TECHNICAL MORTARS Modified with Synthomer Polymers

Polymer dispersions for primers, mortars (pcc), renders, and screedsEssential characteristics such as adhesion, crack resistance or durability are improved through polymers Synthomer polymers in this context suitable for patch repairs of reinforced concrete in particularSelect Lipaton, Revacryl and Plextol products as ideal ingredientsStarting formulations available from our technical service

A saviour for anything made of reinforced steelThis technical bulletin describes the use of Synthomer polymer dispersion and latices in patch repairs of reinforced concrete.

The information given here is suitable for small repair projects. Synthomer polymers are also suitable for use on larger projects, but these should be considered individually by specialist concrete repair companies.

CementitiousCementitious systems featuring so-called PCC-mortars are widely adopted for refurbishment work. This abbreviation stands for: polymer (dispersion) – cement - concrete

Technical mortarsImproved properties by addition of Synthomer laticesThe use of Synthomer polymers in concrete repair system results in the following advantages:

• improved adhesion to substrates e. g. aged concrete• corrosion protection of the reinforcing steel• imp• improved crack resistance• reduced thermal stresses due to thermal expansion coefficient similar to that of unmodified concrete• protection of coated concrete from carbonation• improved durability• improved workability at reduced water demand• imp• improved and homogeneous coverage of the aggregates• increase of water retention capacity• higher early strength development• increase of flexibility and reduction of e-modulus• improvement of the ratio flexural-compressive strength by increasing flexural strength• reduction of the permeability to gases and liquids• • reduced shrinkage• increase of abrasion resistance• improved resistance against aggressive media like acids or salts• excellent resistance against freeze/thaw-cycles and de-icing salts

Applications: wide and practicalApplication stepsPrimerTheThe application of a primer/bond coat is recommended to obtain reliable adhesion of a subsequently applied render, repair mix or floor topping. In addition, site trials have shown that latex can be very effective in improving the adhesion of plaster to difficult substrates. Before using a primer based on a Synthomer polymer dispersion or latex it is important to ensure that the surface to which it is applied isis clean and free from dust and loose material, and has sufficient mechanical strength. When used as a bonding agent below mortars, renders, screeds and toppings the priming mix must be vigorously brushed into the prepared background and the mortar, etc. applied while the priming coat is still wet or tacky, usually this should be within 20 minutes depending on conditions.

It is recommended that concrete or masonry surfaces are well dampened an hour or so before priming (unless already damp, e.g. basement walls) and should be damp but surface dry when the primer coat is applied. Add the cement gradually to the polymer, stirring continuously. A slow speed electric drill fitted with a paddle is suitable.

Concrete repairRRepair mortars modified by Synthomer latices have the following characteristics:

• reduced water / cement ratio• up to 100% increased flexural strength • fast development of mechanical strength, even at lower temperatures • adhesion strength up to 4 N/mm²•• resistant against saponification, no loss in mechanical strength afterwards • storing in calcium hydroxide solution

This information is describes the use of Synthomer polymers in patch repairs of reinforced concrete.

It is important to make a root cause analysis of the reasons for concrete failure prior to remedial action. If the problem has been caused by, for example, chlorides, porous concrete or inadequate cover to steel, areas which appear undamaged may deteriorate at a later date.

Selection Selection of materialsTo obtain maximum performance from mixes modified with Synthomer polymers it is important that attention is paid to the choice of other materials used.

• Sand: should be well washed and sharp. The grade of sand will depend upon the thickness of each layer to be applied.•• Cement: portland, high alumina and sulphate resisting cements are compatible with Synthomer polymer. Masonry cement may lead to excessive air entrainment in the compounds. Portland cement should be fresh but cool. Cement containing air set lumps should not be used.• Air entraining agents should not be used.• Other additives should only be used after seeking further advice f advice from our technical service.

Polymer Matrix inside cement mortar: 50 µm (top), 2 µm (bottom)

I. Removal of unsound concrete • Clean back mechanically to good sound concrete, preferably behind any exposed steel reinforcement. The concrete should be cut back so that the mortar can be applied to a thickness of at least 5mm at the edges of the repair to avoid feather edging. Provide at least 10 mm of co cover to the reinforcement.

II. Preparation• Depending on the size of the repair, abrasive blasting or wire brushing of steel is necessary.• The steel should be washed with clean water and allowed to dry. Chemical cleaners and rust treatments should not be used. (note: If corrosion of steel appears excessive, an engineer engineer's opinion should be sought.)

III. Priming steel• Brush primer coat on to the steel and allow dry. This coat should be applied within 24 hours of preparation of the old concrete and steel.

IV. Brush• 16 - 36 hours after application of first primer coat to the steel dampen surface of background concrete and allow to surface dry.• Brush second coat of primer on to steel and background.

V. Apply mortar• Whilst second coat of primer is still wet or tacky, apply the repair mortar, making sure that it is well packed behind exposed steel.• The second coat of primer will only remain tacky for about 20 minutes depending upon ambient conditions.•• Where conditions require more than one layer of mortar, scratch surface of first layer and leave to just set before applying the second coat of similar thickness to the first.• For added protection, allow first layer of mortar to dry overnight and then apply a coat of primer. While this is still wet or tacky, apply the second coat of mortar.

VI. Smoothing off•• The final coat should be trowelled/floated to a smooth finish as the work proceeds.• In severe drying conditions a repair should be kept damp for 2 days to allow the cement to cure.• A surface coating may then be applied over the whole area when the moisture content of the mortar is sufficiently low.

RenderingThis section is describes the use of Synthomer polymers in renders.

Selection of materialsTTo obtain maximum performance from mixes modified with Synthomer polymers it is important that attention is paid to the choice of the other materials used.

• Sand should be well washed and sharp.• Cement portland, high alumina and sulphate resisting cements are compatible with Synthomer products.• Masonry cement may lead to excessive air entrainment in Synthomer mixes. The cement should be fresh, cool and free of lumps.• Use of lime if used, should not exceed 25% of the cement by volume.• Air entraining agents these should not be used.

Preparation of surfacesBefoBefore using a Synthomer modified mortar or concrete it is important to ensure that the surface to which it is to be applied is clean and free from dust and loose material and that the structure has sufficient mechanical strength. Walls should be wire-brushed and any old paint etc. removed. All contaminants such as oil, grease, or any surface laitence must be removed to ensure adequate development of bondbond when the render is applied. A primer coat is recommended to obtain maximum adhesion of the render. Details on the use of primers see above.

Mix designThe optimum proportions of cement, sand and Synthomer polymer depend upon the background, application and properties required. The following are typical examples.

Coverage ratesAs a rough guide, 1 litre of latex will cover 1m2 at a 15mm thickness (for mix 1 above).

MixingMixingMixing procedure for renders containing Synthomer polymer is similar to that used for conventional compositions, with gauging water being partly replaced by the latex and mixing minimised to limit air entrainment.

MixingMixing should preferably be carried out in a forced action mixer. The usual procedure is to pre-mix sand and cement in the mixer, add the latex, mix for 1 to 2 minutes, and then slowly add water to the required consistency. Over addition of water causes rapid thinning of latex modified mortars owing to the plasticising effect of the latex.

ApplicationApplyApply render onto wet or tacky primer. The first coat should be limited to a thickness of approximately 7mm.scratch the surface and leave to set before applying the second coat of similar thickness to the first.

ForFor added protection, allow first coat of render to dry overnight and then apply a second coat of primer. While this is still wet or tacky, apply the second coat of render. The final coat should be trowelled/floated to a smooth finish as the work proceeds. In severe drying conditions a render should be kept damp for 2 days to allow the cement to cure.

Conventional screedThe use of Synthomer polymer in screeds and toppings over concrete gives several advantages:

• A low water-cement ratio allows a minimum of delay when overcoating is required.• Reduced permeability to liquids.• Imp• Improved chemical, abrasion and impact resistance.• Resistance to dusting.• Thinner screeds, achieving reduction in weight and savings in materials.• Excellent slip resistance.• Good underlay for epoxy surfacing.• Synthomer has a long and successful track record of use in the construction indust the construction industry.

Selection of materialsTo obtain maximum performance from mixes modified with Synthomer polymers it is important that attention is paid to the quality of the other materials used.

• Sand should be well washed and sharp. The grade of sand will depend upon the mix design.

• Cement portland, high alumina and sulphate resisting cements are compatible with Synthomer products. Portland cement should be fresh but cool. Cement containing air set lumps should not be used.• Coarse aggregate e.g. granite chippings. These should be dust free.• Air entraining agents should not be used.• Air entraining agents should not be used.

Substrate requirementsThe substrage must be capable to withstand all stresses which will be put onto it and contain the appropriate joints. If it is to receive a topping the background should have a compressive strength greater than 30 MPa, and/or a tensile strength greater than 1 MPa.

PPreparation of surfacesFlooFloors should be mechanically prepared, e.g. scrabbled or shot blasted, to give an aggregate exposed surface. Dust should be removed by vacuum, not compressed air. All contaminants such as oil, grease, or any surface laitance must be removed to ensure adequate development of bond when the topping is applied. A water drop test is the simplest method to determine whether water repellent contamination is pcontamination is present.

PrimingApplication of a primer coat is necessary to obtain maximum adhesion of the topping or screed. Full details are set out on the information sheet on Synthomer primer systems.

Coverage rateAs a rough guide, 1.2 litres of latex will cover 1m2 of 12mm thickness using the above mixes.

MixingMixing procedures for topping and screeds containing Synthomer polymers are similar to those used to conventional compositions, with gauging water partly replaced by Synthomer products. However, mixing time should be minimised to limit air entrainment.

MixingMixing should be carried out in a forced action mixer. The usual procedure is to pre-mix sand and cement in the mixer, pour in the Synthomer polymer mix for 1 - 2 minutes, then slowly add water to the required consistency.

Over addition of water causes rapid thinning of latex modified mortars owing to the plasticising effect of the latex.

ApplicationApplication1. Apply topping or screed onto wet or tacky primer.2. Compact and level with screed bar.

3. Finish with steel float. It is essential that the topping or screed is finished as the work proceeds.4. The topping or screed should be cured for 1 - 2 days using conventional techniques. Curing should be started quickly after application.

Starting point formula are available on request.

Notes

•• Joints in the screed or topping should coincide with the joints in the background.• It is easier to lay the mix if the ambient temperature is below 25°C.• If overcoating the screed, oleo resinous floor finishes should be avoided.• If the water drop test indicates the presence of water repellants, it may be more suitable to use an epoxy primer in place of the l latex/cement prime latex/cement primer.

Product Solid Content [%] pH value Viscosity [mPa*s] Tg [°C] MFFT [°C]

Lipaton SB 29Y141

Lipaton SB 29Y146

Lipaton SB 30Y160

Lipaton SB 5843

Revacryl R 478

Plextol D 509Notes: 1According to ISO 2555 (Brookfield) 2According to ISO 3219 3According to ISO 1652 *Data describe typical properties - not product specifications

47.0

47.0

47.0

48.5

57.0

50.0

10.0

10.0

10.0

7.5

8.0

7.5

901

901

1653

302

18501

5003

-8

-8

18

-5

23

15

0

0

16

0

18

14

Emulsion properties*

Our broad portfolio for mortar modificationBinders for technical mortar modification

Product

Lipaton SB 29Y141

Lipaton SB 29Y146

Lipaton SB 30Y160

Lipaton SB 5843

Revacryl R 478

Plextol D 509

Application

Specialty binder for industrial flooring and screed application, very good surface finish and compressive strength

Soft binder, high flexural strength, with antifoam, excellent workability, excellent adhesion, ASTM C 1042 certified

High Tg, very high compressive strength, with antifoam, ASTM C 1042 certified, for rigid cementitious applications

Universal binder, ammonia free, with antifoam, excellent adhesion, compromise in compressive & flexural strength

High Tg styrene acrylate binder, high abrasion and chemical resistance

High UV resistance binder, giving high compressive and flexural strength

America, Europe and South East Asia. In March 2017, we acquired the coalescing agents and Butyl Ethyl Propanediol (BEPD) business from Perstorp Oxo Belgium AB. The newly acquired businesses significantly improve our footprint to a number of speciality markets which we will continue to serve through a strong network of local technical service and sales branches, supported by regional application dedevelopment and production in our key markets. We deliver the right formula, globally, individually.

Synthomer is one of the world’s leading suppliers of emulsion and speciality polymers supporting leadership positions in many market segments including coatings, construction, technical textiles, adhesives, paper and synthetic latex gloves. The company has its Head Office in London (UK) and provides customer focused services from operational centres in Harlow (UK), Marl (Germany), Kuala LumpurLumpur (Malaysia), Shanghai (China) and Dubai (UAE). In June 2016 we have acquired the Monomers, Dispersions and Powders business (MDP) from Hexion with dedicated production sales and customer service facilities in North

Disclaimer: This information and any other advice or recommendations given or made by us (collectively “Information”), are provided in good faith and are not intended to, nor do they, constitute professional advice or services. Information is provided “AS IS” and on an “AS AVAILABLE” basis and without warranty. We do not warrant or accept responsibility for the accuracy, timeliness or completeness of the Information, or for the suitability of the Information for a particular purpose. We do not accept responsibility, and exclude all liability (including(including under any implied warranties), for any matters arising out of or in connection with your reliance on the Information (including as to infringement of third party intellectual property rights) to the fullest extent permitted by law. Any Information concerning any possible use or application of Synthomer products is given by us in good faith; we do not warrant the fitness of any Synthomer products for any particular purpose and it is entirely for you to satisfy yourself fully as to the suitability of Synthomer products for any particular purpose. purpose. Synthomer products are sold in accordance with Synthomer’s standard terms and conditions of sale which are available from www.synthomer.com/tc.

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info@synthomer.com

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