Investigation of Old Building Concrete (4)

The forth investigation of the old concrete was carried out on two buildings. The age of the buildings were 40 and 43 years. The main results obtained on the properties of the concrete were as follows; 1) The depth of alkali-lost in concrete was found to be 22-24 mm at the outside of the building. This value is close to the one estimated from the ever presented formula. In the inside，however，the value was twice as much. 2) The compressive strength in prism specimens cut out from structural members was 108-268 kg/㎠. The wide range of the values indicates the level of quality controle at the time. 3) The mixing proportion of cement，f ine and coarse aggregate was evaluated as 1: 3-3.2 : 2.6-6 in weight from the resu1tso f 700℃ heating followed by hydrochloric acid treatment of the concrete