The purpose of this study is to investigate the mechanical property and carbonation resistance of concretes using lightweight aggregate coated surface finishing materials. In order to evaluate mechanical property and carbonation resistance of concrete, slump, air amount, air-dried unit volume weight, compressive strength, and carbonation
depth are tested.
The results of experimentation are as follow;
1) From the result of measuring absorbtion of aggregates, while absorbtion of non-coating lightweight aggregate measured 5.30%, that of coating lightweight aggregate measured 1.33~1.40%.
Therefore, coating lightweight aggregate by surface finishing materials has the outstanding reduction effect on absorbtion of lightweight aggregate.
2) In unit volume weight of concrete, air-dried unit volume weight of concrete using coating lightweight aggregate measured 1,739～1,806kg/m3. Therefore, it is found that when using coating lightweight aggregate, it is possible to be weight lightening as much as 1.37~5.02%, compared to concrete using non-coating lightweight aggregate.
3) When using coating aggregate, compressive strength measured 82.7~95.9% of compressive strength of concrete at 28 day using non-coating aggregate. It is found that compressive strength tend to decrease with coating lightweight aggregate. However, all concretes using coating lightweight aggregate except O-LWAC were satisfied with criteria on 28 day compressive strength suggested in KS. Thus, it is found that coating light weight aggregate is available as coarse aggregate for concrete.
4) From the result of measuring carbonation depth, in case of using water-repellent agent, carbonation depth reduced as much as 2.6~6.1%. On the other hand, when using polymer waterproof agent, carbonation depth reduced as much as 8.6~12.0%.
Consequently, for the improvement of carbonation resistance, polymer waterproof agent was more effective than water-repellent agent. Especially, epoxy showed the most outstanding performance.
5) From the result of estimating carbonation depth in ambient condition, using non-coating lightweight aggregate measured 52 year of persisting period, while using coating lightweight aggregate measured 55 year and over. Especially, it is found that although persisting period exceed 60 year, concrete using polymer waterproof agent is safe.
As mentioned above, it is found that lightweight aggregates coating by surface finishing materials has the benefit effects such as absorbtion reduction of lightweight aggregate and improvement of carbonation resistance.