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 centropvs@polito.it http://www.polito.it/crd-pvs), • websites.

Exercise 2.A_sustainable soil management