The correct answer is option 3, which states that statements 1, 2, and 4 are correct.

Let`s dissect each statement:

1. Silica imparts strength to cement: This statement is correct. Silica is a primary component of portland cement and plays a crucial role in providing strength to the cement. It reacts with calcium hydroxide during the hydration process to form calcium silicate hydrate (C-S-H) gel, which is responsible for the cement`s strength.

2. Alumina makes the cement quick setting: This statement is correct. Alumina acts as a flux during the burning of raw materials in the kiln, facilitating the formation of tricalcium aluminate (C3A). This compound contributes to the early strength development of cement and promotes quick setting.

3. Excess of lime increases the strength of cement: This statement is incorrect. Excess lime in cement can lead to decreased strength and durability. The optimal amount of lime is required to ensure proper hydration and strength development of the cement.

4. Calcium sulphate decreases the initial setting time of cement: This statement is correct. Calcium sulphate, commonly known as gypsum, is added to portland cement to control its setting time. It acts as a