Glued vs Loose Steel Fiber: Which Works Better with Your Concrete Mixing Process?

1. What Changes When Steel Fibers Are Glued Together?

Yian's glued steel fiber product uses a water-soluble adhesive to hold individual hooked-end fibers in bundles. Loose steel fiber is supplied as individual fibers. The bundle is a delivery form that must separate during the intended mixing process. [1]

This approach is also used elsewhere in the industry. Bekaert describes water-soluble glue on its own Dramix products as a means of helping prevent balling and supporting distribution. [3] That explains the purpose of the technology; it does not establish a performance result for a different manufacturer's product.

Keep three questions separate when reviewing an offer. How is the fiber delivered? What are the properties of the individual fiber? How does the resulting concrete perform? A successful answer to the first question does not remove the need to answer the other two.

2. Compare Fiber Specifications Before Comparing Product Forms

A fair purchasing comparison needs more than two descriptions reading "hooked-end steel fiber." Check length, diameter, end geometry, tensile strength, tolerances and the applicable project specification.

The following examples come from Yian's published product tables. They show the information available for an initial enquiry. They are different grades and should not be treated as a controlled experiment comparing glued and loose delivery forms.

Sources: Yian's Glued Steel Fiber and Loose Steel Fiber product pages. Values are supplier-published references. Confirm tolerances, test basis and the specification for the ordered grade.

Notice that the two 60 mm examples have different diameters as well as different stated tensile strengths. If concrete results differ, those differences must be considered before attributing the outcome to glue. Ask for comparable individual-fiber specifications where the purpose of the trial is to isolate the effect of delivery form.

ASTM A820/A820M addresses steel fiber dimensions, tolerances, physical properties and testing. [5] State the required specification and edition in the enquiry, then request documentation applicable to the offered grade.

3. Investigate Steel Fiber Balling at the Point Where It Starts

If a batch contains fiber balls, record where they first become visible. Are fibers accumulating at the hopper? Does material enter the mixer in intermittent piles? Do glued bundles remain together at discharge? These observations lead to different investigations.

A short video of the feeding operation can be more useful to a supplier than a photograph of the rejected concrete alone. Include the equipment, feeding point and timing, while also retaining the batch record.

Bekaert's guidance for its own products includes checks for workability, air content, bundle separation and fiber distribution. It also relates mixing time to equipment efficiency. [4] Use this as context for the questions to ask, and obtain the procedure appropriate to the Yian grade and your plant.

Avoid changing several variables at once during troubleshooting. If you alter the feed rate, addition sequence and concrete consistency in the same batch, it becomes harder to determine which adjustment resolved the issue.

4. Turn the Specified Dosage into a Repeatable Feeding Plan

Obtain the project dosage from the approved design or mix specification. The batching team then needs a clear method for delivering that amount. Confirm whether the declared product mass and dosing basis include the adhesive when purchasing a glued product.

Both Yian product pages describe 20 kg bags. [2] Whole bags may simplify counting, but the selected batch size and dosage do not always produce a whole-bag quantity.

For automatic dosing, check the equipment with the actual product. Ask the equipment supplier whether a change from loose fibers to bonded bundles requires different settings or hardware. Verify delivered mass over the intended operating range before relying on a display value.

For manual feeding, define the counting and weighing responsibilities. Include a method for handling partial bags, interrupted batches and unused material. These details make the process easier to repeat across shifts.

5. Test the Concrete Performance the Project Requires

Fiber tensile strength is a material property. Concrete residual flexural strength is measured on the composite mixture after cracking. A certificate for the fiber cannot establish the latter on its own.

ASTM C1609/C1609M evaluates flexural performance using a beam test. Its published guidance distinguishes first-peak behavior from residual strength at specified deflections and notes that specimen size affects results. [6] Agree the test method and acceptance criteria with the project's technical team.

Decide What the Comparison Is Intended to Prove

A delivery-form trial should control individual-fiber specifications as closely as practical. A commercial selection trial may compare different grades, but the decision must then consider the complete combination of fiber, dosage, concrete formulation and production procedure.

• Identify the fiber grade, sample lot and supporting documents.
• Record the concrete formulation, batch volume and actual fiber mass.
• Record the feeding sequence, duration and mixing procedure.
• Assess fresh concrete and fiber distribution using an agreed procedure.
• Complete the specified hardened-concrete tests.
• Check the intended placing, pumping and finishing process where applicable.

Retain unsuccessful results as well as successful ones. If a revised sequence resolves a problem, the final production instruction should capture that sequence. A sample approval without operating conditions leaves too much interpretation for the production team.

Any proposal to reduce or replace conventional reinforcement requires the project designer's review and approval. A change in fiber delivery form does not itself authorise a reinforcement change.

6. Compare the Cost of the Approved Production Option

Start with delivered material cost, then add measured differences in receiving, feeding and production. If glued fibers improve your process, the trial should show where the benefit occurs. If loose fibers already perform reliably, retain that evidence in the comparison.

Record labor time, equipment interruptions, extra mixing and material loss where relevant. Separate one-time qualification costs from recurring operating costs. Avoid assigning a percentage saving before the plant has measured the proposed change.

For imported steel fiber, align the quotation basis: grade, net mass, packaging, delivery term and required documents. Request a loading plan and confirm transport constraints for the shipment. A nominal container quantity on a product page should not replace the agreed shipping plan.

7. Make the Purchase Order Match the Approved Trial

The order should identify the exact grade and approved requirements. A description such as "60 mm steel fiber" leaves diameter, tensile properties, tolerances and delivery form unresolved.

1. Product identity: model, geometry, dimensions, delivery form and agreed technical specification.
2. Quality evidence: required test reports, traceability and applicable conformity documents.
3. Packaging: net bag weight, labelling, pallet arrangement and approved storage instructions.
4. Production approval: trial reference and the conditions attached to approval.
5. Change control: how a proposed change to the approved product will be reported and reviewed.

At receipt, connect the package identification to the delivery paperwork and agreed reports. Review damaged packaging or unexpected material condition before releasing the shipment to production. Keep the approved sample reference available for any investigation.