Stones: Building Materials - PDF

Chapter 2 Stones iii ARCH214– Chap 2 – Stones Building Material and components – ARCH214 Eng. Lara Rahim Al Yamamah university Outline 1. Historical Significance of Stone in Construction 2. Types of Stone Used in Construction 3. Properties o...

Chapter 2 Stones iii ARCH214– Chap 2 – Stones Building Material and components – ARCH214 Eng. Lara Rahim Al Yamamah university Outline 1. Historical Significance of Stone in Construction 2. Types of Stone Used in Construction 3. Properties of Stones 4. Advantages and Disadvantages of Using Stone in Construction 5. Modern Applications of Stone in Construction Introduction According to Asher Shadmon of the HABITAT center in Nairobi: ‘Stone is the building material of the future. The resources are limitless and evenly spread over the whole globe. Extraction does not require a lot of energy and does not pollute. And most important of all is that the material is durable’ (Shadmon,1983).  I. Historical Significance of Stone in Construction: Stone has been a fundamental building material throughout human history. Its continued relevance is attributed to its durability, availability, and adaptability to various architectural styles and functions. Stone is indeed abundant and can be found in various forms across different geographical regions. This widespread availability makes it a universally accessible material, unlike other resources that are concentrated in specific areas and can lead to geopolitical issues.  The art of building stone walls for protection against the forces of nature goes back to prehistoric times. The earliest remaining stone buildings were built in Egypt and Mesopotamia about 5000 years ago. By the beginning of the First World War the stone industry had lost its status, mainly due to the rapid rise in the use of concrete.  Description and Common Uses There are pre-historic remnants of temples Granite was used at Machu Picchu in Peru. made from sandstone in Egypt and limestone in Greece and India. Karnak temple in Egypt  Description and Common Uses The pre-historic cultures used Romans used limestone in post and lintel construction, arch construction for with the earliest stone arches buildings and bridges more appearing over 5,000 years ago than 2,000 years ago. in northern Mesopotamia (Iraq). Historical Context of Building Construction There is a big Role for Stones in historical landmarks worldwide. Early civilizations and stone construction: 1. Ancient Egypt and the Pyramids. 2. Greece and the Parthenon. 3. Roman architecture and aqueducts. 4. Medieval Europe and Gothic cathedrals. 5. Asian examples: Great Wall of China and Angkor Wat. The usages of stone In Building: Blocks (walls) Slabs Roofing slates Other usages: brokenstone Aggregate for concrete, terrazzo, mortars, plasters, rendering Granules for surfacing bituminous felts Powders for extending paint Rock wool for insulation Rock types and rock cycle Groups of Rocks There are three major groups of rocks by its origin: (1) Igneous rocks (2) Sedimentary rocks (3) Metamorphic rocks Rock Cycles  Type of stones Igneous stones the coding of magma – Granites – Basalt – Mica E Sedimentary Dueto weather – Sandstone – Limestone Metamorphic it comes underpure on its – Slates chemical – Marble – Quartzes  they form under the earth surface Igneous stones structure Dry faster rough Igneous stones are a category of natural rock formed from the cooling and solidification of magma or lava. This process results in a diverse range of textures and compositions, classifying igneous stones into two main types: intrusive (or plutonic) and extrusive (or volcanic). Stones formed by the cooling of the molten magma which include granites, basalt, mica and clearly cannot contain fossils or shells. Igneous stones The structure of igneous stone is dependent on the rate at which they are cooled. Extrusive stone is cooled rapidly and fine grained no crystalline and glassy. (ex: Basalt) Fine Intrusive stones cooled slowly and consequently have medium size crystalline structure. They take a good polish, and some have been used for ornamental purposes, but most used as concrete aggregate. (ex: Granite) Granite Granite, a type of stone known for its durability, is one of the most commonly utilized building stones. Granite is popular because of its hardness and durability, even though it is no longer the most commonly used building stone. It’s a deep-seated igneous rock with a crystalline structure and fine to coarse grain. Because of its crushing strength, this stone is extremely precious. It can also tolerate extreme weathering. Granite stones are usually cut into slabs and then polished. It can then be used for stone-facing slabs as well as floor slabs. The issue with granite is that stone has a low fire resistance. It is, nevertheless, ideal for use in construction since it is resistant to acidic liquids such as curds, vinegar, and lime juice. Granite is hence suitable for kitchen tabletops Advantages of Granite 1. Durability and toughness. 2. Erosion resistance the weatherwillnotaffect it 3. It’s possible to utilize it as a floor covering. 4. This stone can survive harsh weather conditions due to its exceptional hardness. 5. Granite is a beautiful stone with a sophisticated appearance. 6. It has high impact resistance and is difficult to break. Disadvantages of Granite 1. The price is high, as is the expense of installation. 2. Granite installation takes a long time because of the behind-the-scenes stone mortaring process and time- consuming mortar adhesion. 3. In situations with x-ray or gamma radiation or magnetic fields, radioactive wave radiation can grow. Basalt smother than Grinite Basalt is sometimes called white stones, green stones or blue basalt. It’s an ignorant rock. This stone is strong and harsh and nice as well as nasty. This hardness makes it difficult for any purpose to use rock as readily. Basalt has a strong compressive strength between 150 and 190 MPA. The structure of the stone is medium to thin. It is also small with many color options. Basalt stones may be found in black to dark grey, an element which makes house design more popular. Advantages of Basalt 1.Lightweight 2.Rough and tough 3.Good insulation and sound absorption. use it under the 4.Heat preservation and thats why they train 5.Environmental friendly Disadvantages of Basalt 1.Not easily workable The different area’s use of basalt are as follows. Railway ballast Aggregate for concrete Road metals Pavement Dams and river walls Sedimentary Coming from subfety Sedimentary stones are formed from layers of tiny particles such as sand, shells, and even dinosaur bones. These layers are compressed and cemented over millions of years in windswept deserts and dense forests. They are formed either from particle of older rocks which were broken down by the action of water, wind or ice or from accumulation of organic origin. Sediments were carried by water and sometimes by winds, and the tendency of particles to lay horizontally often produced natural grain. Changes in composition from time-to-time produced layers of differing character including soft beds.  I cheaper thancement andthefinish will belighter Sandstone notstrong like Ignios Sandstones consist of fine or coarse particles of quartz. Good brands of sandstone is strong and does not deteriorate easily. The best sandstones are extremely durable, but sandstone become dirty more readily. Hard and durable fine-grained sandstones which are particularly suitable for paving are called York stones Sand stones Sandstone, with its warm colors and intricate patterns, is a multipurpose building material. Its medium hardness makes it workable for detailed carvings and sculptures, while its natural strength ensures long-lasting durability. Some famous examples of sandstone architecture include: The Pyramids of Giza: Constructed from millions of sandstone blocks, these ancient stand as a testament to the stone's resilience. The Sydney Opera House: The iconic shells of the opera house are clad in sandstone panels, creating a unique and visually attractive structure. The Houses of Parliament in London: The Gothic Revival style of these buildings is beautifully showed through the intricate sandstone carvings and enhancements. limestone Limestone, a sedimentary rock formed over millions of years from the compacted remains of marine organisms like shells and coral, is a flexible and beautiful building material. Its definition can be broken down into two key aspects: Formation: Limestone's journey begins in oceans, where the shells and skeletons of tiny creatures like sea creatures and coral accumulate on the seabed. Over time, these layers are buried beneath remains, and the enormous pressure and heat transform them into solid rock.  They were formed from the deposit of mainly in lakes or seas Pure limestone such as chalk, is white or off white, but other ingredients often color the stone cream, yellow, brown, red grey and almost back. limestones are now being employed in a thickness of 25 mm as permanent shuttering on precast concrete wall slabs. Cladding and Facades: Flooring and Interior Design: Historical Monuments and Sculptures: Infrastructure and Construction: Metamorphic stones Comes from pressure outer heat chemical reaction Metamorphic stones are a type of rock formed through the transformation of existing rock types, in a process known as metamorphism, which means "change in form". This transformation occurs under conditions of high pressure, high temperature, or both, deep within the Earth's crust. This process alters the mineral composition and structure of the original rock, resulting in a new type of rock with distinct physical and chemical properties. These consist of older stones which have been subjected to immense heat and pressure causing structural change. the most expensive  Coming dolomite Marble fromlinestone Originally limestone or dolomite, marble is formed under conditions of high pressure and temperature, which cause the recrystallization of the original carbonate mineral grains. This recrystallization process gives marble its characteristic veining and a variety of colors. Marble is widely used in construction and architecture for its beauty and elegance. It is a popular choice for flooring, wall cladding, countertops, and sculptures. However, its susceptibility to acid rain and general weathering makes it less ideal for exterior applications in polluted or harsh climates.  metamorphic rock Marble smooth True marbles is very finely crystalline and ideal for crisp carved details. It is generally very hard dense and resistant to abrasion Like granite, marble takes an excellent self polish which greatly enhances its appearance Unlike granite marble is attacked by acids and a polished surface is not retained for very long externally in polluted atmosphere. It is used as cladding material, flooring and interior decoration. each one is under know  what Slate 5933105 Slate is formed from the low-grade metamorphism of shale, clay, or volcanic ash. This stone is known for its fine grain, foliation, and durability. It splits into thin, stable sheets, making it an ideal material for roofing, flooring, and wall cladding. Slate's resistance to weathering and low water absorption rate makes it suitable for outdoor use as well. Other metamorphic stones include quartzite (transformed from quartz sandstone) and schist (formed from mudstone or shale). These stones are used in various applications, from decorative to structural, due to their strength, durability, and aesthetic appeal. Quartzite It comprises about 96 percent silica, is harder even than granite and it is extremely durable. Quartzite is imported from Norway, Sweden, South Africa. Color are grey, green and gold. Uses: walls tiles or slabs, flooring, and external paving. Production of building stone through cut mountains  Production of building stone The production of natural stone for construction and architectural purposes involves several key steps, from quarrying to final product delivery. Here's an overview of the typical procedures: Quarrying: they use makfesindut.int This is the first and crucial step in the production of stone. It involves extracting stone from a quarry, which is a large deposit of rock. Methods of quarrying vary depending on the type of stone and the depth at which it is located. Common techniques include drilling, blasting, and cutting using diamond, wire, saws. Production of building stone  Production of building stone Transportation: After quarrying, the rough stone blocks are transported from the quarry to processing facilities. This transportation is typically done using heavy-duty trucks. The size of the stone blocks can be quite large, requiring specialized equipment for loading and unloading. Processing: At processing facilities, these large blocks are cut into slabs or tiles. This is usually done using large saws, like gang saws or block cutters. The type of saw used depends on the type and size of the stone. Water is often used during cutting to reduce dust and prolong the life of cutting tools. Production of building stone Surface Treatment: Once cut into the desired shape and size, the stone may undergo various surface treatments. These can include polishing, honing, flaming, bush hammering, or sandblasting. The choice of finish depends on the desired appearance and the stone’s intended use. For example, polished finishes are common for countertops, while flamed or bush-hammered finishes are often used for outdoor applications. Edge Shaping and Other Customizations: In this stage, the stone is further refined to meet specific design requirements. This can include shaping the edges, drilling holes, or carving patterns. Advanced CNC machinery is often used for this process, allowing for high precision and intricate designs. contshipspretson tiff  1 a Quality Control: Throughout the production process, quality control is essential. This includes checking for cracks, uniformity in thickness, color consistency, and other quality parameters. High-quality stone products must meet specific standards and specifications. Packaging and Shipping: The final step involves carefully packaging the stone for shipping. This is a critical step, especially for fragile materials like marble. The stone is typically packed on wooden pallets or in wooden crates, ensuring it is protected during transportation. Installation: While not part of the production process per se, installation is a critical phase in the use of stone. This involves laying the stone tiles or slabs in their final location, which can be a complex process requiring skilled craftsmanship, especially for intricate designs or large, heavy pieces. Dividing and cutting blocks Stones as Structural elements 1.Load-Bearing Walls: Stone has been used for load-bearing walls in many historical structures, including ancient fortresses, castles, and temples. The inherent strength and durability of certain types of stone, such as granite and limestone, make them suitable for supporting the weight of a building. Stones as Structural elements 2.Arches and Vaults: Stone arches and vaults are classic structural elements used in architecture. Arches distribute loads efficiently and are often found in bridges, aqueducts, and buildings. Vaults, such as those in Gothic cathedrals, are curved stone ceilings that provide both structural support and a visually striking design element. Stones as Structural elements 1.Columns and Pillars 2.Foundation 3.Retaining wall 4.Domes 5.Bridges 6.Pavement 7.Structural Art The End Chapter 2 Stones and Aggregates ARCH214– Chap 2 – Stones Building Material and components – ARCH214 Eng. Lara Rahim Al Yamamah university Outline 1. Introduction 2. Definition of aggregates 3. Mechanical properties of aggregates 4. Classification of Aggregates 5. Grading of Aggregates 6. Characteristics of Aggregates 7. Recycled Concrete Aggregates  Introduction What is aggregate? Aggregate, is a building and construction material used for mixing with cement, bitumen, lime, gypsum, or other adhesive to form concrete or mortar. The aggregate gives volume, stability, resistance to wear or erosion, and other desired physical properties to the finished product. Commonly used aggregates include sand, crushed or broken stone and gravel. Introduction The materials used for manufacture of mortar and concrete such as sand, gravel etc. are called as aggregate. It is defined as: “Aggregates are the inert materials that are mixed in fixed proportions with a Binding Material to produce concrete“. These act as fillers or volume increasing components on the one hand and are responsible for the strength, hardness, and durability of the concrete on the other hand. 4  Introduction Aggregates in Concrete: Concrete is basically a mixture of two components Paste (Portland cement, water, and air) Aggregate (sand, gravel, crushed stone) 5 Introduction Aggregates occupy 60 to 80 %of the volume of concrete which makes concrete a rock-like material. Sand and gravel are the primary aggregates used. Sandis referred to asFineAggregates. While gravel is referred to as Coarse Aggregates. All aggregatesmust be essentially clean: 7 free of silt and/or organic matter.  Introduction Uses of Aggregates in concrete mixtures: Filler material Dimensional Stability Strength and Stiffness Economy To make the concrete denser 7 Introduction Uses of Aggregates in concrete mixtures: Aggregate are generally cheaper than cement and impact greater volume stability and durability to concrete. The aggregate is used primarily for the purpose of providing bulk to the concrete which means to increase the density of the resulting mix, the aggregate is frequently used in two or more sizes. 8 Introduction Aggregates may affect the following properties of concrete: Strength Durability Structural Performance Cost 9  Introduction Aggregates have 3 main functions in concrete: 1. To provide a mass of particles which are suitable to resist the action of applied loads & show better durability then cement paste alone. 2. To provide a relatively cheap filler for the cementing material. 3. To reduce volume changes resulting from setting & hardening process & from moisture changes during drying. 10 Introduction The properties of concrete are affected by the properties of aggregates: 1. The mineral character of aggregate affects the strength, durability, elasticity of concrete. 2. The surface characteristics of aggregate affects the workability of fresh mass & the bond between the aggregate & cement paste in hardened concrete. 3. The grading of aggregate affects the workability, density, strength & cost of concrete 11 Mechanical properties of aggregates Strength Hardness Toughness Durability Porosity Water absorption 12 Mechanical properties of aggregates Strength of Aggregates In practice, majority of normal aggregates are considerably stronger than concrete A good average value of crushing strength of aggregates is 200N/mm2. The compressive strength of the majority of rock aggregates commonly used is in the range of 45 to 550 N/mm2. The strength of concrete is generally between 15 to 50N/mm2. 13 Mechanical properties of aggregates Strength of Aggregates The Crushing Test Aggregate crushing test values indicates the strength of aggregate and hence it is very significant. Similarly we can say crushing value is the relative measure of resistance of an aggregate under gradually applied compressive loads. Higher crushing strength means lower crushing value and vice versa. If the aggregate crushing value is less than 10, means an exceptionally strong aggregate, Whereas crushing value of 35 and above means a weak aggregate. 14 Strength of Aggregates: Crushing Test  Strength of Aggregates: Crushing Test 1. Oven dry the aggregates 2. Sieve the aggregate collect the specimen passing through 12.5 mm and retained on a 10mm sieve 3. The aggregate sample should be filled in 3 layers , each layer is subjected to 25 strokes using tamping rod. 4. Weigh the materials 5. Apply load at a uniform rate 6. Weigh the material passing through the sieve 7. calculate the specimen crushing value Aggregate crushing value = W2/ W * 100 W = weight of dry sample W2 = Weight of fraction passing through the sieve after application of load. For a good quality aggregate, the crushing strength value is low.  Example Sample. 1 dry weight = 14 kg Weight of fraction passing through = 2.5 kg Sample. 2 dry weight = 12 kg Weight of fraction passing through = 3.5 kg Find the crushing value for these two aggregates samples. Which on is stronger Solution: Aggregate crushing value 1 = 2.5/14 * 100 = 17.9 Aggregate crushing value 2 = 3.5/12 * 100 = 29.16 Sample 1 has a lower crushing value which means that sample 1 is stronger than sample 2 Mechanical properties of aggregates Hardness of Aggregates Hardness of aggregates is the ability of the aggregate to withstand wear or load or applied pressure. This hardness is depending on the type of parent rock The test that can obtain the hardness is the abrasion test. The principle of Los Angeles abrasion test is to find the percentage wear due to relative rubbing action between the aggregate and steel balls used as abrasive charge. 18 Hardness of Aggregates Mechanical properties of aggregates Toughness of Aggregates Is the resistance of aggregate to failure by impact. This can be determined by aggregate impact test. The need for impact value test is used to measure the toughness of aggregates which is nothing but the ability of aggregates to resist the sudden loading or impact loading. 20 Mechanical properties of aggregates Durability of Aggregates Durability is ability of the aggregate to withstand external or internal damaging attack or in other words the soundness of aggregate. This can be obtained by carrying out the Soundness test. 22 Mechanical properties of aggregates Porosity of Aggregates Aggregate normally have pores of various sizes. Aggregates will absorb water when it is dry but normally release water in the concrete mix when it is wet. The amount of water and its rate of premutation depends on the size and volume of aggregate Since the aggregate comprises 75% of the concrete volume, it is essential to note that porosity of an aggregate contribute to the overall porosity of concrete. 23 Classification of Aggregates agnius metmorice seasement I 1. According to Petrological Characteristics 2. According to the grain size 3. According to their weight 4. According to the particle shape 5. According to the surface texture 6. According to the ASTM Classification of Aggregates The American Society for Testing and Materials (ASTM) has several standards that pertain to the classification and specification of aggregates for use in construction. Here's an overview of the classification of aggregates according to ASTM: Based on Petrological Characteristics : Natural Aggregates Manufactured Aggregates identical they're Recycled Aggregates Based on Grain Size: Fine Aggregates Coarse Aggregates Based on Weight: Normal Weight Aggregates Light Weight Aggregates Heavy Weight Aggregates Based on Particle Shape: Bulky Flaky Based on Surface Texture: Smooth Rough 1. According to Petrological Characteristics Natural Aggregates All natural aggregates particles originally formed as part of a larger parent mass. Many properties of the aggregates depend entirely on the properties of the parent rock E.g. chemical and mineral composition, petrological character, specific gravity etc. Some properties are possessed by the aggregates but absent in the parent rock: particle shape and size, surface texture, and absorption. 26 According to Petrological Characteristics: 1. Igneous rocks: are formed by solidification of molten lava. (granite) 2. Sedimentary rocks: are obtained by deposition of weathered & transported pre-existing rocks or solutions. (limestone) 3. Metamorphic rocks: are formed under high heat & pressure alteration of either igneous & sedimentary rocks (marble). 27 1. According to Petrological Characteristics Natural Aggregates The cheapest among them are the natural sand and gravel. Which have been reduced to their present size by natural agents, such as water, wind and snow, etc. 28 Constituents in naturally occurring Aggregates :  Igneous rocks  Granite  Basalt  Sedimentary rocks  Sandstone  Limestone  Shale  Metamorphic rocks  Marble  slate 29 1. According to Petrological Characteristics Artificial Aggregates They are obtained either as a by-product or by a special manufacturing process such as heating. Natural Artificial 30  Recycled-concrete aggregate In recent years, the concept of using old concrete pavements, buildings, and other structures as a source of aggregate has been demonstrated on several projects, resulting in both material and energy savings. The procedure involves: (1) breaking up and removing the old concrete, (2) crushing in primary and secondary crushers, (3) removing reinforcing steel and other embed-ded items, (4) grading and washing, and (5) finally stockpiling the resulting coarse and fine aggregate. Recycled-concrete aggregate Heavily reinforced concrete is crushed with a beamcrusher Stockpile of recycled- concrete aggregate Recycled- concrete aggregate  2. According to the grain size itThis is the most common classification, where in two types of aggregates are distinguished: clay sand grow 1. Fine aggregates 2. Coarse aggregates 4.758 78 33  1- Sieve Analysis In simple definition: Sieve analysis = shaking the sample through a set of sieves that have progressively smaller openings. WEE WE 10  1- Sieve Analysis U.S. standard sieve numbers and the sizes of openings are given in Table 2.5. 11 2. According to the grain size Fine Aggregates (d ≤ 4.75 mm) Particles of fine aggregates pass through 4.75mm(No.4) sieve. Most commonly used fine aggregates are sand, crushed stone, ash. 36 2. According to the grain size Coarse Aggregates (d > 4.75 mm) Coarse aggregates are retained on 4.75mm sieve. Aggregates the size of whose particle is bigger than 4.75 mm are known as coarse aggregates. It specially includes gravel and crushed stones. 37  1- Sieve Analysis Fine Sieve Coarse Sieve Sieve # decrease/ Soil particle size decrease 12  1- Sieve Analysis Laboratory Sieves Sieve Shaker 13 1- Sieve Analysis 14  1- Sieve Analysis Description: A laboratory procedure that consists of passing the soil through a set of sieves with progressively smaller openings. It is performed by shaking the soil sample through a set of sieves of smaller openings. The size of the sieve openings determines the size of the particles that can pass through them. The smallest-sized sieve is US sieve No. 200 (0.075 mm opening). 15 S  10/22/2015 Concrete is made out of Fine and Coarse aggregates to fillinside thegaps void Fine Influence the 60% to 75% of the concrete concrete’s aggregates volume freshly mixed + 70% to 85% of the concrete and hardened Coarse mass CVLE 321 – Chap 5 –Aggregates For Concrete aggregates properties Fine aggregates Natural sand or (< 4.75 mm) crushed stone Coarse aggregates Combination of (4.75 mm< d < 37.5 gravels or mm) crushed stone 3. According to their weight related Spank longspans light sensis thecost is reduced Protection insulation Heavy weight agg.: Hematite, Magnetite Specific Gravity, Gs > 2.8 spe gravity Normal weight agg.:Gravel, sand, crushed stone 2.8 < Gs < 2.4 Light weight agg.:Expanded perlite, burned clay Gs < 2.4 43 3. According to their weight Normal-weight Normal-weight concrete aggregates (2200 to 2400 kg/m3) Light-weight Light-weight concrete aggregates (1350 to 1850 kg/m3) Heavy-weight Heavy weight concrete aggregates >4000 kg/m3  Examples of Uses for the Weight Aggregates Used Concrete can be sawed or nailed, vermiculite, ceramic, also used for its insulating ultra-lightweight diatomite, pumice, scoria, properties (250 to 1450 perlite, kg/m3). used primarily for making lightweight concrete for expanded clay, shale or lightweight structures, also used for slate, crushed brick its insulating properties (1350 to 1850 kg/m3). crushed limestone, sand, river gravel, used for normal concrete normal weight projects crushed recycled concrete used for making high barlite, magnetite , steel density concrete for heavyweight or iron shot; steel or shielding against nuclear iron pellets radiation 45 Ultra-lightweight Aggregates Pontoise Vermiculite Perlite Pumice Scoria Diatomite 46 Lightweight Aggregates Expanded clay (left) Expanded shale (right) Crushed Brick 47 Normal weight Aggregates River gravel Crushed Limestone Crushed Concrete 48  Heavyweight Aggregates Magnetite (left) Magnetite-sand (right) 49  Requirement of Good Aggregate : It must be clean i.e. it should be free from lumps, organic materials It should be strong. It should be durable. It should not react with cement after mixing. Dry It should have rough surface. It should not absorb water more than 5%. It should not be soft and porous. It should be chemically inert. It should be of limiting porosity. It should preferably be cubical or spherical in shape. 50  4. According to PARTICLE SHAPE & SURFACE TEXTURE: In addition to petrological character, the external characteristics, i.e. The shape & surface texture of aggregates are of importance. Particle Shape Three major categories of particle shape: 1. Bulky 2. Flaky 3. Needle shaped 51 PARTICLE SHAPE & SURFACE TEXTURE: Particle Shape 1. Bulky It can be described as: angular, subangular, rounded and subrounded. Example of Quartz 14 Sand Particles PARTICLE SHAPE & SURFACE TEXTURE: 14 PARTICLE SHAPE & SURFACE TEXTURE: Particle Shape 2. Flaky: Very low sphericity Mostly clay minerals 3. Needle-shaped: Less common. Some coral deposits and clays. 5 4 PARTICLE SHAPE & SURFACE TEXTURE:  Surface Texture This affects the bond to the cement paste & also influences the water demand of the mix. 1. Smooth: Bond btw cement paste & agg is weak. 2. Rough: Bond btw cement paste & agg. is strong. Surface texture is not a very important property from compressive strength point of view but agg. Having rough surface texture perform better under flexural & tensile stresses. 56 SMOOTH ROUGH Bulky bulkey tounted Subrounded 57  more rounded workbilting 4. According to Strength workability PARTICLE SHAPE & SURFACE TEXTURE: Iz The shape and texture of aggregate particles have a significant effect on the properties and performance of construction materials: Workability: Rounded aggregates are more workable than angular aggregates because they produce lesser friction and require less water. Angular aggregates interlock well, which can decrease the workability of the mix but can increase its strength. Strength: Angular and rough-textured aggregates provide better bonding with the cement paste in concrete, leading to increased strength. Rounded aggregates, on the other hand, may not bond as effectively, resulting in lower strength. Durability: The shape and texture of aggregates can influence the durability of the mix. Angular and rough-textured aggregates can lead to a denser mix, which can make it more resistant to wear and weathering. 58 Ranges of particle sizes found in aggregates for use in concrete 59  The particle size distribution in an aggregate sample is known as “gradation”. Strength development of concrete depends on degree of compaction & workability together with many other factors. So, a satisfactory concrete should be compacted to max density with a reasonable work. On the other hand, in good concrete all aggregate particles must be covered by cement paste. The grading of aggregate must be so that the workability, density & volume stability of concrete may not be adversely affected by it. 60  void si Cement 59 Grading effect on concrete mixture In reality, the amount of cement paste required in concrete is greater than the volume of voids between the aggregates. The amount of paste is necessarily greater than the void content of sketch A in order to provide workability to the concrete; the actual amount is influenced by the workability and cohesiveness of the paste. Grading of Aggregates Coarse and fine aggregates to be used for making concrete should be well graded. Gradation means the particle size distribution of aggregates Test for grading of aggregates is carried out using the sieve analysis method. Is 9 sizes  1 courts Grading effect on concrete mixture cement and water requirements,GRIFFIE.it workability, pumpability, iiiiiii toiieitiii economy, porosity, shrinkage, durability of concrete IIIIii IIiii II iII S II iiIIIII.IE IIIIIIIII.I.si i I.IE FirstEnergy iII IIii iiiiiiiiIi ioiitiiiihiiii.fi iEi IN nI iiii.IEi EIII pi I iiiii i iiiii iiiii.li ifeng.io iiooooiiiiiiiiiiiiiiiiiiiiii Grading effect on concrete mixture The mixing water and cement requirement tend to increase as aggregate void content increases. Voids between aggregate particles increase with aggregate angularity. Aggregate should be relatively free of flat and elongated particles. Such aggregate particles require an increase in mixing water and thus may affect the strength of concrete, particularly in flexure, if the water- cement ratio is not adjusted. The End