--- title: "Soundness test of aggregate" subject: "Transportation Engineering I" chapter: 6 key: "semester_6/transportation_engineering_i:aggregate-soundness-test" source: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/aggregate-soundness-test site: BCT Engineering --- # Soundness test of aggregate Transportation Engineering I · Chapter 6: Highway Materials - Asked in: 2081 Ashwin, 5 marks - Video: [Soundness Test Of Coarse Aggregate In Urdu/Hindi(ASTM C88)](https://www.youtube.com/watch?v=4OY03u4B4t4) — Material Testing - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/aggregate-soundness-test - Whole chapter: https://www.bctengineer.com/md/semester_6/transportation_engineering_i/chapter-6 ## Question Describe the laboratory procedure of determining soundness of aggregate and mention its significance. ## Short answer Aggregate fractions are alternately immersed in saturated sodium sulphate for 16–18 h and oven-dried, five cycles. After washing and sieving, the weight loss is computed. The test indicates weathering resistance; losses should not exceed 12% with sodium sulphate or 18% with magnesium sulphate. ## Answer The **soundness test** (IS:2386 Part V) measures the resistance of aggregate to disintegration by weathering, such as freezing and thawing, wetting and drying, and salt crystallisation. It uses repeated immersion in a saturated solution of sodium sulphate or magnesium sulphate. #### Apparatus Wire-mesh baskets, containers for the solution, IS sieves (as per the aggregate size), oven (105-110 degrees C), balance and a hydrometer. Solution: saturated sodium sulphate with specific gravity 1.151 to 1.174 (or magnesium sulphate, 1.295 to 1.308). #### Procedure 1. Wash and oven-dry the aggregate, separate it into the standard fractions and weigh the specified amount of each (for coarse aggregate, for example, 300 g of 10-4.75 mm, 1000 g of 20-10 mm and 1500 g of 40-20 mm; for fine aggregate, 100 g of each fraction). 2. Immerse the sample in the solution for **16 to 18 hours** at 27 +/- 1 degrees C, so that the solution covers it by at least 15 mm. 3. Remove it, drain for 15 minutes, and **dry it in the oven at 105-110 degrees C** to constant weight (a drying period of about 4 to 8 hours); cool to room temperature. 4. This forms **one cycle**; repeat the cycle **five times**. 5. After the last cycle, wash the sample free of salt (checked with the barium chloride test), dry it, and sieve each fraction on the sieve on which it was originally retained. 6. Weigh the retained material and find the loss. $$ \text{Soundness loss}\ (\%) = \frac{W_1 - W_2}{W_1}\times 100 $$ where $W_1$ = initial weight and $W_2$ = final retained weight. The weighted average loss of all fractions is reported. #### Significance - It shows the durability of aggregate under climatic changes; it is useful in places with freezing weather (the hills and high-altitude areas of Nepal). - Limits: loss not more than **12% with sodium sulphate** and **18% with magnesium sulphate** after five cycles (IS/IRC/NRS 2070). ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What does the soundness test measure? A. Resistance to sudden impact B. Resistance to abrasion C. Resistance to disintegration by weathering such as freeze-thaw and wetting-drying D. Shape of particles Answer: C. It uses sulphate solution to simulate weathering. (Key point: Purpose) 2. What does one cycle consist of? A. Soaking in water for four days B. 15 blows of hammer then sieving C. Rotation for 500 revolutions D. Immersion in sulphate solution for 16-18 hours, then oven drying at 105-110 degrees C Answer: D. The cycle is repeated five times. (Key point: Cycle) 3. How many cycles are done? A. Five B. One C. Fifteen D. Five hundred Answer: A. Five cycles of immersion and drying. (Key point: Number of cycles) 4. Which limit applies after five cycles with sodium sulphate? A. Loss not more than 30% B. Loss not more than 12% C. Loss at least 50% D. Loss not more than 1% Answer: B. 12% for sodium sulphate and 18% for magnesium sulphate. (Key point: Limits) ## Close variants set in other exams - [Hardness test of aggregate](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Ahardness-test) — Transportation Engineering I, chapter 6, asked 3× ## Related in Transportation Engineering I - [Aggregate crushing value test](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Acrushing-value) — Transportation Engineering I, chapter 6, asked 7× - [Aggregate impact value test](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Aimpact-value) — Transportation Engineering I, chapter 6, asked 3× - [Marshall stability test procedure](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Amarshall-stability-test) — Transportation Engineering I, chapter 6, asked 3× - [Penetration test of bitumen](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Apenetration-test) — Transportation Engineering I, chapter 6, asked 6× - [Hardness, toughness and aggregate blend](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Ahardness-toughness-blend) — Transportation Engineering I, chapter 6 - [Los Angeles abrasion test](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Ala-abrasion) — Transportation Engineering I, chapter 6, asked 10× ## Related in other subjects - [Soundness test of cement and procedure](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acement-soundness-test-procedure) — Civil Engineering Materials, chapter 5 - [Procedure: test of significance of mean](https://www.bctengineer.com/question.md?key=semester_5%2Fprobability_and_statistics%3Atest-of-significance-mean-procedure) — Probability and Statistics, chapter 6 - [Soundness of aggregate and its measurement](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Asoundness-of-aggregate) — Concrete Technology and Masonry Structure, chapter 1, asked 2× - [Why soundness test of cement](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Awhy-soundness-test-cement) — Civil Engineering Materials, chapter 5