hydroxide and sodium silicate solution. The ratio of sodium hydroxide and sodium silicate ratio was 1:2.5. The range of replacement levels of flyash with steatite powder was from0 – 50 %. In order to improve the workability of geopolymer concrete, a PC based admixture Glenium B233 has been used for all the mixtures. In addition to that the concrete has been cured at oven at 70oC for about 48 hours. The following durability index properties such as water absorption, sorptivity, rapid chloride penetration test and acid attack test were measured at 28days. The observed results indicated that, increase in steatite powder demonstrates low water absorption and low permeability representing that the material was in a high dense pore structure. Additionally in acid resistance test, there was a decline in the percent losses of compressive strength with particular time period but then again the declination was lower when compared to increase in steatite powder.

Mechanical and Durability Properties of Fly Ash and GGBS Based Fiber Reinforced Concrete

Concrete is one of the most commonly and widely adopted material for construction. Cement is used as primary binder material to produce Concrete. However, every tonne of Cement production releases one tonne of greenhouse gases which results in global warming; due to continuous and ever increased usage of Cement and natural sand are causing uncontrollable global warming and depletion of natural resources respectively year by year. This tendency needs to be retarded if not arrested, by developing a comprehensive approach to use more and more pozzolanic mineral admixtures and manufactured sand (M-Sand) in Concrete. In this study on fiber reinforced concrete (with steel fiber @ 1% of binder), Ordinary Portland Cement (OPC) is replaced up to 50% with Fly Ash and Ground Granulated Blast-Furnace slag (GGBS) for M30 grade of Concrete. Mechanical properties like compressive strength and split tensile strength at 7 days and 28day age are tested. Additionally, durability tests like water absorption and sorptivity tests are conducted after 28days of curing. The test results indicated that workability was increased and there was no significant improvement in durability properties on increasing the percentage of OPC replacement. However, 30% of OPC replacement is found to be optimum for strength criteria

Preliminary Study on the Durability Properties of High-Volume Fly Ash Mortar Composites

Abstract The use of fly ash, a common industrial byproduct waste, is gaining popularity, especially in developing countries, in addressing environmental concerns surrounding the construction industry, such as reducing waste and CO2 emissions. However, the full potential of fly ash usage is yet to be exploited. The physical, mechanical, and durability properties of fly ash in concrete are well documented; in contrast, its durability properties in mortar require further investigations. The present study investigated the durability properties of high-volume fly ash (HVFA) mortar composites. Specifically, varying proportions of sand were replaced with cement and fly ash to examine the effects on the durability properties of the resulting mortar composites by studying the porosity, weight loss upon sodium sulfate attack, and ultrasonic pulse velocity (UPV). Specimens with a diameter of 50 mm and height of 100 mm were examined. The results showed that UPVmortar > UPVpastes. Increasing the amount of cement led to a decrease in weight loss for the 50-, 150-, and 250-mm slumps. The maximum weight loss (15 %) was recorded for the HVFA mortar composites comprising 80 % sand. Furthermore, all prepared samples displayed adequate resistance to sulfate (weight loss was below 16 %). Based on the dry unit weight values, all the final products, aside from that comprising 20 wt. % fly ash and 80 wt. % cement, can be considered as a lightweight material, at ∼12.58 kN/m3, and can satisfactorily be used in the manufacture of lightweight aggregates and semi-isolating materials.

Mechanical and Durability Properties of Fly Ash Based Concrete Exposed to Marine Environment

Abstract Efforts over the past few years for improving the performance of concrete suggest that cement replacement with mineral admixtures can enhance the strength and durability of concrete. Feasibility of producing good quality concrete by using alccofine and fly ash replacements is investigated and also the potential benefits from their incorporation were looked into. In this study, an attempt has been made to assess the performance of concrete in severe marine conditions exposed upto a period of 150 days. This work investigates the influence of alccofine and fly ash as partial replacement of cement in various percentages (Alccofine - 5% replacement to cement content) and (fly ash - 0%, 15%, 30%, 50% & 60% to total cementitious content) on mechanical and durability properties (Permit ion permeability test and corrosion current density) of concrete. Usage of alccofine and high quantity of fly ash as additional cementitious materials in concrete has resulted in higher workability of concrete. Inclusion of alccofine shows an early strength gaining property whereas fly ash results in gaining strength at later stage. Concrete mixes containing 5% alccofine with 15% fly ash replacement reported greater compressive strength than the other concrete mixes cured in both curing conditions. Durability test conducted at 56 and 150 days indicated that concrete containing higher percentages of fly ash resulted in lower permeability as well lesser corrosion density.

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Durability of fly ash based geopolymer concrete in the presence of silica fume

Geopolymer is a green cementitious material and has excellent mechanical properties, low energy in its production and emits less carbon dioxide. In this paper, the effect of silica fume on durability properties of fly ash based geopolymer concrete have been investigated by immersing the cubes in 2% sulphuric acid and 5% sodium chloride solutions. The resistance of specimens to chemical attack was evaluated visually, measuring change in the weights and percent losses in compressive strength at different intervals of time. A control mix was also cast as M40 with ordinary Portland cement concrete for comparison. Percent losses in compressive strengths in the case of control (M40) and GPC3 in 2% H2SO4 at 90 d were found 36 and 8%. Percent losses in compressive strengths in the case of control (M40) and GPC3 in 5% NaCl at 90 d were 18% and about 0%.Thus the resistance of geopolymer concrete incorporating silica fume in sulphuric acid and chloride solution was significantly higher than that of the control.

Engineering and durability properties of fly ash treated lime-stabilised sulphate-bearing soils

The paper describes a study carried out to investigate the engineering and durability properties of lime-stabilised soils treated with low-lime fly ash to limit swelling (heave) due to sulphate, associated with the ground improvement process. Two clays (Lias and Oxford with total potential sulphate levels >1.0%), a quicklime, two fly ashes (fine/low loss-on-ignition (LOI)/dry; and coarse/high LOI/wet (pond) stored) and a ground granulated blastfurnace slag (GGBS) were considered. The lime-stabilised soils contained 3% quicklime and various levels of fly ash (up to 24%) and GGBS (up to 9%), and were tested at optimum moisture content and maximum dry density. The properties considered included, immediate-bearing index, unconfined compressive strength, indirect tensile strength, water permeability and frost-heave. The results indicate that for most of these, the fly ash combinations gave improvements compared to lime-only treated soils, with the benefits generally increasing with addition level. Between fly ashes, the fine/dry material mainly gave better properties for those considered. This differs from behaviour noted previously for sulphate-heave, where coarser/wet-stored fly ash was most effective in minimizing the process. At comparable application levels, GGBS contributed more than fly ash to the properties of the lime-stabilised soils. The underlying mechanisms associated with these effects and the practical implications of the study are explored.

Comparison of engineering and durability properties of fly ash blended cement concrete made in UK and Malaysia

Annual global production of fly ash is ∼6 × 108 ton out of which only 20 to 25% is utilised in the construction industry. Largely it is used as a partial replacement of cement for producing concrete. Properties of such concrete depend on the chemical composition of fly ash, source and method of burning of coal in power stations, etc. The present paper presents a comparative study on the properties on concrete containing fly ash obtained from two different sources, Drax Power Station, UK and Manjung Power Station, Malaysia. Fly ash obtained from Malaysia contained 11˙47%CaO and its particles were coarser than the fly ash obtained from Drax, UK, which contained less calcium oxide (2˙55%). Malaysian fly ash concrete required more water to achieve the targeted slump of 55 ± 5 mm of fresh concrete, such concrete showed 4 to 7% high porosity and 27 to 36% low compressive strength as compared with the porosity and compressive strength of the concrete made with Drax, UK fly ash.