In the construction industry and especially for dry mix mortars, workability, water retention, and performance should be balanced when designing your mix.
Whether you are laying bricks, applying plaster, or tiling, the mortar you use will have a huge influence on the success or longevity of the job.
In recent decades, the development of additives has resulted in the formulation of our mortar and cement products. In regard to additives, one of the newer and most exciting is Hydroxypropyl Starch Ether (HPS).
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If you do not work in mortar formulation, you may not have heard of HPS. However, it has risen through the ranks in modern mortar technology to become one of the primary components associated with dry mixes. So, what does Hydroxypropyl Starch Ether do in mortar, and more importantly, what is its rapid rise in popularity?
This blog will explore the properties, functions, and benefits of Hydroxypropyl Starch Ether straightforwardly.
What is Hydroxypropyl Starch Ether?
Hydroxypropyl Starch Ether (HPS) is a modified starch. HPS is typically made from a natural source such as corn or potato starch and modified through a chemical process that adds a hydroxypropyl group into the starch molecule.
Hydroxypropyl introduced modifications give starch unique characteristics that are useful in a variety of construction applications, making HPS an attractive choice, especially in dry mix mortars, cement, and cement products.
The Role of Hydroxypropyl Starch Ether in Mortar
Now let’s discuss the primary functions of Hydroxypropyl Starch Ether in mortar and how it benefits various applications:
1. Improved Workability
One of the main advantages we get when using HPS in a mortar mix is improved workability. Mortars with HPS were more consistently spreadable, and smoother feeling in a way that made them easier to apply.
For each person – whether you are a professional mason or DIY person – having better workability means less distortment in the mortar, quicker application, and easier to clean finishing.
2. Good Water Retention
Whether you call it water retention or water holding capacity, it is one of the most important properties in every mortar application.
If mortar dries too quickly because of air flow, heat or wind, it can lead to weak bonding and shrinkage cracks. HPS helps keep water in the mortar mix and prolongs the time given for the cement to hydrate and bond.
3. Enhanced Sag Resistance
In vertical application areas e.g. plastering or tiling, we need the mortar to stick well and eliminate the sagging or slumping down the wall. HPS should help with sag resistance by keeping the mortar from sliding/down the vertical surfaces like a drip.
4. Increases Open Time
Open time is the amount of usable time the mortar is workable after application. Hydroxypropyl Starch Ether aids in prolonged open time to allow tile/finish trades the ability to shift or further adjust the tile/finish prior to the mortar setting.
Open time is very important for large-format tile work, as often nothing happens perfectly the first time and movement is required.
5. Increased Cohesion and Anti-Slump
Cohesion is the ability of the mortar to hold together without separating into water and solids. Hydroxypropyl Starch Ether upgrades the internal makeup of the mix and prevents separation, while helping to maintain a lump-free and uniform consistency.
This enables the mortar to exhibit reliable behavior during application and during various stages of curing.
The Perks of Using Hydroxypropyl Starch Ether in Mortar
Now that we have covered the functional roles, we want to cover the perks of using Hydroxypropyl Starch Ether in mortar products. The following benefits are very valuable to the manufacturer, applicator, and end-user alike.
1. Consistency In Batches
With Hydroxypropyl Starch Ether, dry mix formulations will show greater stability in the mixture, which means predictable performance and repeatable quality across different batches we use.
Consistency in performance is valuable to manufacturers who need to provide quality, reliable products, and to the people using it on-site who depend on performance to be consistent.
2. Reduced Risk of Cracking
Hydroxypropyl Starch Ether (HPS) in mortar improves resiliency, delaying shrinkage and minimizing surface cracking to help endure or withstand the real-world stresses placed on construction materials – largely due to its excellent water retention and flexibility, which is especially beneficial in conditions where rapid drying occurs. All in all, this means a longer-lasting and more durable finish.
3. Improving Application Efficiency
HPS allows for a faster and easier application method, especially useful on large areas. With HPS in, the mortar spreads smoothly and requires less frequency of mixing and adjustment.
For construction crews working to complete the job quickly, what is efficiency to one is savings in time and labor to another.
4. Broad Application
HPS is not limited to mortar alone; it can be added to all kinds of mortars, including:
- Tile adhesives
- Skim coats
- Wall putties
- Cement plasters
- Self-leveling mortars
- Insulation systems (EIFS)
So, it is not surprising to see HPS gaining use as a preferred product formulation ingredient for manufacturers wishing to optimize formulation across multiple product types and provide for some custom formulations.
5. Natural and Environmentally Safe
Because Hydroxypropyl Starch Ether is derived from all-natural starch sources, it can be classified as non-toxic and environmentally safe. HPS is a simple and easy product to work with in production as it does not have any harmful byproducts going into the mix.
Read More Details of: The Functions of Starch Ether in Mortar
Application Product Insight: Where HPS Impacts Mortar Use
Let’s take a further look at specific examples of AEC construction scenarios where Hydroxypropyl Starch Ether is found in mortar:
1. Tile Adhesives
HPS is suitable when applying wall and floor tiles for adhesion and slip resistance. HPS helps prevent sagging and support wetting of tile and substrate. Open time is increased, helping installers, in case tiles need to be repositioned.
2. Wall Putty and Skim Coats
In putties and skim coats, HPS provides a smoother, creamier consistency that makes spreading and leveling easy. HPS gives better adhesion, less shrinkage, and excellent surface quality—ready for the painter’s brush.
3. Exterior Wall Insulation (EIFS)
Insulation systems need mortars with the strongest bonds to insulation boards and existing walls. HPS addresses bond strength, shrinkage, and workability issues—important in complex, multilayer applications.
4. Self-Leveling Mortar
Self-leveling is not commonly used here, but some self-leveling formulations could have some HPS to control flow, anti-separation, and cohesion.
The Future of Mortar Additives: Increased Use of HPS
As construction practices adapt and sustainability evolves, Hydroxypropyl Starch Ether – HPS will become more useful. Researchers and engineers are increasing the focus on HPS and its compatibility with biobased and low-emission materials that are meaningful to greener construction.
The future of Hydroxypropyl Starch Ether (HPS) is bright, and it is likely to become a part of every dry mix formulation for its ability to save waste and enhance performance.
Takeaways
The construction material industry is becoming increasingly sophisticated. Additives such as Hydroxypropyl Starch Ether in the mortar industry have proven to be disruptive at best – be it in terms of workability, water retention and durability, and HPS offers a long list of benefits to both manufacturers and end-users.
It is efficient, environmentally friendly, and incredibly versatile – and the perfect option for anyone wanting to improve performance of their mortar products without a complicated formulation.
