CVE 236: Civil Engineering Materials - Concrete Technology PDF

CVE 236 : Civil Engineering Materials Introduction to Concrete Technology Assoc. Prof. Weerachart Tangchirapat, Ph.D. Department of Civil Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi “Introduction to Co...

CVE 236 : Civil Engineering Materials Introduction to Concrete Technology Assoc. Prof. Weerachart Tangchirapat, Ph.D. Department of Civil Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi “Introduction to Concrere Technology” Topic Outline What is the concrete? Components of concrete? Advantages and disadvantages of concrete Basic properties of concrete Types of concrete What is the concrete? What is the concrete? Concrete is one of the most widely used construction material in addition to steel and timbers. It is use to build many structures such as building, house, bridges, roads, and other infrastructures. Concrete is a combination of particles closely bound together, normally natural sand and gravel or crushed rock. These are bound together by Portland Cement and activated by water to form a dense semi-homogenous mass. Cement Sand Crushed rock Fresh concrete Hardened concrete  About 4.4 billion tons of concrete are produced per year world wide About 4 tons of concrete / Person About 45 million tons of concrete are produced per year in Thailand About 0.6 tons of concrete / Person This figure is increased annually with the increasing of concrete demand for construction industry. Calcareous Material Argillaceous Material Limestone or Chalk Clay or Shale Temperature of about 1400 0C Portland cement  Although the concrete is a very important material for construction industry to build many things The concrete production contributes 5% of annual global CO production. 2 Every ton of cement produced, one ton of CO is also produced. 2 As you will be civil engineer in the future, please suggest the solution or idea to reduce this problem? Components of Concrete  Components of Concrete Ordinary Concrete Cement Water Paste Fine agg. Mortar Coarse agg. Concrete By volume 25-30% 70-75%  Components of concrete (Cont.) Special Concrete Concrete Chemical admixture Mineral admixture Smart concrete Concrete Advanced technology Advantages and disadvantages of concrete Advantages of concrete Ingredients of concrete are easily available in most of the places. Concrete can be manufactured to desired strength with economy. It can be cast to any desired shape. Advantages of concrete (Cont.) The durability of concrete is very high, low maintenance cost. Concrete makes a building fire-safe. ~ 300 0C ~ 500 0C ~ 600 0C Disadvantages of concrete Concrete is less ductile, tensile strength of concreter is very low. Concrete need more time to develop strength. Brittle Semi Ductile Disadvantages of concrete (Cont.) The weight of compared is very high. Concrete generate high heat evolution. ~ 2,400 kg/m3 ~ 7,850 kg/m3 ~ 1,000 kg/m3 Basic properties of concrete Slump of concrete Slump is the measure of concrete consistency and fluidity. It shows the flow and overall workability of freshly mixed concrete. The decrease in the height of the center of the concrete as compared with original height is called slump. The shape of the concrete slumps also shows the quality of concrete. There are three types of slump that may occur. Strengths of concrete Strength of concrete is commonly considered its most value property and gives an overall picture of the quality of concrete because strength is directly related to the structure of the hardened cement paste Compressive strength *** Tensile strength Modulus of elasticity Compressive strength The compressive strength of concrete is the most common performance measured by the engineer in design building and other structures. It is determined by breaking cube or cylinder concrete sample in compression testing machine. Compressive strength The compressive strength is calculated from the ultimate load divided by cross sectional are resisting load and reported in units of PSI, MPa, and ksc. Compressive strength = Ultimate load P = Area A A = Pi x R2 A = 15x15 cm2 Factors affecting on strength of concrete Water/Cement Ratio ; The lower w/c ratio leads to a higher strength of concrete. Age of concrete ; Strength of concrete is increased with time and usually specified on 28 days (4 weeks). Compressive strength (MPa) Concrete cannot be fully compacted. Compressive strength Concrete can be fully compacted. W/C Ratio Time (Days) Types of concrete How many types of concrete? Normally, concrete can be classified in different type according to : Design of concrete structure. *** Purpose of concrete work. *** Binder materials used in concrete. According to design of concrete Use with steel bar Reinforced concrete > - rig The concrete in which reinforcement (steel bar) is embedded for taking tensile stress. This type of concrete is commonly used of structural member. According to design of concrete (cont.) : Pre-stressed concrete - A concrete that get compressive stress use in large structure The concrete which high compressive stress are artificial induced by pre-tensioning reinforcement before placing the concrete, and the reinforcement is released when the compressive strength reached to specified compressive strength. This type of concrete is widely used in large structural member and long span length. According to design of concrete (cont.) : Pre-stressed concrete According to purpose of concrete High strength concrete > - nernig Potermines , es days compressive , highe tha e According to ACI363, concrete having the 28-day compressive strength higher than 55 MPa can be considered as high strength concrete. High strength concrete is generally more mechanical and durability properties than normal strength concrete. For this reason, high strength concrete has been increasingly and widely used in construction industry, particularly in high-rise building and mega projects. According to purpose of concrete (cont.) : flow easily and fill all of from work by it Self compacting concrete (SCC) - own weight. area a Self compacting concrete is a flowing concrete mixture that is able to consolidate under its own weight into every part of the formwork without any segregation of the coarse aggregate and does not require vibration. The highly fluid nature of SCC makes it suitable for placing in difficult conditions and in sections with heavily reinforcement. According to purpose of concrete (cont.) : 1143 Roller compacted concrete ↑ Roller Compacted Concrete (RCC) is best described as aG - zero G slump concrete that is placed with standard or high density paving equipment and consolidated/compacted using steel- drum rollers to achieve a durable and wear resistant surface. ↓ ↓ neinsi Fomiwinz According to purpose of concrete (cont.) : Light weight concrete > - low light wrightgy are dence -B. Lightweight concrete has density on the order of 1440-1840 kg/m3 compared to normal weight concrete with density of 2400 kg/m3. This concrete can either be lightweight aggregate or foamed concrete. According to purpose of concrete (cont.) : Pervious concrete ↳ Ginnias have only course agg. Pervious concrete is a special type of concrete with a high porosity and allows water to pass through it. Typically, pervious concrete has little or no fine aggregate and has just enough cement paste to coat the coarse aggregate particles. Pervious concrete is used in concrete flatwork applications to reduce runoff, such as parking area, road with light traffic, and pedestrian walkways. According to purpose of concrete (cont.) : have fiber flexural N Fiber reinforced concrete tensile strengths > - Fiber concrete is concrete containing fiber material which increases its structural performance such flexural and tensile strengths. It contains short discrete fibers that are uniformly distributed and randomly oriented. Fibers may be made from steel, glass, synthetic and natural materials.