Water Resources Planning Branch, WRA, MOEAWater Resources Planning Branch, WRA, MOEA

Background and Origin

The Roller Compacted Concrete (RCC) is a slump-free concrete. With the feature of simple, fast and economical working, it is very suitable for being applied in the areas where rapid construction is required, particularly in island-type areas where construction periods are extended due to the raining and damp environment. As the technique of RCC develops, there are increasing dams in the world being constructed by this technique. To be useful to the future planning of water resources and as one of the options of dam type, the Section conducted the tests concerning RCC mix proportion, compressive strength, workability and water permeability in northern Taiwan, along with roller compaction test on-site to understand the workability and mechanical properties of RCC.

Works and details

1. Gathering and summarizing RCC attributes and results of Taiwan’s and overseas research.
2. Tests of aggregate material properties: specific weight, water absorption, soundness test, Los Angeles abrasion test and minimum porosity proportion test.
3. Concrete properties test, including: tests of workability, porosity, compressive strength, permeability coefficient. Caused by RCC is no slump concrete types, it workability need to carry by the particular instrument which named VB test, the equipment photos followed with Figure 1 and 2.
4. Formulation of mix proportions as basis for on-site roller compaction tests.
5. Field compaction test to check the construction capacity showed in Figure 3.
6. Concrete property tests, including : workability measurement and compressive strength test
7. Presentation of mix proportion design and assessment of workability and economics as reference for related projects

Research results

1. Quantity of cementing material used:

   When the quantity of cementing material used per cubic meter exceeds 210 Kg, the compressive strength can reach 210 Kg/cm².

2. Permeability:

   When the quantity of cementing material used per cubic meter is about 200 Kg and the water-cementitious material ratio is between 0.5-0.6, the porosity is less than 3% and the permeability coefficient, k, is less than 1×10-6 cm/sec as well, which coefficient approximates the requirement of earth-rockfill dams for core wall materials.

3. Roller compaction test:

   With the designed strength set at a 28-day compressive strength of 210 Kg/cm², the designed target can be met when 8-10 times of roller compaction is done.

4. Cost effectiveness and increased workable days

   To understand the difference in building cost and workability between RCC and common concrete, the dam upstream of Shuangxi Reservoir was used as case study for analysis. The analytic results suggested that the cost per cubic meter is about NT$2,723, about 78% of the cost of conventional concrete. The result of working day analysis showed that on average, the number of working days per year increases by 30.