Showing papers on "Pervious concrete published in 1993"

Laboratory study of porous concrete for its use as top-layer of concrete pavements

Abstract: Included in the project 'Optimization of Surface Characteristics of Concrete Roads in Accordance with Environmental Acceptance and Traffic Safety' is a lab program being carried out by various European institutes to study the composition and characteristics of porous concrete for use as top-layer of concrete pavements. The main aim of this work is to optimize the composition of porous concrete with respect to strength, acoustic properties, drainage, durability, and costs comparable to porous asphalt. This latter material is now widely used in different European countries due to its noise reducing and drainage properties. These 2 aspects are now considered to be very important because of environmental impact and safety matters. To date, results obtained have given very useful information on the relationship between porous concrete composition and characteristics. These relationships were actually used to define the most appropriate mixtures to be used in specific projects. This paper describes the testing program carried out, as well as the results obtained so far and the corresponding practical consequences.

Chloride diffusion in porous concrete under conditions of variable temperature

Abstract: A diffusion model is presented in this study for describing diffusion of chloride ion in porous concrete under nonisothermal conditions. The process is to simulate chloride diffusion in concrete exposed to daily cyclic temperature change. The effects of cyclic and constant temperatures on the chloride diffusion behavior in concretes are investigated. The time for chloride concentration to reach the corrosion threshold of the reinforcing steel is determined for a given water-to-cement ratio and thickness of concrete layer. Results indicate that the temperature and water-to-cement ratio play a vital role in governing the chloride diffusion process.

Water permeable concrete block and production thereof

Abstract: PURPOSE:To stably produce the water permeable concrete block which is formed by using cement as a binder and has specified water permeation performance and to provide the concrete block which has a flat surface to assure easy walking, has the large exposing area of aggregate to this surface and has good appearance. CONSTITUTION:The surface 1a side of the water permeable concrete block 1 formed by joining the surface layer aggregate 4 and the lower layer aggregate 5 with the cement C as the binder is polished.

Concrete block for greening

Abstract: PURPOSE:To green the surface of a retaining wall constructed by precast concrete blocks with natural plants. CONSTITUTION:A porous concrete layer 2 is integrally provided on the surface of a concrete block main body 1A. Greening aggregates mixed with a hygroscopic swelling material swollen by water absorption and a water-soluble binder and molded and solidified into grains are mixed with granulated aggregates for concrete to form the porous concrete layer 2.

Porous concrete and concrete structure for greening ground

Abstract: PURPOSE:To enable the growth of a plant other than creeping plant on the surface of a wall without using soil. CONSTITUTION:The objective porous concrete body 10 for greening contains spongy porous deformable materials 16 mixed into the body. The porous deformable materials 16 are made to contact with each other and have water- permeability and, accordingly, water supplied from outside can soak into all porous deformable materials 16. Since the porous deformable material has water-retainability, the absorbed water is retained in the material and used as a nutrient for the plant. The porous concrete body 10 for greening having the above construction is bonded to an outer wall 20. Mortar containing seeds is sprayed to the porous concrete body 10 pasted to the outer wall 20 and the porous deformable material 16 is deformed according to the extension of the root after sprouting to form a space 26 for extending the root. Accordingly, the root 24 can be grown in the porous concrete body 10 for greening without restriction.

Tunnel wall and construction method thereof

Abstract: PURPOSE:To drain water oozing out of the underground effectively. CONSTITUTION:Water permeable layers 5 and normal concrete layers 6 are alternately formed in a vertical direction in the internal surface of a tunnel, and through-holes 7 connecting both up and down water permeable concrete layers 5 are opened to the normal concrete layers 6. A surface treatment layer 8 is formed on the external surface of the water permeable concrete layers 5 and the normal concrete layers 6 to drain water oozing out of the underground downward through, the through-holes 7 from the water permeable concrete layers 5 in turn.

Method for producing porous concrete

Abstract: PURPOSE:To arbitrarily control void and shape of concrete by heating concrete mortar containing specific void forming materials and promoting hardening mortar and melting and shrinkage of the void forming materials. CONSTITUTION:Concrete mortar 2 in which void forming materials 3, 4 and 5 comprising a polymer of proper shape such as granular, fibrous or netlike form, optionally containing a metal such as iron powder or copper wire, melting and shrinking by heating are embedded or which is blended with the void forming materials is packed into a frame 1. The mortar 2 is heated, the mortar 2 is hardened and the void forming materials 3, 4 and 5 are melted and shrunk to form voids in concrete.