Presentation on theme: "Pervious Pavement “We can't solve problems by using the same kind of thinking we used when we created them." Albert Einstein. Pervious Pavements are a."— Presentation transcript:
1Pervious Pavement“We can't solve problems by using the same kind of thinking we used when we created them." Albert Einstein. Pervious Pavements are a different way of thinking about roads.John Harrison, B.Sc. B.Ec. FCPA
2What Is Pervious Pavement? Pervious pavement is a permeable pavement surface with a stone reservoir underneath.The reservoir temporarily stores surface runoff before infiltrating it into the subsoil or sub-surface drainage and in the process improves the water quality.Permeable materials such as ancient lime mortars and pervious pavements are made using relatively mono graded materials.Pervious pavements allow the earth to breathe, take in water and be healthy. The stone and soil under them acts as a reservoir and cleans the water just like the filter on a fish tank.Pervious pavements are safer to drive on as they do not develop "puddles", have a good surface to gripSubdivisions made with pervious pavement that also have street trees can be several degrees cooler than surrounding suburbs without.
3The Water CycleThe water or hydrological cycle is powered by the sun and water changes state and is stored as it moves through it.Human intervention is reducing the time it takes for water to return to the oceans resulting in less moisture on land, salinity and aridity.Source:Illustration by John M. Evans USGS, Colorado District (http://ga.water.usgs.gov/edu/watercyclegraphichi.html)
4Australia Before Settlement John Harrison Presentation AASMIC ConferenceAustralia Before SettlementHUGE MATERIALS FLOWS IN THE BUILT ENVIRONMENTThe built environment is our footprint, a major proportion of the techno-sphere and our lasting legacy on the planet. In this dominant proportion of all materials flows and unsustainable practices abound from the logging of old growth forests to the high volume of wastage at landfill.The dominant proportion of what we take, manipulate and make that we do not consume immediately goes into the materials with which we build the built environment or “techno-sphere”. Buildings and infrastructure probably account for around 70% of all materials flows (TecEco estimate).Buildings alone account for 40 percent of the materials and about a third of the energy consumed by the world economy.Construction activities contributed over 35% of total global CO2 emissions in 1999.According to the Green Building Council of Australia Building waste is 40% of all waste going to landfill in Australia.In years gone by grassland and forest covered the land
5Our LegacyIn years gone by forests and grassland covered most of our planet.When it rained much of the water naturally percolated though soils that performed vital functions ofslowing down the rate of transport to rivers and streams,purifying the water andreplenishing natural aquifers.Our legacy has been to pave this natural bio filter, redirecting the water that fell as rain as quickly as possible to the sea.Given global water shortages, problems with salinity, pollution, volume and rate of flow of runoff we need to change our practices so as to mimic the way it was for so many millions of years before we started making so many changes.The key to survival in the future will be learning from nature and mimicking her subtle processes. Road are the arteries, veins and lymphatic system to cities.This presentation focuses on where we have gone wrong with roads and the radical TecEco Permecocrete solution.
6Australia with a Little Lateral Thinking & Effort John Harrison Presentation AASMIC ConferenceAustralia with a Little Lateral Thinking & EffortTecEco technology provides ways of sequestering carbon dioxide and utilising wastes to create our techno - worldLess paper. Other Cl free processes - no salinityEvolution away from using trees – paperless officeCows – CSIO anti methane bredVehicles – more efficient and using fuel cellsOrganic farming Carbon returned to soils.Pervious pavements prevent immediate and polluted run-off. Carbon dioxide and other gases absorbed by TecEco Eco- Cements. Sewerage converted to fertilizer and returned to soils. Buildings generate own energy etc.HUGE MATERIALS FLOWS IN THE BUILT ENVIRONMENTThe built environment is our footprint, a major proportion of the techno-sphere and our lasting legacy on the planet. In this dominant proportion of all materials flows and unsustainable practices abound from the logging of old growth forests to the high volume of wastage at landfill.The dominant proportion of what we take, manipulate and make that we do not consume immediately goes into the materials with which we build the built environment or “techno-sphere”. Buildings and infrastructure probably account for around 70% of all materials flows (TecEco estimate).Buildings alone account for 40 percent of the materials and about a third of the energy consumed by the world economy.Construction activities contributed over 35% of total global CO2 emissions in 1999.According to the Green Building Council of Australia Building waste is 40% of all waste going to landfill in Australia.It is essential we learn to live with nature and change our ways
7One Planet, Many People, Many Interconnected Problems Global Sustainability Alliance Partners are in the BIGGEST Business on the Planet – Economic Solutions to our Energy, Global Warming, Water and Waste Problems.
8Global Fresh Water A finite resource Water-stress Population risingPer capita use risingWater-stress1/3 world's populationBy 2025, 2/3 due to global warming.1 person in 5 do not have access to safe drinking waterYet water is the most common substance on the planet.Water covers 70% of the surfaceOnly =~ 1% is potable
9Australia’s Water Problems Australia is the driest inhabited continent in the world - only Antarctica gets less rain.Most of Australia has experienced drought under El Nino conditions for the past few years.Some major cities are seriously short of water.Yet giga litres of stormwater go into our coastal water ways every year carrying with it significant levels of pollution.
10Stormwater = Rainwater + Pollution Pollution comes from many different sources, however the two main sources are Point and Non-point sources.Stormwater is the major cause of reduction in water quality in rivers and the destruction of marine environments.Stormwater is NOT supposed to include sewerage!Pollution is why it is not a good idea to eat too many fish from many areas near citiesWhy mix rainwater and pollution?
11Point and Non-Point Source Pollution Point Source Pollution Point source pollution is when high levels of pollution enter a water system such as a wetland or river from one source, such as a factory, mine, sewage plant or garbage dump. Point source pollution is easy to trace.Non-Point Source Pollution Non-point source pollution is when levels of pollution enter a water system at various points and from various sources. This type of pollution is the most difficult to monitor and manage. The most common non-point source of stormwater pollution comes from local residents throughout a catchment.
13Sources and Types of Pollution Land usesTypes of pollutionRural/agricultural &market gardensSilt, pesticides, fertilisers, livestock faeces.Residential properties & gardensDetergent, pesticides, fertiliser, dog faeces, leaf litter.Industrial areasIndustrial runoff & acidityRoads & carparksOil, petrol, heavy metals, leaf litterShopping centresLitter, shopping bags, junk food containersService stationsDetergents, oil, petrolConstruction/building sitesSilt, paint, packaging, bricksSewage treatment plantBacteria, phosphorus, nitratesParks and reservesLitter, dog and cat faeces, grass cuttings, leavesAdapted from:
14Types of Pollution (1)Litter Pedestrians dropping food wrappers , cigarette butts etc. Motorists tossing litter from their vehicles. Litter from building sites. Industry packaging and other waste materials. Trucks with uncovered loads which blows onto roads.MacroLeaves Deciduous trees drop their leaves in Autumn creating a significant pollution problem in the waterways. Excessive leaves enter the stormwater system, choking waterways, reducing sunlight penetration and decomposing, causing nitrate pollution. This can create low oxygen conditions, killing animals.Macro Micro and MolecularSediment Sediment is a major source of pollution in stormwater. Excessive sediment chokes creek beds and reduces flow capacity as well as de- grading natural ecosystems by stifling aquatic plants and animals and blocking sunlight. Sources include construction sites, erosion along streams and rivers, soil erosion from poor management of agricultural activities, and road runoff.MicroSoaps and detergents Detergent and soaps tend to contain high levels of phosphorus. This chemical is a limiting factor in plant growth. Excessive amounts provide the nutrients required to fuel an algal bloom.MolecularModified from: EPA stormwater code of practice from
15Types of Pollution (2)Oil and grease Enter the stormwater system via leaking engines, deliberate dumping and accidental spills. High levels of oil can directly threaten the life of animals in waterways.Macro and MolecularNutrients Enter the stormwater system via runoff from parks and farms that use fertiliser, effluent from sewage treatment plants and septic tanks, chemical and fertiliser spills, and rotting vegetation. Nutrients provide fuel for algal blooms which choke waterways, cut off light and hence kill off aquatic ecosystems. Excessive nitrogen is one of the major factors in the die back of seagrass in our rivers.MolecularFaecal coliforms Enter the stormwater system by contamination with human or animal wastes. The main sources are dogs, horses, septic tanks and farm animals.Macro Micro and MolecularHeavy Metals Lead, zinc and copper are the major heavy metals entering the stormwater system via roads, and in the case of lead, via exhaust. Elevated levels can cause death and mutation in animal populations.Modified from: EPA stormwater code of practice from
16Roads Interrupt Natural Drainage We have dissected the landscape with roads and no matter what kind, they modify the drainage network.Roads themselves are impervious and also capture water.Stormwater from buildings and from properties usually goes to the same drainage system.Stormwater = Rainwater + PollutionVarious sources!Source: Keith Stichler, CBF
17Roads are the Drainage Network And represent a huge wasted catchment
18Impervious Watersheds Kill Rivers and Speed up the Water Cycle There is a relationship between the amount of impervious surface cover within a watershed and the quality of surface water within that watershed.10 to 15% of an area is covered by impervious surfaces, the increased sediment and chemical pollutants in runoff have a measurable effect on water quality.15 to 25% of a watershed is paved or impervious to drainage, increased runoff leads to reduced oxygen levels and harms stream life.If more than 25% of surfaces are paved, many types of macro and micro organisms in streams die from concentrated runoff and sedimentsSmith, A. (2001). New Satellite Maps Provide Planners Improved Urban Sprawl Insight, NASA Goddard Space Flight Center, GSFC on-line News Releases.The more impervious the surface the more speed, volume and pollution water acquires.
19Purifying WaterPervious pavements filter water falling on them releasing it slowly to sub-surface drains or aquifers and finally the sea. There is little or now surface run-off to carry rubbish into drains and streams.Water quality is purified by the sub-pavement acting as a giant biofiliter allowing bacteria and oxygen to do their work and because surface rubbish does not contaminate it.
20Pervious Pavements Act Like a Giant Biofilter Just as fish cannot be kept in an aquarium without a filter system they are not healthy in our lakes dams creeks and rivers without natural or man made filtration of run off water.Pervious pavements and their sub structures act as a giant biofiltersPervious pavement with integral bacteria improves water quality entering aquifers, streams and rivers.The critical "first flush" of pollutants is sent rapidly into the cross-section where constantly available sources of bacteria and microbes exist and have sufficient air exchange capability to maintain themselves and perform their cleaning functions.Source Wikipedia. Filtration system in a typical aquarium: (1) Intake. (2) Mechanical filtration. (3) Chemical filtration. (4) Biological filtration medium. (5) Outflow to tank.
21Speed, Volume Sediment Load and Pollution Rainwater does good all the way to the sea. Polluted and salty water do no good at allHigher speed, higher volume, more energy, greater distance covered = more pollution and saltsLow speed, low volume low distance covered = low pollution and salts“The Water Dynamic”
22Traps Do Not Stop Micro and Molecular Pollution SourceTraps are useless for stopping most pollutants other than those that are unsightly
23The Functions of RoadsRoads are the veins, arteries and lymphatic system of cities.They provideThe network forThe transport of resources and wastesDrainageThe route for all servicesWaterSewerageElectricityGasTelephone etc.Many different people are involved
24Current Road Designs are Not Sustainable Drainage and Traffic EngineersSewerage EngineersTraffic EngineersManagementHydraulic EngineersEnvironmental ScientistsGas EngineersRatepayersTelecommunication EngineersGeo Technical EngineersElectrical EngineersThe various groups with an interest in roads do not work together holisticallyHow often do you see the same section of road dug up repeatedly in quick succession?
25Changing the Road Paradigm Roads and associated services as they are today have not been thought out. They have evolved.In the past the agencies that are responsible for these networks and services have more or less acted independently of each other resulting inWasted ResourcesAdditional CostHow often do you see different crews digging up the same bit of road?This is not sustainable!You never change things by fighting the existing reality. To change something, build a new model that makes the existing model obsolete. – Buckminster Fuller
26Building a New ModelThe engineering paradigm too prevalent amongst the road building fraternity is:“Roads are for vehicles” “water on roads in dangerous” “collect it and get rid of it as quickly as possible”Given the current water crisis can this limited thinking be allowed to continue?Only a small % of water reticulated through a community is used for drinking.Most is used for washing, laundry, flushing toilets or watering gardens.Perhaps the water caught by our road drainage systems could be used?
27Heads First for ActionWater, CO2, waste and many other issues are mostly in our heads.We must first think differently thenAct differently!Roads are not just for trafficThey set drainage patternsCarry services under themDefine wildlife zonesPrevent natural percolation to aquifers etc.Roads in the future will have to be:Holistically designedTake into account previously unintended outcomes such as local drainage alteration and pollution.Capture desperately needed waterOur model, measure and mentor for change must be nature.John Harrison with pervious pavement. Photographer Peter Boyer
28Our Guide - Biomimicry - Geomimicry John Harrison Presentation AASMIC ConferenceOur Guide - Biomimicry - GeomimicryThe term biomimicry was popularised by the book of the same name written by Janine BenyusBiomimicry is a method of solving problems that uses natural processes and systems as a source of knowledge and inspiration.It involves nature as model, measure and mentor.Geomimicry is similar to biomimicry but models geological rather than biological processes.The theory behind biomimicry is that natural processes and systems have evolved over several billion years through a process of research and development commonly referred to as evolution. A reoccurring theme in natural systems is the cyclical flow of matter in such a way that there is no waste of matter and very little of energy.Geomimicry is a natural extension of biomimicry and applies to geological rather than living processesWe can learn from nature about how we should construct roads
29Pervious Concrete Pavement - Addressing the Issues Pervious pavement is a unique and effective means of addressing environmental issuesImage source:
30TecEco Permecocrete - Thinking About Water and Roads Pavements are not just for vehicles. They must do much moreCO2CO2CO2CO2CO2CO2Cooling EvaporationSequestrationCleansing microbial activity and oxygenationMoisture retentionThe substrate must be properly designedOptional groundwater rechargeOptional impervious layer, underground drainage and storage. Dual water supply or parks etc. only.
31Holistic Roads for the Future In Australia we run many duplicate services down each side of a road. Given the high cost of installing infrastructure it would be smarter to adopt a system whereby services run down the middle of a road down what amount to giant box culverts.Conventional bitumen or concrete footpath pavementPervious Eco-Cement concrete pavement (Permecocrete) surface using recycled aggregatesPervious gravel under for collection, cleansing and storage of waterServices to either side of the road. All in same trench of conduitService conduit down middle of roadFoamed Eco-Cement concrete root redirectors and pavement protectors. Roots will grow away from the foamed concrete because of its general alkalinity. It will also give to some extent preventing surface pavement cracking.Impermeable layer (concrete or plastic liner) angling for main flow towards collection drainsCollection drains to transport drain or pipe in service conduit at intervalsPossible leakage to street trees and underground aquifersIts time for a road re think!
32TecEco Eco-Cement Permecocrete - Mimicking Nature Permecocrete is made with Eco-Cements that set by absorbing CO2 and can use recycled aggregates. It does not get any greener!Freedom from water restrictions – forever!Pure fresh water from your own block.Filtration through Permecocrete and water feature in garden will keep water pure and fresh.Cooler house and garden (cycle under slab for house cooling/heating option).Lower infrastructure costs for local council.Water feature keeps water cleanAll rainwater redirected to pavement filter.Permecocrete pervious pavementPumpWater storage e.g. under drive
37TecEco PermecocreteTecEco Eco-Cement Permecocrete concrete pavement technologyIs a unique and effective means to address important environmental issues and support sustainable growth.Environmental AdvantagesSlows down the rate of transport to rivers and streamspurifying waterreplenishing natural aquifers.Reducing salinityEco-Cement Pervious concrete sequesters carbon dioxideNon Environmental AdvantagesSafer for trafficImproved acoustic propertiesReduces building maintenanceCooler suburbsReduced drainage infrastructure costsReduces the need for culverts, pies drains, retention ponds, swales, and other storm water management devices.Less watering of street trees
38Environmental Advantages Reduced volume and rate of runoffPervious pavement would allow the replenishment of aquifers and reduced the cost of infrastructure to carry water out to sea as the volume and rate of flow would be less. Not as many pollutants, rubbish and debris would be transported reducing waterway pollution.Cleaner water - less pollutionA pervious pavement with integral bacteria would improve water quality entering aquifers, streams and rivers. The critical "first flush" of pollutants would be sent rapidly into the cross-section where constantly available sources of bacteria and microbes exist and have sufficient air exchange capability to maintain themselves and perform their cleaning functions. Pervious pavements could act as both pavements and bio-filters at the same time.Replenish aquifers or provide waterReducing salinity by replenishment with fresh water.Permecocretes are also carbon sinks.
39Non Environmental Advantages Pervious pavements do not collect puddles of water making it safer for trafficPervious pavements are quieter as the absorb soundPervious pavement prevent the ground drying out under building cracking them.Pervious pavements made with TecEco Eco-Cements are more durableCities with pervious pavement are coolerThey can transpire naturally (loosing latent heat of evaporation)Eco-Cement Permecocrete concrete pavement has a lighter albidoGiven economies of scale Tec-Eco Permecocrete pavement should cost lessLess infrastructureReduced need for culverts, pipes, retention ponds, swales, and other stormwater management devices
40Hot City Syndrome and Pervious Pavement John Harrison Presentation AASMIC ConferenceHot City Syndrome and Pervious PavementEver walked up a pebble beach on a hot sunny day? The heat held by the stones can be unbearable! It’s the same in large cities. There are so many materials with high specific heat that during hot sunny weather and with no natural transpiration, due to the fact that we have paved all the ground, large cities just get hotter and hotter.As architects, engineers and designers of cities we need to come to grips with the macro impacts of the materials we use. Hot city syndrome is one of a number of man made phenomena that the use of pervious Eco-Cement pavements will reduce. The solution is to let the ground breathe and pervious pavements do this. Evaporation after all is still the principle behind many cooling systems – so why do we pave the ground and prevent moisture entering or exiting?
41Solving the Water Problem Collecting Rain Water Using Pervious PavementSolving the Water ProblemAn unknown but huge quantity of water is drained away to sea taking with it polluting substances and articles every time it rains on our cities.This rapid drainage of rain requires a high cost of investment in much larger drains than the original natural drainage replaced because water no longer percolates through natural vegetation and obstacles.In urban and some agricultural areas water gets to the sea in hours not days!This water could be collected by permeable roads also acting as giant bio filters, subterranean reservoirs (the city of Alexandria had huge underground cisterns over 2000 years ago) and collection and redistribution network.An essential component of this paradigm is pervious pavement.
42The Clogging Myth - Cleaning Pervious Pavement Those who remain sceptics please also note that it is better to have pollution collected from a pervious pavement by machinery than pollute our coastal waterwaysFrimokar Australia high pressure jet and suction cleaning in actionThe experience of many engineers is that with relatively minor control and maintenance clogging will not reduce the infiltration rate below a design rate within the lifecycle of the pavement. Like any other kind of surface, pervious pavements should be cleaned periodically to remove debris and water under pressure combined with suction is most effective.
43Making Pervious Pavement John Harrison Presentation AASMIC ConferenceMaking Pervious PavementIdeally a pervious pavement should be made with mono-graded stone aggregates and a binder and be similar to asphalt or concrete to handle and install.In cold areas it is important that the pavement should not trap water otherwise in winter the water would freeze and cause cracking.It is also important to detail a permeable structural base and sub base for the pavement that has a high void ratio as this acts as a reservoir, and provide underground drainage as required.Comparing Concrete Pervious Pavements to AsphaltEco-Cement Permecocrete Pervious PavementSet by absorbing CO2Can use recycled materials as long as they are hard and mono-gradedAsphaltCarcenogenic to workers using it.Becoming more expensive as petroleum supplies dwindle.
44SalinityIncreasing salinity is one of the most significant environmental problems facing Australia.While salt is naturally present in many of our landscapes, European farming practices which replaced native vegetation with shallow-rooted crops and pastures have caused a marked increase in the expression of salinity in our land and water resources.Rising groundwater levels, caused by these farming practices, are bringing with them dissolved salts which were stored in the ground for millennia.Salt is being transported to the root-zones of remnant vegetation, crops, pastures, and directly into our wetlands, streams and river systems. The rising water tables are also affecting our rural infrastructure including buildings, roads, pipes and underground cables.Salinity and rising water tables incur significant and costly impacts.According to the Australian National Action plan (http://www.napswq.gov.au/publications/salinity.html#how) and CSIRO web sites there are two main causes of salinityirrigation salinitydryland salinityCaused by clearingCaused by evaporation
45Irrigation SalinityAccording to the Australian National Action plan website at how salinity occurs through irrigation is because water soaks through the soil area where the plant roots grow, adding to the existing water. The additional irrigation water causes the underground water-table to rise, bringing salt to the surface. When the irrigated area dries and the underground water-table recedes, salt is left on the surface soil. Each time the area is irrigated this salinity process is repeated.The government website quoted above fails to state the obvious which is that:Every time water percolates through rocks and soil it picks up more salts. In the Murray Darling system a lot of irrigation water returns on the surface and underground to the river and is used again for irrigation, exacerbating the problemThe sequence forestry-agriculture-irrigation-salinity-aridity has destroyed many civilisations – will ours be next?Figure from the Australian National Action plan website at
46Dryland Salinity – Caused by Clearing According to the Australian National Action plan website at Dryland salinity is caused when the rising water-table brings natural salts in the soil to the surface.The salt remains in the soil and becomes progressively concentrated as the water evaporates or is used by plants.One of the main causes for rising water-tables is the removal of deep rooted plants, perennial trees, shrubs and grasses and their replacement by annual crops and pastures that do not use as much water.Figures from the Australian National Action plan website at
47Dryland Salinity – Caused by Evaporation Salinity also also develops as excess water moves to and collects in poorly drained discharge zones. The buildup of excess water brings dissolved salts to the surface where evaporation concentrates them.Figure modified from the Manitoba Agriculture Web Site
48Salinity, Agricultural Practices and Pervious Pavement Native tree beltsDeep rooted salt tolerent species (The PundaZoie company)Salinity in untreated areasTecEco permecocrete roadsSalinity in untreated areasContoured swalesDeep drainsSalty waterFresh waterSalinity can be rectified by a combination of:Deep drainage.Mulching to increase humidity at ground level and reduce evaporative loss.Planting deep rooted salt tolerant species and leaving native belts that reduce the overall rate of evapotranspiration of the fresh water lens on top of ground water.Pervious rather than sealed surfaces (TecEco permecocrete pervious pavement).Allowing capture of fresh water rather than run off.Maximising capture and use of fresh water and minimising irrigation water.Replenishing aquifers with fresh rain water rather than recycled water through irrigation.
49How Our Theories Differ on Salinity Many websites including the CSIRO and Australian government website on salinity when discussing salinity that is not clearly related to irrigation and the re-use of water seem to think that the problem relates to reduced evapotranspiration with agriculture and rising water tables that bring “ancient” salts to the surface.We think this analysis wrong. When land is cleared natural mulches and soil humus that retain water and reduce evaporation and rate of run off at the surface of soils are removed.As a consequence what then happens is that fresh water does not enter the water table when it rains. It runs off into our rivers. According to the water dynamic discussed above it also picks up salt and pollution. Gradually during dry periods the fresh water lens on top of our aquifers is used up and the saltier water underneath remains.Reused irrigation water brings with it the salt it has picked up along the way.
50TecEco Eco-Cement Pervious Pavement PermecocreteAllow many mega litres of good fresh water to become contaminated by the pollutants on our streets and pollute coastal waterwaysPermecocreteOrCapture and cleanse the water for our use?TecEco have now perfected pervious pavements that can be made out of mono-graded recycled aggregates and other wastes and that sequester CO2.
51Cities as Profitable Carbon Sinks? THERE is a way to make our city streets as green as the Amazon rainforest. Almost every aspect of the built environment, from bridges to factories to tower blocks, and from roads to sea walls, could be turned into structures that soak up carbon dioxide- the main greenhouse gas behind global warming. All we need to do is change the way we make cement. Pearce, F. (2002). "Green Foundations." New Scientist 175(2351):
52We Must Learn to Recycle Everything Including CO2 During earth's geological history large tonnages of carbon were put away as limestone and other carbonates and as coal and petroleum by the activity of plants and animals.Sequestering carbon in calcium and magnesium carbonate materials and other wastes in pervious pavement mimics nature.CO2CWastePervious pavementWe all use carbon and wastes to make our homes!In eco-cement blocks and mortars the binder is carbonate and the aggregates are preferably wastes “Biomimicry - Geomimicry”
53John Harrison Presentation AASMIC Conference GeomimicryThere are grams of magnesium and about .4 grams of calcium in every litre of seawater.There is enough calcium and magnesium in seawater with replenishment to last billions of years at current needs for sequestration.To survive we must build our homes like these seashells using CO2 and alkali metal cations. This is geomimicryCarbonate sediments such as these cliffs represent billions of years of sequestration and cover 7% of the crust.
54Geomimicry for Planetary Engineers? John Harrison Presentation AASMIC ConferenceGeomimicry for Planetary Engineers?Large tonnages of carbon were put away during earth’s geological history as limestone, dolomite, magnesite, coal and oil by the activity of plants and animals.Shellfish built shells from it andTrees turned it into wood.These same plants and animals wasted nothingThe waste from one was the food or home for another.Because of the colossal size of the flows involved the answer to the problems of greenhouse gas and waste is to use them both in building materials.Materials are very important
55Geomimicry for Planetary Engineers? John Harrison Presentation AASMIC ConferenceGeomimicry for Planetary Engineers?Such a paradigm shift in resource usage will not occur because it is the right thing to do.It can only happen economically.We must put an economic value on carbon to solve global warming byInventing new technical paradigms such as offered by the Global Sustainability Alliance in Gaia Engineering.Evolving culturally to effectively use these technical paradigmsBy using carbon dioxide and other wastes as a building materials we could economically reduce their concentration in the global commons.Materials are very important
56Economically Driven Sustainability John Harrison Presentation AASMIC ConferenceEconomically Driven SustainabilityNew, more profitable technical paradigms are required that result in more sustainable and usually more efficient moleconomic flows that mimic natural flows or better, reverse our damaging flows.ECONOMICALLY DRIVEN SUSTAINABILITYOur approach must not only be holistic, but also economic if we are to have any hope of success.Working for sustainability market forces will make all the difference.The challenge is to move the supply and demand of resources towards more sustainable outcomes by stimulating and harnessing human behaviours which underlay economic demand phenomena, through cultural change push by governments and other leaders, and real improvement in technical and other properties as I will explain in the next slide.Sustainable processes like the new TecEco technologies are more efficient and therefore more economic.$ - ECONOMICS - $Change is only possible economically. It will not happen because it is necessary or right.
57Changing the Technology Paradigm John Harrison Presentation AASMIC ConferenceChanging the Technology ParadigmIt is not so much a matter of “dematerialisation” as a question of changing the underlying moleconomic flows. We need materials that require less energy to make them, do not pollute the environment with CO2 and other releases, last much longer and that contribute properties that reduce lifetime energies. The key is to change the technology paradigms“By enabling us to make productive use of particular raw materials, technology determines what constitutes a physical resource1”Pilzer, Paul Zane, Unlimited Wealth, The Theory and Practice of Economic Alchemy, Crown Publishers Inc. New York.1990
58Cultural Change The media have a growing role Al Gore (SOS) CSIRO reportsSTERN ReportLots of TalkfestIPCC ReportBranson PrizeLive Earth (07/07/07)The media have a growing role
59Sustainability is Where Culture and Technology Meet John Harrison Presentation AASMIC ConferenceSustainability is Where Culture and Technology MeetIncrease in demand/price ratio for greater sustainability due to cultural change.$SupplyEquilibriumShiftGreater Value/for impact (Sustainability) and economic growthECONOMICSWe must rapidly move both the supply and demand curves for sustainabilityDemandCULTURAL CHANGE AND PARADIGM SHIFTS IN TECHNOLOGYChanges in the market interaction of demand and supply reducing energy and resource usage and detrimental linkages with the planet can be achieved through cultural change and innovative changes in the technical paradigm.Increase in supply/price ratio for more sustainable products due to technical innovation.#A measure of the degree of sustainability of an industrial ecology is where the demand for more sustainable technologies is met by their supply.
60John Harrison Presentation AASMIC Conference Making Carbonate Building Materials to Solve the Global Warming ProblemHow much magnesium carbonate would have to be deposited to solve the problem of global warming?12 billion tonnes CO2 ~= billion tonnes magnesiteThe density of magnesite is 3 gm/cm3 or 3 tonne/metre3Thus 22.9/3 billion cubic metres ~= 7.63 cubic kilometres of magnesite are required to be deposited each year.Compared to the over seven cubic kilometres of concrete we make every year, the problem of global warming looks surmountable.If magnesite was our building material of choice and we could make it without releases as is the case with Gaia Engineering, we have the problem as good as solved!We must build with carbonate and wasteGaia Engineering offers technical paradigms allowing us to do so economically
61John Harrison Presentation AASMIC Conference Huge Potential for Sequestration and Waste Utilisation in the Built EnvironmentReducing the impact of the take and waste phases of the techno-process by.including carbon in materials they are potentially carbon sinks.including wastes for physical properties as well as chemical composition they become resources.re engineering materials to reduce the lifetime energy of buildingsA durable low pH high bonding binder system is required for effective waste utilisation such as TecEco Tec and Eco-CementsMany wastes including CO2 can contribute to physical properties reducing lifetime energiesCO2CO2UTILISING WASTE IN CITIESTecEco advocate the development of materials that include waste based on physical as well as chemical properties and that reduce the lifetime energy of buildings by introducing new properties.CO2CCO2WastePervious pavement
62Gaia Engineering Flowchart Portland Cement ManufactureCaOTecEco Tec-KilnIndustrial CO2MgOClaysFresh WaterTecEco Cement ManufactureMgCO3 and CaCO3 “Stone”Brine or Sea waterExtractionWaste Acid or BitternsEco-CementsTec-CementsValuable Commodity Salts or hydrochloric acid.Building components & aggregatesExtraction inputs and outputs depending on method chosenOther wasteBuilt EnvironmentBuilding waste
63The Gaia Engineering Tececology The Gaia Engineering tececology could be thought of as an open technical ecology designed to reverse major damaging moleconomic and other system flows outside the tececologyIndustrial Ecologies are generally thought of as closed loop systems with minimal or low impacts outside the ecologyThe Gaia Engineering tececology is not closed and is designed to reverse damaging moleconomic flows outside the ecology - LIKE A GIANT ECOLOGICAL PUMP
64The Gaia Engineering Process John Harrison Presentation AASMIC ConferenceThe Gaia Engineering ProcessGaia Engineering delivers profitable outcomes whilst reversing underlying undesirable moleconomic flows from other less sustainable techno-processes outside the tececology.Inputs:Atmospheric or industrial CO2, brines, waste acid or bitterns, other wastesOutputs:Carbonate building materials, potable water, valuable commodity salts.Carbonate building componentsCO2CO2Solar or solar derived energyCO2TecEco KilnTecEco MgCO2 CycleCO2Eco-CementMgOMgCO3Extraction Process1.29 gm/l Mg .412 gm/l CaCoalFossil fuelsCarbon or carbon compounds Magnesium compoundsOil
65John Harrison Presentation AASMIC Conference TecEco CementsSUSTAINABILITYDURABILITYSTRENGTHTECECO CEMENTSHydration of the various components of Portland cement for strength.Reaction of alkali with pozzolans (e.g. lime with fly ash.) for sustainability, durability and strength.Hydration of magnesia => brucite fo strength, workability, dimensional stability and durability. In Eco-cements carbonation of brucite => nesquehonite, lansfordite and an amorphous phase for sustainability.PORTLANDPOZZOLANMAGNESIATecEco concretes are a system of blending reactive magnesia, Portland cement and usually a pozzolan with other materials and are a key factor for sustainability.
66John Harrison Presentation AASMIC Conference TecEco FormulationsTec-cements (5-15% MgO, 85-95% OPC)contain more Portland cement than reactive magnesia. Reactive magnesia hydrates in the same rate order as Portland cement forming Brucite which uses up water reducing the voids:paste ratio, increasing density and possibly raising the short term pH.Reactions with pozzolans are more affective. After all the Portlandite has been consumed Brucite controls the long term pH which is lower and due to it’s low solubility, mobility and reactivity results in greater durability.Other benefits include improvements in density, strength and rheology, reduced permeability and shrinkage and the use of a wider range of aggregates many of which are potentially wastes without reaction problems.Eco-cements (15-95% MgO, 85-5% OPC)contain more reactive magnesia than in tec-cements. Brucite in permeable materials carbonates forming stronger fibrous mineral carbonates and therefore presenting huge opportunities for waste utilisation and sequestration.Enviro-cements (5-15% MgO, 85-95% OPC)contain similar ratios of MgO and OPC to eco-cements but in non permeable concretes brucite does not carbonate readily.Higher proportions of magnesia are most suited to toxic and hazardous waste immobilisation and when durability is required. Strength is not developed quickly nor to the same extent.TECECO FORMULATIONSWe have three main formulations to date, Tec-Cements which are really pre-mix concretes, Eco-Cements which have much more magnesia in them and set by carbonation in pervious substrates and Enviro-Cements which are relatively weak as they do not carbonate, they are however potentially suitable for toxic and hazardous wastes.
67Tec & Eco-Cement Theory John Harrison Presentation AASMIC ConferenceTec & Eco-Cement TheoryMany Engineering Issues are Actually Mineralogical IssuesProblems with Portland cement concretes are usually resolved by the “band aid” engineering fixes. e.g.Use of calcium nitrite, silanes, cathodic protection or stainless steel to prevent corrosion.Use of coatings to prevent carbonation.Crack control joins to mitigate the affects of shrinkage cracking.Plasticisers to improve workability.Portlandite and water are the weakness of concreteTecEco remove Portlandite it and replacing it with magnesia which hydrates to Brucite.The hydration of magnesia consumes significant water
68Tec & Eco-Cement Theory John Harrison Presentation AASMIC ConferenceTec & Eco-Cement TheoryPortlandite (Ca(OH)2) is too soluble, mobile and reactive.It carbonates, reacts with Cl- and SO4- and being soluble can act as an electrolyte.TecEco generally (but not always) remove Portlandite using the pozzolanic reaction andTecEco add reactive magnesiawhich hydrates, consuming significant water and concentrating alkalis forming Brucite which is another alkali, but much less soluble, mobile or reactive than Portlandite.In Eco-Cements brucite carbonates forming hydrated compounds with greater volume
69Why Add Reactive Magnesia? John Harrison Presentation AASMIC ConferenceWhy Add Reactive Magnesia?To maintain the long term stability of CSH.Maintains alkalinity preventing the reduction in Ca/Si ratio.To remove water.Reactive magnesia consumes water as it hydrates to possibly hydrated forms of Brucite.To raise the early Ph.Increasing non hydraulic strength giving reactionsTo reduce shrinkage.The consequences of putting brucite through the matrix of a concrete in the first place need to be considered.To make concretes more durableBecause significant quantities of carbonates are produced in permeable substrates which are affective binders.Reactive MgO is a new tool to be understood with profound affects on most properties
70Why do Eco-Cements use Magnesium Compounds? John Harrison Presentation AASMIC ConferenceWhy do Eco-Cements use Magnesium Compounds?At 2.09% of the crust magnesium is the 8th most abundant element.Magnesium oxide is easy to make using non fossil fuel energy and efficiently absorbs CO2Because magnesium has a low molecular weight, proportionally a much greater amount of CO2 is released or captured.A high proportion of water in the binder means that a little binder goes a long wayWHY MAGNESIUM COMPOUNDSBecause magnesium has a low molecular weight, proportionally a much greater amount of CO2 is released or captured.This, together with the high proportion of water in the binder is what makes construction the built environment out of CO2 and water so exciting.Imagine the possibilities if CO2 could be captured during the manufacture of eco-cement!
71Strength with Blend & Porosity John Harrison Presentation AASMIC ConferenceStrength with Blend & PorosityTec-cement concretesEco-cement concretesHigh PorosityEnviro-cement concretesHigh OPCHigh MagnesiaSTRENGTH ON ARBITARY SCALE 1-100
72Solving Waste & Logistics Problems John Harrison Presentation AASMIC ConferenceSolving Waste & Logistics ProblemsTecEco cementitious composites represent a cost affective option forusing non traditional aggregates from on site reducing transports costs and emissionsuse and immobilisation of waste.Because they havelower reactivityless waterlower pHReduced solubility of heavy metalsless mobile saltsgreater durability.denser.impermeable (tec-cements).dimensionally more stable with less shrinkage and cracking.homogenous.no bleed water.TecEco Technology - Converting Waste to Resource
73John Harrison Presentation AASMIC Conference Eco-CementsEco-cements are similar but potentially superior to lime mortars because:The calcination phase of the magnesium thermodynamic cycle takes place at a much lower temperature and is therefore more efficient.Magnesium minerals are generally more fibrous and acicular than calcium minerals and hence add microstructural strength.Water forms part of the binder minerals that forming making the cement component go further. In terms of binder produced for starting material in cement, eco-cements are much more efficient.Magnesium hydroxide in particular and to some extent the carbonates are less reactive and mobile and thus much more durable.ECO-CEMENTS COMPARED TO CARBONATING LIME MORTARSThe underlying chemistry is very similar however eco-cements are potentially superior to lime mortars because:The calcination phase of the magnesium thermodynamic cycle takes place at a much lower temperatureMagnesium minerals are generally more fibrous and acicular than calcium minerals and hence a lot stronger.Water forms part of the binder minerals that forming making the cement component go further.Magnesium hydroxide in particular and to some extent the carbonates are less reactive and mobile and thus much more durable.A less reactive environment with a lower long term pH. (around 10.5 instead of 12.35)Because magnesium has a low molecular weight, proportionally a much greater amount of CO2 is captured.
74John Harrison Presentation AASMIC Conference Eco-CementsHave high proportions of reactive magnesium oxideCarbonate like limeGenerally used in a 1:5-1:12 paste basis because much more carbonate “binder” is produced than with limeMgO + H2O <=> Mg(OH)2Mg(OH)2 + CO2 + H2O <=> MgCO3.3H2O<=> molar mass (at least!)gas <=> molar volumes (at least!)307 % expansion (less water volume reduction) producing much more binder per mole of MgO than lime (around 8 times)Carbonates tend to be fibrous adding significant micro structural strength compared to limeMostly CO2 and waterAs Fred Pearce reported in New Scientist Magazine (Pearce, F., 2002), “There is a way to make our city streets as green as the Amazon rainforest”.
75Carbonation is Proportional to Porosity Carbonation RateMacro Porosity
76Carbonation is Proportional to Time 100 %% Carbonation180 daysTime
77CO2 Abatement in Eco-Cements John Harrison Presentation AASMIC ConferenceCO2 Abatement in Eco-CementsFor 85 wt% Aggregates15 wt% CementPortland Cements 15 mass% Portland cement, 85 mass% aggregateEmissions .32 tonnes to the tonne. After carbonation. Approximately .299 tonne to the tonne.No Capture 11.25% mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate.Emissions .37 tonnes to the tonne. After carbonation. approximately .241 tonne to the tonne.Capture CO % mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate.Emissions .25 tonnes to the tonne. After carbonation. approximately tonne to the tonne.Capture CO2. Fly and Bottom Ash 11.25% mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate.Emissions .126 tonnes to the tonne. After carbonation. Approximately .113 tonne to the tonne.Eco-cements in permeable products absorb carbon dioxide from the atmosphere. Brucite carbonates forming lansfordite, nesquehonite and an amorphous phase, completing the thermodynamic cycle.Greater SustainabilityCO2 ABATEMENT IN AN ECO-CEMENT BLOCKThis slide shows that for an eco-cement concrete in a block which is 15% eco-cement if the eco-cement contains 75% reactive magnesia and with capture of CO2 during the manufacturing process net emissions are less than a third as much..299 > .241 >.140 >.113 Bricks, blocks, pavers, mortars and pavement made using eco-cement, fly and bottom ash (with capture of CO2 during manufacture of reactive magnesia) have 2.65 times less emissions than if they were made with Portland cement.
78Eco-Cement Strength Development John Harrison Presentation AASMIC ConferenceEco-Cement Strength DevelopmentEco-cements gain early strength from the hydration of PC.Later strength comes from the carbonation of brucite forming an amorphous phase, lansfordite and nesquehonite.Strength gain in eco-cements is mainly microstructural because ofMore ideal particle packing (Brucite particles at 4-5 micron are under half the size of cement grains.)The natural fibrous and acicular shape of magnesium carbonate minerals which tend to lock together.More binder is formed than with calciumTotal volumetric expansion from magnesium oxide to lansfordite is for example volume 811%.Mg(OH)2 + CO2 MgCO3.5H2OFrom air and water
79Eco-Cement Strength Gain Curve John Harrison Presentation AASMIC ConferenceEco-Cement Strength Gain CurveEco-cement bricks, blocks, pavers and mortars etc. take a while to come to the same or greater strength than OPC formulations but are stronger than lime based formulations.
80Chemistry of Eco-Cements John Harrison Presentation AASMIC ConferenceChemistry of Eco-CementsThere are a number of carbonates of magnesium. The main ones appear to be an amorphous phase, lansfordite and nesquehonite.The carbonation of magnesium hydroxide does not proceed as readily as that of calcium hydroxide.Gor Brucite to nesquehonite = kJ.mol-1Compare to Gor Portlandite to calcite = kJ.mol-1The dehydration of nesquehonite to form magnesite is not favoured by simple thermodynamics but may occur in the long term under the right conditions.Gor nesquehonite to magnesite = 8.56 kJ.mol-1But kinetically driven by desiccation during drying.Reactive magnesia can carbonate in dry conditions – so keep bags sealed!For a full discussion of the thermodynamics see our technical documents.TecEco technical documents on the web cover the important aspects of carbonation.
81John Harrison Presentation AASMIC Conference Eco-Cement ReactionsJohn Harrison Presentation AASMIC Conference
82Eco-Cement Micro-Structural Strength John Harrison Presentation AASMIC ConferenceEco-Cement Micro-Structural Strength
83John Harrison Presentation AASMIC Conference CarbonationEco-cement is based on blending reactive magnesium oxide with other hydraulic cements and then allowing the Brucite and Portlandite components to carbonate in permeable materials such as concretes blocks and mortars.Magnesium is a small lightweight atom and the carbonates that form contain proportionally a lot of CO2 and water and are stronger because of superior microstructure.The use of eco-cements for block manufacture, particularly in conjunction with the kiln also invented by TecEco (The Tec-Kiln) would result in sequestration on a massive scale.As Fred Pearce reported in New Scientist Magazine (Pearce, F., 2002), “There is a way to make our city streets as green as the Amazon rainforest”.Ancient and modern carbonating lime mortars are based on this principle
84Aggregate Requirements for Carbonation John Harrison Presentation AASMIC ConferenceAggregate Requirements for CarbonationThe requirements for totally hydraulic limes and all hydraulic concretes is to minimise the amount of water for hydraulic strength and maximise compaction and for this purpose aggregates that require grading and relatively fine rounded sands to minimise voids are requiredFor carbonating eco-cements and lime mortars on the on the hand the matrix must “breathe” i.e. they must be permeablerequiring a coarse fraction to cause physical air voids and some vapour permeability.Coarse fractions are required in the aggregates used!
85CO2 Abatement in Eco-Cements John Harrison Presentation AASMIC ConferenceCO2 Abatement in Eco-CementsFor 85 wt% Aggregates15 wt% CementPortland Cements 15 mass% Portland cement, 85 mass% aggregateEmissions .32 tonnes to the tonne. After carbonation. Approximately .299 tonne to the tonne.No Capture 11.25% mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate.Emissions .37 tonnes to the tonne. After carbonation. approximately .241 tonne to the tonne.Capture CO % mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate.Emissions .25 tonnes to the tonne. After carbonation. approximately tonne to the tonne.Capture CO2. Fly and Bottom Ash 11.25% mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate.Emissions .126 tonnes to the tonne. After carbonation. Approximately .113 tonne to the tonne.Eco-cements in permeable products absorb carbon dioxide from the atmosphere. Brucite carbonates forming lansfordite, nesquehonite and an amorphous phase, completing the thermodynamic cycle.Greater SustainabilityCO2 ABATEMENT IN AN ECO-CEMENT BLOCKThe above slide shows that for an eco-cement concrete in a block which is 15% eco-cement if the eco-cement contains 75% reactive magnesia and with capture of CO2 during the manufacturing process and the use of a pozzolan after carbonation net emissions are less than a third as much..299 > .241 >.140 >.113 Bricks, blocks, pavers, mortars and pavement made using eco-cement, fly and bottom ash (with capture of CO2 during manufacture of reactive magnesia) have 2.65 times less emissions than if they were made with Portland cement.
86John Harrison Presentation AASMIC Conference TecEco Cement LCATecEco Concretes will have a big role post Kyoto as they offer potential sequestration as well as waste utilisationTECECO LCA MODELFor more information on the contribution our Tec and Eco-Cements can make to the global carbon balance please consult our LCA model under tools on the web site.The TecEco LCA model is available for download under “tools” on the web site
88Rosendale Concretes – Proof of Durability John Harrison Presentation AASMIC ConferenceRosendale Concretes – Proof of DurabilityRosendale cements contained 14 – 30% MgOA major structure built with Rosendale cements commenced in 1846 was Fort Jefferson near key west in Florida.Rosendale cements were recognized for their exceptional durability, even under severe exposure. At Fort Jefferson much of the 150 year-old Rosendale cement mortar remains in excellent condition, in spite of the severe ocean exposure and over 100 years of neglect. Fort Jefferson is nearly a half mile in circumference and has a total lack of expansion joints, yet shows no signs of cracking or stress. The first phase of a major restoration is currently in progress.More information from
89John Harrison Presentation AASMIC Conference A Post – Carbon AgeECO-CEMENTSThe main magnesium carbonate that form in eco-cement is nesquehonite which is 83 mass % water and CO2 – cheap binder? Lansfordite, another mineral that forms has even more water in it!Magnesium carbonates are generally fibrous and acicular and therefore add microstructural strength.The long term pH is much lower than Portland cement concretes. Combined with the fact that magnesium minerals seem to stick well to other materials the result is that a high proportion of wastes can be included.As mentioned earlier TecEco cements are generally also much more durable. Materials that last longer are much more sustainableWe all use carbon and wastes!
90Eco-Cement compared to Carbonating Lime Mortar. John Harrison Presentation AASMIC ConferenceEco-Cement compared to Carbonating Lime Mortar.The underlying chemistry is very similar however eco-cements are potentially superior to lime mortars because:The calcination phase of the magnesium thermodynamic cycle takes place at a much lower temperatureMagnesium minerals are generally more fibrous and acicular than calcium minerals and hence a lot stronger.Water forms part of the binder minerals that forming making the cement component go further.Magnesium hydroxide in particular and to some extent the carbonates are less reactive and mobile and thus much more durable.A less reactive environment with a lower long term pH. (around 10.5 instead of 12.35)Because magnesium has a low molecular weight, proportionally a much greater amount of CO2 is captured.Carbonation in the built environment would result in significant sequestration because of the shear volumes involved.Carbonation adds considerable strength and some steel reinforced structural concrete could be replaced with fibre reinforced permeable carbonated concrete.ECO-CEMENTS COMPARED TO CARBONATING LIME MORTARSThe underlying chemistry is very similar however eco-cements are potentially superior to lime mortars because:The calcination phase of the magnesium thermodynamic cycle takes place at a much lower temperatureMagnesium minerals are generally more fibrous and acicular than calcium minerals and hence a lot stronger.Water forms part of the binder minerals that forming making the cement component go further.Magnesium hydroxide in particular and to some extent the carbonates are less reactive and mobile and thus much more durable.A less reactive environment with a lower long term pH. (around 10.5 instead of 12.35)Because magnesium has a low molecular weight, proportionally a much greater amount of CO2 is captured.
91A More Sustainable Built Environment John Harrison Presentation AASMIC ConferenceA More Sustainable Built EnvironmentCO2 + H2O => Hydrocarbons compounds using bacteriaCO2OTHERWASTESCO2CO2PERMANENT SEQUESTRATION & WASTE UTILISATION (Man made carbonate rock incorporating wastes as a building material)Pareto’s principle -80% of the build environment in non structural and could be carbonate from Greensols held together by Eco-CementsGREENSOLSMgOECO-CEMENT CONCRETESMAGNESIUM CARBONATETECECO KILNRECYCLED BUILDING MATERIALS“There is a way to make our city streets as green as the Amazon rainforest”. Fred Pearce, New Scientist MagazineTECECO’S DREAMOur dream is to create cities that mimic nature in that have a balance of carbon, other wastes and energy.SUSTAINABLE CITIES
92ConclusionPervious pavements made with TecEco Eco-Cements would utilise a considerable proportion of wastes such as fly ash and as they would carbonate, provide substantial abatement. Water entering aquifers, streams and rivers would be of higher quality and carry less macro pollutants.Cities with pervious pavements would be safer for traffic, be cleaner and have less pollutionFresh water replenishment of aquifers would reduce salinity and reverse falling water tables.Pervious pavements could provide a means for water capture with in situ cleansing thereby solving the water crisis in our cities