Blaine Specific Surface Area Research Articles

결합재의 입도분포가 슬래그 시멘트 페이스트의 유동 특성에 미치는 영향

The rheological properties of slag cement pastes by effect of particle size distribution of binder were investigated using a Rheostress 1 rheometer (Haake) with a cylindrical spindle and the relationship between fluidity particle size distribution using the Rosin-Rammler equation. Samples are combined the two types of slag powder and OPC, fine slag particles sized Blaine specific surface area 8,000 ㎠/g, coarse slag particles sized Blaine specific surface area 2,000 ㎠/g, intermediate OPC particles 3,450 ㎠/g, used to search for the combination that would yield the best quality product. The all flow curves which were measured by rheometer showed hysterisis and could be classified into 4 types. When the combination was based on a ratio of 15-20 vol% fine particles, 40-50 vol% intermediate particles, 30-40 vol% coarse particles of the total volume, a high fluidity and low yield-strength was achieved. The Rosin-Rammler function can explain aboved correlation flow curve types. On type 1, the n-value had a correlation with plastic viscosity however the blend of type 2 and 3 showed consistent n-value regardless of plastic viscosity. In addition, the blend in type 4 tended to a rise in fluidity according to the increase of the n-value.

Farklı Puzolanik Katkıların Çimento Harçlarının Mekanik Özelikleri Üzerine Etkisi

In this study, cement mortar samples containing fly ash obtained from Soma Power Plant, two different types of natural pozzolan supplied from Yenisehir and Bilecik and silica fume from Antalya Ferrocrom Industry partial replacement of cement clinker. The strength of the mortars prepared by these mixtures were investigated. The mixtures were prepared by using 10% fly ash and 5% silica fume and the trass contents varied as 30%, 35%, and 40%. Chemical analyses of these mixtures were carried out and Blaine specific surface area values were measured. In performed tests, the highest strength values were noticed in mortars containing natural puzzolan from Bilecik which has high fineness.

Characteristics and pozzolanic reactivity of glass powders

This paper deals with the morphology, fineness and pozzolanic activity of four glass powders: one (GP-fine) from the screening of crushed waste glasses, one (GP-dust) from a dust collector for the glass crushing process and two (GP-4000 and GP-6000) from further grinding of the powder from the dust collector in a ball mill. GP-fine and GP-dust consist mainly of large flaky particles, while GP-4000 and GP-6000 consist mainly of small angular particles. The finenesses of these glass powders are measured by particle size distribution and Blaine fineness method. For a similar particle size distribution, ground glass powder has a higher Blaine specific surface area than Portland cement due to the angular morphology of glass particles. Finely ground glass powders exhibited very high pozzolanic activity. The finer the glass powder is, the higher its pozzolanic reactivity is. An increase in curing temperature accelerates the activation of pozzolanic reactivity of both glass powder and coal fly ash in terms of strength development rate. Mortar cube strength results (ASTM C109) indicated that curing temperature has a greater influence on the glass powder than on fly ash. The rapid mortar bar expansion test (ASTM C1260) results indicate that the replacement of Portland cement with ground glass powder also reduces the expansion due to alkali–aggregate reactions, although it is not as effective as coal fly ash.

Prediction model of compressive strength development of fly-ash concrete

Based on experimental results concerning the compressive strength development of concrete containing fly ash, the authors derived an estimation equation for compressive strength development. The equation can express coefficient α, which indicates the activity of fly ash as a binder, in the form of a function of age, fly-ash content, and Blaine specific surface area of fly ash. This equation is capable of explaining the increases in the early strength due to fly ash in place of part of fine aggregate, the decreases in the early strength due to fly ash in place of part of cement, the increases in the long-term strength due to pozzolanic reaction, the relationship between the fly-ash replacement ratio and the ratio of strength increase/decrease, and the effect of fly ash's Blaine specific surface area on the strength.

Prediction model of compressive strength development of fly-ash concrete

Based on experimental results concerning the compressive strength development of concrete containing fly ash, the authors derived an estimation equation for compressive strength development. The equation can express coefficient α, which indicates the activity of fly ash as a binder, in the form of a function of age, fly-ash content, and Blaine specific surface area of fly ash. This equation is capable of explaining the increases in the early strength due to fly ash in place of part of fine aggregate, the decreases in the early strength due to fly ash in place of part of cement, the increases in the long-term strength due to pozzolanic reaction, the relationship between the fly-ash replacement ratio and the ratio of strength increase/decrease, and the effect of fly ash's Blaine specific surface area on the strength.

微粉砕乾燥スラッジ (PDS) のコンクリート材料としての用途開発に関する研究

In this paper, the properties of fresh and hardened concrete containing “pulverized dry sludge (PDS)” as both a mineral admixture and a fine powder for high-fluidity concrete were investigated. The so-called pulverized dry sludge is a very fine powder with a Blaine specific surface area of 5,000-15,000 cm2/g made from sludge cake by a process of drying and crushing.It was found that when PDS is used as a part of cement such as mineral admixture, PDS has no harmful effects on hardened concrete although the dosage has sometimes to be limited to about 10% of the cement content because high content of PDS significantly increases the demand of mixing water. Experimental results on high-fluidity concrete showed that concrete containing up to 30 % of PDS content had a good performance in both fresh and hardened properties. This research shows the potential for the effective use of concrete sludge disposed from ready-mixed concrete plants.

Characterization of fly ash directly collected from electrostatic precipitator

Class-F fly ash was obtained from different hoppers at progressively farther distances from the boiler. Examinations showed that the ash collected from the farthest hopper tended to have finer particle size, greater density, lower carbon content, and higher glass content. When the boiler is operated at full load (600 MW) the glass content increased compared to half load (300 MW), but the Blaine specific surface area and carbon content decreased. Pozzolanic reactivity at 40°C is related to the fineness of the fly ash but the glass content has no significant influence on reactivity. There was a negative correlation between carbon content and the apparent viscosity of cement paste with fly ashes and 1.6% added superplasticizer.

Application of high-strength/superworkable concrete to thin-wall prestressed concrete products

Undertaken to develop a practical vertical casting method that can be applied to manufacture efficiently thin-wall prestressed concrete products with high strength (fck = 70 MPa), the work presented in this paper included the development of superworkable concrete made by adding 15–20% fine limestone powder (Blaine specific surface area 7310 cm2/g) to high-early-strength Portland cement along with a polycarboxylic-acid-type air-entraining superplasticizer and viscosity agent (natural polysaccharide polymer of type β-glucan) solution. This was followed by the laboratory testing and trial production of this superworkable concrete at an actual plant to study its suitability as a material for densely reinforced, thin-wall prestressed concrete products. The study confirmed that neither the addition of a viscosity agent (β-glucan) nor the quantity of fine limestone powder added has any effect on the freezing and thawing resistance or the sulphate resistance of superworkable concrete.

風化によるセメントの水和活性の変化と偽凝結現象

The false setting of cement caused by the aeration was studied from the analysis of the cement characters, its hydraulic reactivity, its hydration reaction, the paste rheological properties and the relationship among them. The aeration of cement was simulated by the treatment of cement exposing under an environment of temperature, 20°C and relative humidity, 80%. With a longer treatment, cement showed larger amounts of ignition loss. Hydration products with particle sizes under 0.3 μ m were formed on cement particles and the amount was increased with the increase of treatment time. Although the treatment did not change the Blaine specific surface area, it changed the BET specific surface area as much as 1.4 times higher during seven days of treatment. The treatment significantly decreased the hydration reactivity of interstitial phases of cements. The treatment longer than certain period of time brought a false setting in cements, which was not occurred in fresh cement paste. When aerated cements was mixed with water, sulfate ion was supplied to liquid phase from alkaline sulfates or calcium sulfate hemihydrate. However, the sulfate ion was not consumed by the ettringite formation reaction because of the low reactivity of interstitial phases. As the results of poor consumption of sulfate ion, gypsum crystals deposited from liquid phase to form large automorphic plate crystals and finally cement paste was thought to show the false setting, i.e. plaster set.

The Changes in the Secondary Properties of Zinc Oxide in the Process of Mechanical Treatment

Abstract The changes in the secondary properties of zinc oxide upon mechanical treatment were studied. In the process of the mechanical treatment of zinc oxide, the Blaine specific surface area, the sedimentation volume, and the particle size distribution changed periodically with the treatment time. Such periodical changes are characteristic of the state of association of the particles, and can be interpreted as the changes in the total energy content of the solid.