Cement (Part - 01) PDF

CE 204 CONCRETE TECHNOLOGY Second maximum consumed material – First maximum consumed material is Water Concrete Technology is similar to Cooking – Mixing of several ingredients and processing is cooking – E...

CE 204 CONCRETE TECHNOLOGY Second maximum consumed material – First maximum consumed material is Water Concrete Technology is similar to Cooking – Mixing of several ingredients and processing is cooking – Every cook has different method of cooking – different taste at different times Behavior of Concrete is similar to the behaviour Human beings – Agni (Fire), Jal (Water), Prithvi (Earth), Vayu (Air), Akash (Ether) GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 1 Evolution of construction materials Wood → Bones of Huge animals → Stone Masonry → Steel & Other metals → Brick Masonry → Small pieces of stone + Mortar = Concrete → Concrete + Steel (Passive) = Reinforced Cement Concrete (RCC) → Concrete + Steel (Active) = Prestressed Concrete Modern Materials → Processed Wood → Glass → Plastics (GFRP/ CFRP) → Rubbers (Natural & Artificial) → Adhesives → High Strength Materials (Graphene) etc… GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 2  Issues with Concrete Merits – Easily Available – Can take any shape – Economical – Durable – Fire resistant – Higher Compressive Strength Demerits – Low Tensile Strength – Poor Ductility - Formwork is Required - Long curing time. Treatment for Low Tensile Strength – Reinforced with materials with high tensile strength (i.e., Steel) – Reinforced Cement Concrete (RCC) Treatment for Poor Ductility – Providing Under Reinforced Sections By Providing RCC are we eliminating the defect of Low Tensile Strength? – No, We are living with Cracks – Cracks will lead to durability issues. GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 3  Terminology in Concrete Technology Cement + Water – Paste – Highly reactive – Prohibited Cement + Water + Sand (Fine Aggregate [FA]) – Mortar – Brick laying, Plastering Cement + Water + FA + Coarse Aggregate [CA] – Concrete Cement + Water + FA + CA + Admixtures – Concrete with tailored properties. Cement – Manufactured ingredient – Expensive – Highly reactive – To be used in optimum dosages to obtain economy & durability Water – Optimum dosages only - Potable water to be used FA & CA – Available naturally - resources rapidly depleting – Construction & Demolished Waste Admixtures – natural or artificial – added in small quantities to tailor the properties GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 4 Pantheon (Rome – Italy) – 125 AD Temple of Saturn (Rome -498 BC) Great Wall of China (14th Cen) Roman Aquaduct GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 5 GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 6 Concrete Bridges GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 7 CABLE STAYED BRIDGES – MILLAU VIADUCT, FRANCE GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 8 DIFFERENT TYPES OF BRIDGE PIERS GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 9 GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 10  AIRPORTS – STRUCTURES & RUNWAYS ETC GRADE SEPERATOR – FLYOVER – CLOVER LEAF JUNCTION GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 11 GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 12  HISTORY OF CEMENT Romans, Greeks, Egyptians used cements in different forms – Very durable L. J. Vicat (1823) – artificial cement by calcining mixture of limestone & clay Joseph Aspdin, a Leeds bricklayer – patent on 21 Oct 1824 – Ordinary Portland Cement (OPC) India manufactured first cement in 1904 until then it was imported Per capita cement production/consumption – is an index of growth of the country GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 13  Manufacture of Cement Raw Materials – Calcareous Materials (CM) – contains Ca & Mg (Limestone or Chalk) & Argillaceous Materials (AM) – contains oxides of Si, Al & Fe (Shale or Clay) & Gypsum is small quantities CM & AM are quarried from earth and transported to the plant – Crushed, pulverized and mixed in designated proportions- This mixture is called as RAW MEAL – stored in silos Dry process & Wet process Raw meal is preheated and sprayed in Rotary kiln – Slightly tilted subjected to firing from the farther end – Raw meal will gradually descend and subjected to gradual increase in temperature upto 1300 – 1500 degrees Centigrade – Calcining – Clinkers are produced Clinkers – Stored in silos – Ground along with gypsum & other additives – packed and transported to site. GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 14  The Quality of cement depends on the cooling rate of clinker & Fineness of cement Gypsum will prevent flash set of cement. More gypsum will delay the setting time. GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 15 Diagrammatic representation of manufacture of cement ON BURNING - CLINKER ON GRINDING ROBERT H BOGUE He was thefirst Director of the ON HYDRATION Portland Cement Association Fellowship at the National Bureau of Standards. GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 16  C3S depends on CaO C2S depends on SiO2 C3A depends on Al2O3 C4AF depends on Fe2O3 Na2O & K2O – Alkalies – Bad GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 17  Bogue’s Compounds (Tornebohm) Name of the Compound Formula Abbr. Formula Tricalcium Silicate (Alite) 3 CaO. SiO2 C3S (50-60%) Dicalcium Silicate (Belite) 2 CaO. SiO2 C2S (20-45%) Tricalcium Aluminate (Celite) 3 CaO. Al2O3 C3A (8-12%) Tetracalcium aluminoferrite 4 CaO. Al2O3 Fe2O3 C4AF (6-10%) (Felite) GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 18 Development of Strength of Bogue’s Compounds C3S – Responsible for early strength C2S – Responsible for delayed strength C3A & C4AF – Do not contribute to strength gain GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 19 HYDRATION OF CEMENT Reaction between Cement and Water Exothermic reaction – Heat of Hydration Different compounds hydrate at different rates Fine cement promote quick reaction C3S – Rigorous – Max. heat of Hydration – Responsible for early strength & also deterioration C2S – Responsible for delayed strength – Good from durability considerations C3A – Very Rigorous - Flash setting GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 20  HYDRATION OF CEMENT Hydration of C3S 2C3S + 6H →C3S2H3 + 3Ca(OH)2 100 + 24 → 75 + 49 Hydration of C2S 2C2S + 4H →C3S2H3 + Ca(OH)2 100 + 21 → 99 + 22 Calcium-Silicate–Hydrate Calcium Hydroxide Ca(OH)2 C3S2H3 (C-S-H Gel) Desirable Un Desirable GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 21  Hydration of C3S Hydration of C2S Very Rigorous Less Rigorous More Heat of Hydration Less Heat of Hydration More C3S in High grade Less C2S in High grade cements cements Responsible for Early Responsible for Later Strength of concrete Strength of concrete Quality & Quantity of C-S-H Quality & Quantity of C-S-H Gel is inferior / less Gel is Superior / more More quantity of Ca(OH)2 Less quantity of Ca(OH)2 Why Ca(OH)2 Un Desirable? Ca(OH)2 + CO2 → CaCO3 + H2O CaCO3 Leaches out as white patches GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 22  High Grade OPC – Less Durable!!! High Grade Cement has more C3S and less C2S Quantity and Quality of C-S-H Gel produced by C3S is Less Quantity of Ca(OH)2 produced by C3S is more C-S-H is desirable & Ca(OH)2 is undesirable Ca(OH)2 reacts with sulphates (present in soils) to form CaSO4 – this CaSO4 reacts with C3A (in presence of water) – Calcium Sulpho Aluminate – Ettringite – Sulphate attack Ca(OH)2 is alkaline- pH of 13 – prevents corrosion of steel GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 23  What is the solution? Blended Cements (PPC) Ca(OH)2 + SiO2 + H2O → C-S-H C-S-H much dense, Inert, impermeable, suitable for marine conditions. Limitations - Low Early Strength, Final strength is equal to more than OPC This reaction is called as Pozzolanic Reaction This SiO2 comes from Pozzolanic materials – Natural or Artificial admixtures – Industrial wastes (Fly ash, GGBFS, SF, RHA etc.,) GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 24  BENEFITS OF BLENDED CEMENTS (PPC) Improved Workability, Impermeability, Durability Resistance against Alkali Aggregate Reaction, Sulphate Attack, Carbonation, Chloride Ion Penetration, Chemical attack Low Heat of Hydration, Thermal Shrinkage, Leaching of Ca(OH)2, Low cost, Low Shrinkage, Low Creep, Less vulnerable to cracking Promotes use of industrial wastes – Eco friendly – Helps reduce pollution – Sustainability Suitable for marine construction, underground construction GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 25  HYDRATION OF C3A & C4AF Hydration of C3A [UNDESIRABLE] Responsible for Flash Set – Addition of Gypsum prevents flash set Responsible for high early heat of hydration Avoids corrosion of steel ?? No contribution to strength – Detrimental to the durability of concrete – Responsible for Sulphate Attack – Responsible for compatibility of cement & superplasticizer. Hydration of C4AF [DESIRABLE??] Does not contribute to strength – Produces Hydrated Calcium Ferrite – C3FH6 – Higher resistance to Sulphate attack – responsible for the color of cement GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 26  Heat of Hydration For Mass Concrete – Heat of Hydration is Detrimental – Minimised – Using Cement with Low Heat of Hydration GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 27 Water Requirement for Hydration of Cement C3S requires 24% water & C2S required 21% water – Average 23% 23% water is required for chemical reaction – BOUND WATER Some water is imbibed in Gel pores – GEL WATER About 15% water is required to fill up the Gel Pores – GEL WATER 38% Water is required for complete reaction & occupy the Gel Pores. If water is less than 38% - complete hydration is not possible – High Strength Concrete (HSC) If water is more than 38% - Gel will be less dense – Undesirable –Increase Permeability - Prone to early deterioration Lower water content – Gel will be more dense – Impermeable – Most Desirable – Unhydrated particles of cement if any (in HSC) will hydrate at a later age and fill the cracks – Hence improved durability GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 28 Diagrammatic representation of Hydration of Cement GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 29 Micro Structure of Cement GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 30 Details on Bag of Cement GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 31 Bulkers to transport cement – Transit mixers for concrete GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 32  Storage of Cement SILOS – READY MIX CONCRETE PLANTS STORAGE OF BAGS ON SITES IS 4082:1996: Stacking & Storage of Construction materials GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 33  Testing of Cement on Field Date of Manufacture – Not more than 90 Days old Lumps Test – No Lumps Color Test – Uniform color Rubbing Test – Smooth Feeling (When rubbed between two fingers) Smell Test – No earthy smell Temperature – Cool Feeling (When fist is inserted in the cement bag) Float – Cement should float for some time before sinking GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 34  Ordinary Portland Cement - Grades ORDINARY PORTLAND CEMENT, 33GRADESPECIFICATION – IS 269 – 1989 – NOT AVAILABLE NOW 43 GRADE ORDINARY PORTLAND CEMENT – SPECIFICATION – IS 8112 – 2013 – WITH DRAWN SPECIFICATION FOR 53 GRADE ORDINARY PORTLAND CE – IS 12269 – 2013 – WITH DRAWN Ordinary Portland Cement Specification – IS 269 - 2015 GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 35  Ordinary Portland Cement Specification – IS 269 - 2015 Table – 1 – Performance Improvers; Table – 2 – Chemical Requirements for OPC GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 36  Testing of cement in Laboratory Standard Consistency of Cement Initial & Final Setting time Specific Gravity of cement Compressive Strength of Cement Fineness of Cement Soundness of Cement GARJE RAJESH KUMAR – CE204 CONCRETE TECHNOLOGY - ONE 37