{"id":2053,"date":"2026-01-07T12:30:14","date_gmt":"2026-01-07T12:30:14","guid":{"rendered":"https:\/\/ecocretefiber.com\/?p=2053"},"modified":"2026-01-10T01:42:53","modified_gmt":"2026-01-10T01:42:53","slug":"what-is-macro-synthetic-fiber","status":"publish","type":"post","link":"https:\/\/ecocretefiber.com\/en\/what-is-macro-synthetic-fiber\/","title":{"rendered":"What is macro-synthetic fiber?"},"content":{"rendered":"\n

Macro-synthetic fiber is a synthetic macro fiber<\/strong> <\/a>engineered for concrete reinforcement. It is mixed into fresh concrete. It spreads through the full volume. It helps control cracking. It also improves post-crack performance such as toughness and residual flexural strength.<\/p>\n\n\n\n

Many contractors use macro-synthetic fiber to replace welded wire mesh in slabs-on-ground, or to reduce crack-related repairs in floors, pavements, shotcrete, plus some precast products.<\/p>\n\n\n\n

What is macro-synthetic fiber?<\/h2>\n\n\n\n

Macro-synthetic fiber is a larger synthetic fiber<\/strong> used for concrete reinforcement. It is different from micro synthetic fiber. The main difference is size and job function. ACI guidance describes macro synthetic fibers as having a diameter (or equivalent diameter) greater than 0.3 mm<\/strong>.<\/p>\n\n\n\n

Macro-synthetic fibers are usually made from engineered polymers such as polypropylene, polyethylene, or blends. They are produced in controlled shapes to improve anchoring in the cement matrix.<\/p>\n\n\n\n

The main purpose is not only early-age crack control. The main purpose is post-crack control<\/strong>. The fiber helps the concrete carry load after it cracks.<\/p>\n\n\n\n

\"Close-up<\/figure>\n\n\n\n

How does macro-synthetic fiber work in concrete?<\/h2>\n\n\n\n

Macro-synthetic fibers<\/a> work as three-dimensional reinforcement<\/strong>. Rebar is placed in specific zones. Fibers are mixed into the batch. That means fibers reinforce the concrete everywhere, in many directions.<\/p>\n\n\n\n

When a crack forms, fibers that cross the crack help hold the crack faces together. This limits crack opening. It also improves the concrete\u2019s ability to carry load after the first crack. Sika describes macro fibers as a tool to resist tensile stresses, control crack growth, plus increase residual flexural strength (post-cracking).<\/p>\n\n\n\n

This \u201cdistributed\u201d reinforcement changes jobsite outcomes. You often see tighter crack patterns. You also see less sudden break behavior in slabs under impact or wheel loads. The result is usually fewer surface failures at joints, edges, plus corners when the slab is designed correctly.<\/p>\n\n\n\n

\"Cut<\/figure>\n\n\n\n

Macro vs micro synthetic fiber: what is the difference?<\/h2>\n\n\n\n

Micro fibers focus on fresh concrete <\/a>crack control<\/strong>. Macro fibers focus on hardened concrete performance<\/strong>.<\/p>\n\n\n\n

ACI guidance uses a size threshold. Micro synthetic fibers are below 0.3 mm<\/strong> in diameter (or equivalent). Macro synthetic fibers are 0.3 mm or greater<\/strong>.<\/p>\n\n\n\n

Sika uses the same practical idea. It describes structural macro fibers as having diameter at or above 0.3 mm.<\/p>\n\n\n\n

Typical differences you will notice:<\/p>\n\n\n\n