Replacing Temperature & Shrinkage Reinforcement with Macro Synthetic Fibers

Suitable for architectural engineers, structural engineers, flooring contractors, precast component manufacturers, and technicians.

Temperature and shrinkage reinforcement has traditionally relied on welded wire mesh (WWM) or small-diameter rebar to control crack development. However, modern macro synthetic fibers—such as HTM® Mono and HTM® Mono Blend—are now widely used as a more durable and more cost-efficient replacement.

This article explains why shrinkage cracking happens, how macro fibers provide equivalent or superior performance, and the engineering conditions under which WWM can be fully replaced.

Why Temperature & Shrinkage Cracking Happens

Concrete undergoes thermal and moisture-related volume changes throughout its early life:

• Plastic shrinkage (first 2–12 hours)

• Drying shrinkage (days to months)

• Thermal contraction during cooling

• Differential shrinkage between surface and core

When the restraint (ground, reinforcement, adjacent slabs) exceeds tensile capacity, cracks occur.

Why slabs and pavements are especially vulnerable

Slabs-on-ground are exposed to:

• Uneven subgrade moisture

• Wind and solar heat

• High surface area–to–volume ratio

• Temperature gradients between top and bottom

This makes shrinkage and thermal contraction unavoidable—proper reinforcement is essential.

Why Macro Synthetic Fibers Are Effective for Shrinkage Control

Macro fibers provide shrinkage and temperature reinforcement through:

1. Multi-directional reinforcement

While mesh reinforces only one plane, macro fibers reinforce the entire slab thickness:

• 3D fiber network

• Crack bridging in all directions

• Stress distribution throughout the volume

2. Early-age crack control

Unlike steel mesh—which is passive until cracks widen—macro fibers are active from the moment concrete is placed.

Benefits include:

• Reduced plastic shrinkage

• Reduced drying shrinkage cracking

• Improved crack distribution

• Smaller crack widths

3. Higher crack resistance per unit weight

Macro fiber volume is evenly dispersed, providing reinforcement everywhere—especially at the upper third of slab depth, where WWM is often misplaced.

4. Reducing crack width growth

Fibers limit propagation by:

• Mechanical anchorage

• Polymer elasticity

• Energy absorption during pull-out

Equivalent Reinforcement: When Macro Fibers Replace WWM

In many real-world projects, WWM is installed incorrectly or sits on the ground. Macro fibers avoid these issues.

Macro synthetic fibers can replace WWM when:

• Reinforcement is for temperature and shrinkage

• Design is per ACI 360, ACI 544, EN 14889 guidance

• Slabs are non-structural

• Required residual strength fR1/fR3 is achieved with tested dosage

Typical replacement conditions:

Traditional Reinforcement	Macro Fiber Equivalent
WWM (A142–A393)	4–6 kg/m³ HTM® Mono
Temperature bars	4–8 kg/m³ HTM® Mono / Mono Blend
Light secondary steel	Macro fiber structural dosage

Dosage Recommendations

For temperature & shrinkage reinforcement：

4.0–6.0 kg/m³ (typical)

For joint reduction or thicker slabs：

6.0–8.0 kg/m³

For heavy industrial floors：

6.0–10.0 kg/m³

Always base dosage on residual strength (fR), not compressive strength.

Conclusion

Macro synthetic fibers offer a more reliable, non-corrosive, cost-efficient solution to traditional temperature and shrinkage reinforcement.

HTM® Mono and HTM® Mono Blend are engineered specifically to deliver:

• Better crack width control

• Consistent reinforcement without placement errors

• Faster construction

• Lower total cost

Macro synthetic fibers for slabs

HTM® Mono product page

PP fibers vs steel fibers

Shrinkage crack prevention