---
title: "Fundamental concepts of concrete mix design"
subject: "Concrete Technology and Masonry Structure"
chapter: 3
key: "semester_5/concrete_technology_and_masonry_structure:mix-design-fundamental-concepts"
source: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/mix-design-fundamental-concepts
site: BCT Engineering
---

# Fundamental concepts of concrete mix design

Concrete Technology and Masonry Structure · Chapter 3: Mix design of concrete and property of green concrete

- Asked in: 2064 Jestha (old course)
- Video: [Concrete Mix Design | Part-01 | Technical Civil](https://www.youtube.com/watch?v=eJ1kIO4JfSo) — Technical Civil
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/mix-design-fundamental-concepts
- Whole chapter: https://www.bctengineer.com/md/semester_5/concrete_technology_and_masonry_structure/chapter-3

## Question

Explain in brief the fundamental concepts that are commonly adopted in concrete mix design.

## Short answer

Mix design selects proportions for workability, strength, durability and economy. Key concepts: Abrams' w/c law (lower w/c gives higher strength), target mean strength = fck + 1.65 s, durability limits on max w/c and min cement content, water content for workability depends on aggregate, absolute volume method (sum of volumes = 1 m³), and trial mixes with adjustments.

## Answer

**Concrete mix design** is the selection of the proportions of cement, water, fine and coarse aggregate (and admixtures) to produce concrete with the required workability when fresh, the required strength and durability when hardened, and the lowest cost. The following fundamental concepts are commonly adopted:

1. **Abrams' water-cement ratio law**: strength is governed by the w/c ratio ($f = A/B^{w/c}$); a lower w/c ratio gives higher strength and durability. It is the basis of all methods.
2. **Water content for workability**: the water required depends on the workability (slump), maximum size, shape and grading of aggregate and air content (tables or charts); cement content = water / (w/c ratio).
3. **Target mean strength** is higher than the characteristic strength: $f_{target} = f_{ck} + k\,s$ ($k = 1.65$ in IS 10262), allowing for variation (standard deviation $s$) so that not more than 5% of results fall below $f_{ck}$.
4. **Durability requirements**: limits on maximum w/c ratio and minimum cement content for the exposure condition (IS 456 Table 5), which may override the strength requirement.
5. **Aggregate grading and packing**: the volume of coarse aggregate and the proportion of fine aggregate are chosen for a well-packed, workable and economical mix (by fineness modulus or grading zone).
6. **Absolute volume method**: the total volume of all ingredients (each as mass / specific gravity) plus air equals 1 m$^3$.
7. **Trial mixes and adjustments**: laboratory trial batches are made to check slump and strength; corrections for moisture, absorption and bulking are applied at site.
8. **Economy**: use the minimum cement that meets the requirements, the maximum practicable aggregate size, and admixtures.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is the role of Abrams' w/c law in mix design?
   A. It sets aggregate size
   B. It determines the cost
   C. It fixes sand zone
   D. It links strength to w/c and is the basis of all methods
   Answer: D. Strength is governed by w/c, which is the basis of all mix design methods. (Key point: Abrams' law role)

2. In IS 10262, the target mean strength is
   A. fck + 1.65 s
   B. fck - 1.65 s
   C. fck
   D. fck + 0.825 s
   Answer: A. Target strength = fck + 1.65 s so that not more than 5% of results fall below fck. (Key point: Target strength)

3. How is cement content found once water content and w/c are known?
   A. water x w/c
   B. water / (w/c)
   C. water + w/c
   D. w/c / water
   Answer: B. Cement = water / (w/c). (Key point: Cement content)

4. The absolute volume method states that
   A. total mass equals 1000 kg
   B. only aggregates fill 1 m3
   C. the sum of volumes (mass/SG) of all ingredients plus air equals 1 m3
   D. cement volume equals water volume
   Answer: C. All ingredient volumes plus air must add to 1 m3. (Key point: Absolute volume)

## Related in Concrete Technology and Masonry Structure

- [ACI mix design for M35 concrete (numerical)](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aaci-mix-design-m35-numerical) — Concrete Technology and Masonry Structure, chapter 3, asked 2×
- [ACI mix design for M25 concrete (numerical)](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aaci-mix-design-m25-numerical) — Concrete Technology and Masonry Structure, chapter 3, asked 2×
- [ACI mix design for 25 MPa concrete (numerical)](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aaci-mix-design-25mpa-numerical) — Concrete Technology and Masonry Structure, chapter 3
- [DOE mix design for M25 concrete (numerical)](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Adoe-mix-design-m25-numerical) — Concrete Technology and Masonry Structure, chapter 3
- [ACI method of mix design steps](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aaci-mix-design-steps) — Concrete Technology and Masonry Structure, chapter 3, asked 9×
- [DOE method of mix design steps](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Adoe-mix-design-steps) — Concrete Technology and Masonry Structure, chapter 3, asked 8×

## Related in other subjects

- [Fundamental concepts and principles of mechanics](https://www.bctengineer.com/question.md?key=semester_1%2Fapplied_mechanics%3Amechanics-fundamental-concepts-principles) — Applied Mechanics, chapter 1, asked 4×
- [Site engineer uses weaker mortar and concrete mix](https://www.bctengineer.com/question.md?key=semester_8%2Fengineering_professional_practice%3Amortar-ratio-friend-silence) — Engineering Professional Practice, chapter 7
- [Marshall method of bituminous mix design](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Amarshall-mix-design) — Transportation Engineering I, chapter 6, asked 9×
- [Cloud and grid computing concepts](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Acloud-grid-computing) — Internet and Intranet, chapter 7, asked 2×