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Rutting, depending on the wear of studded tyres, is a problem in the Skandinavian couritiis. Concrete pavements have a good wear resistance. In Ai.ustria they have recently developed a low noise concrete with small aggregate size and exposed aggregate. Earlier experiences have shown that the wear resistance of concrete is...

Various air-entraining agents were investigated for their physicochemical characteristics and for their foaming power. Correlations were found between this power and the parameters characteristic of entrained air. These parameters were determined on the fresh concrete using the DBT "Air Void Analyser". Air-entrained concretes have a water absorption very similar to...

To determine the concrete strength of a road surface the authors of this paper have used an ultrasonic method. In this method, longitudinal waves are directed to a concrete slab by means of transducers applied to the upper surface of the slab. If the propagation time and the distance between...

The main goal of curing is to protect the young concrete against drying out. These investigations indicate, that concrete temperatures during the first day of hardening are decisive for the magnitude of thermal stresses of the hardened concrete and the related cracking risk. High thermal tensile stresses occur, if the...

Cement for concrete pavements has to meet special requirements. Besides cement properties which influence the fresh concrete, the cement is of great importance for the durability of concrete pavements. If the joints in the young concrete are not sawn early after paving, cracks can form in the pavement. With cracking-frame...

The problem of using fine-grained (sand) concrete instead of the "classic one in the construction of road and airfield pavements is analysed. In sand concrete the coarse aggregate, crushed stone or gravel, are substituted by natural sand or a blend of natural sand and screenings 0.5 (10) mm. The use...

This paper describes the application of a relatively simple and inexpensive laboratory test deiived Iiuiii ASTM procedure C779 for evaluating abrasion resistance of concrete surfaces. Factors affecting the reproducibility and precision of the test are quantified. The paper describes the use of the test to evaluate trial mixes of paving...

Aggregates were obtained from an alkali-silica damaged concrete road slab aggregates and used for road base concrete with different kinds of cement (low alkali cement, high alkali cement). After analysing the samples produced with these mixes, which were exposed for up to one year to different hardening conditions, no alkali-silika...

The provisions of the European Prestandard ENV 206 "Concrete - Performance, Production, Placing and Compliance Criteria" place the accent on the qualitative requirements (physical, chemical and mechanical ones) of a durable road concrete. The theoretical life of a rigid road pavement obviously r1.pends on the design and the quality control...

The use of CD 40-A cement eliminates the classical procedures of measuring plastifying and air entraining additives at the preparation on site of the road concrete. The article presents the main characteristics of CD 40-A and the results of laboratory tests carried out to establish the influence of this type...

Requirements for concretes in colder environments are stricter than those normally requested for standard commercial concretes. Therefore, a concrete produced with (i) high quality ingredients, (ii) a water/cement ratio of 0.35 to 0.40 by mass, (iii) 3.0 to 6.0 percent entrained air, (iv) an adequate maturity, i.e. when the compressive...

The aim of this paper is to discuss some defects of the concrete pavement during the construction of the second northern expressway project in Taiwan. The possible reasons of and techniques for repairing these defects are studied in the paper. The defects discussed include the cracks in the lean concrete...