Standard Temperature for Specific Gravity Measurement in India

Specific gravity is a dimensionless quantity that represents the ratio of the density of a substance to the density of a reference substance. For liquids, the reference substance is usually water. Since density changes with temperature, the temperature at which both the substance and the reference substance are measured must be specified for specific gravity to be meaningful.

Different standards and industries may specify different standard temperatures for reporting specific gravity. For example, some international standards use $20^\circ\text{C}$ or $25^\circ\text{C}$.

According to Indian standards, specifically for materials like cement, aggregates, and other civil engineering materials, the standard temperature adopted for determining and reporting specific gravity is typically $27^\circ\text{C}$. This temperature is considered suitable for the climatic conditions prevalent in India for laboratory testing.

Therefore, when specific gravity is reported as per Indian Standards, it implies that the measurement was conducted at a temperature of $27^\circ\text{C}$.

Let's look at the options provided:

• $23^\circ\text{C}$
• $21^\circ\text{C}$
• $27^\circ\text{C}$
• $25^\circ\text{C}$

Based on the Indian standards, the correct standard temperature for reporting specific gravity is $27^\circ\text{C}$.