Umaflow

Umaflow is a one-component cement mortar, pre-mixed, with fast setting and hardening, available in grey and anthracite colours, based on a mix of special cements, selected aggregates, fibres and specific additives. A fluid and cohesive mix is obtained after mixing with water. A slight expansion during both the plastic and the post-hardening phases compensates for hydraulic shrinkage, with a considerable improvement of the final adhesion characteristics, and at the same time preventing fracturing. The optimum water retention reduces the risk of “burning” when it applied in small thicknesses (which, in any case, must not be less than 2 cm) and, if suitable care is taken, even during critical weather conditions (summer temperatures and windy); however, in this case it is necessary to adopt suitable precautions (do not expose to direct sunlight, mix with cold water, apply the product preferably at coolest times of the day and in the shade, etc). Specific additives make the hardened mortar impermeable to water and resistant to the penetration of CO2. Umaflow is a product for the structural repair of concrete structures using hydraulic mortar type CC and class R4 in accordance with EN 1504-3.

Instructions for use

Preparation
Remove all crumbling and loose parts from the substrate by careful hammering and chiselling, until a sound and strong substrate is reached. Scrape down to a depth of at least 2 cm. The scraped substrate must also be carefully roughened, with bumps of at least 5 mm, and then cleaned, so as to be free of dust, loose material and dirt of any kind. Any oil or grease residue must be carefully removed. In the case of repairs to flooring and other reinforced concrete elements, fully expose the reinforcement bars which can be seen and remove completely any concrete, cleaning them by wet or dry sandblasting. For effective anticorrosive protection, apply Restoration Irons to the reinforcing bars and allow it to harden so that subsequent applications do not damage it (see the appropriate data sheet for application methods). Wet the substrate well with pressurized water until refusal and allow excess water to evaporate or remove it with a sponge. Roughening and saturating the substrate with water is necessary to ensure adhesion and counteract the expansion of the expansive action of Umaflow.

Mixing the product
Mix Umaflow with approx. 13 – 15 % of water (which is equal to approx. 3,25 – 3,75 litres for a 25 kg bag), mixing it with a mechanical mixer (low-speed drill with mixer attachment or mortar mixing plant) until the mix is homogeneous and free from lumps. In the cases of small quantities of mixes, do not mix manually with a trowel, as the amount of water needed to prepare the mix would be greater, with consequent worsening of the mechanical performance and reduction of the resistance to carbonation (if the mixing water is much greater than that specified there can be the risk of cracking caused by excessive hydraulic shrinkage).

Application
The mix prepare in this way is workable for approx. 30 minutes under normal conditions (+20 °C). The workability time is shortened at higher temperatures and increased at lower ones. Place the Umaflow mix directly into the space to be filled. Smooth the surface using a trowel or palette knife. The minimum application thickness is approx. 2 cm, so do not smooth “flush”. The maximum total thickness which can be applied is approx. 10 cm. For thicknesses greater than 10 cm, dilute Umaflow with up to a maximum of 30 % by weight of washed gravel (3 – 8 mm), that is, approx. 3 parts by weight of Umaflow and 1 part by weight of gravel; in practical terms, this corresponds to approx. 2 builder’s buckets of 3 – 8 mm gravel for every 100 kg (four 25 kg bags) of Umaflow. This addition results in a modification of the mixing water, which changes from 13 – 15 % to 11 – 13 %, and a reduction by approx. 10 % in the mechanical strength, guaranteeing a compressive strength after 28 days of more than 55 MPa. Carry out any finishing with a plastering trowel when the mortar starts to set, that is, when it is only possible to make a slight impression when pressing with a finger. The inserts and repairs carried out with Umaflow must be suitably protected during the summer months and in the presence of strong winds by spraying the surface with water or covering with polyethylene sheets, in order to avoid the formation of cracks in the mortar when it is still in the plastic state due to too fast an evaporation of the mixing water.

Cleaning
The tools used can be cleaned with water before the mortar hardens. Once hardened, the mortar must be scraped off.

Storage

Store Umaflow in a dry, protected place. Unopened in its original bags, the product can be stored for at least 9 months.

Warnings

• Do not mix with other binders such as cement, hydraulic lime, gypsum, etc.
• Do not add water once the mix has started to set.
• Do not use the mixed product when it has already started to set. Therefore, always prepare quantities of mix which can be used within the workability time.
• Do not use in temperatures which are too high or when it is very windy. Protect from direct sunlight. During the summer months wait for the coolest hours of the day before application, mix with cool water and protect the surface against strong winds, spraying the surface with water or covering it with polyethylene sheets.
• Do not apply Umaflow when the temperature is less than +5 °C or more than +30 °C.
• Attention: when laying horizontally, the surface of the substrate must be solid, strong, durable and stable with a roughness (roughness more than 5 mm deep) in order to achieve the necessary adhesion between the substrate and the Umaflow material.