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In most Dutch power stations secondary fuels are co-combusted. It is important that the quality of the generated fly ash does not degrade because of co-combustion, as this will hinder utilization. Therefore, a project was started to assess the consequences of co-combustion of selected fuels (demolition wood, chicken manure and refuse de-rived fuel) on the properties of the fly ashes. The co-combustion experiments were carried out in the KEMA Test boiler (pilot-scale, 1 MW1h). The properties of the generated fly ashes were analyzed and the behavior of the fly ashes when applied as pozzolanic filler was assessed. It was concluded that the cystalline components as identified by X-ray diffraction are the same as normally found in Dutch fly ashes (ASTM class F), with exception of fly ash from chicken manure. The glass content is reduced by co-combustion depending on the co-fired fuel. If chicken manure is co-combusted, the chemical composition changes due to the increase of Ca, P, K and S. Co-combustion of demolition wood and refuse derived fuel (RDF) causes an increase of Ca, Na and K. The pozzolanic behavior of fly ash appears not to be influenced by co-combustion of demolition wood. However, co-combustion of RDF causes a decrease in pozzolanic behavior, but relatively high percentages are possible up to the point where it no longer meets the limits. Co-combustion of chicken manure appears to have a positive influence, but this is related to other reaction mechanisms than pozzolanity. It can be stated that fly ashes from high percentages of co-combustion are able to meet the basic requirements of the European standard (EN 450). It all depends on the nature of the co-fired fuel and especially on its inorganic matter and ash content.

A research project was undertaken at the Australian Centre for Construction Innovation, University of New South Wales to investigate the sulphuric acid resistance of various concretes using different types of cements and aggregates. The cements included a general purpose portland cement, a slag-blended cement, and ternary blended cements containing both silica fume and fly ash, or both silica fume and slag. Two combinations of aggregates, limestone coarse and fine aggregates and, crushed river gravel coarse aggregates and silica sands, were used in the concrete mixtures. The standard compressive strengths of the concretes tested at 28 days were in the range of 45 to 58 MPa. Concrete cylinders were immersed in regularly refreshed 1% and 0.02% sulphuric acid solutions. These cylinders were assessed by visual inspection of the surface deterioration, measuring mass change and testing for crushing load during the immersion period. It is found that the use of limestone aggregates was a quite promising option in order to reduce the rate of concrete degradation in acidic environments. The best acid resistance was found with the concrete using limestone aggregates and the ternary blend cement containing 7% silica fume and 33% fly ash.

When low-heat portland blast-furnace slag cement is used, the thermal expansion strain of concrete shows reversal deformation in spite of the continuous temperature rising as the result of rapid autogenous shrinkage greater than the thermal expansion. In this study, the autogenous shrinkage strain was investigated in terms of gypsum con-tent in cement. It was possible to reduce the autogenous shrinkage by increasing the gypsum content in cement. Prevention of the early-age rapid hydration development of granulated blast-furnace slag at high temperature was also examined. Moreover, the amount of transition from ettringite to monosulfate of hydration product was deter-mined. As the result, it affected autogenous shrinkage of blast-fumace slag cement concrete significantly.

Although the water-cement ratio of concrete for the prestressed concrete is low, deterioration due to salt attack of prestressed concrete structures has appeared in recent years. Blast-furnace slag is effective in resisting penetration of chloride ions. However, the influences of blast-furnace slag on the durability properties of high-strength concrete for steam-cured pretensioned elements are not clear. In this study, carbonation and chloride penetration of the high-strength concrete using blast-furnace slag were examined. As the result, the addition of blast-fumace slag increased the concentration of chloride ion near the surface, but decreased the penetration to the interior concrete. Blast-furnace slag improved the resistance to erosion by a calcium chloride solution. Moreover, it was found that carbonation of the concrete made with blast-furnace slag was slow and there was no problem in this respect.

The rheological properties, the packing density, and the final matrix strength of high performance cementitious materials can all be improved by adding fine-grain materials such as fly ash, silica fume, slag, and natural pozzolans. Beside size and shape of the added materials, their pozzolanic activity can improve the bond between the particles in the matrix and can reduce the shrinkage. In this study, the fine-grain binder systems were evaluated for application in high performance fiber reinforced cementitious composites with different type of non metallic fibers (carbon, PVA, PP). The rheological and mechanical properties of fiber reinforced composites based on ordinary portland cement and blended with micro-fine cement (mostly based on blast furnace slag), fly ash, silica fume, and limestone filler, respectively, were measured and compared to the pure fiber-cement matrix. In this context, micro-fine cement shows clear advantages compared to the other fillers. Very good mechanical properties of the composites (flexural strength > 25 MPa, compressive strength > 150 MPa) were obtained. For the estimation of the consistency of fiber-cement mixtures, a new experimental method was developed and applied.