Minimum compressive strength in N/mm² for H1 type mortar used for masonry is:
🔬 Understanding Mortar Classification by Strength
In India, masonry mortars are classified and graded according to IS 2250: Code of Practice for Preparation and Use of Masonry Mortars. This code categorizes mortars based on their 28-day compressive strength, which is the primary indicator of their performance and suitability for different types of masonry work.
Mortar Grades: The code specifies different grades, typically designated by a letter and a number. The letter indicates the strength category (H for High, M for Medium, L for Low), and the number further refines the grade within that category.
⚖️ Detailed Analysis of IS 2250 Mortar Grades
The question asks for the minimum compressive strength of an H1 type mortar. The table below, based on IS 2250, shows the strength requirements for various mortar grades.
| Mortar Grade | Strength Category | Minimum Compressive Strength at 28 days (N/mm²) |
|---|---|---|
| H1 | High Strength | 10.0 |
| H2 | High Strength | 7.5 |
| M1 | Medium Strength | 5.0 |
| M2 | Medium Strength | 3.0 |
| L1 | Low Strength | 2.0 |
| L2 | Low Strength | 0.7 |
(d) 10
Why it's correct: As shown in the table, H1 is the highest standard grade of masonry mortar, and it is defined by a minimum 28-day compressive strength of 10 N/mm² (or 10 MPa). This type of mortar is made with a rich cement-sand ratio (e.g., 1:3) and is used for heavy-duty, load-bearing structural masonry.
💡 Study Tips for Mortar Grades
- H is for High: Remember that the "H" in H1 and H2 stands for High Strength. H1 is the highest in this category.
- Memorize the Key Values: The most commonly asked grades are H1, M1, and M2. It is highly beneficial to memorize their corresponding strengths:
- H1 → 10 N/mm²
- M1 → 5 N/mm²
- M2 → 3 N/mm²
- Strength Follows the Number (Mostly): Notice that within a letter category, a lower number means higher strength (H1 > H2, M1 > M2).