Superplasticizers are commonly used in concrete and mortars to improve flow, workability, and wet-out. They eliminate the need for excess water in the mix, thereby improving strength and reducing shrinkage properties in the concrete or mortar. But, some superplasticizers can take a long time to activate and wet-out the dry-mix to the desired consistency. A slow-acting superplasticzer can cause the mix to appear “too-dry” to start, and it’s common for applicators to add additional water prematurely, rendering the mix too-fluid once the superplasticzer activates. The mix is then either applied too-fluid, or there is a yo-yo addition of more dry-mix, then more water, and more mix… Either way, the ratio is not as the prescribed causing adverse properties and performance of the final dried product.
See the difference your choice in Superplasticzer can make!
The Azelis Americas Construction Solutions Lab helped a customer reformulate their unsanded grout formulation. The results could be seen instantly!
This particularly challenging formula1 uses only fine powder contents: white cement is the sole binder and fine limestone powder is the main filler. It is designed for applications that require very smooth aesthetic and little to no abrasion, such as glass tile. The lack of aggregate allows for minimal scratching. Azelis optimized this grout formula with a fast-acting superplasticizer and cut the mixing time in half!
This example is based on an extremely difficult fine particle formula, but the fast-acting benefits of these superplasticizers also translate to larger aggregate formulas such as SLUs where the mixing time is cut-down to a few seconds.
Traditional Superplasticizer
Fast-Acting Superplasticizer
Lab Report:
The Azelis lab was improving a recipe for an unsanded grout. A customer was obtaining feedback that their formulation was too dry in the early stages of mixing and the applicators were adding more that the recommended dosage of water. This was frustrating for the customer since the material passed all market test requirements. Azelis adjusted their formulation with a fast-acting superplasticizer resulting in a faster wet-out speed as shown in the video above. Most importantly, the unsanded tile grout formula kept the same performance properties.
Performance Results
The formulation submitted exceeded all testing requirements. The replacement of the existing superplasticizer for a fast-acting superplasticizer improved the wet-out speed significantly: from 3 minutes to 1.5 minutes!
| Physical Properties | Result |
|---|---|
| Wetout Speed | 1.5 minutes |
| Linear Shrinkage (target <0.3% at 28 days | 0.13% |
| Absorption (target <18% at 28 days) | 12% |
| Compressive Strength (target 3000 psi) | 5150 psi |
| Tensile Strength (target 250 psi at 28 days) | 375 psi |
| Flexural Strength (target 500 psi at 28 days | 950 psi |
Conclusions:
The Azelis unsanded grout formulations not only exceed the physical testing requirements specified, but also made a user-friendly material, reducing the chances of over-watering the mortar. Not only was the wet-out time cut in half by introducing a very powerful and fast-acting superplasticizer, but the existing physical properties easily surpassed the requirements.
The improvement to wet-out allows for less labor-intensive mixing and a more creamy, workable mortar which is very important in the market. This new formulation allows the applicators to have a mortar that they deem to have excellent workability with without compromising physical properties by introducing excess water.
Melflux® Fast-Acting Superplasticizers
Highly efficient superplasticizers based on polycarboxylate ethers (PCEs) with excellent fluidification and water reduction properties for dry mortar systems, such as SLUs. All Melflux grades are very low in VOC (volatile organic components), therefore useful to formulate SLUs according to EMICODE® EC-1
Melfux 2651 is a water-reducing and high-performance superplasticizer for cement-based construction materials.
Melflux 6618 F gives the fastest fluidification (final consistency) after short mixing time
Melflux 4930 F offers fast and high strength development in Portland cement and calcium sulphate alpha-hemihydrate based systems
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1 Full raw material list and formulation details of the Azelis unsanded grout formula is available from your Azelis representative.
The information contained in this document is made without guarantee and warranty, express or implied, regarding the suitability for use, merchantability, or performance of the formulation and its ingredients in any application. It is the sole responsibility of the user of this information to determine validity, applicability, and performance of the information, formulations, and claims prior to commercialization, use, and application thereof.
