Conplast RP264 is a dark brown liquid based on selected lignosulphonates, mixed with retarding agents. When added to concrete mixes, the cement particles absorb the additive, which acts as a dispersing agent, breaking the agglomerations formed by cement particles and allows the water in the mix to behave more efficiently.

In addition, the additive retards the initial hydration of the cement, resulting in a delay of the setting time. However, once the concrete has passed the initial setting, the hardening process continues normally.

Uses

• To improve the effectiveness of water in a concrete mix.
• To help maintain the workability of ready-mixed concrete in high temperature conditions.
• To extend the workability times of concrete and minimise transport delay problems.
• Particularly suitable for use in mixes with low cohesion, as well as for the placement of roller-compacted concrete batches.

Advantages

• Water reduction significantly improves ultimate strengths at all ages and increases durability and setting time, facilitating placement.
• Controlled retardation extends the workability period and setting time, facilitating placement.
• Setting control improves the pour and helps prevent the formation of cold joints in large pours, as in the case of roller-compacted concrete.
• They minimise problems caused by delayed transport, maintaining placement and reducing the risk of blockage in pumping.
• Slight air occlusion improves cohesion in mixes with narrow sand size distribution or a lack of fine material, minimising bleeding and segregation.
• It allows certain strengths to be achieved with a reduction in cement content or an increase in workability.

Standards

Conplast RP264 complies with UNE-EN 934-2:2010 Table 8 as a setting retarder.

Typical dosage

The optimum dosage of Conplast RP264 to achieve specific requirements should be determined by tests using the materials and conditions that will be used in practice.

This allows optimisation of the additive dosage and mix design, providing a complete assessment of the mix. The usual dosage is between 0.25 and 0.6 litres of Conplast RP264 per 100 kg of cementitious material, including fly ash, slag and microsilica.

Properties

The following results were obtained at a temperature of 20°C:

• Appearance: Dark brown liquid
• Density: 1,21 ± 0,01 kg/l
• pH: 3,0 ± 1,0
• Water soluble chloride content (CI-): ≤ 0,10%.
• Alkali content (Na2O equivalent): max. 5 mass %.
• Primary function: Retarder, setting retarder
• Secondary function: Plasticiser, water reducer

Application method: Retarder

Delay

The level of retardation obtained may vary depending on the dosage of Conplast RP264 used, which also alters the level of water reduction. The setting delay is also affected by factors other than the additive, such as the characteristics of the mix and the conditions in which it is found.

The main factors are as follows:

(a) Other cementitious materials provide higher levels of retardation than that experienced with ordinary Portland cement mixtures at the same dosages of admixture.

b) Higher temperatures require higher dosages to achieve the same result.

c) Changes in cement content, origin and chemical composition can lead to variations in the retardation obtained. The amount of tricalcium aluminate in the cement has been identified as one of the main contributing factors in this respect, with a low level leading to a higher retardation.

Compatibility

Conplast RP264 is compatible with other Fosroc Euco admixtures used in the same concrete mix. If more than one admixture is used, they should be added to the concrete separately and not mixed together prior to being added. The resulting properties of concrete containing more than one admixture must be checked by prior testing. Conplast RP264 is suitable for use with all cements complying with RC-08.

Dosing system

The correct amount of Conplast RP264 will be measured by means of a recommended dosing system. The admixture is normally added to the concrete together with the mixing water, in order to obtain the best results. Contact Fosroc Euco's Technical Department for advice on suitable equipment and installation.

Effects of overdosage

Overdosing twice the intended amount of Conplast RP264 will result in a significant increase in setting delay. Provided adequate curing is maintained, the ultimate strength of the concrete will not be affected by the delay and will generally increase. The effects of overdosing will be increased if sulphate resistant cement or other cementitious materials are used.

Overdosing may also cause increased air entrapment, which will tend to decrease the strength of the concrete. The degree of this effect will depend on the particular mix and the level of overdosage. Overdosing greatly affects the plasticising effect of the admixture. As concrete is always mixed to a certain workability the plasticising effect will allow a further reduction of water. This has the effect of increasing the ultimate strength and will partially or fully counteract the effect of the increase in air entrainment.

If water is not reduced, and the workability is significantly higher, there is the possibility of segregation. Higher initial workability tends to increase the handling time of the concrete, which will delay finishing and setting.

Curing

The final characteristics of all structural concrete will depend on good curing practice. Therefore, it is very important to use a Fosroc Euco Concure curing membrane, water spray or wet burlap.

Clean-up and disposal

Spills of Conplast RP264 should be absorbed with sand or earth and transferred to suitable containers. Product residues should be flushed away with a large amount of water. Disposal of the product and packaging is the responsibility of the end user.

Storage

Conplast RP264 has a storage period of 12 months if kept in a dry place and in its original, closed containers at a temperature between 2ºC and 40ºC.

Freezing point: -3 ºC approx.

Precautions

Safety and Hygiene

Conplast RP264 is alkaline and irritant and should not be ingested or put in contact with skin and eyes. Wear protective gloves and goggles. Splashes on the skin should be washed off with water. In case of contact with eyes, flush with plenty of water and seek medical advice. If swallowed, seek immediate medical attention. Do not induce vomiting.

For further information, please refer to the Material Safety Data Sheet.

Fire

Conplast RP264 is water based and non-flammable.