Chapter 1 - Introduction to Concrete Technology PDF

Bachelor of civil engineering (Civil engineering materials) Prepared by: Dr. Faisal Amsyar Civil engineering materials (kns1042) Chapter 1: Introduction to Concrete Technology  Group WhatsApp… First thing first, please join KNS1042 Civil Engine...

Bachelor of civil engineering (Civil engineering materials) Prepared by: Dr. Faisal Amsyar Civil engineering materials (kns1042) Chapter 1: Introduction to Concrete Technology  Group WhatsApp… First thing first, please join KNS1042 Civil Engineering Materials Sem 1-2024/2025 group WhatsApp for course updates:  Course Learning Outcome… By completing this chapter, students shall be able to: 1.0 Analyze the characteristics of engineering materials used in civil engineering construction. (Chapter 1, 3, 4) 2.0 Develop concrete mix design based on typical environmental condition. (Chapter 2) – used for Concrete Lab 1 3.0 Relate and select materials for different applications in civil engineering works. Course Learning Outcome… I will be teaching for Week 1 – Week 4 on Concrete Technology: a) LU1 & LU3 will combine in week 1 b) LU2 will be in week 2 c) LU4 will be in week 3 d) LU5 will be in week 4 Concrete… What do you know about concrete? Concrete… Or these? 1.1 Introduction to Concrete Concrete: A composite construction material composed of cement and other cementitious materials such as fly ash and slag cement, aggregate (generally a coarse aggregate made of gravels or crushed rocks, plus a fine aggregate such as sand), water and sometimes with chemical admixtures. 1.1 Introduction to Concrete Simplify: Concrete is widely used construction material which is a mixture of cement, aggregates (coarse & fine), water and admixture. 1.1 Introduction to Concrete What is mortar? Mortar: Combination of cement, fine aggregates and water. 1.1 Introduction to Concrete What is paste? Paste: Combination of cement and water only. 1.1 Introduction to Concrete Now what is concrete again? Concrete: Combination of mortar (cement, fine aggregate and water) with coarse aggregate. 1.1 Introduction to Concrete Cement vs. Concrete vs. Mortar Cement Concrete Mortar Binding element in both Made of cement, sand and Made of cement, sand and water concrete and mortar. gravel (coarse) and water. only. Made of limestone, clay, shells Used for buildings: foundations, Used as the glue to hold bricks, and silica sand. slabs, patios and masonry. blocks etc. together. Sets & hardens when combined Most flexible, forming into any Various types available for with water. mold and rock hard. specific applications. 1.2 Types of Concrete Used in Industry The requirement of concrete properties is varying depending on the types of structural elements, geometrical features of the structure, time of concrete placement and number of skill labourers. 1.2 Types of Concrete Used in Industry Normal strength concrete High Precast strength concrete concrete Types of Concrete High Reinforced performance concrete concrete Light- Self- weight compacting concrete concrete 1.2 Types of Concrete Used in Industry (A) Normal Strength Concrete Composition: Standard mixture of cement, aggregate (sand and gravel) with water. Usage: Used in general construction work, including residential buildings, pavements and structure that do not require high strength. Strength: Typically, around 20 – 40 MPa (MegaPascal) 1.2 Types of Concrete Used in Industry (A) Normal Strength Concrete In Malaysia, the grading of concrete is based on its compressive strength, similar to international standards. The most commonly referred standard for concrete in Malaysia is the MS 523: Part 1: 2005 (Code of Practice for Structural Use of Concrete), which align with other standards such as British Standard (BS 5328) and Eurocode (EC2). 1.2 Types of Concrete Used in Industry 1.2 Types of Concrete Used in Industry 1.2 Types of Concrete Used in Industry (B) High Strength Concrete Composition: Similar to normal concrete but with a higher ratio of cement and lower water-to-cement ratio. Sometimes admixtures are used to improve performance. Usage: Suitable for high-rise buildings, bridges, and structures requiring superior load-bearing capacity. Strength: Usually greater than 50 MPa. 1.2 Types of Concrete Used in Industry Water-to-Cement Ratio Definition: The water-cement ratio (w/c ratio) is the ratio of the weight of water to the weight of cement used in a concrete mix. It is a key factor that determines the strength and workability of concrete. Range: Common w/c ratios range between 0.40 – 0.60 in general concrete mixes. A lower ratio means higher strength but lower workability, and vice versa. 1.2 Types of Concrete Used in Industry Water-to-Cement Ratio Formula: 𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑊𝑎𝑡𝑒𝑟 𝑊𝑎𝑡𝑒𝑟 − 𝑡𝑜 − 𝐶𝑒𝑚𝑒𝑛𝑡 𝑅𝑎𝑡𝑖𝑜 = 𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝐶𝑒𝑚𝑒𝑛𝑡 *Note: This ratio directly affects the hydration process, which is the chemical reaction between cement and water gives concrete its strength. 1.2 Types of Concrete Used in Industry Water-to-Cement Ratio Strength: A lower w/c ratio leads to higher strength because there is less water, leaving fewer voids after the concrete hardens. A higher w/c ratio creates weaker concrete as excess water leaves more voids and reduces the density of the hardened structure. 1.2 Types of Concrete Used in Industry Water-to-Cement Ratio Workability: A higher ratio improves workability, making the concrete easier to mix and pour. However, it compromises durability and strength. A lower ratio results in less workability, which can make the concrete hard to handle, but provides stronger, more durable. 1.2 Types of Concrete Used in Industry Water-to-Cement Ratio 1.2 Types of Concrete Used in Industry Water-to-Cement Ratio Durability: The right balance ensures that the concrete can withstand weathering, corrosion and wear overtime, reducing maintenance costs. 1.2 Types of Concrete Used in Industry Water-to-Cement Ratio Concrete mix design: Engineers must carefully balance water content and cement to achieve the desired strength and workability for specific applications. 1.2 Types of Concrete Used in Industry Water-to-Cement Ratio 1.2 Types of Concrete Used in Industry (C) High Performance Concrete Composition: A mixture designed with specific properties such as high strength, durability and resistance to environmental stressors such as corrosion or freeze-thaw cycles. Usage: Used in critical infrastructure like bridges, tunnels, marine structures and high-rise buildings. Strength: Usually above 60 MPa. 1.2 Types of Concrete Used in Industry (D) Self-compacting Concrete Composition: High-flow concrete that does not require mechanical vibration to fill in formwork, advantageous of its fluid nature. Usage: Used in complex structures where access to vibrate the concrete is limited, such as heavily reinforced elements or narrow spaces. Strength: Can vary but typically in the range of 30 – 60 MPa. 1.2 Types of Concrete Used in Industry (E) Light-weight Concrete Composition: Made using lightweight aggregates such as expanded clay, shale or pumice, reducing its density. In lightweight concrete, they are controlling the density below 1800 kg/m3 (by removing coarse agg.) Usage: Applied in non-load-bearing structures, roof decks, and partition walls where reduced weight is important. Strength: Lower than normal strength or normal- weight concrete, typically between 7 – 17 MPa. 1.2 Types of Concrete Used in Industry 1.2 Types of Concrete Used in Industry (F) Reinforced Concrete Composition: Concrete that is strengthened with steel rebar or mesh to handle tensile stresses better. Usage: Used in most structural components like beams, columns, slabs and foundations in buildings, bridges and infrastructure. Strength: Varies depending on design, but typically used where high tensile strength is needed. 1.2 Types of Concrete Used in Industry (G) Precast Concrete Composition: Concrete components are cast and cured off-site in a controlled environment (confined factory), then transported to the site for assembly. Usage: Frequently used for repetitive, modular components such as beams, slabs, panels and columns in large projects. Strength: Can be customized to project needs but generally similar to reinforced concrete. 1.2 Types of Concrete Used in Industry (H) Ready-mix Concrete Composition: Pre-mixed concrete delivered to the construction site, typically produced in a batching plant. Usage: Widely used in large-scale construction projects for consistency and quality control, such as highways, commercial buildings and infrastructure projects. Strength: Can be altered to the project’s needs, ranging from normal to high strength. 1.2 Types of Concrete Used in Industry (I) Green Concrete Composition: Eco-friendly concrete that uses recycled materials or supplementary cementitious materials like fly ash, slag or silica fume. Usage: Increasingly used in sustainable construction practices to reduce the environmental impact. Strength: Comparable to conventional concrete (normal strength concrete), depending on the mix design. 1.3 Main Components in Concrete (A) Cement Cement: A binder, a substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement: Adhesive substances of all kinds, but, in a narrower sense, the binding materials used in building and civil engineering construction. 1.3 Main Components in Concrete (A) Cement Used in construction are usually inorganic, often lime or calcium silicate Hydraulic based, which can be characterized as non- Cement hydraulic or hydraulic respectively, depending Non-hydraulic on the ability of the cement to set in the presence of water. 1.3 Main Components in Concrete (A) Cement (Non-hydraulic) Does not set in wet conditions or under water. Rather, it sets as it dries and reacts with carbon dioxide in the air. It is resistant to attack by chemicals after setting. 1.3 Main Components in Concrete (A) Cement (Non-hydraulic) A less common form of cement is non-hydraulic cement, such as slaked lime (calcium oxide mixed with water), hardens by carbonation in contact with carbon dioxide, which is present in the air (~ 412 vol. ppm ≈ 0.04 vol. %). First, calcium oxide (lime) is produced from calcium carbonate (limestone or chalk) by calcination at temperature above 825 °C (1517 °F) for about 10 hours at atmospheric pressure: 1.3 Main Components in Concrete (A) Cement (Non-hydraulic) The calcium oxide is then spent (slaked) mixing it with water to make slaked lime (calcium hydroxide): Once the excess water is completely evaporated (this process is technically called setting), the carbonation starts: 1.3 Main Components in Concrete (A) Cement (Non-hydraulic) This reaction is slow, because the partial pressure of carbon dioxide in the air is low ( ~ 0.4 millibar). The carbonation reaction requires that the dry cement be exposed to air, so the slaked lime is a non-hydraulic cement and cannot be used under water. 1.3 Main Components in Concrete (A) Cement (Hydraulic) The chemical reaction results in mineral hydrates that are not very water-soluble and so are quite durable in water and safe from chemical attack. This allows setting in wet conditions or under water and further protects the hardened material from chemical attack. The chemical process for hydraulic cement was found by ancient Romans who used volcanic ash (pozzolana) with added lime (calcium oxide). 1.3 Main Components in Concrete (A) Cement (Hydraulic) By far the most common type of cement is hydraulic cement, which hardens by hydration of the clinker minerals when water is added. Hydraulic cements (such as Portland cement) are made of a mixture of silicates and oxides. 1.3 Main Components in Concrete (A) Cement (Hydraulic) The four main minerals phases of the clinker, abbreviated in the cement chemist notation, being: 1.3 Main Components in Concrete (A) Cement (Hydraulic) The tricalcium aluminate and Tetra Calcium Alumino Ferrite are essential for the formation of the liquid phase during the sintering (firing) process of clinker at high temperature in the kiln. 1.3 Main Components in Concrete (A) Cement (Hydraulic) First, the limestone (calcium carbonate) is burned to remove its carbon, producing lime (calcium oxide) in what is known as a calcination reaction. This single chemical reaction is a major emitter of global carbon dioxide emissions. 1.3 Main Components in Concrete (A) Cement (Hydraulic) The lime reacts with silicon dioxide to produce dicalcium silicate and tricalcium silicate. The lime also reacts with aluminium oxide to form tricalcium aluminate. 1.3 Main Components in Concrete (A) Cement (Hydraulic) The lime also reacts together with aluminium oxide, and ferric oxide to form cement. 1.3 Main Components in Concrete (B) Fine Aggregate (Sand) Definition: Small-size granular materials, typically sand or crushed stone, used in concrete mixes. They help fill voids between larger aggregates, improving the overall density of the concrete. Size: Typically particles smaller than 4.75 mm. Types: (a) Natural sand: Obtained from riverbeds or seashores. (b) Manufactured sand (M-sand): Crushed stone sand produced in a quarry or crushing site. 1.3 Main Components in Concrete (B) Fine Aggregate Shape and texture: (a) Round particles improve workability. (b) Angular particles provide better bonding. Fineness modulus: A measure of the particles size distribution. The optimal range is 2.3 to 3.1 for concrete. Considerations in selection: (a) Must be clean and free from silt, clay and organic impurities, as these can weaken the concrete. 1.3 Main Components in Concrete (C) Coarse Aggregate (Gravel) Definition: Larger pieces of crushed rock or gravel that are mixed with cement and water to form concrete. They provide bulk, strength and stability to the concrete structure. Size: Particles larger than 4.75 mm. Common sizes used in concrete range from 10 mm and 20 mm. Types: (a) Natural gravel: Rounded stone from riverbeds. (b) Crushed stone: Sharp, angular stones produced from quarrying rocks. 1.3 Main Components in Concrete (C) Coarse Aggregate Shape and texture: (a) Angular aggregates interlock better, providing stronger bonding. (b) Rounded aggregates contribute to higher workability but may reduce strength. Surface texture: Rough textures provide better adhesion with cement paste. Considerations in selection: (a) Size should be chosen based on the type of structure (e.g., smaller aggregates for smoother finishes or heavily reinforced sections). 1.3 Main Components in Concrete (D) Water Used for mixing concrete should be free from substances such as silt, soil, organic acids and other organic materials such as salt and alkali. Role in hydration process: Essential for the chemical reaction between cement and water, known as hydration. This reaction forms calcium silicate hydrate (C-S-H), which gives concrete its strength. Role in workability: Water lubricates the mix, allowing it to be easily shaped and moulded. Th right amount of water ensures that the concrete is workable without being too fluid. 1.3 Main Components in Concrete (D) Water Types of Water Suitable for Concrete: (a) Portable water: Fit for drinking is suitable for concrete. (b) Water containing impurities such as salts, oils, acids, or organic materials can weaken the concrete, causing long-term durability issues (e.g., corrosion of reinforcements). Considerations in water quality: Should be free from harmful chemicals such as chloride or sulphates that can react with the cement and weaken the concrete. 1.3 Main Components in Concrete Take a break.. 1.4 Types of Portland Cement Ordinary Portland Cement (OPC) Rapid- High Strength Hardening Portland Portland Cement Cement (HSPC) (RHPC) Types of Sulphate Portland White & Resisting Cement Coloured Portland Portland Cement Cement (SRPC) Low Heat Portland- Portland Blast Furnace Cement Cement (LHPC) 1.4 Types of Portland Cement (A) Ordinary Portland Cement (OPC) Definition: OPC is the most common type of cement used in general construction work. Made primarily from limestone and clay, containing calcium silicate, alumina and iron oxide. Application: Used in general construction where special properties like rapid hardening or resistance to sulphate are not required. Advantages: (a) Good strength development. (b) Suitable for any general construction purposes. 1.4 Types of Portland Cement (B) Rapid-Hardening Portland Cement (RHPC) Composition: RHPC is a special type of cement that gains strength faster than OPC. It contains higher amounts of tri-calcium silicate (C3S) to enhance early strength. Applications: Used in construction requiring fast-setting cement, such as in pre-cast concrete, repairs and road works. Advantages: (a) Attains high strength in early stages. (b) Reduces project completion time. 1.4 Types of Portland Cement (B) Rapid-Hardening Portland Cement (RHPC) Advantages: (a) Rapid hardening cement needs the shortest time to set up and consolidate. It achieves higher strength on lesser days. (b) It can attain three (3) days strength in equivalent to seven (7) days strength of normal strength concrete. 1.4 Types of Portland Cement (C) White & Coloured Portland Cement White Portland Cement: Composition: Low in iron and manganese, which prevents coloration. Made up: Using white clinker (containing little or no iron) and white supplementary materials such as high-purity metakaolin. Applications: Used for aesthetic purposes in architectural finishes like tiles, flooring and decorative works. 1.4 Types of Portland Cement (C) White & Coloured Portland Cement Coloured Portland Cement: Composition: Produced by adding pigments during the manufacturing process. Applications: Used for aesthetic purposes in projects requiring specific colours for architectural appeal, such as tiles or decorative facades. Other standards (e.g., ASTM) do not allow pigments in Portland cement and coloured cements are sold as blended hydraulic cements. 1.4 Types of Portland Cement (D) Low Heat Portland Cement (LHPC) Definition: Specifically designed to produce less heat during the hydration process, reducing the risk of cracking in large structures. Composition: Lower in tri-calcium silicate (C3S) and higher in di-calcium silicate (C2S), which produces less heat. Applications: Used in mass concrete structures such as dams, bridges and large foundations. Advantages: Minimizes thermal cracking in large structures due to lower heat generation. 1.4 Types of Portland Cement (D) Low Heat Portland Cement (LHPC) 1.4 Types of Portland Cement (E) Portland-Blast Furnace Cement Definition: A blend of Portland cement and granulated blast furnace slag. Composition: Contains 25-70% blast furnace slag, which improves durability. Applications: Used in marine structures, concrete exposed to sulphates and general construction where enhanced durability is required. 1.4 Types of Portland Cement (F) Sulphate Resisting Portland Cement (SRPC) Definition: Designed to resist sulphate attacks, which can cause expansion and cracking in concrete. Composition: Lower in tri-calcium aluminate (𝑪𝟑 𝑨), the compound that reacts with sulphates. Applications: Ideal for foundations, sewerage treatment plants and structure exposed to soils or water high in sulphates. Advantages: Prevents deterioration in sulphate-rich environments, ensuring structural durability. 1.4 Types of Portland Cement (G) High Strength Portland Cement (HSPC) Definition: A type of Portland cement with higher compressive strength than OPC. Composition: Similar to OPC but has a lower water-cement ratio and finer particles. Applications: Used in high-performance structures, such as high-rise buildings, bridges and tunnels where higher strength is required. 1.4 Types of Portland Cement (H) Masonry Cement Definition: A special type of cement used in the construction of masonry structures such as brickwork, plaster and block laying. Composition: Blended with lime or other fine materials to improve workability and cohesion. Applications: Used for plastering, brick/block laying and other non-load-bearing masonry applications. 1.4 Types of Portland Cement (I) Air Entraining Cement Composition: A special cement which has air bubbles introduced in the cement or concrete that provides the space for expansion of minute droplets of waters in the concrete due to freezing and thawing and protects from cracks and damage of concrete. Advantageous: (a) Bleeding, segregation and laitance in concrete reduces. (b) Entraining air improves the sulphate resisting capacity of concrete. 1.5 Main Properties of Portland Cement (A) Portland Cement Composition – Chemical Properties Oxide Content (%) Lime (𝐶𝑎𝑂) 60 – 67 Silica (𝑆𝑖𝑂2 ) 17 – 25 Alumina (𝐴𝑙2 𝑂3 ) 3–8 Iron Oxide (𝐹𝑒2 𝑂3 ) 0.5 – 6.0 Magnesia (𝑀𝑔𝑂) 0.1 – 4.0 Sulphur Trioxide (𝑆𝑂3 ) 1–3 Soda and/or Potash (𝑁𝑎2 𝑂 + 𝐾2 𝑂) 0.5 – 1.3 1.5 Main Properties of Portland Cement (B) Typical Oxide Composition – Chemical Properties Oxide Content (%) Lime (𝐶𝑎𝑂) 63 Silica (𝑆𝑖𝑂2 ) 20 𝐶2 𝑆 = 17% Alumina (𝐴𝑙2 𝑂3 ) 6 𝐶3 𝑆 = 54% Iron Oxide (𝐹𝑒2 𝑂3 ) 3 𝐶3 𝐴 = 11% Magnesia (𝑀𝑔𝑂) 1.5 𝐶4 𝐴𝐹 = 9% Sulphur Trioxide (𝑆𝑂3 ) 2 Soda and/or Potash (𝑁𝑎2 𝑂 + 𝐾2 𝑂) 1 1.5 Main Properties of Portland Cement (C) Hydration Characteristics Compounds Reaction Rate Strength Heat Liberation 𝐶3 𝑆 Moderate High High 𝐶2 𝑆 Slow Low initially; High Later Low 𝐶3 𝐴 + 𝐶2 𝐻2 Fast Low Very high 𝐶4 𝐴𝐹 + 𝐶𝑆𝐻2 Moderate Low Moderate 1.5 Main Properties of Portland Cement (C) Hydration Characteristics (Rate of Hydration) 1.5 Main Properties of Portland Cement (C) Hydration Characteristics (Rate of Hydration) 1.5 Main Properties of Portland Cement (C) Hydration Characteristics Hydration of cement is the key to concrete’s performance in terms of durability and strength. Definition: Heat generated when cement and water react. The amount of heat generated is dependent upon the chemical composition of the cement, with 𝑪𝟑 𝑨 and 𝑪𝟑 𝑺 being the compounds primarily responsible for high heat evolution. 1.5 Main Properties of Portland Cement (C) Hydration Characteristics (Hydration Phases) Cement particles reacts with water (𝐻2 𝑂). 𝐶3 𝐴 reacts quickly with water to form ettringite crystals. Later, slower growing calcium silicate hydrate (C-S-H) crystals also form. Generally, the slower the crystal growth, the greater the eventual strength. Hydration products are gel plus 𝑪𝒂(𝑶𝑯)𝟐 1.5 Main Properties of Portland Cement (C) Hydration Characteristics (Hydration Phases) Initial crystal growth causes only a slight stiffening of the paste, as the cement particles are far enough not to interact. But as the crystals grow and intersect, setting (stiffening of the paste) and eventually hardening (strength increase occurs). The closer the particles, i.e. the lower the water-to- cement ratio, the higher the eventual strength, density and durability. 1.5 Main Properties of Portland Cement (D) Physical Properties Properties Values Specific Gravity 3.16 Normal Consistency 29% Initial Setting Time 65 mins Final Setting Time 275 mins 2 Fineness 330 𝑘𝑔Τ𝑚 Soundness 2.5 mm 3 Bulk Density 830 – 1650 𝑘𝑔Τ𝑚 1.5 Main Properties of Portland Cement (E) Strength Development  THANK YOU… Prepared by: Dr. Faisal Amsyar [email protected] 0138370829