Construction Materials

Laboratory Portfolio (2019-20)

Contents

1 Carbon content of steel 2

2 Making concrete 4

3 Aggregates 5

4 Steel reinforcement 6

5 Timber 7

6 Set concrete 8

7 Masonry 9

1 Carbon content of steel

Based on your laboratory test results and further reading:

1. plot the stress-strain graph for the three metals
2. define the ultimate, yield and fatigue stress levels for the three metals
3. define the Young’s modulus for the three metals
4. plot the variation of yield and tensile strength with carbon content
5. plot the variation of ductility with carbon content.

Tips

• The stress – strain graph with be similar to the load-extension graph.
• 0.001 can be expressed as a percentage as 0.1%.
• To find the Young’s Modulus you can either use the 0.1% strain or you can pick two points within the elastic region of the stress – strain curve and approximate the difference in stress and strain values between them (E = Difference in stress / Difference in strain).

2 Making concrete

1. Does the methodology used in the laboratory for the slump test comply with BS EN 12350-2:2019 Testing fresh concrete Part 2: Slump-test?

1. Do the concrete cube moulds comply with EN 12390-1:2012 Testing hardened concrete Part 1: Shape, dimensions and other requirements for specimens and moulds?
2. Does the methodology used in the laboratory for preparing the concrete cure comply with BS EN 12390-2:2019 Testing hardened concrete Part 2: Making and curing specimens for strength testing?

Comment on meaningful deviations from the standard method and how this may affect the result. 

3 Aggregates

Provide hand drawn sketches (scanned in) of aggregate grading curves for gap graded, well graded and poorly graded aggregate based on your experimental data. Which describes the aggregates tested the most closely?

4 Steel reinforcement

1. Using BS 4449:2005+A3:2016 answer the following questions:

• Is the equivalent diameter within 8% of the nominal diameter?

YES / NO

• Is the ‘mass per metre’ within the range specified by table 7 and Clause 7.3.2?

YES / NO

• Are the yield strength, stress ratio and total elongation at maximum force above the specified value in table 4?

YES / NO

1. The subgrades A, B, and C in Grade 500 can be identified by the rib pattern. These are illustrated in Figures 2-4 (Clause 10.2). Grade 250 bars are plain. Why are ribs required for bars with a higher yield stress?

5 Timber

1. Which specimen had the highest strength to weight ratio?

1. Which specimen had the lowest strength to weight ratio?
2. What was the average strength to weight ratio?
3. A prefabricated disaster relief shelter is being designed. It will be made of timber, or a timber product. Propose a timber or timber based product for the shelter and support your proposal by the laboratory test results and any other sources of information. Highlight three advantages and three disadvantages of the proposed timber product.

a) Proposed timber product:

b) Supportive evidence (x3):

• …
• …
• …

b) Advantages (x3):

• …
• …
• …

b) Disadvantages (x3):

• …
• …
• …

6 Set concrete

1. Does the methodology used for testing the concrete cubes comply with BS EN 12390-3:2019 Testing hardened concrete Part 3: Compressive strength of test specimens? Comment on meaningful deviations from the standard method and how this may affect the result.
2. From the laboratory data plot a graph of strength vs. age and insert it below. Provide three suggestions how the mix could be modified to enhance early age strength of the concrete.

7 Masonry

1. During the laboratory session were bricks tested according to the current standard described in BS EN 772-1:2011+A1:2015 (Section 7.2) or according to the old standard BS 3921:1985 (Section 7)?

Differences in testing procedures are described in BS EN 771-1:2011+A1:2015 (Section NA.3.6).

1. What is the difference in the strength of engineering bricks between the two standards? Why? See BS 3921:1985 (Table 4) and BS EN 771-1:2011+A1:2015 (Table NA.6).