Materials

The replacement of traditional aggregates (limestone) by crushed blastfurnace slag or LD steelmaking slag in lean concrete and in cement-stabilized hardcore was investigated. The effect of adding fly-ash to mixes of the conventional type was also studied. For mixes of equal composition (in parts by volume) and equal grading (by...

A special session of the 65th annual meeting of the Transportation Research Board in Washington, in January 1986, brought together some 50 practitioners and research workers on the theme "Erosion of sub-bases; stepping of slabs and pumping of concrete pavements"; ~he presentation of 3 U.S. papers and two French ones...

A number of research projects relating to the cementbound sub-base (CBSB) are currently in progress in the Federal Republic of Germany. Their object is to develop an optimized technological approach with a view to further improvement and even greater economy in the use of this well proven form of construction....

At Hamburg, sand-cement stabilization (SCS) conseructed by the central-mixed (stationary plant) method is successfully used for frose-protection courses. The requirements applicable to these courses, which as a rule are 15 em thick, are based on those for cementbound sub-bases as laid down in the TVT regulations: degree of compaction ~98%,...

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...

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...

The curing compounds hitherto employed have not always been found satisfactory when applied to road concrete with superplasticizer, to concrete on small jobs, to concrete placed by slipforming and to cement-boundsurfacings. For this reason three new types of curing compound have been introduced, namely, compounds which - give good protection...

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...

Road concrete made with superplasticizers has successfully been used for about ten years now. Its special features with regard to mix composition and method of placing were reported in detail at the London symposium in 1982. This method of construction is increasingly being applied in Austria: - For the maintenance...

Many minor roads are constructed with a cement-bound sub-base not provided with a surfacing. Two such experimental se~tions of road are described in this paper. One of these sections comprises a cement-bound crushed stone sub-base (shell limestone 0 - 45 mm size). It was constructed with a binder content of...

Cycling is "in". The bicycle manufacturers' sales figures show an increase from 1 million to 5 million machines per year over the period from 1956 to 1980. To extend and develop a cycle track network in response to this increase is a logical consequence. Environmental protection and health-conscious behaviour patterns...

Seven experimental sections of thin overlay construction on old concrete and asphalt road pavements have been built in Belgium since 1982. These comprise a total area of 107 000 m2 of fibre reinforced concrete (five sections) of la cm and 12 cm thickness and 34000 m2 of continuously reinforced concrete...