Cemix Cemscreed40 is a high strength floor screed, topping & paving bedding mortar for 10mm - 50mm deep applications. Cemix Cemscreed40 is a blend of specifically selected and graded aggregate, sand, Portland cement and other performance enhancing admixtures which improve the workability and performance of the product. It has increased abrasion resistance as well as a high early and ultimate strength.
Typical Applications & Uses:
- Toppings & screeds on concrete slabs
- Floor preparation screeds
- Shower and bath bases
- Paving bedding
- Cost effective
- Good compressive strength
- Good bond strength
- Shrinkage compensated
Concrete substrates should be sound & roughened to ensure a good bond. They should be uncoated & clean, free from all contaminants, loose particles, dirt, oil, mould, curing compounds, sealers & paints etc. Acid washing, rough honing or scabbling & then water blasting is required to prepare the surface depending on substrate condition. Washing with soap & water blasting may also be required if oil is present. Cracks should be repaired with a suitable Cemix® repair product. The better the substrate preparation & condition the better the end result. The concrete substrate should ideally be at least 1 month old.
When using Cemix® Cemscreed40 as a paving bedding mortar, the back of the pavers should be sound, clean, roughened & damp to ensure a good bond. The rougher the back of the pavers the better the end result. Concrete pavers should ideally be at least one month old.
Movement / Control Joints:
Honour any control joints in the concrete substrate – do not apply product over control joints. Mimic control joints in concrete substrate up into the mortar. Install control joints in the topping. Recommended control joint spacing is 4m x 4m. Control joints are required at topping penetrations & distinct depth changes in the topping.
Mix whole bags of product. Add approximately 2.8L of water to mixer, then add product to water. Add rest of water slowly whilst mixing until the desired consistency is achieved. Maximum total water is approximately 3L per 25kg bag. For improved bonding & screed performance, mix Cemix® Cemscreed40 with 1L of Cemix® Multibond and approx. 2L of water. Mix thoroughly for 2 - 3 minutes using a drill & paddle or mechanical mortar mixer. Use product immediately as this is a reasonably fast setting product. Do not mix more product than can be mixed, placed & finished in 45 minutes. Use chilled water in hot weather as well as to extend working time slightly in normal ambient temperatures.
Screed / Topping:
Dampen the roughened concrete substrate & then prime it with Cemix® Multibond brushed undiluted into the surface just prior to mortar application. Do not let the Cemix® Cemix® Multibond dry. Firmly push the Cemix® Cemscreed40 into the surface to compact it & obtain a wet bond, while the Cemix® Multibond is still wet. Application is from one side of the floor to the other.
Apply product to a minimum depth of 10mm & a maximum depth of 50mm. Avoid featheredging. Compact, screed & trowel finish final surface as required. Apply product in layers for thicker repairs - Roughen the preceding layer prior to it hardening & prime the preceding layer after it has hardened as discussed above.
Paving Bedding Mortar:
Dampen the roughened concrete substrate & then prime it with Cemix® Multibond brushed undiluted into the surface just prior to mortar application. Only prime the area about to come into contact with mortar & do not let the Cemix® Multibond dry.
Dampen the roughened back & top of the pavers & then prime them with Cemix® Multibond brushed undiluted into the surface just prior to paver installation. It is useful to dip the pavers in water prior to priming to wet the whole paver. Only prime the pavers about to be used & do not let the Cemix® Multibond dry.
Apply Cemix® Cemscreed40 mortar to the wet or tacky Cemix® Multibond on the concrete substrate. Apply mortar in a manner that will facilitate paver installation to the correct nominal thickness (10mm - 50mm) after tamping, by overfilling mortar ready for tamping down level.
Install primed paver onto the Cemix® Cemscreed40 and tamp it down into place. Tamp the paver down level ensuring falls and levels are correct. Ensure that after tamping, the mortar is in contact with the complete underside of the paver and that no voids exist. Let the mortar stiffen slightly and then tool the edges of the mortar with a suitable tool to tightly compact the mortar underneath the paver. Pavers must not rock after laying.
Screed / Topping: It is very important to prevent early plastic state moisture loss prior to the product setting. Cure product thoroughly after it has set by keeping it wet & covered for at least 7 days. Avoid product freezing for at least 3 days.
Paving Bedding Mortar: Keep the top of the pavers damp for approx 3 - 4 hours immediately after installation. Thereafter & once set, keep the pavers and bedding mortar damp and covered for at least 7 days. Avoid pedestrian traffic on the pavers for at least 7 days. Avoid product freezing for at least 3 days.
Appearance – Sand/cement grey powder
Strength (MPa) – 40MPa @ 28days.
Application Temp - 5ºC - 30ºC
Yield / Coverage - Approximately 12.5L or 0.0125m3 per 25kg bag.
Packaging – 25kg
Bond Strength – > 3MPa
Thermal Coeff. Of Exp – 9.0 x 10-6 mm/mm/ ºC
Working Time – 45 minutes at 20ºC
The data shown above reflects typical results based on laboratory testing under controlled conditions. Reasonable variations may occur on site.
Substrate Temperature - +5°C min. / +30°C max.
Ambient Temperature - +5°C min. / +30°C max.
Cemix® Cemscreed40 can be stored in its original packaging in a dry place well sealed for a period of six (6) months after production. Do not store opened bags.
Clean all tools with water & brush immediately after use.