Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
ISBN 1305386647 9781305386648
Full download link at: Solution manual: https://testbankpack.com/p/solutionmanual-for-civil-engineering-materials1st-edition-sivakugan-gnanendrantuladhar-kannan-isbn-13053866479781305386648/
Chapter 5
1. Main sources of aggregates:
- Crushed rock aggregate from quarries
- Natural aggregate from gravel pits and river deposits
- Recycled and reclaimed aggregate (e.g. crushed PCC and claybricks)
Common uses of aggregates include:
- Manufacture of Portland cement concrete
- Unbound aggregate as base and subbase of road pavements
- Fill material, for example in the construction of road embankments
- Drainage layer behind retaining walls
- Manufacture of Hot Mix Asphalt (or Asphalt concrete)
- Appropriately graded aggregate as filter material
- Recycled aggregate
2.
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Cumulative Cumulative mass retained retained % finer or Size (mm) retained (g) amount (g) amount (%) % passing 12.5 0 0 0 100 9.5 38.7 38.7 4.0 96.0 6.7 36.8 75.5 7.8 92.2 4.75 77.5 153.0 15.8 84.2 2.36 127.8 280.8 29.0 71.0 1.18 164.6 445.4 46.0 54.0 0.6 174.3 619.7 64.0 36.0 0.3 141.4 761.1 78.6 21.4 0.15 105.6 866.7 89.5 10.5
The calculations for the grading are given below:
Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
ISBN 1305386647 9781305386648
Full download link at: Solution manual: https://testbankpack.com/p/solutionmanual-for-civil-engineering-materials1st-edition-sivakugan-gnanendrantuladhar-kannan-isbn-13053866479781305386648/
The gradation plot is given below:
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0.075 67.8 934.5 96.5 3.5 Pan 33.9 968.4 100.0 Total amount 968.4
Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
ISBN 1305386647 9781305386648
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3. The calculations for the dense grading according to FHWA are given in the table below:
The gradation of the material referred in Question 2 is compared with the FHWA dense gradation in the figure below.
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Dense grading using (size)^0.45 (% finer or Size (mm) % passing) 12.5 100 9.5 88.4 6.7 75.5 4.75 64.7 2.36 47.2 1.18 34.6 0.6 25.5 0.3 18.7 0.15 13.7 0.075 10.0
Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
ISBN 1305386647 9781305386648
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It could be noted that the grading of the material is significantly different from FHWA dense gradation. Compared to that of FHWA dense gradation, the given material has:
- less proportion of particles greater than ~ 4.75 mm
- less proportion of fines (i.e. particles less than 0.075 mm)
- more intermediate size particles (~ 0.5 mm to ~6.7 mm).
4.
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Cumulative Cumulative mass retained retained % finer or Size (mm) retained (g) amount (g) amount (%) % passing 50 0 0 0 100 37.5 107.4 107.4 11.3 88.7 25 161.6 269 28.3 71.7 19 190.9 459.9 48.4 51.6 12.5 235.4 695.3 73.2 26.8 9.5 227.8 923.1 97.1 2.9
The calculations for the dense grading according to FHWA are given in the table below:
Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
ISBN 1305386647 9781305386648
Full download link at: Solution manual: https://testbankpack.com/p/solutionmanual-for-civil-engineering-materials1st-edition-sivakugan-gnanendrantuladhar-kannan-isbn-1305386647-
The gradation plot is given below:
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9781305386648/ 4.75 26.0 949.1 99.9 0.1 Pan 1.1 950.2 100.0 Total amount 950.2
Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
ISBN 1305386647 9781305386648
Full download link at: Solution manual: https://testbankpack.com/p/solutionmanual-for-civil-engineering-materials1st-edition-sivakugan-gnanendrantuladhar-kannan-isbn-13053866479781305386648/
5.
Dense
The gradation of the material referred in Question 2 is compared with the FHWA dense gradation in the figure below.
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grading using (size)^0.45 (% finer or Size (mm) % passing) 50 100.0 37.5 87.9 25 73.2 19 64.7 12.5 53.6 9.5 47.4 6.25 39.2 4.75 34.7
The calculations for the dense grading according to FHWA are given in the table below:
Solution Manual for Civil Engineering Materials 1st
1305386647 9781305386648
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It could be noted that the grading of the material is significantly different from FHWA dense gradation, particularly the particles less than 25 mm size/diameter. Compared to that of FHWA dense gradation, the given material has:
- Approximatelysame proportion of particles greater than 25 mm
- less proportion of particles of size less than 25 mm
- proportion of particles less than 4.75 mm size/diameter is almost nil whereas it is about 35% in FHWA dense gradation
- more intermediate size particles (~ 4.75 mm to 25 mm) compared to that of FHWA dense gradation
6. Main points concerning the significance of different shapes of aggregate particles:
- How dense aggregate particles will pack into depends heavily of the shapes of aggregate particles. The strength and stiffness of compacted aggregates depends on the density (In general, higher the density, higher the strength and stiffness).
- The shear strength of compacted unbound aggregate (e.g. in road pavement base/subbase construction) depends on the shapes of aggregate particles. Shear strength is achieved mainly from interlocking of aggregate particles and it is better in aggregate having angular particles than with other shapes.
- The skid resistance of unpaved roads constructed with compacted unbound aggregate surface course depends on the shapes of aggregate particles in the
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Edition Sivakugan Gnanendran Tuladhar Kannan ISBN
Solution Manual for Civil Engineering Materials 1st
1305386647 9781305386648
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surface course material. It is better with aggregate having angular particles than those with other shapes.
- The skid resistance of paved roads constructed with HMA surface course depends on the shapes of aggregate particles in the manufacture of HMA of the surface course. It is better with aggregate having angular particles than those with other shapes.
Different shapes:
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Edition Sivakugan Gnanendran Tuladhar Kannan ISBN
Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
ISBN 1305386647 9781305386648
Full download link at: Solution manual: https://testbankpack.com/p/solutionmanual-for-civil-engineering-materials1st-edition-sivakugan-gnanendrantuladhar-kannan-isbn-13053866479781305386648/
- Angular
- Flat
- Elongated
- Flat and elongated (or flaky and elongated)
- Sub-rounded
- rounded
7. Main points on the desirable characteristics of aggregates for use in concrete (NOTE: some of these points are discussed further in Chapter 8)
- aggregate particles having high strength
- aggregate particles having good soundness and durability under varying environmental conditions (e g. minimal effect or strength variation for wet-dry cycles; minimal effect or strength variation for freeze-thaw cycles)
- appropriate grading for the fine and coarse aggregate particles (e.g. as given in Tables 5.7 and Table 5.8 respectively)
- aggregate having mostly angular particles, which enable better bonding with cement paste
- aggregate having rough/coarse surface texture, which enable better bonding with cement paste
- aggregate that is clean and contain less deleterious substances such as clay, coal and friable particles
- aggregate that has good chemical stability with cement
8. Main points on the desirable characteristics of aggregates for use in hot mix asphalt (HMA) or asphalt concrete (AC) - NOTE: some of these points are discussed further in Chapter 7)
- aggregate particles having high strength
- aggregate particles having good soundness and durability under varying environmental conditions (e g. minimal effect or strength variation for wet-dry cycles; minimal effect or strength variation for freeze-thaw cycles)
- appropriate grading for the fine and coarse aggregate particles
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Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
ISBN 1305386647 9781305386648
Full download link at: Solution manual: https://testbankpack.com/p/solutionmanual-for-civil-engineering-materials1st-edition-sivakugan-gnanendrantuladhar-kannan-isbn-13053866479781305386648/
- aggregate having mostly angular particles, which enable better bonding with asphalt cement
- aggregate having high abrasion resistance
- aggregate that is clean and contain less deleterious substances such as clay, coal and friable particles
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Solution Manual for Civil Engineering Materials 1st
ISBN 1305386647 9781305386648
Full download link at: Solution manual: https://testbankpack.com/p/solutionmanual-for-civil-engineering-materials1st-edition-sivakugan-gnanendrantuladhar-kannan-isbn-13053866479781305386648/
- aggregate having rough/coarse surface texture, which enable better bonding with asphalt cement. Alternatively, particles with fractured faces are desirable and for fine aggregates this is assessed through uncompacted void content.
- aggregate particles that have good affinity for asphalt cement (i.e. asphalt nonstripping from aggregate) but having less asphalt absorption
9. Main points on the significance of soundness of aggregate particles:
- An important consideration for aggregate used in PCC such that it is durable under varying environmental (e.g. changing moisture, temperature) conditions
- An important consideration for aggregate used in HMA such that it is durable under varying environmental (e.g. changing moisture, temperature) conditions
- Different limits on the percent loss from soundness test for different classes of aggregates are given in specifications such as AASHTO M 283
Main points on how soundness is assessed:
- wet strength and wet-dry strength variation tests
- sodium sulphate or magnesium sulphate soundness test
Further details are given in Section 5.3.6 and ASTM C88 – 13
10. What is meant by ASR and the conditions in which ASR could occur: The following is from Section 5.3.7 which answers the question:
ASR refers to the reaction between highly alkaline cement paste and silica (i.e., noncrystalline SiO2) found in many common aggregates. In the presence of moisture, the alkalis found in cement break down the silica in the aggregate, producing an expansive (ASR) gel. This expansion causes tensile forces in PCC, leading to loss of strength or spalling Some reactive aggregate source rocks and the reactive components in them are listed in Table 5.11.
Main points concerning how the occurrence of ASR could be avoided or its adverse effects minimised:
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Edition Sivakugan Gnanendran Tuladhar Kannan
Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
ISBN 1305386647 9781305386648
Full download link at: Solution manual: https://testbankpack.com/p/solutionmanual-for-civil-engineering-materials1st-edition-sivakugan-gnanendrantuladhar-kannan-isbn-13053866479781305386648/
- use non-reactive aggregate and/or alkali-free cement for the concrete (see Table 5.11 for some reactive aggregate source rocks and the reactive components in them)
- Mix aggregates of different source rocks to dilute reactive components.
- Use additives such as flyash with cement.
11. Main points concerning the definition of ‘saturated surface-dry’ condition and the determination of moisture content at ‘saturated surface-dry’ condition:
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Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
ISBN 1305386647 9781305386648
Full download link at: Solution manual: https://testbankpack.com/p/solutionmanual-for-civil-engineering-materials1st-edition-sivakugan-gnanendrantuladhar-kannan-isbn-13053866479781305386648/
- Pores in aggregate vary in size and some of the pores are wholly within the solid particle and some are at the surface as illustrated in Fig. 5.15.
- When all the pores in the aggregate are full with moisture, it is said to be ‘saturated and surface dry’ (Neville, 2011)
Refer to Figure 5.15, Schematic representation of moisture in aggregate, which is reproduced here:
Details concerning its determination:
For coarse aggregate:
mass of a representative oven-dry sample of coarse aggregate is measured (A). Recall that coarse aggregate refers to the material retained on 4.75 mm sieve.
The test sample of coarse aggregate is immersed in water for about 24 hours.
The sample is then taken out, rolled over a moisture absorbent cloth, and all visible water film from the aggregate particles is removed. The aggregate particles are said to be in saturated surface-dry condition and its mass (B) is determined.
The moisture content at SSD condition is determined as,
Moisture content at SSD condition = Absorption =
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Moisture Impermeable void Permeable void Free water/moisture on surface Oven-dry Air-dry Saturated surface-dry Moist
B A
A
100%
Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
ISBN 1305386647 9781305386648
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For fine aggregate:
- A representative sample (~500 g) of fine aggregate that passes 4.75 mm sieve is immersed in water for 24 hours to saturate the pores.
- The sample is then removed from the water, surface dried to SSD condition and its mass (S) determined following the procedure detailed in ASTM C128 - 12. Typically, the sample is spread on a flat non-absorbent surface and exposed to gently moving current of
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Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
ISBN 1305386647 9781305386648
Full download link at: Solution manual: https://testbankpack.com/p/solutionmanual-for-civil-engineering-materials1st-edition-sivakugan-gnanendrantuladhar-kannan-isbn-13053866479781305386648/
warm air. Mechanical aids such as stirring are employed to achieve SSD condition (see ASTM C128 – 12 Section 8: ‘Preparation of test specimen’ for further details).
- The volume of the sample is determined by placing it in a pycnometer, a constant volume flask, and adding water to the known volume mark (for example, 500 cm3). The mass of the pycnometer with the sample and water (B) is determined, which is required for determining SSD specific gravity and Apparent specific gravity.
- The sample is then poured out and dried in an oven and its oven-dry mass determined (A).
- Mass of the pycnometer filled with water to the known volume mark is also determined. Moisture
12.
Ms = mass of aggregate solids
Vs = volume of aggregate solids (excluding permeable and impermeable voids)
Vmpv = volume of permeable voids in aggregate
Vmiv = volume of impermeable voids of aggregate
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w
content at SSD condition = Absorption = S A 100 A percent
Bulk dry specific gravity, Gsb Dry massof aggregate 1 M s 1 Total volumeof aggregate w V s V mpv Vmiv w Apparent specific gravity, Gsa G Dry mass of aggregate 1 sa Volume of aggregate solids Volume of impermeable voids G M s 1 sa V V s miv w
Definitions of bulk dry specific gravity and apparent specific gravity are:
Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
ISBN 1305386647 9781305386648
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Mwpv = mass of moisture in the permeable voids of aggregate in SSD condition
Main difference between these two specific gravities:
- The apparent specific gravity (Gsa) is higher than the bulk dry specific gravity (Gsb) since the volume calculation for Gsa does not include the moisture permeable voids.
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Solution Manual for Civil Engineering Materials
1305386647 9781305386648
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13. Main points concerning the meaning of absorbed moisture in aggregate and how it is determined:
Note: The answer for this question is close to that of Question 11.
- The following modified Figure 5.15, illustrates the absorbed moisture in aggregate.
- Moisture absorption of aggregate is determined by measuring the mass increase of an oven-dry sample when immersed in water for 24 hours, with the surface water being removed.
- The ratio of the increase in mass with reference to the dry mass, reported in %, is referred as ‘absorption’
Details concerning its determination:
For coarse aggregate:
mass of a representative oven-dry sample of coarse aggregate is measured (A). Recall that coarse aggregate refers to the material retained on 4.75 mm sieve.
The test sample of coarse aggregate is immersed in water for about 24 hours.
The sample is then taken out, rolled over a moisture absorbent cloth, and all visible water film from the aggregate particles is removed. The aggregate particles are said to be in saturated surface-dry condition and its mass (B) is determined.
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Edition Sivakugan Gnanendran Tuladhar Kannan ISBN
1st
Absorbed moisture Free moisture Moisture Impermeable void Permeable void Free water/moisture on surface Oven-dry Air-dry Saturated surface-dry Moist
Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
1305386647 9781305386648
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ISBN
(B
A) represents the absorbed moisture and it is usually reported in % as follows:
Moisture absorption = B A 100% A
For fine aggregate:
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–
Solution Manual for Civil Engineering Materials 1st
ISBN 1305386647 9781305386648
Full download link at: Solution manual: https://testbankpack.com/p/solutionmanual-for-civil-engineering-materials1st-edition-sivakugan-gnanendrantuladhar-kannan-isbn-13053866479781305386648/
- A representative sample (~500 g) of fine aggregate that passes 4.75 mm sieve is immersed in water for 24 hours to saturate the pores.
- The sample is then removed from the water, surface dried to SSD condition and its mass (S) determined following the procedure detailed in ASTM C128 - 12. Typically, the sample is spread on a flat non-absorbent surface and exposed to gently moving current of warm air. Mechanical aids such as stirring are employed to achieve SSD condition (see ASTM C128 – 12 Section 8: ‘Preparation of test specimen’ for further details).
- The volume of the sample is determined by placing it in a pycnometer, a constant volume flask, and adding water to the known volume mark (for example, 500 cm3). The mass of the pycnometer with the sample and water (B) is determined, which is required for determining SSD specific gravity and Apparent specific gravity.
- The sample is then poured out and dried in an oven and its oven-drymass determined (A).
- Mass of the pycnometer filled with water to the known volume mark is also determined.
(S – A) represents the absorbed moisture and it is usually reported in % as follows:
Absorption = S A 100 A percent
14. Main points concerning the importance of grading of aggregates and the different types of grading:
- Grading is the among most important criteria for almost all uses of aggregates such as PCC, HMA, unbound granular base/subbase material in the construction of unpaved/paved roads, and construction of granular filter and granular drain.
- Aggregate particles mix used for any particular application is ensured/controlled by checking the grading against the specification
- Grading is important for achieving a dense aggregate mix which in turn influences the strength and stiffness of the material (e.g. in PCC, HMA and unbound granular base/subbase material in the construction of unpaved/paved roads).
- Appropriate grading of aggregate is important when it is used as granular filter
- Appropriate grading of aggregate is important when it is used as granular drain (e g drains behind retaining walls, subsurface drains in roads)
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Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
ISBN 1305386647 9781305386648
Full download link at: Solution manual: https://testbankpack.com/p/solutionmanual-for-civil-engineering-materials1st-edition-sivakugan-gnanendrantuladhar-kannan-isbn-13053866479781305386648/
15. By trialling different mix proportions and comparing with the lower and upper limits with the given specification:
50% of 1 70% A + Material A Material B + 50% of 2 30% B
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Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
ISBN 1305386647 9781305386648
Full download link at: Solution manual: https://testbankpack.com/p/solutionmanual-for-civil-engineering-materials1st-edition-sivakugan-gnanendrantuladhar-kannan-isbn-13053866479781305386648/
The 50% A + 50% B mix marginally fails to satisfy the specification limits.
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Size (mm) % passing % passing (% passing) (% passing) 50 100 100 100 100 37.5 89 100 94.5 92.3 25 74 100 87 81.8 19 60.4 100 80.2 72.28 12.5 46 96.2 71.1 61.06 9.5 38.5 91.5 65 54.4 4.75 20 76.1 48.05 36.83 2.36 7.1 62 34.55 23.57 0.425 0.1 32.1 16.1 9.7 0.075 0 16.4 8.2 4.92
Plotting the above results in the gradation plot:
Solution Manual for Civil Engineering Materials 1st
Edition Sivakugan Gnanendran Tuladhar Kannan
ISBN 1305386647 9781305386648
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However, the 70% A + 30% B mix satisfies the specification limits very well and therefore it is acceptable.
Note: There could be other mix proportions closer to 70/30 which could also be acceptable.
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