The loss rate of ready- mixed concrete is the degree of loss of the main components in the concrete mixing process, including cement, sand, stone, water, and admixtures. Also, transportation and construction can possibly cause some losses to the quantity of concrete mortar.
The reason for the loss of concrete
There are many causes leading to concrete loss, including:
– Materials dropped during concrete mixing, mold sticking or shrinkage
– Weather effects during pouring: it rains…
– The formwork is sagging or expanding…
Of the above reasons, the loss is mainly due to the process of pouring concrete into the work. So to reduce the loss in the concrete pouring process, it is necessary to know how to calculate the loss norm of commercial concrete and how to overcome it.
HOW TO CALCULATE THE NORMAL LOSS RATE OF READY-MIXED CONCRETE
The loss rate of concrete is the total of the loss rate of mortar during transportation and on-site concreting and is calculated relative to the original volume. The calculation is shown as follows: (According to Circular No. 10/2019/TT-BXD) (Theo Thông tư số 10/2019/TT-BXD)
|Type of Concrete||Loss Rate (%)|
|On-site poured concrete with concrete pump with cranes||2,5|
|On-site poured concrete with concrete pump||1,5|
|On-site poured concrete for bored piles with Bentonite||15,0|
|On-site concrete for bored piles with casing||10,0|
|On-site poured concrete for siphons, hoses, sewer pipes, aqueducts, arches, and funnels||5,0|
Note: Bảng tính mang tính chất tham khảo, trên thực tế sẽ có nhiều nguyên nhân ảnh hưởng đến tỷ lệ hao hụt không như cách tính trên.
TIPS TO MINIMIZE LOSSES WHEN POURING CONCRETE
Check Concrete Frames
Before carrying out construction, the worker needs to conduct a general and detailed check on the concrete frame. If the concrete frame changes at this time, it will be easier to control and adjust after pouring. This method will help ensure that the work is of the highest possible quality and integrity.
Height Limits on Concrete Free Fall
The free fall of concrete is restricted to no more than 1.5m in order to minimize loss when pouring concrete. In addition, limiting the height of concrete free fall at maximum of 1.5m also helps to prevent concrete from being cracked and stratified during the pouring process.
Concrete pouring time
The interval between concrete hauling trucks is an important factor – less than half an hour is the most reasonable time to ensure the quality of concrete and its surface (foundation).
Regarding to concrete columns, it should be poured continuously, not halfway. As for floor concrete, it should be accompanied by a needle vibrator to ensure the desired thickness.
DA NANG, QUANG NAM, QUANG NGAI READY MIXED CONCRETING SERVICE
Pouring concrete in Da Nang