Q1GATE 2025NAT

If the weights retained on the $2.36 \mathrm{~mm}, 1.18 \mathrm{~mm}, 600 \mu \mathrm{~m}$ , and $300 \mu \mathrm{~m}$ sieves are $30 \%$ , $35 \%, 15 \%$ , and $20 \%$ , respectively, of the total weight of an aggregate sample, then the fineness modulus of the sample is _________ (rounded off to 2 decimal places).

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📖 Explanation

To calculate the Fineness Modulus (FM), we take the cumulative percentage retained on each standard sieve and divide the sum by 100. Given weights retained: On 2.36 mm sieve = 30% On 1.18 mm sieve = 35% On 600 $\mu m$ sieve = 15% On 300 $\mu m$ sieve = 20% Step 1: Compute cumulative percentages retained: - 2.36 mm sieve: $30\%$ - 1.18 mm sieve: $30 + 35 = 65\%$ - 600 $\mu m$ sieve: $65 + 15 = 80\%$ - 300 $\mu m$ sieve: $80 + 20 = 100\%$ Step 2: Sum of cumulative percentages retained: $30 + 65 + 80 + 100 = 275$ Step 3: Fineness Modulus: $\text{FM} = \frac{275}{100} = 2.75$ Final Answer: $\boxed{2.75}$

Q2GATE 2024MCQ

Concrete of characteristic strength $30 \mathrm{MPa}$ is required. If 40 specimens of concrete cubes are to be tested, the minimum number of specimens having at least $30 \mathrm{MPa}$ strength should be

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📖 Explanation

As per IS456:2000, atleast $95 \%$ of the specimen should have strength equal to more than the characteristics strength. $\therefore$ Minimum number of specimens $=0.95 \times 40=38$

Q3GATE 2023MCQ

In cement concrete mix design, with the increase in water-cement ratio, which one of the following statements is TRUE?

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Q4GATE 2022MCQ

Which of the following equations is correct for the Pozzolanic reaction?

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📖 Explanation

Pozzolanic materials have no cementing properties itself but have the property of combining with lime to produce stable compound. Pozzolana is considered as siliceous and aluminous materials and when added in cement it have $SiO_2$ and $Al_2O_3$ form. So, pozzolanic reaction : $H_2O$ + Reactive slilica-di-oxide + $H_2O \rightarrow C-S-H$ gel or tobermonite gel

Q5GATE 2022NAT

It is given that an aggregate mix has 260 grams of coarse aggregates and 240 grams of fine aggregates. The specific gravities of the coarse and fine aggregates are 2.6 and 2.4, respectively. The bulk specific gravity of the mix is 2.3. The percentage air voids in the mix is ____________. (round off to the nearest integer)

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📖 Explanation

Given that, Coarse aggregate = 260 gms Fine aggregate = 240 gms $G_{CA}=2.6$ $G_{FA}=2.4$ Bulk specific gravity $G_m=2.3$ Percentage air voids in the mix = ? $G_t$ (Theoretical specific gravity)

\begin{aligned} &=\frac{\Sigma W}{\Sigma \frac{W}{G}}\\ &=\frac{260+240}{\frac{260}{2.6}+\frac{240}{2.4}}\\ &=2.5 \end{aligned}

\begin{aligned} % \text{ air voids} (V_V)&=\frac{G_t-G_m}{G_t} \times 100\\ &=\frac{2.5-2.3}{2.3}\times 100\\ V_V&=8% \end{aligned}

Q6GATE 2022MCQ

Match all the possible combinations between Column X (Cement compounds) and Column Y (Cement properties):

\begin{array}{|c|l|}\hline \text{Column X}&\text{Column Y} \\ \hline (i) C_3S & \text{(P) Early age strength} \\ \hline (ii) C_2S & \text{(Q) Later age strength}\\ \hline (iii) C_3A& \text{(R) Flash setting}\\ \hline & \text{(S) Highest heat of hydration}\\ \hline & \text{(T) Lowest heat of hydration}\\ \hline \end{array}

Which one of the following combinations is correct?

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📖 Explanation

$C_3S-$ Responsible for early age strength $C_2S -$ Responsible for later age strength and lowest heat of hydration $C_3A-$ Flash setting and highest heat of hydration

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