Frequently Asked Questions – Construction Chemicals

What are the differences between different forms of polycarboxylate superplasticizers (liquid, powder)?

Comparison items	PCE powder	PCE liquid
Production process	Synthesized liquid, spray-dried into powder	Synthesized liquid
Solid Content (%)	> 95%	Generally 40-50%
Transportation Cost	Low	high
Customs Clearance Costs	Low	high
Packaging & Storage	Bagged, easy to store	Tank storage, anti-freeze needed
Application areas	Dry-mix mortar, dry-mix UHPC, can be used in concrete after re-dissolving	Only for wet-mix concrete

Does polycarboxylate superplasticizer meet the requirements of green, low-carbon and sustainable development?

Yes. Polycarboxylate superplasticizers are green, low-carbon, and sustainable materials. This can be inferred from both the material itself and its application value.
1. Compared with naphthalene-based superplasticizers, PCE offers higher water reduction rate and contains no harmful substances.
2. Polycarboxylate superplasticizers, when used in cement-based or gypsum-based building materials, can significantly reduce the consumption of cement and other supplementary cementitious materials while maintaining equivalent strength levels. Alternatively, PCE can significantly enhance the strength levels of concrete or mortar while keeping cement usage constant, improving the service life of the materials. Its application value makes concrete and mortar more green, low-carbon, and sustainable.

For typical cementitious materials such as Portland cement, aluminate cement, sulphoaluminate cement, gypsum, etc., are there any differences in the adaptability when using PCE?

Yes, Portland cement, aluminate cement, sulfoaluminate cement, and gypsum are different cementitious materials with distinct primary components, and PCE compatibility varies accordingly. Some PCEs work well only with one supplementary cementitious material type, while others perform well across multiple systems. Therefore, it is recommended to consult the manufacturer and run tests before final application. Sunbo provides different PCEs that can meet the application requirements of the above different cementitious materials.

When selecting PCEs, how to evaluate them more scientifically?

Beyond evaluating water-reducing rate of PCE in your cement or gypsum paste, it's essential to fully evaluate its performance by adding it in the mortar or concrete you are going to use it. This should examine the polycarboxylate superplasticizer's compatibility with the cement, admixtures, fillers, and other additives. Besides the water-reducing rate, it's also important to observe the concrete or mortar's condition, viscosity, air content, and early and late strength.

What types of superplasticizers does Sunbo have? What are the main application scenarios of Sunbo superplasticizers?

Sunbo offers a range of polycarboxylate superplasticizers and Sulphnate melamine based superplasticizers. Sunbo superplasticizers can be used in the following applications.

1) Cement-based mortar materials: such as cement self-leveling, repair mortar, non-shrinkage grouting material, cement-based waterproof mortar, decorative mortar, caulking agent, plaster and leveling mortar, UHPC, etc.

2) Gypsum-based materials such as gypsum self-leveling, mold gypsum, and caulking gypsum.

3) Concrete of different strength grades such as C30, C50, C80, C120 and above.

4) Other types of materials based on cement or gypsum.

Is the chloride ion content high in powder polycarboxylate superplasticizer?

Powder polycarboxylate superplasticizers contain almost no chloride ions, with detection values generally well below 0.1%. Of course, chloride content may vary between manufacturers, please consult the manufacturer for exact values.

Can polycarboxylate superplasticizer that performs well in ordinary Portland cement be used directly in quick-drying cement self-leveling mortar or quick-drying repair mortar?

It is not recommended to use it directly without verification, testing is required. The main components of ordinary portland cement are dicalcium silicate, tricalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrate. The binders for fast-drying self-leveling cement or fast-drying repair mortars are either aluminate cement-gypsum-Portland cement or sulfoaluminate cement-Portland cement-gypsum ternary cementitious system. The adsorption of polycarboxylate superplasticizers by the various cement components or their hydration products varies significantly.

What is the general dosage of polycarboxylate superplasticizer?

The dosage of polycarboxylate superplasticizer is generally between 0.05% and 0.5% of the total mortar volume, depending on the degree of water reduction and the desired workability. Generally speaking, the higher the water reduction rate, the higher the mortar fluidity requirements, or the longer mortar workability time, the higher the polycarboxylate superplasticizer dosage.

Does the higher dosage of polycarboxylate superplasticizer, the higher the mortar water reduction rate?

Within a certain dosage range, increasing the polycarboxylate superplasticizer dosage can increase the water reduction rate and improve mortar workability. However, once the dosage reaches a certain critical point, the adsorption of polycarboxylate superplasticizers in mortar has reached or even exceeded the saturation adsorption level. Further increasing the superplasticizer dosage at this point may actually reduce the mortar's water reduction rate, making the mortar more viscous and resulting in lower workability. Furthermore, the mortar's setting time may be significantly prolonged.

Can cement self-leveling be used outdoors?

This is a complex question that cannot be generalized. It must be compared based on the specific differences between indoor and outdoor environments. Compared to indoor environments, outdoor temperature, humidity, load, and other factors vary more significantly. Therefore, it is necessary to evaluate the strength and dimensional stability of the developed cement self-leveling material within the range of temperature, humidity, and load variations in the outdoor environment to determine whether the cement self-leveling material can be used outdoors.

Why do self-leveling materials have excellent flowability during pouring but develop issues such as hollows and delamination after 7-14 days?

First, the excellent flowability of self-leveling ensure the integrity of the construction surface during pouring. Problems such as hollowing and delamination that occur 7-14 days after pouring may be due to poor shrinkage control and dimensional stability of the self-leveling material, resulting in significant shrinkage or expansion. If the substrate has a low strength or inadequate preparation, this issue will be exacerbated.