Too much or too little water can sabotage cement mixtures


Denise Troiano

 May 1, 2019. 4:45 PM

“How much water do I need to use in mixing cement-based products?” That is not such a simple question. To answer it, we need to look at the chemistry of cement and how water plays such an important role.
What many in the industry do not realize is that there is a science behind the curing of cement-based products. When water is added to cement, it starts to crystalize and form “fingers” that interlock with one another to create a strong bond. When excess water is used in cement-based mortars, grouts, levelers or patches, it increases spacing between the molecules of the mixture and stops the fingers from interlocking tightly, weakening the cement. This can lead to shrinkage cracks, along with decreased flexural and tensile strengths.

Tensile strength measures how long a material can withstand being stretched before breaking. We all know that no one is actually “stretching” a tiled floor; however, when a wall and a floor move independently of one another, the grout and mortar is “stretched.” This is why flexible sealants or caulks are required in any installation, especially around the perimeter – to allow the floor to move independently and help prevent cracks.

Flexural strength is how much a cement product can bend. This is important when considering heavy loads, such as those seen in a warehouse. Flexural strength determines how much weight a system can withstand before cracking.
It is important to understand the type and amount of movement that cement products experience in order to recognize the role of the water/cement ratio during mixing and installation. When too little water is used or if water evaporates out too quickly, the cement never reaches a full chemical cure, causing a weakened product.
So, how much water do you need to use in mixing? Considering how critical the correct water ratio is to any cement-based product, we always recommend that you follow the manufacturer’s guidelines on water quantity. Not all cement-based products are the same.
For inquiries, please contact our Product Support line at 1-800-992-6273.


Denise Troiano

Denise Troiano

Denise Troiano brings 24 years of experience in the tile, stone and installation products industry to MAPEI. Working with manufacturers, retailers, designers and installers during this span allows her to answer a wide range of questions from homeowners and industry professionals.


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