--- title: "First class brickwork in 1:6 mortar numerical" subject: "Building Technology" chapter: 3 key: "semester_6/building_technology:mortar-first-class-1to6" source: https://www.bctengineer.com/q/semester_6/building_technology/mortar-first-class-1to6 site: BCT Engineering --- # First class brickwork in 1:6 mortar numerical Building Technology · Chapter 3: Mortars & Masonry works - Asked in: 2070 Bhadra, 3+5 marks - Video: [Materials Calculation for first class brick (19×9×9cm.) work with 1:6 cement mortar.](https://www.youtube.com/watch?v=f0PSw9dKpeM) — MANOJ VARSHANEY TUTORIALS - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/building_technology/mortar-first-class-1to6 - Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-3 ## Question What is first class brick work in 1:6 cement sand mortar? Calculate materials for 10 cum brick work except bricks. ## Short answer First class brickwork uses well-burnt, uniform bricks (strength ≥10 N/mm²) with 1:6 cement-sand mortar, proper bond and 10 mm joints. For 10 m³ brickwork excluding bricks: cement 0.451 m³ (13 bags of 50 kg) and sand 2.705 m³. ## Answer #### First class brickwork in 1:6 cement-sand mortar First class brickwork is masonry built with **first class bricks** (well burnt, uniform in size, shape and colour, free from cracks, with a crushing strength of not less than about 10 N/mm² and water absorption of not more than 15-20%), laid in **cement-sand mortar 1:6** in a proper bond (English or Flemish), with 10 mm joints, full mortar beds, staggered vertical joints, bricks soaked before laying, and the wall kept wet for curing for at least 7 days. It is used for the important walls of buildings. #### Materials for 10 cum (10 m³) brickwork except bricks **Given:** brickwork volume $= 10\ \text{m}^3$; brick size 57 mm x 115 mm x 240 mm (actual size, without mortar); mortar joint $= 10$ mm; mortar 1:6 (cement : sand). **Step 1: Size of brick with mortar** $$ (0.25 \times 0.125 \times 0.067) = 0.002094\ \text{m}^3 $$ **Step 2: Number of bricks** $$ N = \frac{10}{0.002094} = 4776.1 \approx 4777\ \text{bricks} $$ **Step 3: Volume of bricks without mortar** $$ 4777 \times 0.24 \times 0.115 \times 0.057 = 7.515\ \text{m}^3 $$ **Step 4: Wet volume of mortar** $$ 10 - 7.515 = 2.485\ \text{m}^3 $$ **Step 5: Dry volume of mortar** (add 27% for dry bulk, voids in sand, wastage and shrinkage) $$ 2.485 \times 1.27 = 3.156\ \text{m}^3 $$ **Step 6: Cement and sand** for 1:6 (sum of ratio $= 7$) $$ \text{Cement} = \frac{1}{7} \times 3.156 = 0.451\ \text{m}^3 = 649\ \text{kg} \approx 13\ \text{bags (50 kg, 0.0347 m}^3\text{ each)} $$ $$ \text{Sand} = \frac{6}{7} \times 3.156 = 2.705\ \text{m}^3 $$ **Answer: Cement = 0.451 m³ (about 13 bags of 50 kg); sand = 2.7 m³.** ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which set describes first class bricks used in first class brickwork? A. Sun-dried bricks with straw B. Over-burnt, vitrified, distorted bricks C. Well burnt, uniform in size and shape, crushing strength about 10 N/mm^2 or more D. Under-burnt, irregular, absorbing over 25% water Answer: C. First class bricks are well burnt, uniform, crack free, strong and with low water absorption. (Key point: First class brick properties) 2. Which practice belongs to first class brickwork? A. Joints 25 mm thick for speed B. Continuous vertical joints C. Bricks soaked before laying, staggered vertical joints, cured at least 7 days D. Dry bricks laid without soaking Answer: C. Proper bond, full 10 mm joints, soaking and curing give the quality required. (Key point: Practice in first class work) 3. For 10 m^3 brickwork, dry mortar is 3.156 m^3. What is the cement volume in 1:6 mix? A. 0.451 m^3 B. 0.526 m^3 cement with 2.63 m^3 sand C. 0.789 m^3 D. 0.526 m^3 Answer: A. Sum of ratio = 7, so cement = 3.156/7 = 0.451 m^3 and sand = 6/7 x 3.156 = 2.705 m^3. (Key point: Mortar for 10 m^3, 1:6) 4. Number of bricks 4777 occupy 7.515 m^3. What is the wet mortar volume? A. 7.515 m^3 B. 2.485 m^3 C. 3.156 m^3 D. 12.515 m^3 Answer: B. Wet mortar = 10 - 7.515 = 2.485 m^3; the 1.27 factor then gives the dry volume. 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