Mix ratio of
sand/cement screed for floor varied based on the intended use of the screed. Added
to that, cement type, grade of aggregate and the method of storage of screed
material are also influence mix ratio to a certain extend. Suitable type of
cement shall be selected, and sand need to be free of deleterious materials.
It is reported
that, for traditional screeds a mix proportion of 1:6 Portland cement:
sand/aggregate is a normal range that is commonly used; mix proportions of 1:4
cement to sand is widely applied.
Standards set guidance with respect to the types of cement that are best suited
for different kinds of screeds. It is important to choose the specified cement
type for best results, as variations in cement quality can affect the strength
development of the screed and its susceptibility to poor curing.
The size and
shape of sand can have considerable impact on the performance and appearance of
a screed. It should be guaranteed that the presence of deleterious materials does
not exceed acceptable level.
The size of
aggregate is specified based on the function of the screed for instance for normal
duty screed, maximum size of sand is 4mm. However, for heavy duty screed, maximum
size of aggregate ranges from 6mm and 10mm. Where possible, the sand should be
tested in a laboratory beforehand.
The quantity of
water added to the mixture could be adjusted on site. Snowball test can be
conducted to make sure that suitable amount of water is added to the mixture.
should be avoided because it reduces strength and increases risk of cracking. A
stiff mix with too little water does not allow full compaction, and the screed
may crumble over time.
is carried out to ensure that adequate amount of water is added. The test
involves squeezing a handball of the screed mix. The consistency is right if
the screed holds together without dripping water.
The mix ratio varies dependent on the intended use of the screed. In addition to cement type, grade of aggregate and the method of storage of screed material that also influence mix ratio to a certain extend.
It is reported that, for traditional screeds a mix proportion of 1:6 Portland cement: sand/aggregate is a normal range that is commonly used. However, mix proportions of 1:4 cement to sand is widely applied which comply with British Standard (BS12). Mix ratio should produce a plastic, easy-working, cohesive mortar of plastering consistence.