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Laboratorio materiali
materials science
01PQKPQ Cusco Sun City: an experimental territory on the site of the Alejandro Velasco Astete Airport
Simonetta Pagliolico
Politecnico di Torino
4th lesson_sustainable use of soil materials on construction
soil
one hectare of topsoil can contain up to 5 tonnes of living organisms
more than 500 years to form a layer of 2cm in thickness
non-renewable, but a diffuse resource, widespread all over the world
subsoil crumbling rock, gravel, sand, silt, clay, and water
food and fibre production
environmental interaction (with water and air)
support of ecological habitats and biodiversity
support for the landscape
protection of cultural heritage
providing raw materials
providing a platform for construction.
soil functions
soil has a large social function
Green spaces: gardens, sport and playing fields, and public open space
cultural and social benefits
well-being, physical and psychological health, and connection with nature
soil and construction_ adverse impacts
Construction activity can have adverse impacts:
• mining and transporting from quarries to cities and building sites consume raw material and produce GHGs
• covering soil with impermeable sealing materials affects drainage characteristics
• contaminating soil by chemicals reduces soil quality and increases toxicity
• over-compacting soil reduces the possibility of soil cultivation and permeability
• mixing top soil with subsoil reduces soil quality for cultivation
• transforming the soil into waste by mixing with C & D (construction wastes) or other materials require treatments for reuse or disposal at landfill
soil management during construction_ Soil Resource Plan
Careful management of topsoil and subsoil
A Soil Resource Plan must include: • maps showing topsoil and subsoil types, and the areas to be stripped and left in-situ. • methods for stripping, stockpiling, respreading and ameliorating the soils. • location of soil stockpiles and content. • schedules of volumes for each material. • expected after-use for each soil: topsoil to be used on site or sold off site, or subsoil to be retained for landscape areas, used as structural fill or for topsoil manufacture. • identification of person responsible for supervising soil management.
re-use practices on and off-site provide credit for LEED certification
• re-use of soil as grading material, re-use of stone aggregate as a raw material for concrete, re-use of crushed concrete material as sub-base material for roadways and parking lots. • C&D (construction and demolition wastes) and ABC (Asphalt, Bricks, Concrete) can
substitute virgin building materials such as sand and aggregates. • on-site and off-site: the displacement of excavated material is often necessary for
contaminant removal or for sale. But also onsite treatment (such as sieving to modify particle size distribution and compactability) are possible to make soil suitable on-site for grading and landscaping.
soil conservation_ terraces
Terracing is one of the oldest techniques of cultivation of the soil and represent the distinctive components of many hilly and mountain landscape.
The terrace consists of the construction of a flat surface to allow the cultivation of sloping areas.
The terraces enable better management of soil and water, improving access to land and facilitating agricultural operations.
soil conservation_ terraces The main reason for terracing is the conservation of water and soil: • redistribution of soil in sloping areas with moderate
soil depth,
• increase in depth of the roots of the plants in order to absorb the nutrients and the water,
• make it less steep terrain, facilitating access and
agricultural operations,
• clean soil from stones that can interfere with the cultivation,
• decrease the surface water runoff and increase the absorption of water from the soil during periods of intense precipitation, preventing erosion and flooding
• control of soil erosion in sloping areas preventing loss of organic matter and nutrients allowing a more intensive cultivation.
• increase groundwater reserves allowing cultivation during dry season.
• create a special microclimate that intensified cultivation.
terraces and canals in Cusco
INCA’s terraces
Four natural depressions were used at Moray , between Machu Pichu and Cusco, to create concentric circles for irrigated crops. Hydraulic drop structures (vertical channels) add order and detail to each set of circles.
the genius of the Incas was their ability to grow a surplus of food
flying stairs
on each terrace it was created a special microclimate that intensified cultivation
INCA’s terraces
The fundamental characteristics of bench terraces were: • High retaining walls made of stacked
stones (from 1 m to 3-4 m),
• Level platform surfaces
• Valley-side positions closely following slope contours
• Arrangement in closed vertical serial rows
• Cut-and-fill construction method
• Inward sloping walls (batter)
• Built-in irrigation and other devices, such as side walls, water drops, canals, deains, intakes and offtakes, steps, and niches.
INCA’s terraces Builders used cut-and-bench (cut-and-fill) methods to contruct these terraces: • they escave through A horizon to emplace
wall base stones ranging in size from 30 to 60 cm in diameter. Stability and interloking fit were more important than the size of wall stones.
• Next, soil was removed from the exposed vertical face in order to set the background drainage horizon by cobble and earth.
• Stripped and stockpiled soil was moved down from the slope behind the wall, while stone masons built the wall higher to retain the soil.
INCA’s terraces
Scrap coarse stones (crumbling rocks) are placed to form background of the fill, than a layer of smaller stones, followed by a layer of gravel and sand, promote drainage, at the top of the fill, earth strip (humus) allow the cultivation.
bibliography
• N. F. Miller, K. L. Gleason, The Archaeology of Garden and Field, University of Pennsylvania Press, 1994.
• http://books.google.it/books?id=MARsWXbqFCsC&printsec=frontcover&hl=it&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
•
• Kenneth R. Wright, The triumph of Incan civil engineering over scarce water resources survives today, Water Environment & Technology, Denver, Colo., 2008. www.we f.org/magazine
• J.W. Duggan, Teaching Sustainable Design in Construction: A Module on the Recycling and Re-use of Urban Soil, Stone, Fill and Related Construction Material, CCEV417 – Sustainability in the Built Environment. This elective course is offered to Civil Engineering
Technology, Construction Management, Facilities Management and Environmental Science majors. The course reviews several sustainability concepts and practices, including green building. The re-use and recycling of urban fill and ABC is addressed in this course under the broader theme of LEED certified buildings.
bibliography
• Construction Code of Practice for the Sustainable Use of Soils on Construction Sites, Department for Environment, Food and Rural Affairs, London, 2009. http://www.defra.gov.uk/
•
Exercise 2.A_sustainable soil management
1. Quickly read the bibliography and 4th lesson
2. Choose a subject of interest
3. Deepen the subject by new literature sources
4. Produce A1 format poster (produce one or more layouts of your choice) and/or a brief report
Exercise 2.A_sustainable soil management
2. Choose a topic of your interest
2.1 Play a critical and comparative reading of the articles and papers 2.2 Synthesize and integrate the different literature sources 2.3 Plan an index of the arguments to be processed
Exercise 2.A_sustainable soil management
The subjects could be: 1. soil and construction_ Construction Code of Practice for the Sustainable Use of
Soils on Construction Sites, Department for Environment, Food and Rural Affairs, London, 2009. http://www.defra.gov.uk/
2. re-use applications both on and off-site. Such opportunities include use of soil as grading material, re-use of stone aggregate as a raw material for concrete and re-use of crushed concrete material as sub-base material for roadways and parking lots_ J.W. Duggan, Teaching Sustainable Design in Construction: A Module on the Recycling and Re-use of Urban Soil, Stone, Fill and Related Construction Material and supplementary literature*
3. INCA’s terraces
4. remediation and decontamination of polluted soils_ Ing. R. Ghisu
5. soil and urban landscape
*Supplementary bibliography given by Pagliolico
3. Deepen the topic by new literature, library research: • Valentino and C.so Duca degli Abruzzi Central Library,
• Centro di ricerca e di documentazione in 'Tecnologia, architettura e città nei
Paesi in via di sviluppo‘ _ c/o Galileo Ferraris, Corso Massimo d'Azeglio, 42, 2nd floor
tel. + 39 0110906439/6429 [email protected] http://www.polito.it/crd-pvs), • websites.
Exercise 2.A_sustainable soil management