Showing papers on "Pervious concrete published in 2006"

Measuring hydraulic conductivity in pervious concrete

Abstract: A computerized falling head permeameter system was used to measure hydraulic conductivity of pervious concrete from samples taken from three different field-placed slabs with known porosities Important differences between samples were found, and these follow the same trend as differences in porosity The relationship between porosity and hydraulic conductivity is suggested as a tool for designing pervious concrete pavements as a stormwater pollution best management practice A quantitative relationship between porosity and hydraulic conductivity was established based on the Carman-Kozeny equation for the samples tested Samples with porosities less than 15% presented limited hydraulic conductivity Important considerations on the measurement of hydraulic conductivity of pervious concrete samples are discussed, and the Ergun equation is used to explore the flow regime inside pervious concrete samples

Mix Design Development for Pervious Concrete in Cold Weather Climates

Abstract: Portland cement pervious concrete (PCPC) is increasingly being used in the United States in sidewalks and parking lots due to its benefits in reducing the amount of runoff water and improving water quality. In the United States, PCPC typically has high porosity and low strength, which has resulted in limited use of pervious concrete in hard wet freeze environments (i.e., the Midwest and Northeast). The purpose of this research is to develop a PCPC mix that not only has sufficient porosity for stormwater infiltration, but also desirable strength and freeze-thaw durability. In this research, concrete mixes were designed with various sizes and types of aggregates, water-to-binder ratios, binder contents, and amounts of admixtures. Porosity, permeability, strength, and freeze-thaw durability of these mixes were evaluated. Preliminary research results indicated that the use of single-sized aggregate could provide concrete with high porosity but not adequate strength. Above a certain level, increasing cement content resulted in a reduced concrete porosity with insignificant influence on concrete strength. Using sand and latex significantly improved the workability of PCPC and resulted in higher strength, appropriate permeability, and freeze-thaw resistance at 180 cycles to date.

Development of Mix Proportion for Functional and Durable Pervious Concrete

Abstract: Portland cement pervious concrete (PCPC) mixes made with various types and amounts of aggregates, cementitious materials, fibers, and chemical admixtures were evaluated. Porosity, water permeability, strength, and freezing-thawing durability of the concrete were tested. The results indicated that the PCPC made with single-sized coarse aggregates generally had high permeability but not adequate strength. Addition of a small amount of fine sand (approximate 7% by weight of total aggregate) to the mixes significantly improved the concrete strength and freezing-thawing resistance while maintaining adequate water permeability. Addition of a small amount of fiber to the mixes increased the concrete strength, freezing-thawing resistance as well as void content. Based on these results, performance-based criteria are discussed for proportioning functional and durable PCPC mixes.

Vertical Porosity Distributions in Pervious Concrete Pavement

Abstract: Pervious concrete is an alternative paving material that may alleviate many of the environmental problems caused by urban runoff from developed areas. Additional research is important so that pervious concrete can be better specified and more effectively used. An important property of pervious concrete is porosity, which will affect the hydrological and strength properties of the material. This research shows that there is a vertical distribution of porosity in slabs placed with certain placement techniques. The vertical variation of porosity can affect the strength distributions within the material and the permeability of the system and its potential for clogging. These studies indicate that for slabs approximately 15 cm (6 in.) in height and placed with an approximately 10% surface compaction technique, the porosity increases significantly from top to bottom. A series of vertical porosity distribution equations have been developed to effectively model this using the percent compaction and average cored porosities.

Long-term in-situ infiltration performance of permeable concrete block pavement

Abstract: SUMMARY Since it is a design criteria for road drainage and sewer systems, the infiltration performance of permeable concrete block pavement (CBP) is of important significance during the service life of a road construction. Due to the entrainment of mineral and organic fines into the pores of porous concrete blocks or into the aggregates used in joints or openings, the irreversible reduction of water permeability can be assumed. Research results show that the infiltration performance decreases in the order of the power to ten after a few years. These results are confirmed by in-situ field tests with a special infiltration-meter. This instrument measures the infiltration capacity in the laid condition with no disturbance and gives immediate results, taking into consideration local conditions such as age and traffic-load. The infiltration curves are shown as regression curves of the averaged infiltration values. These tests can be continuously repeated to observe the long-term performance. These tests show especially a significant relation between infiltration and age. The study states moreover that the long-term in-situ infiltration performance and its observed decrease depend from the grain size of the aggregates used for joint filling. It is furthermore partly induced by the ratio of openings of permeable pavements respectively the pore size of porous concrete blocks. The overall conclusion is that although permeable concrete block pavements cannot drain a traffic area entirely, they can still have a considerable impact on the run-off process of the entire catchment area. Due to the fact that part of the rainfall is retained, this part is not added to the run-off total and it can dampen the run-off peaks because of its delaying effect. In view of an overloaded sewer system this is of considerable ecological importance since the overload can be reduced by permeable concrete block pavements thus also avoiding discharge into the receiving water with the accompanying pollution. The respective relation between surface run-off and actual infiltration means for the hydraulic sizing of a drainage system that a more precise design method can be applied.

Finite element analysis of various methods for protection of concrete structures against spalling during fire

Abstract: A mathematical model of hygro-thermo-mechanical phenomena in heated concrete, treated as multiphase porous material is briefly presented. Some modifications necessary to analyse high–temperature performance of a concrete containing the PP-fibres have been introduced, experimentally validated and applied for analysis of performance of a concrete tunnel lining during a 10-MW fire and the ISO standard fire. Three methods for protecting concrete structures against excessive degradation in fire conditions have been numerically analysed by means of the computer model. The analysed protection methods are based either upon application on a structure surface of a reflective layer, or covering it with a protective layer made of a very porous concrete or an addition of the PP fibres to the concrete mix. Efficiency of these methods has been numerically analysed in thermal conditions corresponding to the ISO-834 standard fire. The results obtained show that even relatively simple methods, like application a protective layer or increasing the surface reflectance, can retard to some extent concrete degradation during a fire.

Scaling and saturation laws for the expansion of concrete exposed to sulfate attack

Abstract: Reinforced concrete structures exposed to aggressive environments often require repair or retrofit even though they were designed to last >50 years. This statement is especially true for structures subjected to sulfate attack. It is critical that fundamental models of life prediction be developed for durability of concrete. Based on experimental results obtained over a 40-year period, scaling and saturation laws were formulated for concrete exposed to sulfate solution. These features have not been considered in current models used to predict life cycle of concrete exposed to aggressive environment. The mathematical analysis shows that porous concrete made with high and moderate water-to-cement ratios develops a definite scaling law after an initiation time. The scaling coefficient depends on the cement composition but does not depend on the original water-to-cement ratio. Dense concrete made with low water-to-cement ratios develops a cyclic saturation curve. An index for “potential of damage” is created to allow engineers to design concrete structures with better precision and cement chemists to develop portland cements with optimized composition.

Pervious Concrete Construction: Methods and Quality Control

Abstract: The beneficial properties of pervious concrete on stormwater control are well understood. As the use of pervious concrete becomes more prevalent throughout the United States, the issue of constructability will become more of a concern. A number of practices exist to place pervious concrete, without any theoretical underpinnings or correlation to laboratory scale studies. This paper describes the current state of practice in Portland Cement Pervious Concrete (PCPC) placement and also presents results from a study performed at Iowa State University to determine a field level QC/QA check for fresh PCPC. Test slabs were placed using a variety of techniques currently employed for field placement of PCPC. Results show that PCPC samples with void ratios ranging from 15% to 20% have 7-day compressive strengths of about 3,000 psi and permeabilities of about 300 in./hr., both values have been shown suitable for pervious concrete applications. Our studies show that samples with 15% to 20% voids have unit weights around 129 pcf, which suggests the development of a unit weight QC/QA check to be promising. The construction technology of PCPC is evolving, but the correlation between laboratory and field placement will allow standard QC/QA checks to be developed for producing permeable, strong, durable, and long-lasting pervious concrete.

Evaluation of various types of permeable pavements with respect to water quality improvement and flood control

Abstract: In North Carolina and several other U.S. states, all permeable pavements are currently considered to have similar capabilities in reducing runoff, but are not credited with improving water quality. Previous research conducted by the North Carolina State University on one particular permeable block pavement type has shown that when compared to runoff from an adjoining asphalt lot, permeable pavement exfiltrate contained significantly lower concentrations of phosphorous and zinc, as well as reductions in total nitrogen. To further test various permeable pavement designs, a parking lot consisting of four different types of permeable pavements and standard asphalt was constructed in Kinston, NC. The permeable pavement sections consist of permeable interlocking concrete pavers (PICP) with 8.5 % void space, PICP with 12.9 % void space, concrete grid pavers (CGP), and porous concrete (PC), each covering a 1200 sq. ft. area with a 10 in. gravel storage layer. The purpose of this study is to evaluate and compare the effects of each pavement type on water quality and runoff reduction. Conclusions on the difference in reduction between each pavement type have not been determined. Site analyses on every rainfall event will be conducted beginning January, 2006 and will continue for one year. As a result of the Kinston study, it is expected that the state of North Carolina will be able to make an informed judgment on how much pollutant removal credit permeable pavements should receive when implemented as stormwater best management practices. Also, this study can be used to determine whether or not stormwater credit should vary based on pavement type.

Hydrologic Properties of Pervious Concrete

Abstract: Pervious concrete is concrete made by eliminating most or all of the fine aggregate (sand) in the concrete mix, which allows interconnected void spaces to be formed in the hardened product. These interconnected void spaces allow the concrete to transmit water at relatively high rates. The main objective of this project was to conduct research on the potential application of pervious concrete in agricultural settings, specifically for use in animal feed lots, manure storage pads, animal manure and bedding compost facilities, or floor systems in animal buildings. Laboratory tests were conducted on replicated samples of pervious concrete formed from two rock sources (river gravel and limestone) for coarse aggregates and different size fractions to determine hydrologic relationships. Linear relationships were found between density and porosity, density and permeability, porosity and permeability, and porosity and specific yield. The results suggest that properties such as permeability, porosity, and specific yield are not significantly affected by different aggregate types. However, density and porosity can be effective methods for predicting porosity, specific yield, and permeability. In addition, t-tests were conducted to determine the effect of aggregate types on the solid/liquid separation properties of the pervious concrete after adding composted beef cattle manure and bedding to the surface of the specimens. The amount of composted beef cattle manure and bedding retained within the specimens was significantly less (p = 0.012) when samples constructed of #8 river gravel were used rather than the other aggregates. The #8 river gravel also had significantly less reduction in permeability compared to other aggregates. Although the #8 river gravel had a different effect on the compost retained and the reduction in permeability for the specimens, all four aggregates exhibited a significant reduction in the permeability after the compost was applied.

Area-Rated Rational Coefficients for Portland Cement Pervious Concrete Pavement

Abstract: Surface area specific runoff coefficients were measured for nonclogged Portland cement pervious concrete systems according to the rational method. The systems were simulated with pervious concrete blocks with porosities ranging from 16 to 27% placed over sand subbases. Rainfall was simulated in a flume setup with surface slopes ranging from 2 to 10%. There was negligible runoff for typical rainfall events under 100 years frequency in South Carolina. Runoff rates were also simulated for a combination of direct rainfall and additional stormwater runoff from adjacent areas. The results obtained are important for the design of pervious concrete runoff management systems.

Evaluation of U.S. and European Concrete Pavement Noise Reduction Methods

Abstract: This document contains the results of Part 1, Task 2 of the ISU-FHWA project entitled "Concrete Pavement Surface Characteristics Project." It addresses the noise issue by evaluating conventional and innovative concrete pavement noise reduction methods. The first objective of this task was to determine what if any concrete surface textures currently constructed in the United States or Europe were considered quiet, had long-term friction characteristics, could be consistently built, and were cost effective. Any specifications of such concrete textures would be included in this report. The second objective was to determine whether any promising new concrete pavement surfaces to control tire-pavement noise and friction were in the development stage and, if so, what further research was necessary. The final objective was to identify measurement techniques used in the evaluation. The Part 1, Task 2 evaluation reported herein included (1) examination of conventional concrete pavement noise reduction methods used in the United States; (2) identification of promising new concrete pavement surfaces to control tire-pavement noise and friction in Europe; and (3) initial consistent field measurements of tire-pavement noise and friction with respect to texture. The evaluation concludes that (a) careful construction practices in the United States for artificial turf and burlap drag, longitudinal tining, and diamond grinding can be used to initially control noise (99/100-104/105 dBA) and provide adequate initial friction; (b) the noisiest pavements (>104/105 dBA) should be rehabilitated immediately, with no new noisy pavements constructed; (c) to achieve the quietest concrete pavements (<99/100 dBA), innovative solutions such as exposed aggregate and pervious concrete, need to be advanced; and (d) more study is necessary to understand the change of noise and texture characteristics over time and to increase consistency.

Compressive Strength of Pervious Concrete Pavements

Abstract: The pervious concrete system and its corresponding strength are as important as its permeability characteristics. The strength of the system not only relies on the compressive strength of the pervious concrete but also on the strength of the soil beneath the support. Previous studies indicate that pervious concrete has lower compressive strength capabilities than conventional concrete and will only support light traffic loadings. This project conducted experimental studies on the compressive strength of pervious concrete as it related to water-cement ratio, aggregate-cement ratio, aggregate size, and compaction. Since voids are supposed to reduce the strength of concrete, the goal is to find a balance between water, aggregate, and cement in order to increase strength and permeability, two characteristics which tend to counteract each other. Also important is appropriate traffic loads and volumes so that pervious concrete is able to maintain structural integrity. This research confirms that pervious concrete does in fact proved a lower compressive strength than that of conventional concrete; compressive strengths in acceptable mixtures only reached about 1700 psi. Analysis of traffic loadings reinforce the fact that pervious concrete cannot be subjected to large numbers of heavy vehicle loadings over time, although pervious concrete would be able to sustain low volumes of heavy loads if designed properly. In all cases, high permeability rates were achieved regardless of the compressive strength.

An Overview of Pervious Concrete Applications in Stormwater Management and Pavement Systems

Abstract: Recent interest in the use of Portland Cement Pervious Concrete (PCPC) for pavements has been very high, due primarily to the Federal Clean Water Act mandate that government agencies and private entities manage stormwater runoff—both quantity and quality. Such pavements are full depth and are currently being placed primarily in parking lot applications and areas of limited truck traffic. Pervious pavements provide a path for water movement from pavement surfaces and provide increased skid resistance. In addition, PCPC has great potential to reduce roadway noise, either in full-depth applications or as a wearing course. A PCPC mix design must meet the competing criteria of sufficient permeability to allow water to flow through the section while maintaining adequate strength and durability under site-specific loading and environmental conditions. To date, two key issues that have impeded the use of PCPC in the United States are that compressive strengths of PCPC have been lower than necessary for required applications and the freeze-thaw durability of PCPC has been suspect. In this paper a summary of recent research efforts on PCPC mix designs for cold weather applications, reduction of road noise, stormwater management and constructability issues is discussed. In addition, the efforts to develop a comprehensive and integrated study for full depth and wearing course applications under the auspices of the National Concrete Pavement Technology Center at Iowa State University are discussed.

Comparative degradation of pultruded E-glass/vinylester in deionized water, alkaline solution, and concrete leachate solution

Abstract: The use of E-glass/vinylester composites, fabricated by processes such as resin infusion and pultrusion involving low-moderate temperature cure regimes, in civil infrastructure applications is increasing. A major consideration in these applications is long-term durability in the presence of aqueous solutions ranging from water to alkaline environments such as would be seen from pore water of concrete in the case of a reinforcing bar in concrete, or from an alkaline rich concrete leachate due to water migrating through porous concrete to the surface of a composite overlay. This study characterizes mass uptake, tensile, and interlaminar shear response of a pultruded E-glass/vinylester immersed in deionized water, alkali solution, and concrete leachate solution for periods up to 75 weeks. The high pH solutions are seen to cause a greater degree of irreversible damage at the resin, interface, and fiber levels. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1405–1414, 2006

Laboratory scale study of infiltration from pervious pavements

Abstract: Increased urbanization causes pervious greenfields to be converted to impervious areas increasing stormwater runoff. Most of the urban floods occur because existing drainage systems are unable to handle peak flows during rainfall events. During a storm ev

Mixture Ratio Design Method of Porous Concrete Based on Orthogonality Test

Abstract: Based on Talbol Formula and foreign experience,four kinds of gradation of porous concrete are designed and effective particle size and uniform coefficient are taken as the effective descriptive targets of aggregate gradation.Three factors of cement dosage,water cement ratio and aggregate gradation are considered in an orthogonality test with four levels adopted in every factor.A series of regression relationships of 7 d compression strength and effective porosity of porous concrete with regression software are derived on the basis of variance analysis of the test results.Finally,according to the orthogonality test,the mixture ratio design method of porous concrete is proposed.

Compressive strength of pervious concrete pavements: report 3 of 4: hydraulic performance assessment of pervious concrete pavements for stormwater management credit

Abstract: This report is part three of a four part report that explores the performance of pervious concrete at sites where it has been in use for several years The reports 1 examine infiltration rates for eight pervious concrete parking lots and their subsoils; 2 investigate pervious concrete construction and maintenance techniques; 3 review the compressive strength of pervious concrete compared to conventional concrete; and 4 evaluate the wear and infiltration of a pervious concrete roadway shoulder

Pervious Concrete: A Hydrologic Analysis For Stormwater Management Credit

Abstract: Portland Cement pervious concrete’s ability to permit water infiltration has encouraged its use as a stormwater management tool. However, the material has suffered historically poor support due to a number of factors, including failures due to poor mix design and improper construction techniques, concern about lesser structural strength, concern about poor long term performance due to clogging of surface pores and undefined credit for stormwater management. This study focuses on long term performances of pervious concrete parking lots and their stormwater management credit. Before stormwater management credit could be estimated, it was necessary to develop a testing device to gather information from existing pervious concrete parking lots currently in use. Eight parking lots were examined to determine the infiltration rates of the pervious concrete, as well as to verify the soil makeup beneath pavement. A total of 30 cores were extracted from pervious concrete parking lots and evaluated for infiltration rates. Three of the sites had a pervious concrete section that included a gravel reservoir. Infiltration rates were measured using the application of an embedded single-ring infiltrometer. In an attempt to provide an estimate of credit, a mass balance model was created to be used for simulation of the hydrologic and hydraulic function of pervious concrete sections. The purpose of the model is to predict runoff and recharge volumes for different rainfall conditions and hydraulic properties of the concrete and the soil. The field derived hydraulic data were used to simulate infiltration volumes and rainfall excess given a year of rainfall as used in a mass balance operated within a spreadsheet. The results can be used for assessing stormwater management credit.

Study on Pervious Road Brick Prepared by Recycled Aggregate Concrete

Abstract: The influence of aggregate to cement ratio(A/C), sand to aggregate ratio(S/A) and water to cement ratio(W/C) on mechanical properties and pervious coefficient of pervious concrete prepared by recycled aggregate were systematically investigated in the paper. The optimum mix proportion by weight of pervious concrete prepared by recycled aggregate were 3.5 of aggregate to cement ratio, 0.15 of sand to aggregate ratio and 0.34 of water to cement ratio, resulted from an effect coefficient method. Flexural strength and compressive strength of pervious concrete road brick prepared by recycled aggregate concrete could satisfy the requirements of Chinese Standard for Concrete Road Brick (JC/T466-2000) and had good pervious performance.

Method for making permeable pavement material and permeable molded/machined product

Abstract: PROBLEM TO BE SOLVED: To solve the problems that conventional asphalt pavement has the tendency of making progress in wear resistance and life to cause decrease in wear resistance, exfoliation due to freezing/thawing and cracks, and that the conventional asphalt pavement does not have water permeability. SOLUTION: Capabilities of andesite and crushed stone such as strength, water retaining capability and water cleaning capability are utilized, and a molded/machined product is manufactured. The surface is paved with water permeable concrete to allow rain water to go into the ground. The surface temperature of the pavement using the water permeable concrete is 5-10°C lower than the surface temperature of the asphalt pavement and concrete pavement because of the water retention capacity possessed by the water permeable concrete of a porosity of 13-25.5% and natural evaporation. COPYRIGHT: (C)2008,JPO&INPIT

Porous concrete box for biological river water purification

Abstract: PROBLEM TO BE SOLVED: To provide a method for biological river water purification capable of actively utilizing microorganisms regarded as effective in the purification, of easily exchanging an adsorbent in a porous concrete box for a new one at any time when the adsorbent has deteriorated, and of exterminating a harmful insect. SOLUTION: The porous concrete box has some openings in each of its surfaces so that a material for environmental purification packed in a mesh bag for preventing the adsorbent from escaping can be charged into or discharged from the concrete box selectively through the openings in the top surface at any time. COPYRIGHT: (C)2006,JPO&NCIPI

Method for proceeding ecological alteration to river concrete bank slope

Abstract: The invention discloses a method for processing ecological modifying on the river concrete, which uses PVC short pipe as outer mould to be filled porous concrete; planting plant seeds after alkali reduction and filling vital stuffing; when the plants are 5-10cm high, moving the prefabricated elements into the round holes with relative sizes on the concrete bank; the holes has been smoothed and filled vital material; then filling the space between PVC pipe and concrete wall with sand pulp, to be compressed; and finishing the plants on the bank. The invention has simple device, lower cost and the application for ecological modifying of river concrete bank, while the modified bank has stable structure, anti-brush, and better economic and environment benefits.

Hydrologic Properties of Pervious Concrete

Abstract: Linear relationships were found between density and porosity, density and permeability, porosity and permeability, and porosity and specific yield. This suggests that properties such as permeability, porosity, and specific yield are not significantly affected by different aggregate types. However, density and porosity can be an effective method for predicting porosity, specific yield, and permeability. T-tests were also conducted to determine the effect aggregate types had on the solid/liquid separation properties of the pervious concrete. The amount of compost retained within the specimens was significantly less where #8 river gravel was used as opposed to the other aggregates. This was also noticed when the mean reduction in permeability was analyzed. The use of #8 river gravel resulted in significantly less reduction in permeability when compared to the other aggregates. Although the #8 river gravel had a different effect on the compost retained and the reduction in permeability for the specimens, all four exhibited a significant reduction in the permeability after the compost was applied.

Concrete block for seaweed bed

Abstract: PROBLEM TO BE SOLVED: To solve the problems of conventional concrete blocks for seaweed beds, wherein the conventional concrete blocks are generally produced from Portland cement and thereby give pH 12 to 13 on their peripheries which are too high (namely, the alkaline property is too strong) for animals and plants, while the pHs of general seas are about 8.2 to 8.4, and further wherein the iron contents of ordinary cements are small, for example, a ferric oxide content of 2 to 5% in a case of Portland cement, while the iron content is generally essential for algae which fast grow in a high iron content. SOLUTION: This concrete block for the seaweed bed is characterized by comprising porous concrete prepared by curing a mixture comprising at least steel making slag and blast furnace slag fine powder with water to give a porosity of 10 to 30%, wherein the porous concrete is molded in various shapes. COPYRIGHT: (C)2006,JPO&NCIPI