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...
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...
Construction of airfield pavements with concrete
Concrete pavements have for years been successfully used in airfield construction. The relatively high weight of the landing gear of large aircraft requires pavement thicknesses which are considerably higher than those of concrete roads. The construction of airfield concréte pavements requires appropriate placing techniques. On account of the high loads...
Critical views on the procedure for and assessment of concreteroad conditions (Results of an investigation carried out on behalf of the Ministry of Transport
The resu l.cs of a research project are reported in ,which a method for the visual surveying of the condition of concreee roads was developed. In collaboration with three Federal German States, the road maintenance procedure hitherto applied was examined. The furcher investigation comprised the development of data recording sheets...
Use of slags in concrete pavements and sub-bases
Industrial by-products have long been used in French road construction. Experience gained over the last twenty years with che extensive use of by-product gravel-sand stabilized with hydraulic binders as a sub-base material, as well as the results of highway engineering practice in neighbouring countries like Germany and Belgi~prompted the LPC...
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...
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,...
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...