The principal criteria applicable to the mix design and the properties of lean concrete are: - splitting tensile strength in the region of 1.7 MFa and compressive strength in the region of 15 MPa at 28 days; - good erosion resistance; - lowest possible modulus of deformation; - possibility of...
Mix design and properties of lean concrete for sub-bases
Retarders and their influence upon the properties of a cement stabilised soil
The engineering properties of a soil-cement mix are adversely influenced by any delay between mixing and compaction. This problem is more serious in hotter climates where the initial setting period is relatively short. As a consequence of this situation, the final product often fails to meet specification requirements. A laboratory...
Spanish realizations of steel fiber pavements
The development of the steel fiber reinforced concrete pavements has experienced a big apogee in Spain in the last three years. The object of this work is to display the most important realizations made in the field of roads. harbours, airports, etc., analyzing their characteristics and behaviour. ROADS - Base...
Assessment of the performance of the structural properties of concrete pavements by means of the falling mass deflectometer
The paper describes the survey and assessment of the structural properties of concrete pavements with the aid of in-situ and non-destructiveloading tests performed with the Dynatest 8000 falling-weight deflectometer (FWD). The following parameters for carriageway slabs with joints are considered: (I) modulus of elasticity of the concrete slabs; (2) modulus...
The use of concrete and masonry waste as aggregates for concrete in the Netherlands
In che paper, results are presented of laboratory research and applications in practice of concrete and masonry waste as aggregates for concrete. In a thorough study the amounts, composicion and relevant properties of the waste were investigated. Based on the results of tests in the laboratory and of full scale,...
Connecting devices between concrete road pavements and existing highway structures
Civil engineering structures, such as bridges, flyovers and underbridges, are discontinuities in a concrete road. Usually, the concrete pavement has to be cut across and in those cases, such as small underbridges, where the concrete pavement can be laid without any discontinuity, differential settlements between embankment and structure have to...
Effect of cement-bound sub-bases on cracking
Cement-bound sub-bases (CaSBs) are constructed ~ithout joints. During and after hardening, cracks may be formed in consequence of drying and/or cooling, even if the sub-base has noc yet been subjected co any traffic load. It would be desirable to have no cracks or only very fine ones (capable of eransmieting...
Theoretical study of technical and economic improvements resulting from the use of equipment train in concrete pavement construction
The report deals with technical and economic improvements resultiRg from the use of a concrete paving train in the construction of concrete roads. The following parameters are investigated: number of trucks needed for the transport of concrete depending on the capacity of the mixing ~lantt the progress rate of the...
Effect of the distribution of air entrained in superplasticized and high workability concrete for traffic areas
For obtaining a high degree of resistance to the action of frost and de-icing salts on concrete, it is essential to have an adequate content of air-filled micropores adjusted to the amount of fine-grained mortar in the mix. With QOI1ventional road concrete, correctly made, it can be presumed that if...
Criteria for the technical choice of priority sections to be reinstated on roads with concrete pavements
Concrete pavements have been used to a wide extent in France on the st.rategic motorway network of the Paris area and on development trunk roads such as the Paris- Lyons. Due to the age of such road pavements, some of which are more than 25 years old, and the large...
Use of cement-bound industrial wastes and recycled materials in earthworks and road construction
For environmental reasons, it is becoming increasingly difficult and eherefore expensive to find fresh sites for wasee disposal. Investigations have shown that coal fly-ash, refuse incinerator grate ash, demolished road asphalt and concrete rubble can, when suicably treated with cement, be economically reused for road construction, for which purpose they...
Structural design of concrete pavements
Under present economic conditions the use of bitumen is being reduced as much as possible. For more than twenty years the application of semi-rigid pavements has revealed the drawbacks but also the advantages of such structures. The chief advantage is their low cost, which can be further reduced if the...