CE243 - Civil Engineering Materials Lecture 3: Cement PDF

# CE243 - Civil Engineering Materials ## Module (A): Binders & Fillers ### Lecture 3: Cement Dr. K. V. Harish Faculty, Department of Civil Engineering Indian Institute of Technology Kanpur Uttar Pradesh 208016 Email: [email protected] Phone: +91-512-259-6427 ## Presentation Contents - Chemical Pr...

# CE243 - Civil Engineering Materials ## Module (A): Binders & Fillers ### Lecture 3: Cement Dr. K. V. Harish Faculty, Department of Civil Engineering Indian Institute of Technology Kanpur Uttar Pradesh 208016 Email: [email protected] Phone: +91-512-259-6427 ## Presentation Contents - Chemical Properties of PC - Physical Properties of PC - Types of Portland Cement - Blended Cements - Blend Materials for Cement, Mortars & Concrete - Special Cements ## Introduction - Plain Concrete (PCC) consists of 2 parts: - Binder - Portland cement + Water - Filler - Fine aggregate + coarse aggregate - Portland Cement (PC) - + water → cement paste - + fine aggregate → mortar - + coarse aggregate → concrete (PCC) - Admixtures/additives may be added to improve specific properties of PCC ## Chemical Properties of Cement ### General - Chemical properties of PC usually refers to its oxide contents and/or compound composition - The latter refers to Bogue’s compounds and other minor compounds - Reactions of PC hydration is due to the reaction of the compounds and not the oxides - We have already seen the following: - Cement chemist notations - Bogue’s compounds - Cement hydration reactions - Components and characteristics of hcp - Stages, mechanism and development of products ### Determination of chemical properties - (i) Oxide contents - XRF - (ii) Compounds - QXRD (crystalline), FTIR (amorphous phases), Microscopy (point count), Bogue’s formula (approximate) ## Oxide Composition of Cement & Importance - Free lime is embedded in normal CaO - expansion determined by Le-Chatlier test - Can cause 'unsoundness' along with free lime - CO2-unburnt carbon must not be present. It affects air entrainment (will discuss later) - Water or moisture must NOT be present. Otherwise, hydration can happen when cement is stored in bags (which will reduce its ‘shelf life’) - A 5%-10% batch-batch variation in oxide contents is normal and expected | Oxide | Cement chemist notation | Short Hand Notation | Common Name | Weight Percent | |---|---|---|---|---| | CaO | C | lime | 64.67 | | SiO2 | S | silica | 21.03 | | Al2O3 | A | alumina | 6.16 | | Fe2O3 | F | ferric oxide | 2.58 | | MgO | M | magnesia | 2.62 | | K2O | K | alkalis | 0.61 | | Na2O | N | 0.34 | | SO3 | S | sulfur trioxide | 2.03 | | CO2 | C | carbon dioxide | | H2O | H | water | - Major oxides - embedded as compounds in PC - Imp. To know the values approximately - Minor oxides - Can trigger ASR (if reactive aggregates are used) - Maintain high pH for corrosion resistance - Can cause 'internal' sulphate attack if present in higher quantities ## Chemical Requirements - IS 269 spec. (Recap from Lecture 2) ### Table 2 Chemical Requirements for Ordinary Portland Cement (Clause 6.1) | Sl No. | Characteristic | OPC 33 | OPC 43 | OPC 43S | OPC 53 | OPC 53S | |---|---|---|---|---|---| | 1 | Non-cementing material | | | | | | | | Ratio of percentage of lime to percentages of silica, alumina, iron oxide, when calculated by the formula: Cao - 0.7 SO3 2.8 SiO2 + 1.2 Al2O3 + 0.65 Fe2O3 | 0.66 - 1.02 | 0.66-1.02 | 0.80 -1.02 | 0.80-1.02 | 0.80 -1.02 | | | Quality of clinker (burnability) | | | | | | | | Ratio of percentage of alumina to that of iron oxide, Min | 0.66 | 0.66 | 0.66 | 0.66 | 0.66 | | | Insoluble residue, percent by mass, Max | 5.0 | 5.0 | 2.0 | 5.0 | 2.0 | | | Magnesia, percent by mass, Max | 6.0 | 6.0 | 5.0 | 6.0 | 5.0 | | | Total sulphur content calculated as sulphuric anhydride (SO₃), percent by mass, Max | 3.5 | 3.5 | 3.5 | 3.5 | 3.5 | | | * Indication of unburnt carbon | | | | | | | | Loss on ignition, percent by mass, Max | 5.0 | 5.0 | 4.0 | 4.0 | 4.0 | | | Chloride content, percent by mass, Max | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | | | ‘Corrosion’ from internal sources | | | | | | | | Alkali content ASR perspective – durability | 0.05 (for prestressed structures) | 0.05 (for prestressed structures) | 0.05 (for prestressed structures) | 0.05 (for prestressed structures) | 0.05 (for prestressed structures) | ## Physical Properties of Cement ### General - Specific gravity (S = 3.15) - higher S indicates higher C4AF in cement - determined using Le-Chatlier flask - IS 4031 (Part 11) - Fineness (S or SSA = 225 m²/kg) - higher fineness indicates lower particle size - For 33/43/53 grade cement: S = 225 m²/kg - For sleeper grade cement: S = 370 m²/kg - Measurement technique/principle: - Blain’s Apparatus (Principle: Resistance to air flow) - Wagner’s Turbidimeter (Principle: Resistance to light passage) - X-ray Sedigraph (Principle: Larger particles settle faster) - Particle size distribution (PSD) - Laser Particle Size Analyzer (Principle: Measuring angular variation in intensity of light scattered as a laser beam passes through a dispersed particulate sample) - Large particles scatter light at small angles relative to the laser beam and small particles scatter light at large angles) - % retained on 45-micron sieve (#325 sieve) (Dry sieving and atleast 63-67% pass through the sieve) ## Effect of fineness on properties of PC system - Benefits (of high cement fineness) - Hydration reactions become faster - Strength gain is faster (early-strength benefits) - Permeability decreases faster - Larger grains never completely hydrate - Better hydration behaviour overall - Better uniformity/consistency in cement - Reduces bleeding - Disadvantages - Water-demand is higher - More water required to satisfy slump (not-preferred) - More WRAs required to satisfy slump (preferred) - Require AEAs required due to higher adsorption on cement grains - Heat of hydration is high - Unsuitable for thermal crack situations (dams, hot-weather, etc.) - Higher gypsum contents required to offset the C3A reactivity - Disadvantages (contd...) - Cost is higher - More energy is required during production - More WRA/AEA/Gypsum used as a result of high cement fineness - Important - Total hydration at later ages remains the same - ‘a’is higher initially but lower at a later stage ## Size and colour of PC - Particle size (D50) & size distribution (PSD) - Avg. D50 size: 15-35 µm - For two cements with same fineness, cements having ‘uniform distribution PSD’ have higher water demand than those having ‘well-graded PSD’ - Colour - Grey (due to Fe2O3 or C4AF or MnO or C) - White cement - for architectural purposes - when pigments make colored cements ## Physical Requirements - IS 269 spec. (Recap from Lecture 2) ### Table 3 Physical Requirements for Ordinary Portland Cement (Clause 7) | Sl No. | Characteristic | OPC 33 | OPC 43| OPC 43S | OPC 53 | OPC 53S | Method of Test, Ref to | |---|---|---|---|---|---|---| | 1 | Fineness, m²/kg, Min | 225 | 225 | 370 | 225 | 370 | IS 4031 (Part 2) | | | Soundness: | | | | | | | | | By Le-Chatelier method, mm, Max | 10 | 10 | 5 | 10 | 5 | see Note 1 | | | By autoclave test method, percent, Max | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | see Note 1 | IS 4031 (Part 3) | | | Setting time: | | | | | | | | | Initial, min, Min | 30 | 30 | 30 | 30 | 30 | see Note 2 | IS 4031 (Part 5) | | | Final, min, Max | 600 | 600 | 600 | 600 | 600 | see Note 2 | | | Compressive strength, MPa (see Note 4): | | | | | | | | | 72 ± 1 h, Min | 16 | 23 | 23 | 27 | 27 | see Note 2 | IS 4031 (Part 6) | | | 168 ± 2 h, Min | 22 | 33 | 37.5 | 37 | 37.5 | | | 672 ± 4 h, Min | 33 | 43 | 43 | 53 | 53 | | | Max | 48 | 58 | | | | | | Transverse strength (optional) | See Notes 3 and 4 | See Notes 3 and 4 | See Notes 3 and 4 | See Notes 3 and 4 | See Notes 3 and 4 | IS 4031 (Part 8) | ## IS 269 specification (Table 3 contd...) ### NOTES 1. In the event of cements failing to comply with any one or both the requirements of soundness specified in the above table, further tests in respect of each failure shall be made as described in IS 4031 (Part 3), from another portion of the same sample after aeration. The aeration shall be done by spreading out the sample to a depth of 75 mm at a relative humidity of 50 to 80 percent for a total period of 7 days. The expansion of cements so aerated shall be not more than 5 mm and 0.6 percent when tested by Le-Chatelier method and autoclave test respectively. For OPC 43S and OPC 53S, the requirement of soundness of unaerated cement shall be maximum expansion of 5 mm when tested by the Le-Chatelier method. 2. If cement exhibits false set, the ratio of final penetration measured after 5 min of completion of mixing period to the initial penetration measured exactly after 20 s of completion of mixing period, expressed as percent, shall be not less than 50. In the event of cement exhibiting false set, the initial and final setting time of cement when tested by the method described in IS 4031 (Part 5) after breaking the false set, shall conform to the value given in the above table. 3. By agreement between the purchaser and the manufacturer, transverse strength test of plastic mortar in accordance with the method described in IS 4031 (Part 8) may be specified. The permissible values of the transverse strength shall be mutually agreed to between the purchaser and the supplier at the time of placing the order. 4. Notwithstanding the compressive and transverse strength requirements specified as per the above table, the cement shall show a progressive increase in strength from the strength at 72 h. - *Soundness, false set, etc., have been discussed in previous lectures* ## Types of Portland Cement ## Types of Portland Cement [International (USA)] ### TABLE 5.7 Types of Hydraulic Cements Designated in ASTM C 1157 | Type| Description | Equivalent ASTM C 150 | |---|---|---| | GU | General Use | I | | HE | High Early Strength | III | | MS | Moderate Sulfate Resistance | II | | HS | High Sulfate Resistance | V | | MH | Moderate Heat of Hydration | II | | LH | Low Heat of Hydration | IV | ## Types of Portland Cement [International (USA)] - Reduce C3S/C3A, increase C₂S/CAF | |GU| |MS & MH| HE| LH| HS| Reduce C3A, increase C₂S/CAF| |---|---|---|---|---|---|---|---| | ASTM C1157 (Performance-based) | I’ | | II| III| IV | V| | | ASTM C150 (Prescriptive-based) | | | | | | | | | C3S | 55| | 55 | 55 | 42 | 55 | | | C2S | 18| | 19 | 17 | 32 | 22 | | | C3A | 10| | 6 | 10 | 4 | 4 | | | C4AF | 8 | | 11 | 8 | 15 | 12 | | | CSH2 | 6 | | 5 | 6 | 4 | 4 | | | Fineness (Blaine, m²/kg) | 365 | | 375 | 550 | 340 | 380 | | | Compressive strength [1 day, MPa (lb/in.²)] | 15 | | 14 | 24 | 4 | 12 | | | (2200) | | (2000)| (3500) | (600) | (1750) | | | Heat of hydration (7 days, J/g) | 350 | | 265 | 370 | 235 | 310 | | | | | | | | | * CSA designations are 10, 20, 30, 40, and 50, respectively. | | | | | | | | | * ASTM C 109 50 mm mortar cubes. | | Sleeper cement (43/53 grade) | | | | | | | No equivalent IS code | | | | | | | | | No equivalent IS code | | | | | | | | | Low heat cement (IS 12600 spec.) | | | | | | | | | High sulfate resistance and low heat cement | - *** IS 33/43/53 grade cement have lower fineness levels (220 m²/kg) than foreign cements *** ## Low-Heat Cement (IS 12600 spec.) ### Table 1 Chemical Requirements for Low Heat Portland Cement (Clauses 5.1 and 5.2) - Stringent than 33/43/53 grade cement | SI No. | Characteristic | Requirement | |---|---|---| | i)| Ratio of percentage of alumina to that of iron oxide | Not less than 0.66 | | ii) | Insoluble residue, percent by mass | Not more than 4 percent | | iii)| Magnesia, percent by mass | Not more than 6 percent | | iv)| Total sulphur content calculated as sulphuric anhydride (SO₂), percent by mass| Not more than 2.5 and 3.0 when tricalcium aluminate (see Note 1) percent by mass is 5 or less and greater than 5 respectively| |v)| Total loss on ignition| Not more than 5 percent| ### NOTES 1. The tri-calcium aluminate content (C₃A) is calculated by the formula: $C₃A = 265(Al₂O₃) - 1.69(Fe₂O₃)$. where each symbol in brackets refers to the percentage (by mass of total cement) of the oxide, excluding any contained in the insoluble residue referred at Sl No. (ii). 2. Alkali aggregate reactions have been noticed in aggregates in some parts of the country. On large and important jobs where the concrete is likely to be exposed to humid atmosphere or wetting action, it is advisable that the aggregate be tested for alkali aggregate reaction. In the case of reactive aggregates, the use of cement with alkali content below 0.6 percent expressed as sodium oxide (Na₂O), is recommended. Where, however, such cements are not available, use of Portland pozzolana cement or cement pozzolanic admixture is recommended. 3. The limit of total chloride content in cement for use in plain and other reinforced concrete structures is being reviewed. Till that time, the limit may be mutually agreed to between the purchaser and the manufacturer. ## Low-Heat Cement (IS 12600 spec.) - [We will look into the important properties directly from the IS 12600 code] ## Supersulphated Cement (IS 6909 spec.) - [We will look into the important properties directly from the IS 6909 code] ## Blended Cements - Portland Slag Cement – IS 455 – 2020 year - [We will look into the important properties directly from the IS 455 (2020) specifications] ## Blended Cements - Portland Pozzolana Cement (Fly ash Based) - IS 1489 (2020) - Part 1 - Portland Pozzolana Cement (Metakaolin Based) - IS 1489 (2020) - Part 2 - [We will look into the important properties directly from the IS 1489 Part 1 & 2 specifications] ## Blend Materials For Cement, Mortars & Concrete - Fly ash as Pozzolan as Pozzolan - IS 3812 (Part 1) - Fly ash/Bottom Ash/Pond Ash/etc. as Mineral Admixture – IS 3812 (Part 2) - [We will look into the important properties directly from the IS 3812 (2022) specifications] ## Summary - Chemical Properties of PC - Physical Properties of PC - Types of Portland Cement - Blended Cements - Blend Materials for Cement, Mortars & Concrete - Special Cements ## Thank You!