FIRE-PROTECTION WITH ALKALI-ACTIVATED CEMENT BINDER

Fire resistance of unprotected steel structures is very low and steel elements must be protected from fire. One possibility is to create a protective layer of a cement-based material. Most types of cement have a low resistance to high temperatures, reducing mechanical properties. In flammability tests, cement activated with alkaline compounds showed better properties compared to conventional types of cement. This paper represents the determination of the properties of two H-Cement mortars with experlite or fireclay sand. Experiments carried out in a small kiln simulating a 1D load showed differences between elements in terms of heat transfer to the tested elements. The calculation model created to predict the course of the experiments has been validated and the unknown properties of the material have been calculated based on the data collected. The samples were tested in a small fire furnace. Finally, the thermal conductivity pattern was determined depending on the temperature

Free profinite R-trivial, locally idempotent and locally commutative semigroups

This paper is concerned with the structure of implicit operations on R intersection with LJ1, the pseudovariety of all R-trivial, locally idempotent and locally commutative semigroups. We give a unique factorization statement, in terms of component projections and idempotent elements, for the implicit operations on R intersection with LJ1. As an application we give a combinatorial description of the languages that are both R-trivial and locally testable. A similar study is conducted for the pseudovariety DA intersection with LJ1 of locally idempotent and locally commutative semigroups in which each regular D-class is a rectangular band.INVOTAN, grant 4/ A/94/PO.PRC-GdR AM

On Decidability of Intermediate Levels of Concatenation Hierarchies

It is proved that if definability of regular languages in the Sigma(n) fragment of the first-order logic on finite words is decidable, then it is decidable also for the Delta(n+1) fragment. In particular, the decidability for Delta(5) is obtained. More generally, for every concatenation hierarchy of regular languages, it is proved that decidability of one of its half levels implies decidability of the intersection of the following half level with its complement

Full vs Partial Market Coverage with Minimum Quality Standards

The consequences of the adoption of quality standards on the extent of market coverage is investigated by modelling a game between regulator and low-quality firm in a vertically differentiated duopoly. The game has a unique equilibrium in the most part of the parameter range. There exists a non-negligible range where the game has no equilibrium in pure strategies. This result questions the feasibility of MQS regulation when firms endogenously determine market coverage

High-Volume Municipal Solid Waste Incineration Bottom Ash Concrete.

About 50% of Municipal Solid Waste is incinerated (MSWI) in Europe what represent ca. 50 Mt/a of MSWI bottom ash (BA). Bottom ash contains several marketable components (iron scrap, non-ferrous metals, glass) which can by separated from the main BA stream and placed on the market with secondary sources. The resting material is, by its composition and properties, similar to natural aggregates and can be used in this way. The influence of metals separation form BA on its behaviour in concrete was tested by using BA from Praha Malešice Waste-to-Energy Plant. Particle size fractions 4/8 and 8/16 mm of this BA can be used as aggregates in concrete up to 50 vol. % of given fraction without any significant loss of concrete strength. The combination of valuable component separation form BA and recycling of the rest portion as aggregates feature promising way of BA management reducing the amount of BA to be landfilled to minimum