TREMIE METHOD

 

Tremie Method of Concreting

Table of Contents:

1. What is tremie.

2. Workability of concrete.

3. Tremie concrete.

4. Tremie method.

5. Tremie pipe equipments.

6. Tremie concrete mix.

A tremie is used to pour concrete underwater in a way that avoids washout of cement from the mix due to turbulent water contact with the concrete while it is flowing. ... Builders use tremie methods for materials other than concrete, and for industries other than construction.

Workability of concrete:

Workability of concrete can be improved by more cement and water with proper water cement ratio. ... Explanation: Workability of concrete is inversely proportional to the Water cement ratio because if the amount of w/c ratio increases, workability decreases.

Tremie Concrete:

It refers to placement by gravity feed from a hopper through a vertical pipe extending for above the surface to the underwater floor. As concrete flows from the bottom of the pipe, more is added to the hopper so that the tremie pipe is continuously charged with fresh mix.

The Major aim i underwater concreting is to place the mix in its final position with as little disturbance as possible. A mix with sufficient slump to used in tremie should be highly workable.

It can be seen in the following table that the test for highly workable cncrete is flow table test.

Workability Test	Degree of Workability
Flow table test	Very high (Slump value >150mm)
Vee-Bee consistometer	Very low (Slump value <50mm)
Compaction factor test	Low to medium (Slump value 25-100mm)
Slump test	Medium to high (Slump value 50-150mm)

Hence the measurement of workability for a tremie concrete will be appropriate by determination of its flow value.

Tremie Method: There are no of methods used in tremie concreting which is stated as below.

1- Build

2- Place

3- Locate

4- Pour

5- Deconstruct

Tremie Pipe equipment: tremie pipe equipment used in concreting are stated below.

1. Concreting tremie pipe.

2. Tremie hopper.

3. Tremie socket.

4. Tremie funnel.

5. Tremie concrete hopper plug.

Tremie Concrete mix:

•Special mix with plasticizer

•High slump concrete with set retarders

•Smaller aggregate sizes

•Four-hour workability

•Designed for placement under water via tremie pipe.

Underwater Concrete Mixes:

•Structural concrete

•Coarse Aggregate: Gravel of 3/4” max. size.

Use 50-55 % of the total aggregate by weight.

•Fine Aggregate: Sand, 45-50% of the total

aggregate by weight.

•Cement:Type II ASTM(moderate heat of hydration),

600 lbs/yd3.

•Pozzolans: ASTM 616 Type N or F, 100 lbs/ yd3.

•Water/Cement Ratio: 0.42 (0.45 Maximum).

•Water-Reducing Admixture(preferably it is also

plasticizer): Do not use superplasticizers.

•Air-Entrainment Admixtures: To give 6% total air.

•Retarding Admixture: To increase setting time to

4-24 hours, as required.

•Slump: 6 1/2 in. ± 1 in.

•This mix will develop compressive strength in the

range of 5,600 – 7,000 psi at 28 days.

• It will flow out on a slope of 6:1 to 8:1 horizontal/

vertical and, if properly placed, should give

nominal segregation and laitance.