SBR latex to improve cement mixes:a compehensive guide(1st)
SBR is an acronym which stands for Styrene Butadiene Rubber.
SBR latex for use in construction is a mainstream product with a multitude of uses. It is used as an admixture for the general and holistic improvement of concrete and cement mixes.
It’s produced as an aqueous dispersion of a styrene-butadiene-copolymer. It contains an emulsifier system and normally an antifoam and an antimicrobial agent.
When the water evaporates, the SBR globules coalesce and form polymer networks within the cementitious matrices. By doing this they alter the properties of cement/concrete mixes and when used in big dosages they do so in a very pronounced way.
Other polymer dispersion admixtures used in the construction industry are these based on:
- styrene acrylic esters and
- polyacrylic esters.
The emphasis of this article will be on SBR lattices.
DESCRIPTION OF SBR LATEX
SBR latex is a milky liquid with low viscosity and a total solids content of about 47-49% by weight. It is presented under the form of a water dispersion with polymer particles of about 200-250 nanometers.
WHAT ARE THE BENEFITS FROM THE USE OF AN SBR LATEX
IN CONCRETE/CEMENT MIXES ?
1) Improved flexural strength due to the flexibilising polymer network inside the cementitious matrix.
2) For this reason it will reduce cracking and especially the width of the cracks. The polymer matrix will work to keep the walls of the cracks together.
3) The cement mixes will be less water permeable due to its pore blocking effects.
4) Thus, cement mixes will be more resistant to freeze/thaw cycles and the action of deicing salts.
5) The adhesion to hardened concrete/mortars will be considerable increased. SBR lattices can be considered as integral bonding aids due to the powerful bonding power of their polymer matrix.
6) Resistance to wear and abrasion will be enhanced (less cracking).
7) For the same reason resistance to chemicals will be higher.
8)Because of its strong liquefying effect, coefficient W/C will be reduced for the same workability. This means an overall better durability.
9) Bleeding is reduced due to the air entraining properties of the SBR latex. SBR is suitable for potable water, resistant to hydrolysis and to saponification even in a highly alkaline environment. This is a strong advantage over classical PVAc admixtures.
Chris Strogilis
Civ. Eng. – MBA – DipM
http://maconwaterproofing.blogspot.com/
About the Author
Civil engineer with postgraduate studies in MBA and Marketing
