Top Anti-Cracking Additives for Cement Mortar and Concrete Durability

Cracks in cement mortar and concrete are more than just a cosmetic problem. They create channels for water and aggressive ions, speed up reinforcement corrosion, and shorten the service life of structures. For modern projects that aim at long-term performance, it is not enough to focus only on strength; controlling cracking has become a basic requirement. One of the most practical ways to do this is to select suitable concrete additives to prevent cracking at the mix-design stage.

This article looks at four widely used additive types—HPMC, HEMC, polypropylene (PP) fiber, and PCE superplasticizers—and explains, in simple terms, how they help improve durability in cement mortar and concrete.

Concrete cracking affects durability and long-term performance

Concrete is a volume-changing material. From the time water is added until long after the structure is in service, it is constantly responding to moisture and temperature. Typical crack-related behaviors include:

• Shrinkage as the material dries and loses internal moisture

• Plastic shrinkage in the first hours after placement, especially in hot, dry, or windy weather

• Thermal movement from heat of hydration and daily temperature swings

• Internal stress at restraints, joints, corners, and embedded elements

If these movements are not properly controlled, visible cracks and microcracks can appear. Over time they may:

• Reduce waterproofing performance

• Accelerate steel corrosion

• Lead to scaling, spalling, and loss of cover

• Increase the need for maintenance and repair

Good structural design, reinforcement detailing, and curing are essential, but many projects now rely on concrete additives to prevent cracking as a standard part of their durability strategy.

Key anti-cracking additives improve mixture performance

Instead of expecting a single “magic” product to solve all cracking problems, modern practice uses several types of additives that each target different aspects of concrete behavior. The four groups below cover a large share of common applications.

HPMC improves water retention and early-age crack resistance

HPMC (Hydroxypropyl Methylcellulose) is a cellulose ether used in dry-mix mortars and site-mixed concretes where water retention and consistency are important. In cement-based materials it helps the mix hold onto moisture for longer and improves stability.

By slowing down surface water loss and supporting more complete hydration, HPMC can:

• Reduce plastic shrinkage cracking in the first hours after placing

• Support more uniform hardening between the surface and the interior

• Improve workability and adhesion during placement and finishing

HPMC is commonly used at standard temperatures and in relatively dry conditions, for example in plastering mortars, repair mortars, tile adhesives, and general-purpose concretes where surface cracking and poor finish are concerns.

HEMC maintains water retention in hot climates

HEMC (Hydroxyethyl Methylcellulose) has a similar role to HPMC but is designed to keep its water-retaining effect at higher temperatures and in more alkaline environments. In hot or tropical regions, standard cellulose ethers may lose performance, whereas HEMC remains active.

In hot-weather concreting and mortar work, HEMC helps to:

• Prevent rapid evaporation from fresh surfaces

• Maintain workable time during placement and finishing

• Support more even curing and reduce temperature-related stress

By improving moisture control when evaporation is strongest, HEMC lowers the risk of plastic shrinkage and early-age cracking in mass pours, summer pours, and pumpable mixes.

Fibers and superplasticizers provide internal crack control

While cellulose ethers mainly address moisture behavior, fibers and superplasticizers work more on the mechanical and microstructural side of crack control.

PP fiber controls microcracks and improves toughness

Polypropylene (PP) fiber is a micro-synthetic fiber widely used as a concrete fiber additive. When distributed throughout the matrix, it forms a three-dimensional network that supports the material during volume change and early stress.

PP fiber contributes to crack control by:

• Limiting plastic shrinkage cracking near the surface

• Restraining microcracks produced by internal drying and temperature differences

• Increasing toughness and resistance to impact and abrasion

Instead of one or two large cracks, concrete with PP fiber tends to show finer, more closely spaced cracking, which is less harmful for durability. Typical uses include industrial floors, slabs-on-ground, overlays, tunnels, bridge decks, precast elements, and shotcrete.

PCE superplasticizers optimize water content and compactness

PCE (Polycarboxylate Ether) superplasticizers are high-range water reducers that significantly increase workability at lower water–cement ratios. They are an important component in many concrete additives to prevent cracking packages.

By allowing less mixing water for the same slump, PCE superplasticizers help to:

• Reduce drying shrinkage linked to excess water

• Achieve higher strength and stiffness at equal cement content

• Produce a denser, less porous microstructure with fewer internal voids

• Support early strength development in fast-track or cold-weather concreting (when used in suitable formulations)

This combination of reduced shrinkage potential and denser paste makes PCE-based systems attractive for high-performance concrete, precast production, and projects with tight schedules or demanding durability requirements.

Main anti-cracking additives can be compared by function

The table below gives a compact overview of how these four additive types work and where they are typically applied in practice.

Practical selection of concrete additives to prevent cracking

Selecting the right concrete additives to prevent cracking starts with understanding the main risks on a project rather than choosing products only by name. In simple terms, the key questions are:

1. What is the climate like during construction (hot, cold, windy, dry, humid)?

2. Which elements are most sensitive to cracking (slabs, walls, overlays, precast parts)?

3. How will the concrete be placed (pumped, cast in situ, sprayed, prefabricated)?

4. What are the performance requirements (allowable crack width, service life, exposure class)?

For example:

1. In standard climates where surface cracking and finish are the main issues, HPMC plus PP fiber can already provide effective support.

2. In hot climates, HEMC is usually more reliable than HPMC for water retention, and it can be combined with PP fiber for additional crack control.

3. In high-performance or precast concretes, PCE superplasticizers are often essential to control water content and compactness, and may be used together with fibers and cellulose ethers.

Because materials, standards and jobsite conditions vary, it is often helpful to discuss mix design and additive choice with the TJCY technical team before finalizing specifications. In many cases, project teams can get tailored guidance from TJCY on how to combine cellulose ethers, fibers and superplasticizers to meet both cracking and durability targets.

Integrated use of additives supports durable concrete structures

Cracks cannot always be completely avoided, but their formation and severity can be significantly reduced by combining good design, proper curing and well-chosen concrete additives to prevent cracking. HPMC and HEMC improve moisture behavior, PP fiber strengthens the internal network against microcracking, and PCE superplasticizers help deliver dense, low-shrinkage mixtures.

When these additives are used as part of an integrated durability concept instead of as isolated products, cement mortar and concrete structures are better able to maintain appearance, waterproofing performance and structural reliability throughout their service life.