136 



CEMENT AND CONCRETE 



since concrete is weak in tension, it is apparent that to make 

 the lower part of the beam as strong as the upper part, we 

 must imbed some material in the beam that is high in tensile 

 No Reinforcing 

 Brvkerf I4O* 



T 



"Rein forcing in Top 

 Broke-bit I4S* 



lZeinibrcing in Middle 

 Broke 



Reinforcing in botfon? 

 Broke at 8J '5* 



FIG. 144. Results of different placing of reinforcing, 

 strength. Steel is not only high in tensile strength, but its 

 co-efficient of expansion is the same as that of concrete, so a 

 strong bond between the two can be maintained. It must be 

 kept in mind that the steel must be placed as far as possible 

 from the neutral axis to be most effective. It must not be 

 placed too near the surface of the concrete. It must be kept 

 in mind, further, that in any reinforcing job, the steel must be 



