Universidad de A Coruña Escuela Técnica Superior de Ingenieros de Caminos, Canales y Puertos

1. SD Water supply and drainage systems Hochschule Magdeburg-StendalFachbereichWasser und Kreislaufwirtschaft Universidad de A CoruñaEscuela Técnica Superior de Ingenieros de Caminos, Canales y Puertos

2. SD Index 0. Introduction (2h, Pablo Rodríguez-Vellando) Water supply and drainage, a historical approach (8h, AlberteMartínezLópez) Water provision and consumption, distribution networks (8 h, Gustavo V. Herrero) Abstraction of water (4h, Jordi Delgado Martín) Water supply treatment (8h, Pablo Rodríguez-Vellando) Water drainage treatment (4h HéctorGarcíaRábade + 4h Gustavo V. Herrero ) Constructive aspects of water supply and drainage systems (4h, Cristina V Herrero) Water law (8h, Javier SanzLarruga)

3. SD 6. Constructive aspects of water supply and drainage systems 6.0 Introduction 6.1. Concrete components 6.2. Concrete mix design 6.3. Loadsonwatersupply and drainagestructures 6.4. Structuraldesigncriteria 6.5. Installationrecommendations 6.6. Summary and conclusions Bibliography Annex. Glossary

4. 6.0. Introduction

5. Key concepts • Practice • Criticalanalysis • Research

6. SD Objectivesof these lectures The purpose of these lectures is to provide the students a general insight of the constructive aspects that should be considered to design, build and maintain water supply and drainage systems with the minimum overall cost, accounting for maximum durability of the water supply and drainage systems and with minimum environmental impact. Due to the diverse background of the students, the lectures are aimed at providing general criteria.

7. Reinforced concrete is the main material used in water supply and drainage systems, whose durability is conditioned by concrete quality. Let us study the main constructive aspects related to this material! Whatis concrete? Concrete is a mixture of paste and aggregates. The paste, composed of portland cement and water, coatsthesurface of the fine and coarseaggregates. Throughchemicalreactionscalledsetting, the paste hardens and gainsstrength.

8. Withinthisprocessliesthekeyto a remarkabletrait of concrete: it'splastic and malleablewhennewlymixed, strong and durable whenhardened. Concrete’s ECO2 measuresitsenvironmentalimpact.

9. Theproblem: • Whatdesign and constructioncriteriashould be consideredformaximumdurability of concrete pipes and tanks?

12. Concrete ManufacturersAssociation. Design manual for concrete pipe outfallsewers. April 2009

13. Factorscontributingtocorrosionbyhydrogensulfidegeneration: • Retention time in sewer • Velocitiestha are notself-cleansing • Siltaccumulation • Temperature • Biochemicaloxygendemand • Dissolvedoxygen in effluent • Dissolvedsulfides in effluent • Effluent pH

14. Factorscontributingtocorrosionbyhydrogensulfidereleasefromtheeffluent:Factorscontributingtocorrosionbyhydrogensulfidereleasefromtheeffluent: • Concentration of hydrogensulfide in effluent • High velocities and turbulence Factorscontributingto H2SO4onthesewerwalls: • Concentration of H2S in sewerwalls • Rate of acidformation • Theaoumnt of moistureonsewerwalls

15. Concrete ManufacturersAssociation. Design manual for concrete pipe outfallsewers. April 2009

17. http://eurocodes.jrc.ec.europa.eu/doc/WS2008/EN1992_1_Walraven.pdfhttp://eurocodes.jrc.ec.europa.eu/doc/WS2008/EN1992_1_Walraven.pdf

20. What are thechemicalagentsresponsibleforcorrosionof concrete pipes and tanks?

21. 6.1. Concrete components

22. Cement • Coarseaggregate • Fine aggregate • Water • Air • Additives • Admixtures • SCMs http://www.concretethinker.com/solutions/Stewardship.aspx

23. Whatis concrete made of? http://www.cement.org/basics/concretebasics_concretebasics.asp

24. What are RAs? Ras accountsforrecycledaggregatesthat come fromdebris

25. What are RCAs? RCAsaccountsforrecycled concrete aggregatesthat come fromdemolition of concrete

26. What are admixtures? Admixtures account for materials other than water, aggregates, cement and fiber reinforcement used as an ingredient of concrete and added to the batch immediately before or during its mixing.

27. Admixture, accelerating – an admixture that accelerates the setting and early strength development of concrete. Admixture, air-entraining – an admixture that causes the development of a system of microscopic air bubbles in concrete, mortar or cement paste during mixing. Admixture, water-reducing – admixture that either increases the slump of freshly mixed concrete without increasing the water content or that maintains the slump with a reduced amount of water.

28. Acceleratingadmixtures (ASTM C494,“Specification forChemicalAdmixturesfor Concrete”) Air entrainmentadmixtures (ASTM C260, “Specificationfor Air-EntrainingAdmixturesfor Concrete”) Waterreducingadmixtures (ASTM C494, “SpecificationforChemicalAdmixturesfor Concrete”) High-rangewater-reducingadmixturesorsuperplasticizers (ASTM C494, “Standard SpecificationforChemicalAdmixturesfor Concrete; ASTM C1017, “ChemicalAdmixturesfor Use in ProducingFlowing Concrete”)

29. What are SCMs? SCMsaccountsforsupplementaryCementitiousMaterials. 1. Cementitiousmaterials – GroundGranulatedblastfurnaceslag (ASTM C989) 2. Pozzolanicmaterials – Class F flyash, silica fume, metakaolin (ASTM C618, ASTM C1240) 3. Pozzolanic and cementitiousmaterials – Class C flyashes (ASTM C618)

30. 6.2. Concrete mix design

31. Whatis concrete mix design? Concrete mix designisaimed at determiningthemosteconomical and practicalcombination of readilyavailablematerialsto produce a concrete thatwillsatisfythe performance requirementsunder particular conditions of use. Componentsshould be provided in kg/m3 Normal weight concrete specificweight: ρ=2000-2400 kg/m3

32. Example: SCC=self-compacting concrete

33. Whatisimportantabout concrete mix design? A compact concrete isintended, withtheminimumcement paste Watertight=waterresistant

34. Wellgradedaggregate Tecnovalproject, Innterconnecta-FEDER

35. Factorsto be consideredinclude: • Workability • Cohesiveness, slump • Placementconditions • Strength • Durability • Appearance • Economy • Minimizetheamount of cement • Minimize w/c ratio • Minimizeamount of water

36. Mixdesigns are selectedbaseduponseveralnecessaryfactorsincludingpermeability, consistency, workability, strength and durability (ACI 211). Theelementsnecessarytoachievehigh-qualitywatertightprecast concrete include: • Minimumcompressivestrength of 4,000 psi (28 MPa) at 28 days • Lowwater-cementitious ratio (lessthan 0.45) • Use of goodquality and properlygradedaggregate • Proper concrete consistency.

37. The following recommendations are aimed at specifying concrete with a low environmental impact (low ECO2): • Do not over-specify concrete strength. • Consider the possibility of strength conformity at 56 days rather than the conventional 28 days, answering the question: When will be the structure put to use? Will it be after 28 days? • Specify responsibly-sourced concrete and reinforcement (so as to guarantee quality and sustainable production).

38. Do not specify aggregate size below 10 mm unless necessary (as it demands more cement paste). • Permit the use of recycled or secondary aggregates but do not over specify. Current standards allow 20% recycled aggregates. Beware of the transport distance, as it increases cost and ECO2! • Specify that concrete should always contain CEMII/CEMIII or an addition, as ECO2 is lower than CEMI cement’s

39. Permit the use of admixtures, as they reduce the embodied C02(ECO2). Beware of concrete colour and appearance! • Consider the local environmental regulations, i.e. BREEAM (UK)

40. 6.2.1. Exposureclass

42. 6.2.2. Cement http://iti.northwestern.edu/cement/monograph/Monograph3_8.html

43. There is actually little difference between a Type I and Type II cement, and it is common to see cements meeting both designations labeled as “Type I/II”.  It should be noted here that the most effective way to prevent sulfate attack is to keep the sulfate ions from entering the concrete in the first place.  This can be done by using mix designs that give a low permeability (mainly by keeping the w/c ratio low) and, if practical, by putting physical barriers such as sheets of plastic between the concrete and the soil. 

44. Types II and V OPC are designed to be resistant to sulfate attack.  Sulfate attack is an important phenomenon that can cause severe damage to concrete structures.  It is a chemical reaction between the hydration products of C3A and sulfate ions that enter the concrete from the outside environment.  The products generated by this reaction have a larger volume than the reactants, and this creates stresses which force the concrete to expand and crack.  Although hydration products of C4AF are similar to those of C3A, they are less vulnerable to expansion, so the designations for Type II and Type V cement focus on keeping the C3A content low. 

45. Classexercise: Whatexposureclass and whattypes of cementwouldyou use? • Septictankexposureclass • Watersupplysystemsubmerged in seawater • Watersupplysystem in aggresivesoils • Waterdrainagesystem in highway, coldweather, use of deicingagents

46. Solution:

47. 4.2.3. Aggregates • Concrete isexposedtocontinuousmoist and corrosiveconditions in wastewaterapplications. Itisimportanttospecify a well-graded, sound, nonporousaggregate in accordancewith ASTM C33, “Standard Specificationfor Concrete Aggregates.”

48. Ensureaggregatesconformtotherequirements of ASTM C33. Evaluatetheaggregates and maintaindocumentation at theplantforpotentialdeleteriousexpansionduetoalkalireactivity, unlesstheaggregates come from a statedepartment of transportationapprovedsource.

49. Themaximumsize of coarseaggregateshould be as large as practical, butshouldnotexceed 20% of theminimumthickness of theprecast concrete tankor 75% of theclearcoverbetweenreinforcement and thesurface of thetank. Largermaximumsizes of aggregatemay be usedifevidence shows thatsatisfactory concrete products can be produced.

50. RecycledaggregatesRAsRCAs http://iti.northwestern.edu/cement/monograph/Monograph3_8.html RA: recycled aggregates RCA: recycled concrete aggregates