Ordinary Fly Ash Research Articles

Effect of Desulfurization Ash with Different Calcium Sulfite Content on Performance of Cement Based Materials

According to the desulphurization reaction temperature and the content of calcium sulfite, FGD ash is simulated, that is the ordinary fly ash mixed with different weight percentage of CaSO3·1/2H2O is followed by drying at 100°C. And then by the experiment of workability, strength, sulfate resistance and rebar corrosion, the effect of the fly ash with different of CaSO3·1/2H2O on material properties are studied. The results show that: compared with ordinary fly ash, the desulphurization ash contained 4~12% CaSO3·1/2H2O can improve workability, but it has a 4% threshold, over critical value, the improving ability declined; secondly increasing the content of CaSO3·1/2H2O in desulphurization ash can decrease strength, and while the effect of 7 day strength is higher than 28 days’; Thirdly, with the increase of calcium sulfite, the desulphurization can decrease resistance to sulfate attack , especially for more than content of 8% CaSO3·1/2H2O , but it is harmless for steel rebar.

Effect of Desulfurization Ash with Different Gypsum Content on Rheology Characteristic, Hydration Structure and Rebar Protection of Cement Based Materials

Depending on the desulfurization reaction temperature, it can be divided into fly ash generated at high- temperature furnace zone and at low-temperature flue gas zone. For simulating those two kinds of desulfurization ash, the ordinary fly ash mixed with different weight percentage of CaSO4·2H2O is divided into 2 groups, the first group is fol- lowed by calcining at 900°C, another drying at 100°C. And then by the experiment of workability, strength and steel rebar protection, the effect of morphology and amount of gypsum on material properties and the pretreatment method are studied. The results show that: compared with ordinary fly ash, those two kinds of desulfurization ash can improve workability, but the improving ability of desulfurization ash at high-temperature furnace zone weaker than another's, in addition, amount of gypsum in desulfurization ash on fluidity has a threshold; Secondly, the structure forming of the sample with 10% gypsum drying at 100°C are faster than that of control sample, however the structure forming is slower than the control sample when gypsum drying at 100°C increase to 20%. As for gypsum calcining at 900°C, the structure forming of sample with 20 mass% gypsum are fastest, with 10 mass% gypsum follows closely next, the control sample falls behind. Thirdly, desulfurization ash can decrease strength, and the early strength of desulfurization ash at high-temperature furnace zone higher than another's, but the development trend of later strength is in the opposite direction. Lastly, those two kinds of desulfurization ash are harmless for steel rebar, and the steel rebar's passive film compactness is followed desulfurization ash formed at low-temperature flue gas zone>desulfurization ash formed at high-temperature furnace zone>ordinary fly ash.

Effect of alkali on tropical peat stabilized with different stabilizers

The paper presents the effect of alkali on tropical peat stabilized with ordinary portland cement (OPC), fly ash (FA) and different chemicals e.g., accelerator (a combination of 2.0% sodium sulfate, 0.5% sodium chloride and 0.1% triethanolamine); 2.6% aluminum sulfate; and 2.6% calcium sulfate. Various physical and engineering properties tests were conducted on original peat, FA and stabilized peat samples to check the effect of alkali and chemicals. Unconfined Compressive Strength (UCS) tests were carried out on treated (i.e., peat treated with 2% NaOH to reduce its acidity) and untreated stabilized peat samples with OPC, FA, and different chemicals for various curing periods. The results show that UCS value increases with curing periods and treated peat samples show better results than untreated peat for both OPC and FA stabilized peat samples. The highest UCS value was found on treated stabilized peat where calcium sulfate and OPC were used as stabilizers for 120 days curing period. In addition, specific gravity (<i>G_s</i>), pH, loss on ignition (<i>N</i>), Organic Content (OC) and Scanning Electron Microscope (SEM) studies were also carried out on stabilized peat samples to investigate the stabilized behavior and micro-structure of the peat.

Toughness increase of self compacting concrete reinforced with polypropylene short fibers

Increases in bending tests by the addition of low volume fractions of Polypropylene (PP) Short Fibers PP. These toughness increases are similar to those attained by Fiber Reinforced Concrete (FRC) referred elsewhere as Engineered Cementitious Composites (ECC), having some ductility and strain hardening in direct tensile and flexural tests. Concretes mixtures were manufactured using natural pozzolanic blended Portland cement, volcanic crushed coarse aggregates and fine sand from Sahara desert dunes (0-1 mm) from Canary Islands quarries and sand reservoirs, respectively, besides ordinary siliceous sand (0-4 mm) and fly ash from an anthracite-coal heat generator.

Effect of Desulfurization Ash with Different Desulfurization Temperature and Gypsum Content on the Fluidity, Strength and Rebar Protection of Cement Based Materials

Depending on the desulfurization reaction temperature，it can be divided into fly ash generated at high-temperature furnace zone and at low-temperature flue gas zone. For simulating those two kinds of desulfurization ash, the ordinary fly ash mixed with different weight percentage of CaSO4•2H2O is divided into 2 groups, the first group is followed by calcining at 900 , another drying at 100 . And then by the experiment of workability, strength and steel rebar protection, the effect of morphology and amount of gypsum on material properties and the pretreatment method are studied. The results show that: compared with ordinary fly ash, those two kinds of desulfurization ash can improve workability, but the improving ability of desulfurization ash at high-temperature furnace zone weaker than another’s, in addition, amount of gypsum in desulfurization ash on fluidity has a threshold; Secondly, desulfurization ash can decrease strength, and the early strength of desulfurization ash at high-temperature furnace zone higher than another’s, but the development trend of later strength is in the opposite direction. Thirdly, those two kinds of desulfurization ash are harmless for steel rebar, and the steel rebar’s passive film compactness is followed desulfurization ash formed at low-temperature flue gas zone＞desulfurization ash formed at high-temperature furnace zone＞ordinary fly ash.

Dielectric Study on Fly Ash Blended Cement

In this paper, the hydration behaviour of ordinary portland cement (OPC) and fly ash blended cement (10, 25 and 40%) replaced by two different fly ashes (FA) were investigated. The samples were hydrated with distilled water (DW) in water to solid ratio 0:4 and its setting time and dielectric measurement are carried out. Results of the study found that the fly ash blended cement composites have slow hydration than OPC during early stages (up to 24 h).

Effect of fly ash fineness on compressive strength and pore size of blended cement paste

Abstract This paper presents an experimental investigation on the effect of fly ash fineness on compressive strength, porosity, and pore size distribution of hardened cement pastes. Class F fly ash with two fineness, an original fly ash and a classified fly ash, with median particle size of 19.1 and 6.4 μm respectively were used to partially replace portland cement at 0%, 20%, and 40% by weight. The water to binder ratio (w/b) of 0.35 was used for all the blended cement paste mixes. Test results indicated that the blended cement paste with classified fly ash produced paste with higher compressive strength than that with original fly ash. The porosity and pore size of blended cement paste was significantly affected by the replacement of fly ash and its fineness. The replacement of portland cement by original fly ash increased the porosity but decreased the average pore size of the paste. The measured gel porosity (5.7–10 nm) increased with an increase in the fly ash content. The incorporation of classified fly ash decreased the porosity and average pore size of the paste as compared to that with ordinary fly ash. The total porosity and capillary pores decreased while the gel pore increased as a result of the addition of finer fly ash at all replacement levels.

The Effect of Substituting Rdf on the Physical and Environmental Properties of Coal Fly Ash

ABSTRACTRefuse-derived-fuel (RDF) consisting mainly of waste paper and plastics is a viable fuel source for the production of power. An experimental test burn partially substituting coal with RDF was undertaken by the Public Service of New Hampshire at the Merrimack Power Station.Five percent and ten percent RDF were substituted, on a BTU basis, for coal in the test bums. The chemical and physical properties of the resulting fly ash were determined. Twelve test burn days were run with 4 days of 5% RDF and 8 days of 10% RDF. Emphasis was placed on investigating the effect of the RDF fly ash on Portland cement concrete.Most of the chemical and physical properties of the coal-RDF fly ash were found to be comparable with ordinary coal fly ash except for the amount of cadmium and lead, the pozzolanic activity index and the compressive strength of fly ash concrete. Cadmium and lead were at average levels of 5.1 ppm and 102.6 ppm for the 5% RDF, and 7.8 ppm and 198.3 ppm for the 10% RDF, respectively. Although the pozzolanic activity index of coal-RDF fly ash increases over normal coal fly ash, preliminary results show that the 28-day compressive strength of concrete with direct replacement of cement and sand decreases by up to 30%. Leaching tests on crushed concrete were conducted to evaluate the environmental effect of acid rain.