Cast Beam Structures Set
Make your own cast beams which look like pre-stressed concrete beams. Test them and you'll find they perform like them, too. These beams are cast with a mixture of sand and plaster of Paris (not included). The rebar is made of the same plastic used for the I-beams. Students can explore how the strength of the beam is affected by the amount of tension put on the rebar, the mixture of sand and plaster of Paris, or using one or two rebar.

Displacement of beam is measured as load is increased.

Both the tension fixture and the test fixture can be built concurrently with this set.

The graph of hanging mass versus displacement shows the relative strengths of three beams: One cast beam made with no pre-load; one cast beam made with 60 N of pre-load; and one normal plastic I-beam. Notice that the traces for the cast beams show discontinuities when the beams cracked. Also notice that the pre-loaded cast beam is stronger than the plastic I-beam until the cast beam cracks.

Step 1: The rebar with connecting ends snaps into the plastic mold.

Step 2: Insert rebar into tensioning apparatus and pour a mixture of sand and plaster of Paris into the mold.

Step 3: After it dries, it is easy to remove the flexible plastic mold from the cast beam.

Measure Young's Modulus for the rebar.

The connecting ends can be cut off from the rebar allowing the rebar to fit into the Stress/Strain Apparatus (AP-8213).