--- title: "Comparison of masonry units" subject: "Design of Timber and Masonry Structures" chapter: 4 key: "semester_5/design_of_timber_and_masonry_structures:masonry-units-comparison" source: https://www.bctengineer.com/q/semester_5/design_of_timber_and_masonry_structures/masonry-units-comparison site: BCT Engineering --- # Comparison of masonry units Design of Timber and Masonry Structures · Chapter 4: Masonry Structures - Asked in: year not given, 6 marks - Video: [5TH SEM CIVIL ENGINEERING SD-II CHAPTER-7 DESIGN OF MASONRY STRUCTURES PART-1](https://www.youtube.com/watch?v=ryM93QGRov8) — Nilachal Polytechnic College Of Engineering - Answer checked by Claude Sonnet 5.5 on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_5/design_of_timber_and_masonry_structures/masonry-units-comparison - Whole chapter: https://www.bctengineer.com/md/semester_5/design_of_timber_and_masonry_structures/chapter-4 ## Question Differentiate between brick, stone, concrete block, hollow block and compressed earth block as masonry units, giving their characteristics and typical uses. ## Short answer Burnt clay bricks: 3.5–20+ N/mm², heavy, high energy. Stone: 20–100+ N/mm², durable but heavy. Solid concrete blocks: 4–10 N/mm². Hollow blocks: 3–8 N/mm², light, can be reinforced. Compressed earth blocks (CEB): 2–6 N/mm², low energy, needs water protection. ## Answer | Property | Burnt clay brick | Stone | Solid concrete block | Hollow block | Compressed earth block (CEB) | |---|---|---|---|---|---| | Material | Clay moulded and burnt | Natural rock (granite, sandstone, limestone) | Cement, sand, aggregate | Same as concrete, with cores | Soil with 5–10% cement/lime, pressed | | Compressive strength | 3.5–20+ N/mm² | 20–100+ N/mm² | 4–10 N/mm² | 3–8 N/mm² (net-area basis) | 2–6 N/mm² | | Density | 1700–1900 kg/m³ | 2300–2800 kg/m³ | 2000–2300 kg/m³ | 1400–1800 kg/m³ | 1800–2000 kg/m³ | | Water absorption | up to 20% | Low (1–5%) | 5–10% | 5–10% | Higher, needs protection | | Weight and ease | Handy, light | Heavy, hard to dress | Heavy | Light, large unit, quick | Medium | | Energy | High (burning) | Quarrying and dressing | Cement energy | Lower | Very low (no burning) | | Typical use | Load-bearing and partition walls | Foundations, retaining walls, hill houses | Load-bearing walls | Partitions, framed buildings | Low-cost housing | #### Notes - **Brick** quality is judged by compressive strength, water absorption (not above 20 percent), efflorescence and a ringing sound when struck. - **Stone** is durable and strong in compression, but heavy and weak in tension; it needs mortar and good bonding with through stones. - **Hollow blocks** have cores (voids more than 25 percent of the gross area); they are light, reduce dead load and can be reinforced and grouted for seismic resistance. - **CEB** is environment friendly, needs no firing and has good thermal behaviour, but it must be protected from water and erosion by plaster and projecting eaves. - All masonry units are strong in compression but weak in tension and shear, so masonry is mainly used for gravity load-bearing walls. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which statement fits stone as a masonry unit? A. Light and easy to handle B. Low strength but high water absorption C. Very strong in compression and durable, but heavy, hard to dress and weak in tension D. Made from soil with cement and pressed, no firing Answer: C. Stone has compressive strength 20-100+ N/mm^2 and low absorption but is heavy and weak in tension; it is used for foundations, retaining walls and hill houses. (Key point: Stone vs other units) 2. What are hollow blocks mainly used for? A. Foundations in rock B. Light partitions and framed buildings, since they are light and large C. Retaining walls D. The highest-strength load-bearing walls Answer: B. Cored blocks have lower density, reduce dead load and build quickly, so they suit partitions and framed buildings. (Key point: Hollow block use) 3. Which is true of compressed earth blocks (CEB)? A. They need no firing and use little energy, but must be protected from water B. They are burnt at high temperature C. They have the highest strength of all units D. They are waterproof without plaster Answer: A. CEB uses soil with 5-10 percent cement or lime, needs no burning, but has higher absorption and needs plaster and eaves. (Key point: Compressed earth block) 4. Which is a brick quality test, and what do all masonry units share? A. Colour only; all are strong in tension B. Water absorption not above 20 percent; all are strong in compression but weak in tension and shear C. Water absorption above 30 percent; all are weak in compression D. Efflorescence is desirable; all are strong in shear Answer: B. Bricks are judged by strength, absorption (not above 20 percent), efflorescence and ring; masonry is weak in tension and shear, so it is used for gravity load-bearing. (Key point: Brick quality and masonry limits) ## Related in Design of Timber and Masonry Structures - [Types of stone masonry and characteristics](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Astone-masonry-types-characteristics) — Design of Timber and Masonry Structures, chapter 4 - [Typical damage patterns in masonry buildings](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Adamage-patterns-masonry-lateral-loads) — Design of Timber and Masonry Structures, chapter 6 - [Safe load on a brick masonry column](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Abrick-masonry-column-safe-load) — Design of Timber and Masonry Structures, chapter 5 - [Seismic bands and vertical reinforcement in masonry](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Aseismic-bands-and-vertical-reinforcement) — Design of Timber and Masonry Structures, chapter 7 ## Related in other subjects - [Hollow blocks and compressed earth blocks](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Ahollow-block-compressed-earth-block) — Concrete Technology and Masonry Structure, chapter 7 - [Use of hollow concrete block](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Ahollow-concrete-block-use) — Concrete Technology and Masonry Structure, chapter 7 - [Characteristics of good brick earth](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acharacteristics-good-brick-earth) — Civil Engineering Materials, chapter 3 - [Types of stone masonry](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Astone-masonry-types) — Building Technology, chapter 3, asked 5×