--- title: "Detailed specification of cement sand mortar 1:6" subject: "Construction Management" chapter: 12 key: "semester_8/construction_management:detailed-spec-cs-mortar-1-6" source: https://www.bctengineer.com/q/semester_8/construction_management/detailed-spec-cs-mortar-1-6 site: BCT Engineering --- # Detailed specification of cement sand mortar 1:6 Construction Management · Chapter 12: Specification - Asked in: 2073 Magh - Video: [How to do Rate Analysis for Cement mortar 1:6 Construction Items#cstechguruji #subscribers#civilEngg](https://www.youtube.com/watch?v=P4NYG8A8oBE) — Civil StructuresTechguruji Consultancy & Academy - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_8/construction_management/detailed-spec-cs-mortar-1-6 - Whole chapter: https://www.bctengineer.com/md/semester_8/construction_management/chapter-12 ## Question Write down the detailed specification for cement sand mortar 1:6. ## Short answer Cement sand mortar 1:6 by volume, mixed until colour uniform, used within 30 minutes without re-tempering.28-day strength about3–5 N/mm². Measured by volume(m³). ## Answer #### Detailed specification: cement sand mortar 1:6 **Scope:** Preparation of cement sand mortar of 1 part cement to 6 parts sand by volume, for general brick masonry, stone masonry and similar work where moderate strength is needed. **Materials** - **Cement:** fresh OPC 43 grade/PPC conforming to the Nepal Standard/IS, free from lumps and moisture, stored on a raised platform in a dry shed. - **Sand:** clean, hard, well-graded river sand, free from clay, silt (< 4%), mica, organic matter and salts; fineness modulus 1.5–2.5. - **Water:** potable, free from oil, acid, alkali and organic matter. **Proportion:** 1 : 6 by volume; cement measured as 0.035 m³ per 50 kg bag; sand in gauge boxes with allowance for bulking of damp sand. Approximate material for 1 m³ mortar: about 5.5–6 bags cement and 1.2 m³ sand (indicative). **Mixing** - Dry mixing of sand and cement until the colour is uniform, then add water slowly and mix to a workable, non-segregated paste, either in a mixer or on a watertight platform by hand (turned at least three times). - The least water that gives workability should be used. **Use:** Used within 30 minutes of mixing; stale mortar is rejected and re-tempering is not allowed. **Strength:** 28-day compressive strength of standard mortar cubes about 3–5 N/mm², tested if asked by the engineer. **Measurement and payment:** By volume (m³) when separate; otherwise included in the item rate. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. For what type of work is 1:6 mortar used? A. Heavy structural columns B. Water tank lining only C. Road surfacing D. General brick and stone masonry where moderate strength is needed Answer: D. 1:6 mortar is for general masonry needing moderate strength. (Key point: Use of 1:6) 2. Why is an allowance for bulking made for sand in gauge boxes? A. Dry sand shrinks B. Damp sand increases in volume, so measured volume would give less actual sand C. Cement bulks D. To save cement Answer: B. Damp sand bulks, so volume must be corrected to get the true proportion. (Key point: Bulking) 3. What 28-day cube strength is typical for 1:6 mortar? A. About 25 N/mm2 B. About 50 N/mm2 C. About 0.5 N/mm2 D. About 3-5 N/mm2 Answer: D. 1:6 mortar gives roughly 3-5 N/mm2 at 28 days. (Key point: Strength) ## Close variants set in other exams - [Detailed specification of cement sand mortar 1:4](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Adetailed-spec-cs-mortar-1-4) — Construction Management, chapter 12, asked 2× ## Related in Construction Management - [Detailed specification of brick work in 1:4 mortar](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Adetailed-spec-brick-1-4) — Construction Management, chapter 12, asked 5× - [Detailed specification of brick work in 1:6 mortar](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Adetailed-spec-brick-1-6) — Construction Management, chapter 12, asked 5× - [Detailed specification of cement plaster 1:4](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Adetailed-spec-plaster-1-4) — Construction Management, chapter 12 - [Detailed specification of stone masonry in 1:6 mortar](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Adetailed-spec-stone-masonry-1-6) — Construction Management, chapter 12 - [Types of specification: general and detailed](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Aspec-types-general-detailed) — Construction Management, chapter 12, asked 7× - [Detailed specification of RCC M20 column](https://www.bctengineer.com/question.md?key=semester_8%2Fconstruction_management%3Adetailed-spec-rcc-m20-column) — Construction Management, chapter 12 ## Related in other subjects - [Mortar properties; cement and sand for 10 cum](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Amortar-quantity-10cum) — Building Technology, chapter 3 - [Preparing cement mortar by manual process](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Amortar-prep-manual) — Building Technology, chapter 3, asked 2×