Methods of Transportation of Concrete

Definition:

Transporting the concrete mix is defined as the transferring of concrete from the mixing plant to the construction site. The main objective in transporting concrete is to ensure that the water-cement ratio, slump or consistency, air content, and homogeneity are not modified from their intended states. Concrete produced from a mixer is required to be transported to the forms for placement. This handling may producesegregation and loss of slump, if the distance is long.

That is further defined in different ways like:

混凝土运输方法

运输和解放军的方法cing concrete which are used widely, are:

1. 通过短斜槽直接放电
2. By barrows:
   1. Wheel burrows and handcarts.
   2. 电力兵话或电源网站
3. Dumpers and trucks (agitating or non agitation)
4. Monorail system
5. Elevating towers and hoists
6. 跳过由起重机或架空电缆的方式操作
7. 皮带输送机和动臂输送机，可以在小型位置使用
8. TREMIE.
9. 具体的pumps and pneumatic placers
10. Any combination of above.

因此，现在详细讨论运输方法：

a. Direct Discharge, Manual Transport in Containers and short chutes

• Free fall of concrete over a height of 2 m should be avoided.
• 具有适当的下端处理的短斜槽（混凝土通过通过漏斗形管道或落水槽通过下端重新混合，使混凝土混合是可行的并且凝聚力易于使用和经济。
• Chutes which are Metallic, half round in section, stiffened at places may last to handle about 1500m³of concrete.
• 长腿不太理想，因为它们具有在混凝土混合物中引起偏析的趋势。

湾洞穴

• 手动轮钻有高达80千克的混凝土（2.5 CU-FT）。它用于长水平距离。
• Power burrows' capacity is up to 800 kg and can be used for horizontal distances upto 300m. They can also be used to haul concrete to a gradient of 20%. Part of the mixer is single burrow. If you take a part of concrete in one burrow and the other part of concrete in another burrow, it might be problematic because uniformity of concrete will be disturbed.

C。倾销器和卡车

• 倾销器和卡车（水平运输）用于长时间。由于地面上的颠簸，普通卡车和折料倾向于在运输过程中引起混凝土的偏析。

d. Monorail system

• 单轨系统需要轨道，包括安装在单轨轨道上的电动车，可以以80-90米/分钟的速度移动。这种轨道用于隧道，水坝和其他这种结构的建造。
• 由于在每个轨道接头上的马车中的混凝土颠簸，混凝土的分离可能会发生。因此，湿混合通常不适合单轨运输。当轨道轨道在板式形式上运行时，马车可以直接在表格上排出。

e. Elevating towers and hoists (Vertical transport)

• 升降塔用于升降混凝土桶，可以使用滑槽或其他方式分布，例如诸如兵话等。这种运输可用于construction of multi-storey building, bridges and towers.
• 升降机在类似的原则上运作;悬臂平台葫芦沿钢格桅杆操作。
• 具体的skip can be used directly, that can till and discharge the concrete on some distribution system.

F。起重机和电缆方式（二维或三维运输）

起重机和索道用于运输的三维目的。它可以用于混凝土将在谷或一些障碍物中转移混凝土或像河流，海或道路的障碍物的项目中。起重机也可用于各种高层建筑和许多其他类型的结构。

• 起重机或缆绳可用于三维混凝土传输。电缆方式可用于河谷项目;各种类型的起重机在拥挤的地点的高层建筑施工中也是有用的。
• Depending upon the site, cranes may be any one of the following types such as derrick crane, tower crane, crawler mounted, or wheel mounted, or a hydraulic crane.
• 选择起重机的主要考虑因素是高度和操作半径。

G。皮带输送机

Belt conveyor is used for very short distance, not for large distances

• Belt conveyors needs small power.
• 放电可以高达115 CU-M /小时在窄带上，选择起重机的主要考虑是高度和操作半径。
• 通过带式输送机也可以通过有限的30度输送混凝土。
• For wet mixes the capacity of the belt is reduced as the inclination through which concrete can be lifted is also lowered.
• It is recommended that low slump concrete be used for slower moving belts and higher slump concrete by faster moving belts.
• 具体的tends to segregate in steep inclines as the belt passes over the rollers, this problem is less acute in drier mixes, and segregation at the discharge point may be avoided using proper hopper and the chute arrangement.
• 在机器击穿的情况下，皮带中的大量混凝土需要通过其他方式除去，并将皮带清洁并洗涤。
• 他们的建立初始成本也很高。

具体的Buckets or Skips

The buckets and skips are very common equipments. They are used together with many things. Some different types of buckets which are used in concrete transporting are:

1. Roll-over and
2. 恒高度类型

• 跳过的容量可能会计为0.2米³in small jobs to 10m³. It depends upon the size.
• The control of discharges is obtained from good design in terms of shape of the gate for proper flow. The ease of filling and resistance to wear and tear are other aspects of good design.
• Buckets are also used for under water concreting.

Transportation of Concrete in Under Water Concreting:

在水上放置混凝土造成一些问题，因为混凝土不能压实，混凝土可以与水混合。每当，在水连接下可能的情况时，应避免。为了克服上述问题，混凝土必须自压制和湿足够湿，以便在其自身的重量下流动，并且必须放置在最小干扰。

在水下运输混凝土的方法

1. Pre packed or grouted concrete
2. Termite or buckets
3. 泵送
4. Dumping by bags

Each of this method is used in different situation. First let look at buckets, buckets can be used through cranes and that sort of equipment. It is filled up from top and lifted off up, when its reach the ground where it is supposed to discharge, open the screws at the bottom, when buckets is lifted up more so the scot is actually on the ground and concrete is discharged with in scot which does not immediately come into water, this is one common way to use under water concrete.

TREMIE.

The most common way to use concrete under water is tremie; this is done by tremie pipe. There are 2 retaining walls beside the tremie pipe. This pipe is made piece by piece, and concrete is discharged at the bottom. Only the cement of top surface will contact with water, rest of the concrete will not contact with the water. The other method which can be used for mixing and can transport over a large distance is through "ready mixed concrete". This is very much used where the area is congested and one cannot mix the concrete on site.