Portland cement is a primary component of concrete, mortar, stucco, and grout. These cement-based products have been in use for millennia and continue to be the most widely used building materials in the world. Each year billions of pounds of Portland cement and cement-related commodities are packaged in multi-wall paper bags and FIBCs (bulk bags).
How is Cement Made?
Cement is manufactured through a closely controlled chemical combination of calcium, silicon, aluminum, iron and other ingredients.
Limestone and clay are blasted from rock quarries by boring the rock and setting off explosives. Once the rock has been blasted and fragmented, they are then transferred to the manufacturing facility. The quarry stone is crushed and reduced in size to pieces approximately 1 ½ inches in size.
Raw materials are transported separately to silos, where they will be added in specific amounts according to the type of cement being produced. Next, the raw materials are fed to a vertical steel mill, which grinds the material through the pressure exerted by conical rollers. Horizontal mills may also be utilized in this phase where the material is pulverized by means of steel balls.
Portland cement clinker is made by heating the mixture of materials in huge rotary kilns. The kilns heat the mixture to a temperature approximately 1,400 degrees F. At this temperature the raw materials are transformed into clinker: small, dark gray nodules 3-4 centimeters in diameter. The clinker is ground by different-size steel balls while it works its way through the mill’s chambers, with gypsum being added to extend cement setting times.
After the clinker is cooled, the plant grinds it a fine powder for packaging and transport. Cement is so fine that 1 pound of cement contains 150 billion grains.
How is Cement Packaged?
Portland cement is packaged in a range of paper and poly bag styles. These styles include:
- Multi-wall paper valve bags (PVSE)
- Multi-wall paper sewn open mouth bags (SOM)
- Woven Polypropylene block bottom valve bags
- Polyethylene block bottom valve bags
- Form, Fill, and Seal Film bags
- FIBC bulk bags
For purposes of this post, we will review multi-wall paper valve bags and FIBC bulk bag cement packaging.
Multi-Wall Paper Valve Bags for Cement
Cement bags make up a significant portion of all multi-wall paper bags produced in the world each year. The most common bag style for packing cement is a Pasted Valve Stepped End bag (“PVSE” or “valve bag”).
Dry cementitious products commonly packed in valve bags include:
- Concrete Mix
- Portland Cement
- Masonry Cement
- Mortar Mix
Valve bags are packed on equipment that deposits material into the bag via horizontal filling spout. Valve packing equipment can range from manual, hand-spouted equipment to modern fully-automated equipment. Valve bags are filled through an opening located in the top corner of the bag. Product is pumped or forced into the bag via air pressure, impeller, or auger. When the bag is discharged from the packing equipment, forces generated by the product inside the bag allow the valve opening to self-seal. Cement is most commonly packed using impeller and air packing equipment.
In general, cement is aerated before it enters the bag. In order to pack properly, oftentimes the paper plies of the bag are perforated to dissipate air entrained in the product. Most cement bags include a polyethylene film barrier for moisture protection. The film ply is typically buried in between the paper plies.
The valve bag construction results in a squared-up bag, which palletizes very securely and can be printed with product information on the side or end panels for easier product identification in pallet loads.
FIBCs (Bulk Bags) for Cement
A Flexible Intermediate Bulk Container or “FIBC” is an industrial packaging product made from woven polypropylene (plastic) fabric. The fabric components are sewn to form the shape of a large bag. The purpose of the bag is to store and transport dry flowable products such as Portland cement, sand, resin, and food ingredients. FIBCs can be designed to carry loads up to 5,000lbs.
Like valve bags, FIBC bulk bags are widely used for packaging dry cementitious products. Bulk bags are most often used to package common cement-based products including:
- Class I, II, and III Portland
- Type N, M and S Masonry
- Class A, C and H Well Cement
- Concrete Mix
- Mortar Mix
Bulk bags are filled on equipment that deposits material into the bag via vertical filling spout. FIBC packing equipment can range from manual equipment to modern fully-automated equipment. Bulk bags are filled through an inlet spout or open duffle located on the top of the bag. Product is dropped or pumped into the bag using gravity or air pressure respectively. When the bag is discharged from the packing equipment, the bag is tied off at the top to prevent contamination or moisture intrusion. Bulk Bags can be equipped with a discharge spout for easy, safe release of the packaged product.
Due to the moisture sensitivity of cement-based products, coated or poly lined bulk bags are recommended. Coated bags offer protection against moisture and contamination by sealing the microscopic gaps between the woven PP tapes.
Benefits of Coated Cement Bags Include:
- Improves water/moisture resistance of the FIBC
- Reduces likelihood of product contamination
- Reduces fraying of PP tapes
- Helps maintain product freshness
- Eliminates dusty, unsightly packaging
Coating only acts as a limited moisture and dust barrier. Coating alone will not make the bag waterproof and certain ultra-fine products may sift through the coating. When product protection and sift resistance are critical, we recommend choosing a bulk bag with a PE film liner.
FIBC Liners can be loosely inserted, attached at 8 points using tabs, or glued into the body of the bag. In addition, the liner openings can be cuffed and sewn to the filling and discharge spouts of your bag.
Benefits of PE Lined Cement Bags Include:
- Eliminates Sifting and Leakage
- Oxygen and Moisture Barrier
- Puncture Resistant Barrier
- Liner can be attached inside the bag using tabs or glue
- Liners can be reused
Bulk Bags are the ideal package when bulk tank delivery is impossible and small bagged product is too labor intensive. Cement bulk bags are especially suitable for:
- Space restricted soil stabilization projects
- Oil well pads and access roads
- Slip repairs and erosion control
- Utility works
- Limited access or remote projects
- Silo space restrictions or limitations
- Projects requiring lower quantities than a full tanker
Are you looking for paper valve bags or bulk bags for your building product manufacturing operation?
In addition to custom designed packaging, we offer plain on-demand packaging for immediate shipment. We stock common cement bag sizes and styles for just-in-time delivery.
Stock Cement Valve Bag Sizes:
- 14 x 19 x 4.5
- 15 x 17.5 x 4.25
- 16 x 19 x 5
- 19 x 23 x 4.75
Stock Cement Bulk Bag Sizes:
- 34 x 34 x 38 with PE Liner
- 35 x 35 x 36 with PE Liner
- 35 x 35 x 36 Coated
- 35 x 35 x 42 with PE Liner
- 35 x 35 x 42 Coated
- 35 x 35 x 45 Coated
- 35 x 35 x 52 with PE Liner
- 35 x 35 x 55 Coated
Please contact one of our sales professionals to assist you or send us an email.