The Difference Between Wet Cast & Dry Cast

WET CAST

DRY CAST

# pours per form per day / production

Wet cast forms can only be stripped and poured again a couple of times a day. 

Dry cast can be stripped more often and increase production. 

Flowability to get around complex shapes

Wet cast is flowable (SCC even more) and can get around/through complex shapes and reinforcing

Dry cast is very stiff and is better suited for simpler shapes.

Cost of equipment

Wet cast can be vibrated with less expensive vibrators or none at all (SCC). 

Producing dry cast structures can require more equipment to adequately vibrate the stiff mix and also keep up with the higher production rate. 

Admixtures

Wet cast generally uses more admixtures

Dry cast generally uses less admixtures such as water reducers and air entrainers. 

Hearing Protection

Generally, vibratory equipment used (if any) with wet cast is not as loud as dry cast. 

Dry cast vibratory equipment has to be powerful; therefore loud. 

Strength

Wet cast has more water content and that can lead to lower strength than dry cast. 

Dry cast has less water content, therefore generally higher strength. 

Durability

Wet cast has more water content and that can increase porosity and as a result permeability.  This can result in lower durability than dry cast. 

Dry cast has less water content, therefore is less permeable and more durable.   

Appearance (smooth)

Wet cast can be formed to produce a very smooth surface.

Dry cast surface is rougher.

Formwork

Hydraulic pressure can be higher on formwork. Forms can be made adjustable to accommodate different product configurations.

Formwork must be designed to handle force of vibration and repeated use, often making it less adjustable.

Air entrainment

Air entrained through admixtures.

Cannot be air entrained through admixtures but is naturally freeze-thaw resistant due to low water percentage and high density due to compaction.

Embeds

Embeds (lifters, etc.) can be attached for formwork prior to pouring.

Embeds cannot be added due to intensity of vibratory force.

Mixes

Can use larger coarse aggregates, adding economy to the mix. Also, can use higher percentage of coarse aggregates.

Must use smaller coarse aggregates to reduce wear on equipment. Also uses higher percentage of sand.

Post pour openings

Openings must either be blocked out during pouring or made with a coring machine.

Portions of concrete can be removed immediately after casting to form openings or skewed ends.

Cement usage

Requires more cement and water to make more “paste” to bind the aggregates together.

Often needs less cement in order to reach design strength due to low w/cm ratios.

Unit weight

Usually not greater than 150 lb/ft³

Usually slightly higher than 150 lb/ft³ due to less water and cement relative to aggregates.

Filling formwork

Fresh concrete delivered in buckets or drums.

Concrete delivered on conveyor belts.