Showing papers on "Pervious concrete published in 1998"

Service life model for concrete structures in chloride laden environments

Abstract: Bridges are a major element in ground transportation networks. Of the present $70 billion backlog of bridge rehabilitation needs, $28 billion dollars is attributed to the corrosion of steel in concrete. The chloride corrosion of steel in concrete structures is not confined to bridges but also reduces the service life of parking garages and sea and coastal structures. The service life model for reinforced concrete structures in chloride laden environments consists of the following serial phases: diffusion to the depth of the steel that would precipitate first maintenance actions; corrosion of the steel at the first maintenance depth until cracking and spalling occurs; and continue spalling until a damage level is reached which is defined as the end-of-functional service life for an element or structure. The diffusion phase is described by Fick's Law and the boundary conditions define the solution form. The time-to-cracking model is dependent upon factors as concrete strength properties, cover depth, and corrosion rate. Corrosion rate has a significant influence on the time-to-cracking, which typically occurs 3-7 years after initiation. The utility of the model in estimating the service life of corrosion protection systems as increased cover depth, corrosion inhibitors, and low permeable concrete is presented. As is the means for determining the time-to-first maintenance and annual maintenance requirements to the end-of-functional service life. The model in conjunction with a life-cycle cost model will enable the selection of the least cost solution to corrosion protection.

Optimization Methods for Material Design of Cement-based Composites

Abstract: Introduction Mathematical foundations of the optimization of composites Review of concrete mix design methods Optimization of reinforcement of the fibre-reinforced concretes Optimization of the polymer cement concretes Optimization of water permeable concrete Design and optimization based on large databases Concluding remarks Index

Properties of High-Strength Porous Concrete

Abstract: A new method of producing high-strength porous concrete has recently been developed in Japan. In this method, porous concrete is produced by coating the coarse aggregates with a high-strength mortar, then applying vibration to fuse them. Porous concrete produced by this method has the following properties. It has a continuous void system with a volume-to-total-void ratio exceeding 85% and a compressive strength of 20 MPa or greater when water permeability is 2 cm/sec. The porous concrete produced exhibited good durability in freezing and thawing tests (ASTM C666, Procedure B) and, while the amount of drying shrinkage is about 60%, or smaller than that of conventional concrete, such shrinkage occurred very rapidly.

Elastic water-permeable concrete composition, formulation method therefor, elastic water-permeable concrete structure formed of the composition, and method for constructing the structure

Abstract: An elastic water-permeable polymeric concrete composition, a formulation method therefor, an elastic water-permeable polymeric concrete structure using the composition, and a method for constructing the structure. The polymeric concrete composition is formulated by integrating a rubber powder ground from waste tires or waste rubber and an aggregate using a polymeric binder, and if required, by adding a pigment and aromatic capsules capable of providing remedial and psychological effects. The polymeric concrete structure manufactured using such polymeric concrete composition has appropriate elasticity, water permeability, strength and a pleasant aroma. Thus, the polymeric concrete composition is useful for paving a footpath, a roadway, a bikeway, a railway crossing, a parking lot, a stadium, a racing track, a landing strip, etc., and as a material for civil engineering and constructions such as blocks, tile sound-absorbing plates, soundproofing plates, soundproofing walls and retaining walls.

Corrosion Protection Service Life of Low-Permeable Concretes and Low-Permeable Concrete with a Corrosion Inhibitor

Abstract: The results of a 1.5-yr laboratory study and field investigation of three Virginia bridges are presented. Specimens with fly ash, slag cement, silica fume, silica fume with a corrosion inhibitor, and two specimens (controls) with Virginia Department of Transportation specification concrete (A-4) were built to study diffusion characteristics of these concretes and to estimate corresponding corrosion initiation times. The methodology used to estimate the corrosion initiation times is based on Fick's Second Law of Diffusion. It uses laboratory concrete diffusion characteristics and cumulative distribution functions of the field surface concentration and diffusion coefficient values. The calculations are performed for various cover depths, and a set of curves is provided for each concrete type and for low, mean, and high values of surface concentration (exposure severity) and diffusion coefficient (concrete quality). The analysis results demonstrate the benefits of using mineral admixtures, especially when combined with a corrosion inhibitor.

Concrete block for creating seaweed colony and seaweed reef

Abstract: PROBLEM TO BE SOLVED: To provide a seaweed colony creating concrete block enabling the effective adherence and growth of seaweeds under the surface of the sea, enabling the growth of a phytophagous animal such as abalone, top shell or sea urchin from its larva to a grown body, enabling the smooth cycling of the alternation of generations, and suitable for each generation, and to provide a seaweed reef thereof. SOLUTION: This concrete block has a double-layered structure 10 consisting of the upper part of porous concrete 1 and the lower part of ordinary concrete or a porous concrete whose concrete strength is increased. It enables the free adherence and growth of objective small-sized or large-sized seaweeds that the decay speed of the surface is controlled by adjusting the particle sizes of aggregates, and the compounding state of cement and mixing materials of the upper porous concrete.

Production of porous concrete and porous concrete

Abstract: PROBLEM TO BE SOLVED: To provide instant stripping porous concrete and porous concrete to be cast in place that has a porosity of >=25% and high coefficient of permeability, can attain a high flexural strength not lower than that of the plain concrete with a reduced polymer-cement ratio. SOLUTION: An instant stripping porous concrete is prepared by previously mixing high-early-strength portland cement with 5-20 wt.% of silica fume in the inner percentage, then kneading together the resultant cement powder, coarse aggregate, water-reducing agent, a water-absorbing resin and water. In this production process, the water-absorbing resin is added in an amount of 0.01-0.1 pt.wt., per 100 pts.wt. of the cement powder and the resin is dispersed in the kneading water in an amount of 1.1-4.0 times the water absorption capacity of the resin before the dispersion. The porous concrete to be cast in place is prepared by kneading the cement powder as a mixture of high-early-strength portland cement with silica fume in an amount of 5-20 wt.% in the inner percentage, together with fine aggregate, coarse aggregate, water-reducing agent and water where the amount of the fine aggregate with an average particle size of 0.15-1.2 mm is used in an amount of 50-150 pts.wt. per 100 pts.wt. of the cement powder.

Vegetation concrete block and vegetation concrete block construction

Abstract: PROBLEM TO BE SOLVED: To aim at the water permeability, imbedding and growing of plant in vegetation concrete block by fixing a product of natural fiber to a surface of a porous concrete molding so as to be exposed. SOLUTION: Rolled products 2 made vegetable fiber material such as coconut palm, hemp palm and straw are fixed to a top surface of a block plate 1 of porous concrete for integration so as to be exposed in parallel with each other or so as to be exposed and cross each other. The block plate 1 with the porous structure has ventilation with back surface soil and water permeability, and the rolled product 2 is appropriate for imbedding of root of plant, and weathered in 2-10 years and assimilated with soil, and furthermore, the rolled product 2 does not discharge harmful material, which gives bad influence to environment. The block plate 1 is formed with a chamfering surface at each corner thereof and provided with a connecting member 17. Adjacent blocks 1, 1 are connected by the connecting fitting and filling of mortar or concrete. Consequently, water permeability is secured by the block plate 1, and the imbedding and growing of plant can be aimed.

Properties and Performance of Green Concrete

Abstract: Green Concrete is a concrete on which plants such as grasses and bushes directly grow up. It is utilized for increasing the amount of the green around buildings and civil structures. It consists of no-fines concrete, water retentive material in the voids and a thin soil layer sprayed on the surface. The no-fines concrete is made of single size crushed stone and low alkaline cement paste. Chopped peat moss which retains water and fertilizer is used to fill in the voids. Seeds mixed with the soil germinate, take root into the voids and grow up. In this paper the results of studies of the relationship between the strength and the void ratio of concrete, and the effects of cement types on the alkalinity leached from hardened cement are presented. Plant growth performance of the Green Concrete is also presented based on planting tests using lawns and actual applications. The optimum void ratio of concrete was approximately 25-30% when the compressive strength was approximately 10-15 N/sq mm. In this condition of concrete, it is demonstrated that herbaceous plants and some kinds of trees sufficiently grow on the Green Concrete.

Manufacture of composite type porous block

Abstract: PROBLEM TO BE SOLVED: To give the characteristics of a porous concrete and the characteristics of a concrete block in combination by a method wherein a porous concrete part is provided on the surface layer part of a base made of dense solid concrete so as to integrally bond the porous concrete and the dense solid concrete to each other SOLUTION: Under the condition that a form 12 is placed on a surface plate 11 equipped with a table vibrator 10, a porous concrete 21 kneaded with a mixer is placed in the form 12 After the surface of the placed concrete is leveled, the concrete is compacted A mortar 22 of dry consistency having no slump is kneaded under a predetermined mixing ratio of a cement and a fine aggregate and then is laid on the surface of the porous concrete placed in advance in the form 12 and leveled Then, the top surface of the mortar is tamped with a trowel and rolled A normal concrete 23 is kneaded with a mixer and cast on the mortar layer 22 so as to produce the anchoring part concretes 24 of a slope surface block After that, the resultant concrete assembly is compacted by being given vibration by means of a table vibrator 10 Finally, the placed surface of the concrete assembly is finished

Execution method for concrete structure, and concrete panel capable of planting

Abstract: PROBLEM TO BE SOLVED: To provide an execution method for a concrete structure in which plants can be grown on the surface. SOLUTION: A panel 1 comprises a double layer structure of an upper layer 12 of porous concrete having a continuous cavity part 2 at a volume ratio of 15% or more and less than 45%, and a lower layer 11 of a base plate without permeating cement paste, a plant growing base plate is filled in the cavity part of the concrete, and young plants of drying resistant plants such as Sedum- genus plants are planted, or seeded. This panel is used as form for constructing a concrete structure, then alkali of concrete is shielded by the lower layer base plate to be prevented from reaching the upper layer, and bad effects are not given on plants growing on the upper layer, so the plants are grown to provide a surface green view on the concrete structure continuously for a long period.

Properties and Application of Environmentally Friendly Porous Concrete

Abstract: The void diameter and the internal surface area of porous concrete, prepared with crushed stone and glass balls of differing diameters as aggregate, were determined by slicing off the central cross section, cutting it into pieces at constant intervals and making an image analysis of those sections to examine the effect of the analytical results on the physical properties of the porous concrete and the growth of plants. The results indicated that the mean void diameter of the porous concrete is approximately 0.22 to 0.24 times the particle diameter of the aggregate packed with 30% binder and that the interconnected void, approximately 3 mm in mean diameter, is appropriate for grass-planting concrete.

Vegetation unit for greening concrete structure

Abstract: PROBLEM TO BE SOLVED: To provide a vegetation unit for greening concrete structure by which a plant sowing bed is easily arranged and also which is suitable for raising plants widely and transplanting them. SOLUTION: The vegetation unit 1 for greening concrete structure consists of flat vegetation mats 2 and support frames 3 for supporting the edge parts of the vegetation mats 2. In the unit 1, the vegetation mat 2 is provided with a sowing layer 17, a porous concrete fixing layer 18 where a part of concrete enters so as to be hardened and an impermeable layer 19 which is held between the sowing layer 17 and the concrete fixing layer 18. The support frame 3 is combined with other support frames 3, has a shape constituting a mold frame for casting concrete and is provided with a holding means 9 for holding the vegetation unit 1 while being resistant to the side pressure of cast concrete.

Sound absorbing plate

Abstract: PROBLEM TO BE SOLVED: To enhance strength by providing a porous concrete part formed by kneading aggregate and a cement group binder and molding it, and a high strength concrete part with tendons embedded in high strength concrete. SOLUTION: Aggregate is formed of crushed material of unglazed brick, crushed stone of natural pumice and burned beads of waste plastic, waste glass, or the like. The aggregate is kneaded with a cement group binder and molded on a slab from the from a porous concrete part 1 with parts 4a of cavities 4 continuous in the lengthwise direction of a concrete plate body. A plurality of tendons 3 such as prestressing wires are disposed in a tensed state on the porous concrete part 1, and high strength concrete is placed in the form the embed the tendons 3. After the concrete is hardened, the tendons 3 are cut to impart presser, and a high strength concrete part 2 is formed to form a sound absorbing plate 5 with the cavities 4. Strength can therefore be enhanced.

Porous concrete granulate for cultivation of plants

Abstract: Plants are grown in a granulate of porous concrete produced from a mixture of: 10% quartz sand; > 10% lime; 1-10% cement; 1-10% natural gypsum; 1% aluminium powder; and > 10% water. The mixture is formed as required and allowed to set. Granules are preferably 5-15 mm in size and are made from porous concrete waste from the manufacture of porous concrete blocks or slabs. The granulate may also be used as a layer on a flat roof in which e.g. grass can be grown to form a `green' roof covering.

Production of high strength water permeable concrete

Abstract: PROBLEM TO BE SOLVED: To obtain high strength concrete having water discharging performance, sound absorbing property, antislipping effect and water permeability by blending and kneading Portland cement with #7 macadam, #6 macadam, a binder, a pigment and water in a specified ratio and carrying out concrete placing or press hardening with a form on a surface to be paved. SOLUTION: A concrete mixture is prepd. by blending 350-400kg Portland cement based on 1m of the mixture with 90-1001 water, 750-800kg #7 mecadam, 800-850kg #6 macadam, 1.5-2.0kg binder and 10-15kg pigment. The #7 macadam and #6 macadam area aggregate and preferably have a Mohs hardness of >=6 and >=700kgf/mm Knoop hardness. By the aggregate, the objective water permeable concrete having a large void volume and high strength is obtd. The binder is an inorg. binder such as anhydrous gypsum or kaolin or an org. binder such as resin latex.

Mold made of porous concrete

Abstract: For thermoforming a sheet of plastic material, a mold is made of porous concrete. More specifically, the mold comprises a body of porous concrete having a mold surface section and a second surface section. An impervious wall made of high performance concrete is applied to the second surface section of the body of porous concrete for sealing this second surface section. A duct is formed through the high performance concrete of the impervious wall and is connectable to a vacuum equipment for sucking air through the mold surface section, the porous concrete of the body and the duct in view of applying a heated sheet of plastic material to the mold surface section of the porous concrete body. Preferably, the body of porous concrete comprises a core of concrete having a higher porosity, and an outer layer of concrete having a lower porosity in view of providing a smoother mold surface section.

Vegetation concrete and its production

Abstract: PROBLEM TO BE SOLVED: To produce vegetation concrete which ensures water holding property, reliably maintains its water holding and a holding state and can efficiently applicate greening on the ground, a surface of a slope or the like, by using a bentonite ore aggregate as a coarse aggregate. SOLUTION: The vegetation concrete 1 consists of an artificial aggregate 2, cement, water, a fine aggregate and an admixture. The artificial aggregate 2 comprises a bentonite ore aggregate as a coarse aggregate or is formed by mixing a pulverized bentonite ore aggregate with a fertilizer or the like necessary for planting. When water is supplied to the concrete 1, the bentonite ore aggregate absorbs the water, swells and ensures the water, and the growth of the roots of a plant is promoted by the softening of the bentonite ore aggregate. Production efficiency is enhanced by forming concrete or porous concrete blocks and handling is simplified even in application to a surface of a slope or the like. COPYRIGHT: (C)2000,JPO

Cement for clay concrete, clay concrete and its production

Abstract: PROBLEM TO BE SOLVED: To obtain neutral porous concrete of a high mechanical strength by firmly binding coarse aggregate with coarse aggregate without addition of fine aggregate and utilize it for greening of rooftop, river bulkhead, retaining wall and the like. SOLUTION: This cement for clay concrete contains >=38wt.% of belite. This cement is mixed with coarse aggregate and water and they are kneaded, formed and carbonated. In this case, the kneaded product of a mixture of this cement, coarse aggregate and water is formed (or molded) and the formed product is carbonated in an atmosphere containing >=1% carbon dioxide.

Porous Concrete for Underwater Organisms in a River

Abstract: Concrete is an essential material for creating infrastructures. However, with the growing awareness of environmental problems in recent years, concrete is now required to function in harmony with nature and help preserve ecosystems. Porous concrete has received a great deal of recent attention. It is believed that porous concrete has water purification functions in flowing water through organism membranes created in a series of inner voids, and that it also creates a new environment for organisms because aquatic organisms and algae adhere to the insides and surface of porous concrete. This paper describes changes over time in the type and number of organisms adhering to porous concrete placed in streams of a river. In addition, the physical properties of porous concrete exposed in a river are discussed. It was concluded that porous concrete can be used as an environmentally-friendly concrete.

Concrete block for plantation, planted concrete block and its construction

Abstract: PROBLEM TO BE SOLVED: To provide a concrete block hardly causing incompleteness of the object of greening by allowing the growth of a plant to be prevented, when the concrete block is used at a parking space where cars do not pass so frequently, an unusual vehicle passage where cars usually do not pass but pass when an accident or an emergent business occurring facilities, or a footpath. SOLUTION: This concrete block C for plantation composed of a porous concrete having 20-40% porosity has a concave part and/or a convex part on the surface of the concrete block C for the plantation so that a gap may be formed between the base surface of the concrete block C for the plantation and the surface of a tire D within a pressing region of the tire D when the tire D pressing the surface of the concrete block C for the plantation.

Vegetation concrete block and lining structure using the concrete block

Abstract: PROBLEM TO BE SOLVED: To promote the growth of a turf and grasses from water-permeable base vegetation surfaces exposed among imitation stones made of concrete by the vegetation action of water-permeable concrete bases while effectively attaining the object of complete lining on an execution surface by the water- permeable concrete bases, and to create an approximately natural landscape effectively in cooperation with a decorative effect by the imitation stones SOLUTION: In a vegetation concrete block, a plurality of concrete imitation stones 1 imitating natural stones are disposed integrally on the surface of a water-permeable concrete base 1, on which vegetation is carried out, and the surface of the water-permeable concrete base 1, on which vegetation is carried out, is exposed among each concrete imitation stone 2 and creek-shaped continuous vegetation surfaces 1' are formed Imitation stone seats 1a consisting of the same raw material as the water-permeable concrete base 1 are projected integrally from the surface of the base 1 at every imitation stone 2, and each imitation stone 2 is arranged integrally on the surface of the water-permeable concrete base 1 through the imitation stone seats 1a

Wire gauze frame lightweight aggregate porous concrete wall slab

Abstract: The utility model belongs to the field of building material products, which utilizes a three-dimensional net rack as a framework and utilize concrete as cementing material for solidifying into integration. The utility model is characterized in that the three-dimensional net rack is a steel wire frame which is formed by machine welding; the concrete cementing material is lightweight aggregate with disperse phases and the concrete cementing material and multihole inorganic mixing slurry of material flow with continuous phases are formed into the inner layer of a wallboard; one surface layer of the wallboard can also be formed into convex-concave decorative textures. The utility model has the advantages of fire-proofing performance, anti-seismic performance, thermal insulation performance, heat insulation performance, etc. of the existing concrete wallboard of the net rack of steel wires, light weight, energy saving, nontoxic performance and good volume stability; the utility model has a definite decorative effect.

Block for vegetation bulkhead made of concrete

Abstract: PROBLEM TO BE SOLVED: To perform vegetation of the whole of a bulkhead surface by a method wherein a porous concrete block part having continuous gaps is integrally joined with an ordinary concrete block part in which a vertical through-hole is vertically formed SOLUTION: A porous concrete block part 2 and an ordinary concrete block part 4 in which a through-hole is vertically formed are integrally joined together The through-hole is filled and closed with the porous concrete block part 2 and the two concrete parts 2 and 4 are firmly coupled together through reinforcing bars In laying of blocks 1 for a vegetation bulkhead made of concrete, the porous concrete block part 2 is filled with seeds and a culture medium After laying, rain water and a moisture content in a ground are sucked through the porous concrete block parts 2 by capillary tube phenomenon to effect water- retention in gaps Thus, vegetation of the whole of a bulkhead surface is effected by the porous concrete block parts and firm bulkhead is provided by the ordinary concrete block parts as a water front is rendered approximately similar to natural environment

Porous concrete for planting use and its production

Abstract: PROBLEM TO BE SOLVED: To obtain the subject concrete containing a sufficient amount of soil material, suitable in the use as a concrete base for greening by mutually mixing a hydraulic component, coarse aggregate, soil material and specific resin followed by hardening the hydraulic component. SOLUTION: This porous concrete for planting use is obtained by mutually mixing pref. 150-350 kg/m3 of a hydraulic component, pref. 1,000-1,900 kg/m3 of a coarse aggregate, 30-400 kg/m3 of a soil material, and a finely granular highly water-absorbing resin impregnated with water followed by hardening the hydraulic component; wherein it is preferable that the amount of the water impregnated in the above resin is at 10-35 wt.% based on the hydraulic component, and it is more preferable that the granular sizes of the coarse aggregate, soil material and highly water-absorbing resin are 10-30 mm, 0.5-10 mm and 0.02-1 mm, respectively.

Concrete part body for road surface drainage and road surface drain device

Abstract: PROBLEM TO BE SOLVED: To improve the construction property by providing a water permeation part made of porous concrete in a part of a side to collect water. SOLUTION: A lid receive stepped part 11 part which is an upper part on one side of a U-shaped side ditch concrete block 10 in which lid receive stepped parts 11 constructed by drop lid form are provided opposingly is a water permeation part 1 made of porous concrete which uses cement and resin as binder and permeates water. Consequently, rainwater which drops on a road surface permeates into a drain pavement, and rainwater which flows down on a shoulder side of a road is drained into the U-shaped side ditch concrete block 10 through the water permeation part 1. As a result, a drain system from the road surface to a side ditch can be formed without forming the construction for water drainage in a foundation part of the road in particular by making the road surface or a water permeation layer of the road surface continuous for a concrete part body for water drainage, and the effective drainage of water from the road surface becomes possible by simple construction.

Water-permeable concrete sheet pile

Abstract: PROBLEM TO BE SOLVED: To provide a concrete sheet pile constituted so that water permeability is ensured and the flow of natural groundwater can be maintained. SOLUTION: Water-permeable sections 2, through which groundwater can be permeated, are formed between the surface side and the rear side in a sheet pile body 1c, a surface 1a on the cutting side and a surface on the bedrock side, at specified places in the water-permeable concrete sheet pile 1. A natural flow can be maintained without obstructing the flow of groundwater by the water-permeable sections 2 (such as the sections of porous concrete 4) formed at the specified places, and a sheet pile bulkhead having the preservation of an ecosystem and a flood control function can be provided.

Water permeable concrete

Abstract: PROBLEM TO BE SOLVED: To obtain a water permeable concrete capable of maintaining a prescribed strength required for the water permeable concrete, and also making the quantity uniform and the production easy. SOLUTION: This water permeable concrete is obtained by intermingling an alkali-degradable polyester fiber with the concrete and uniformly forming vacancies in the concrete. Further, the polyester fibers having about 1mm diameters and 20-30mm lengths are used therefor.

Water permeable natural sand pavement

Abstract: PROBLEM TO BE SOLVED: To give a sufficient water permeability to natural sand pavement being as a water permeable concrete pavement layer by paving a binder course surface consisting of a water permeable concrete pavement with a pavement material consisting of relatively coarse sand of a predetermined grain size blended with an epoxy resin emulsion and dehydrate additives as a binder. SOLUTION: On the water permeable concrete forming a foundation layer 3, natural sand surface layer pavement 2 is spread which is formed of natural sand blended as a binder with epoxy resin for giving stickiness and adhesiveness and dehydrate additives for removing surface water adhered to the surface. Such natural sand is allowed to be in the range of 0.6mm sieve permeability 30% and 0.3mm sieve permeability 20% in its grain size in order to ensure the permeability. A foundation layer 3 of the water permeable concrete has a superior adhesiveness and water permeability between it and the natural sand surface layer pavement 2, and rain water flowed down through the natural sand surface layer pavement 2 of a thin layer positively flows in a roadbed 6 passing through interstices. By paving the surface layer with natural sand having surface water removed and water permeability enhanced, water permeable concrete pavement is improved in its water permeability.

Method and arrangement for producing vapour-hardened building materials

Abstract: The invention concerns a method of producing lightweight building materials, in particular gas or porous concrete, and an arrangement for carrying out this method, the porous concrete pat being subjected to an additional heat treatment after cutting and before vapour-hardening. As a result, the amount of time the porous concrete pats have to remain in the autoclave is reduced and the production cycles increased, such that the arrangement can be of compact construction. The arrangement according to the invention provides for the additional heating of the porous concrete pat in one or a plurality of heating chambers (6a). The operating sections are aligned in a mutually parallel manner with the autoclaves (7a), heating chambers (6a), preheating chambers (5a) and stations in which the porous concrete pats are processed. Transfer devices at the two end regions transfer the moulds from one section to any other section.