Construction

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...

In the last few years the interest for preventive environment measures has increased. That is the reason for stimulating the re-use of waste materials as a means of recycling. With the aim of stimulating the recycling of waste materials, the interest in using cement to stabilize different materials increased. This...

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...

In Switzerland deposits of gravel are growing scarce. For this and ecological reasons an effort is being made to recycle material, i.e. material produced by roadway demolition -instead of being dumpedshould be re-used in a way to achieve the highest possible quality. This means orderly reconstruction and separation of the...

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...

In Germany the use of concrete with aggregates obtained from crushed concrete (RC aggregate) has been quite limited in comparison to other countries such as the USA and Austria. This situation is caused mainly by the lack of appropriate regulations for this kind of application. For this reason, the award...

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...

Two test sections were constructed with a base course of porous concrete under the emergency lane of a motorway. This base composed of new aggregates or recycled aggregates, has the strength of a cement treated base and the function both of bearing capacity and drainage. Mixed in Plant and placed...

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...

This paper deals with the design, construction and performance of a freeway section over a thick layer of compressible mud. Halfway on the Madrid to Zaragoza freeway, in the valley of the Jalón River, several very soft clayey deposits were found, originated by endorreic drainage basins. The ground treatment systems...

In January 1 9a9 1ro, ad section of 12 km, the access to Zaragoza from Huesca (Spain), was opened to the traffic. Works presented two main technical singularities in Spanish road design and construction. The first one was the introduction in Spain of the construction of rigid pavements on bituminous...

Since the overlay thickness must be decided considerinq the structural condition of the existing pavement, FWD was introduced to evaluate the mechanical properties and to obtain input data for the overlay design. In the case of concrete overlays for concrete pavements, the overlay thickness depends on the existing slab thickness...