Shotcrete is simply, sprayed concrete. It is also the process that allow cement-based materials to be discharged under high pneumatic pressure onto vertical and overhead surfaces (rock faces, underground tunnel walls and backs). Shotcrete is used to stabilize rock and soil, to provide support to underground frames and headings, and for the structural repair or reinforcement of cement pilings, retaining walls and damns.
Our Standard Multicrete Shotcrete is packed in 20 kg. paper bags, 700 kg. mini-bulk reusable bags or 1200 kg. reusable bulk bags.

Multicrete Systems has formulated Specialty Shotcrete Mix Designs for use where water, cold temperatures or broken ground are inhibiting factors.

Dry-mix Shotcrete Portland cement, sand, aggregates and select additives are fed as dry materials into the hopper of a dry-mix shotcrete machine. Here the material is mixed and discharged under high pressures through a length of hose to the spraying nozzle. A union in the body of the nozzle allows for water to be introduced and this wet cement, or shotcrete, is then sprayed, or impacted onto the prepared surfaces.
Ideally, dry cement materials should be augured through a pre-dampener where it is pre-moistened. These units greatly reduce the amount of dust and are almost a necessity when working underground.

From the pre-dampener, the material enters a shotcrete pot where air form a compressor (minimum 900 cm) mixes and disperses the shotcrete through the outlet chamber and along heavy duty, abrasion resistant hose (usually 50 mm (2") 0r 65 mm (2.5") diameter.

The advantages of dry-mix machines are that they are easily transported, even underground; the units are relatively easy to set-up, and at the end of the shift, clean-up requirements are minimal. As few as two trained personnel can operate and spray with a dry mix unit.

A process where cement, sand and specified admixtures are blended together or "batched". The blended material is combined with water and delivered "wet" via ready-mix truck to the job site. Alternatively, large tractor-trailer units deliver the dry pre-blended materials in bulk to be mixed with the water on-site. Large displacement units pump the wet shotcrete along delivery lines, or hose, to the nozzle. Air is introduced to the wet material and it is sprayed under high velocity onto the prepared surfaces.

Dual-purpose shotcrete machines that can convert from dry to wet are rapidly gaining popularity. The thin-stream method allows wet-mix shotcrete to be conveyed peneumatically through the shotcrete pot and along the hose to where air and liquid accelerator is introduced at the nozzle. Thick-stream wet-mix shotcrete requires large concrete pumps to move the material through the lines

Air cells, or bubbles, are encapsulated in a cement-based grout to produce low-density cellular concrete. This low-strength concrete is most commonly used to fill voids in rock and loose soil.

This flow-able grout is a carefully weighed and batched mixture of Portland cement, sand and specially selected additives. For continuous batching/pumping of this slurry, the use of a colloidal-style mixer with large agitator tanks is strongly recommended.

A foam generator is required for mixing air and water into the Multicrete Foam Concentrate to produce a highly aerated frothy cream. An in-line foam injection system infuses this foam into the cement-based grout.

The result of combining these two separate processes is a cellular concrete ready for pumping or spraying.

In order to ensure proper mixing and to control the consistency of cellular concrete, Multicrete Systems Inc. will customize equipment for any size application. Contact us for rentals and purchase options, or to discuss the design and manufacture of project-specified equipment. Our qualified field technicians can also assist with the initial startup, maintenance procedures and operator training.