CChemistryMathematicsS3 to S6Building construction

Construction lab: mix, cure and test concrete

Every school, house and bridge needs good concrete. Mix it, cure it, crush test cubes and find the recipe that is strong enough and not too expensive.

▶ Start the lab 🧠 Questions 📄 My report

LevelS3 to S6 (and TVET)

TimeAbout 40 min

You useRatios, pressure, volume, costs

PriceFree: no account

🎯 Aim

To investigate how the mix, the water–cement ratio and curing affect the strength of concrete, and to calculate materials and costs.

You will learn to

Calculate strength = load ÷ area.
Explain the effect of water and curing (hydration).
Use ratios to calculate materials for a volume of concrete.
Estimate the cost of a concrete slab.

🧭 What to do

Choose 1 : 2 : 4 (normal), w/c 0.55 and 28 days. Tap Crush the cube.
Change the Water–cement ratio and crush again.
Change the Age of the cube and the Curing.
Read the materials and cost for 1 m³.
Answer the questions with the class data.
Write your conclusion and download your lab report.

🔬 Lab bench

📋 The data

Failure loads of 150 mm cubes of a 1 : 2 : 4 mix with different water–cement ratios and ages.

🧠 Investigate: answer from the data

Type your answer and tap Check. Use 💡 Hint first; open the method only when you are stuck.

📄 My lab report

Your report collects the aim, your data table, the graphs, your answers and your conclusion. It is made on your phone or computer: nothing is sent to anyone.

My conclusion

Check your conclusion

Strength = failure load ÷ area of the cube. Less water (a lower water–cement ratio) gives stronger concrete, as long as it can still be placed and compacted. Concrete gains strength over 28 days because cement reacts with water (hydration), so it must be kept wet; dried in the sun it is much weaker. A 1 : 2 : 4 mix needs about 6–7 bags of cement per cubic metre.

➕ Get more from this experiment

📝 Free

Print the worksheet (button above), download the data, and save your report. Teachers can project this page in class.

📦 Premium Lab Pack

1 000 RWF

Practical worksheet: make small concrete cubes at school
Materials and costing problems
Teacher guide and answer key
Exam-style questions with marking scheme

See the pack

👩‍🏫 For teachers

Use it as a practical when apparatus is missing, as homework, or as a project. Free lesson plans help you plan, teach and assess.

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