aggregates properties and all details
- 31. Sieve size Weight retained (g) Cumulative weight retained(g) Cumulative percentage weight Retained (%) 4.75mm 0 0 0 2.36mm 100 100 10 1.18mm 250 350 35 0.6mm 350 700 70 0.3mm 200 900 90 0.15mm 100 1000 100 Total 275 F.M of Fine aggregates KITS CIVIL KODADA
- 32. fineness modulus of aggregate = (cumulative % retained) / 100 = (275/100) = 2.75 Fineness modulus of fine aggregate is 2.75. It means the average value of aggregate is in between the 2nd sieve and 3rd sieve. It means the average aggregate size is in between 0.3mm to 0.6mm as shown in below figure. KITS CIVIL KODADA
- 33. Type of sand Fineness modulus range Fine sand 2.2 2.6 Medium sand 2.6 2.9 Coarse sand 2.9 3.2 Values of Fineness Modulus of Sand Fineness modulus of fine aggregate varies from 2.0 to 3.5mm. Fine aggregate having fineness modulus more than 3.2 should not considered as fine aggregate. Various values of fineness modulus for different sands are detailed below.Fineness modulus limits for various zones of sand according to IS 383-1970 are tabulated below. KITS CIVIL KODADA
- 34. Sieve size Zone-1 Zone-2 Zone-3 Zone-4 10mm 100 100 100 100 4.75mm 90-100 90-100 90-100 95-100 2.36mm 60-95 75-100 85-100 95-100 1.18mm 30-70 55-90 75-100 90-100 0.6mm 15-34 35-59 60-79 80-100 0.3mm 5-20 8-30 12-40 15-50 0.15mm 0-10 0-10 0-10 0-15 Fineness modulus 4.0-2.71 3.37-2.1 2.78-1.71 2.25-1.35 ZONE WISE F.M KITS CIVIL KODADA
- 35. Sieve size Weight retained(g) Cumulative weight retained (g) Cumulative % retained (g) 80mm 0 0 0 40mm 250 250 5 20mm 1750 2000 40 10mm 1600 3600 72 4.75mm 1400 5000 100 2.36mm 0 5000 100 1.18mm 0 5000 100 0.6mm 0 5000 100 0.3mm 0 5000 100 0.15mm 0 5000 100 Sum = 717 Let us say dry weight of coarse aggregate = 5000g Values after sieve analysis areTherefore, fineness modulus of coarse aggregates = sum (cumulative % retained) / 100 = (717/100) = 7.17 Fineness modulus of 7.17 means, the average size of particle of given coarse aggregate sample is in between 7th and 8th sieves, that is between 10mm to 20mm. KITS CIVIL KODADA
- 36. Limits of Fineness Modulus Fineness modulus of coarse aggregate varies from 5.5 to 8.0. And for all in aggregates or combined aggregates fineness modulus varies from 3.5 to 6.5. Range of fineness modulus for aggregate Maximum size of coarse aggregate Fineness modulus range 20mm 6.0 6.9 40mm 6.9 7.5 75mm 7.5 8.0 150mm 8.0 8.5 KITS CIVIL KODADA
- 37. Standard Grading Curve The grading patterns of aggregate can be shown in tables or charts. Expressing grading limits by means of a chart gives a good pictorial view. The comparison of grading pattern of a number of samples can be made at one glance grading curves are those produced by Road Research Laboratory (U.K.). COARSE AGGREGATES KITS CIVIL KODADA
- 41. Where concrete of high strength and good durability is required, fine aggregate conforming to any one of the four grading zones may be used It is recommended that fine aggregate conforming to Grading Zone IV should not be used in reinforced concrete KITS CIVIL KODADA
- 60. Deleterious Materials In Aggregate : The materials whose presence in aggregates may adversely affect the strength, workability & long-term performance of concrete are termed as deleterious materials. These are considered undesirable constituents. The total amount of deleterious materials in aggregate should not exceed 5% as per IS 383-1970 The deleterious substances found in the aggregates are as follows: a) Organic matter consisting of decayed vegetable matter b) Coal & Lignite c) Clay lumps d) Shale KITS CIVIL KODADA
- 61. Deleterious material present in the aggregates may affect the concrete as follows: a) The organic matter interferes with the chemical reaction of hydration. b) The clay & other fine materials present in the form of surface coating interfere with the bond between the aggregate &cement paste. c) Presence of shale & other particles of low density adversely affects the strength of concrete. KITS CIVIL KODADA
- 62. Soundness of Aggregate: Soundness refers to the ability of aggregate to resist excessive changes in volume as a result of changes in physical conditions Aggregates which undergo more than the specified amount of volume change is said to be unsound aggregates KITS CIVIL KODADA
- 63. soundness test: APPARATUS Balance 500 g Oven 105 to 1100C Sieves 80 mm, 63 mm, 40 mm, 31.5 mm, 25 mm, 20 mm, 16 mm, 12.5 mm, 10 mm, 8.0 mm, 4.75 mm, 4.0 mm, 2.36 mm, 1.18 mm, 600 micron, 300 micron, 150 micron Wire mesh basket container KITS CIVIL KODADA
- 64. Chemicals and wire mesh basket CHEMICAL SOLUTION Sodium Sulphate Solution Magnesium Sulphate Solution KITS CIVIL KODADA
- 69. Alkali-Aggregate Reactions Alkali aggregate reactions (AAR) occur when aggregates in concrete react with the alkali hydroxides in concrete producing a hygroscopic gel which, in the presence of moisture, absorbs water and causes expansion and cracking over a period of many years. KITS CIVIL KODADA
- 70. Alkali-Aggregate Reactions Alkali-Carbonate Reaction (ACR) Alkali-SilicaReaction (ASR) KITS CIVIL KODADA
- 71. Alkali-Carbonate Reaction (ACR) is related to a dedolomitization of dolostones and dolomitic limestones, and the associated expansion of the coarse aggregate particles. ACR is a serious, but fortunately rare, variety of AAR. Alkali-Silica Reaction (ASR) is associated with the dissolution of silica (SiO2) in the aggregate and the subsequent formation of alkali-silica gel in the aggregate and concrete. KITS CIVIL KODADA
- 72. ACR Prevention Selective quarrying Blending aggregate Reducing aggregate size Not effective Use of pozzolans Low-alkali cement KITS CIVIL KODADA
- 77. ASR EXAMPLES Cracking KITS CIVIL KODADA
- 78. Misalignment of Sections KITS CIVIL KODADA
- 79. Concrete crushing KITS CIVIL KODADA
- 81. Cement paste Reactive aggregate Reaction product ASR in Concrete Polished Section KITS CIVIL KODADA
- 82. Rock and aggregate possesses three thermal properties which are significant in establishing the quality of aggregate for concrete constructions. They are: (i) Coefficient of expansion; (ii) Specific heat; (iii) Thermal conductivity Thermal Properties Out of these, specific heat and conductivity are found to be important only in mass concrete construction where rigorous control of temperature is necessary. Coefficient of expansion: the ratio of the increase of length,area,or volume of a body per degree rise in temperature to its length ,area,or volume When we are dealing with the aggregate in general it will be sufficient at this stage to deal with only the coefficient of expansion of the aggregate KITS CIVIL KODADA
- 83. An average value of the linear thermal coefficient of expansion of concrete may be taken as 9.9 x 106 per 属C, but the range may be from about 5.8 x 106 per 属C to 14 x 106 per 属C depending upon the type and quantities of the aggregates The linear thermal coefficient of expansion of common rocks ranges from about 0.9 x 106 per 属C to 16 x 106 per 属C. From the above it could be seen that while there is thermal compatibility between the aggregate and concrete or aggregate and paste at higher range KITS CIVIL KODADA
- 84. From the above it could be seen that while there is thermal compatibility between the aggregate and concrete or aggregate and paste at higher range, there exists thermal incompatibility between aggregate and concrete or aggregate and paste at the lower range. This thermal incompatibility between the aggregate and concrete at the lower range causes severe stress which has got damaging effect on the durability and integrity of concrete structures KITS CIVIL KODADA
- 85. If quartz is used as aggregate for concrete that is going to be subjected to high temperature the concrete is sure to undergo disruption as quartz changes state and suddenly expands 0.85 per cent at a temperature of 572.7属C. Where the difference between these coefficients exceeds 5.4 x 106 per 属C caution should be taken in the selection of the aggregate for highly durable concrete KITS CIVIL KODADA
- 86. KITS CIVIL KODADA Gap grading : continuous grading: Originally in the theory of continuous grading, it was assumed that the voids present in the higher size of the aggregate are filled up by the next lower size of aggregate, and similarly, voids created by the lower size are filled up by one size lower than those particle and so on. It was realised later that the voids created by a particular fraction are too small to accommodate the very next lower size. The next lower size being itself bigger than the size of the voids, it will create what is known as particle size interference, which prevents the large aggregates compacting to their maximum density
- 87. KITS CIVIL KODADA Gap grading: In GAP grading aggregates the size of voids existing between a particular size of aggregate is of the order of 2 or 3 size lower than that fraction. In other words, the void size existing between 40 mm aggregate is of the size equal to 10 mm or possibly 4.75 mm or the size of voids occurring when 20 mm aggregate is used will be in the order of say 1.18 mm or so. Therefore, along with 20 mm aggregate, only when 1.18 mm aggregate size is used, the sample will contain least voids and concrete requires least matrix.
- 88. KITS CIVIL KODADA Recycled Aggregate
- 89. KITS CIVIL KODADA Recycled aggregate are comprised of crushed, graded inorganic particles processed from the materials that have been used in the construction and demolition debris These materials are generally from buildings, roads, bridges, and sometimes even from catastrophes, such as wars and earthquakes Recycled aggregate is generally produced by two stages crushing of demolished concrete, screening and removal of contaminants such as reinforcement Concrete made with such aggregates is called as Recycled aggregate Concrete (RAC). Recycled aggregate Concrete (RAC).
- 90. KITS CIVIL KODADA characteristic of recycled aggregates could be different by its parent concrete because the parent concrete was designed for its purposes such as permeable, durable and high strength concrete Its a lower density , elastic modulus, strength and a higher water absorption capacity. Its a lower density , elastic modulus, strength and a higher water absorption capacity. In addition, since recycled aggregates require a more amount of water than natural aggregate, shrinkage issue could be a problematic to use RAC in practically. What Is Recycle aggregate concrete Characteristics of recycle aggregate concrete :
- 91. KITS CIVIL KODADA Recycle aggregate concrete has a Crushed sound and clean waste concrete of at least 95% by weight of concrete with typical total contamination lower than 1% of the bulk mass Class 1A RCA is a well graded RCA with no more than 0.5% brick content Its used for many types of general bulk fills Filling drainage structures Noise barriers and embankments Road constructions The applications of aggregate
- 92. KITS CIVIL KODADA -It reduces the amount of CO2 in the atmosphere because, while crushing into smaller particles a large amount of carbon dioxide is absorbed. -It creates more employment opportunities for the recycling industry. When Recycled Aggregate Concrete is used it leads to a reduction in construction cost as per a few research studies. -It is regarded as green construction material. -When recycled aggregate is used it reduces the number of virgin aggregates, which are created thus, it means less use of natural resources. -Recycled aggregate concrete can be used for different purposes. It is suitable for use at various construction projects, landscaping and for home improvements. -It is reliable as natural aggregate and safe to use. Conserves landfill space thus, reducing the need for new landfills. Advantages of recycled Aggregates:
- 93. KITS CIVIL KODADA It downgrades the quality of concrete. Workability of concrete reduces. Specifications and guidelines arent available It has lesser durability, but research shows that when mixed with special materials like fly ash its durability is improved. The compressive strength of concrete decreases by 10-30%. Recycled concrete increases water absorption capacity. Disadvantages of recycled aggregate: