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2 years ago

What are the reasons why fine grained of alkali igneous rocks can not be used in cement

1 answer:

8 0

Fine grained of alkali igneous rocks cannot be used in cement because of the volume expansion caused by the Alkali-silica reaction, fine-grained igneous rocks cannot be used as aggregates in cement.

<h3>What does fine grained mean in an igneous rock?</h3>

Extrusive igneous rocks have a fine-grained or aphanitic texture, with grains that are too small to see without a magnifying glass. The fine-grained texture suggests that the rapidly cooling lava did not have enough time to form large crystals. A petrographic microscope can be used to examine these tiny crystals.

The texture of an igneous rock (fine-grained vs coarse-grained) is determined by the rate at which the melt cools: slow cooling produces large crystals, while fast cooling produces small crystals.

The chemical reaction that occurs in both alkali cations and hydroxyl ions in the pore solution of hydrated cement paste and certain reactive silica phases present in concrete aggregates is known as the alkali-silica reaction (ASR).

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On a cold winter day, wind at 55 km/hr is blowing parallel to a 4-m high and 10-m long wall of a house. If the air outside is at

koban [17]

Answer:

16.21 kW

Explanation:

Solution

Given that,

The velocity of wind = 55 km/hr

The length of the wall L = 10m

The height of the wall w = 4m

The surface temperature at wall Ts = 12° C

Temperature of air T∞ = 5°C

Now,

The properties of the air at atm and average film temperature =( 12 + 5)/2 = 8.5°C, which is taken from the air table properties.

k= 0.02428 W/m°C

v= 1.413 *10 ^⁻5

Pr =0.7340

Now,

Recall Reynolds number when air flow parallel to 10 m side

[ 55 * 1000/3600) m/s (10 m)/1.413 *10^⁻5 m²/s

Rel =1.081 * 10⁷

This value is greater than Reynolds number.

The nusselt number is computed as follows:

Nu =hL/k

(0.037Rel^0.08 - 871)Pr^1/3

Nu =1.336 * 10 ^4

The heat transfer coefficient is

h = k/L Nu

= 0.2428 W/m°C /10 m (1.336 * 10 ^4)

h = 32.43 W/m°C

The heat transfer area of surface,

As = 40 m²

= ( 4 m) (10 m)

As = 40 m²

The rate of heat transfer is determined as follows:

Q = hAs( Ts - T∞)

= (32.43 W/m²°C) (40 m) (12 - 5)°C

=9081 W

Q = 9.08 kW

When the velocity is doubled,

let say V = 110km/hr

The Reynolds number is

Rel = VL/v

= [110 * 100/3600) m/s] (10 m)/ 1.413 *10^⁻5 m²/s

Rel = 2.163 * 10 ^7

This value is greater for critical Reynolds number

The nusselt number is computed as follows:

Nu =hL/k

(0.037Rel^0.08 - 871)Pr^1/3

[0.037 ( 2.163 * 10 ^7)^0.08 - 871] (0.7340)^1/3

Nu =2.344 * 10^4

The heat transfer coefficient is

h = k/L Nu

= 0.2428 W/m°C /10 m (2.384 * 10 ^4)

h= 57.88 W/m²°C

The heat transfer area of surface,

As = wL

= ( 10 m) (4 m)

As = 40 m²

he rate of heat transfer is determined as follows:

Q = hAs( Ts - T∞)

= (57.88 W/m²°C) (40 m²) (12 - 5)°C

= 16,207 W

= 16.21 kW

3 0

4 years ago

A 300 mm long steel bar with a square cross section (25 mm per edge) is pulled in tension with a load of 83,051 N , and experien

umka2103 [35]

Answer:

the answer is attached with required units.

Explanation:

5 0

3 years ago

1. A pipeline constructed of carbon steel failed after 3 years of operation. On examination it was found that the wall thickness

jek_recluse [69]

Answer:

check the explanation

Explanation:

Thickness Loss = $t =\frac{t_{o}-t_{i}}{2} = \frac{114.3-102.3}{2} = 2mm$

$t_{f} = \frac{1}{2}*6 = 3mm$

Hence Rate of Corrosion = $6*\frac{1-0.5}{3} = 1mm/year$ = 0.03 inches per year

As the expected future life is 7 years,

40 carbon steel pipe has to be replaced every 3 years as given in the question,

Cost per unit length is the sum of material cost and installation cost.

Cost of 40 carbon steel = (5 dollars + 16.5 dollars) * 3 = 64.5 dollars

For 80 carbon steel pipe, first calculate the thickness loss,

$\frac{114.3-97.2}{2} = 8.55mm$

The critical thickness is given to be 3mm, Hence change in thickness is 8.55-3 = 5.5mm

This 80 carbon steel pipe has to be replaced one more time

Hence, Cost per unit length is the sum of material cost and installation cost.

Cost of 80 carbon steel = (8.3 dollars + 16.5 dollars) * 2 = 49.6 dollars

The best is of stainless steel which does not undergo corrosion at all and thus it needs to be replaced only once throughout the plant operation. Its cost = 24.8 dollars + 16.5 dollars = 41.3 dollars

Hence, stainless steel is the recommended pipe to be used.

3 0

3 years ago

What camera battery does the canon 250d use?

Mila [183]

Answer:

The Canon EOS 250 is a digital DSLR that features a 24MP sensor. It is powered by the Canon LP-E17, which is a rechargeable Lithium-Ion battery pack.

Explanation:

8 0

3 years ago

Read 2 more answers

What motivated software engineers to move from the waterfall model to the incremental or spiral model

scoray [572]

Answer:

1. They needed to develop multiple components in software programs.

2. The ability to overlap the development to be more evolutionary in nature.

3. The need to be more risk-averse or the unwillingness to take risks led to the use of a spiral model.

Explanation:

Software development life cycle (SDLC) can be defined as a strategic process or methodology that defines the key steps or stages for creating and implementing high quality software applications.

In SDLC, a waterfall model can be defined as a process which involves sequentially breaking the software development into linear phases. Thus, the development phase takes a downward flow like a waterfall and as such each phase must be completed before starting another without any overlap in the process.

An incremental model refers to the process in which the requirements or criteria of the software development is divided into many standalone modules until the program is completed.

Also, a spiral model can be defined as an evolutionary SDLC that is risk-driven in nature and typically comprises of both an iterative and a waterfall model. Spiral model of SDLC consist of these phases; planning, risk analysis, engineering and evaluation.

<em>What motivated software engineers to move from the waterfall model to the incremental or spiral model is actually due to the following fact;</em>

They needed to develop multiple components in software programs.

The ability to overlap the development to be more evolutionary in nature.

The need to be more risk-averse or the unwillingness to take risks led to the use of a spiral model.

6 0

3 years ago