Dowel Bar

Dowel is a tool that is used to connect the slab by slab, slab concrete with asphalt pavement, which serves to lock the plate edges and reduce the occurrence of crack between the concrete.

• First type is dowel bar connection. This dowel has two types of connections made from a plain which is made of steel dowel connections and the connection end of the dowel. Dowel connections installed in the middle of slab concrete, while the connection is installed at the edge of the dowel end slab concrete. The difference between them lies in the length of anti-rust coating.  

• Second type is dowel with a tie bar which serves to lock the top edge slab concrete (end). The dowel is using steel threaded connections without grease.

• Third type is dowel with the crack inducer that functions to reduce the occurrence of cracks in slab concrete and between slab concrete.

• Fourth type is dowel as expansion joint.

• Fifth type is connection with the thickening of the edge of the tie bar. This connection is used on the plate with the transition between the concrete pavement with asphalt pavement.

Self Compacting Concrete on Suramadu Approach Bridge Project

Initially the Suramadu Bridge Approach Project, the basis for planning to use concrete pile bore under water. But in practice, because the condition of pile bore so deep, the weight of the concrete itself will push the concrete. Fresh concrete will be crushed because the pressure from the weight and meet the formwork. So generally bore pile of concrete near the criteria of SCC though not a concrete SCC.

 

Self-Compacting Concrete (SCC) is a type of concrete that does not require the placement of vibration. SCC can flow due to their own weight and put itself in the formwork with a good compaction. SCC began to be used because of the need for concrete that has durability and high strength continues to grow. Many studies have been conducted to determine the standards for SCC, but until now has not obtained standard for SCC. However, the main problem of SCC has resolved most of the preparation method of mix-design and workmanship field testing method that can reach the SCC.

There are some conditions on the site that by using the SCC would be more helpful than the implementation using ordinary concrete. Those are:

a. Concreting carried out in the water 

Condition that the project was in the middle of the ocean into consideration for the use of concrete that requires no vibration. Because to prevent segregation of concrete required vibration in concrete placement or compaction. Bore pile conditions that has the depth to 80m below the water surface is not possible to be done on concrete vibration. The best solution is to use SCC, because it can flows with their own weight and can meet all of the formwork with a good compression, even int the formwork are tightly spaced reinforcement though.

b. Reduce the use of workforce

By using the SCC, the amount of labor used will be reduced, because the SCC can flow evenly the weight of their own without the help of many workers. But the special training necessary in the existing workforce to create the appropriate mix of standard SCC.

The objectives of SCC:

a. Fast implementation

b. Quality homogeneous

c. Reducing human involvement in the case of compaction

d. Avoiding brittle due to concreting mistake

e. Good for location difficult to reach, even though meeting with tight reinforcement.