LIGHT-WEIGHT CONCRETE.

Taihape Daily Times, 15 October 1919, Page 5

LIGHT-WEIGHT CONCRETE.

' Considerable interest has been crea‘-r ed among engineers in Britain in 'a lightweight. concrete employed in the construction. of ‘meinfprce‘d, .con_£cret‘_e vessels, of largeitonnage, building "in: America for the United States Government. This concrete wa‘s~adop-ted for this form of construction after an extensive series of tests on coneretes of all kinds carried out by the United States’ Shipping Be«ard.- The tests proved that a concrete eminently'suitable for use in reinforced concrete structures, and having a much lower specific gravity less than unity. It is .Well known that the strength of con_crete depends primarily ‘on the .stl'ength_. of :the binding material, and on 'it‘§ adhesion to the larger aggregate. This adhesion is greater to a nrarkcd de-. gree with the light aggregate under discussion owing to its greater surface area. To" produce this increased adhesion a larger proportion of cement must necessary be introduced, resulting in whajti's_comnlonly known as a rich mixture; and, 'e‘o~nseque-nt‘.-131, a :more costly material. However, says the British journal, Engineering, its adops tion in certain reinforced concrete structures nmst undoubtedly prove economical. Large span reinforced concrete bridges and similar works are at present handie"apped owing to the weight of concrete or: j-loyed in their construction. and it is ".2 cases of this nature that the light aggregate will: serve to overcome this diffieulty to a. large -degree.