Plasticizing of concrete
BEVETOL-SPL Concrete superplasticizer, type G
REOTOL-SPL Concrete superplasticizer, type F
PLASTIPROOF Plasticizing/water reducing admixture for concrete
I. NATURE OF THE PROBLEM – REQUIREMENTS
Extreme or difficult concreting applications, because of their position, shape, or dense reinforcement of structural elements, cases of exposed concrete etc., which are usually found in modern constructions, require plasticizing of concrete without adding additional water, which reduces its strength.
Also, for the preparation of high-strength concrete in site, as in the construction of bridges, tunnels etc., the concrete prepared must have its water/cement ratio (w/c) drastically reduced, while simultaneously it should maintain its plasticity.
In order either to achieve the desired plasticizing of the concrete (increased flow) without adding water, or to reduce the water/cement ratio in order to increase its strength, the following liquid admixtures are used:
BEVETOL-SPL, concrete superplasticizer, type G (according to the ASTM C-494 specification). Certified with the CE marking as set retarding – high range water reducing – concrete superplasticizing admixture according to EN 934-2: T11.1 and T11.2, certificate number: 0906-CPD-02412007.
REOTOL-SPL, concrete superplasticizer, type F (according to the ASTM C-494 specification). Certified with the CE marking as high range water reducing – concrete superplasticizing admixture according to EN 934-2: T3.1 and T3.2, certificate number: 0906-CPD- 02412007.
PLASTIPROOF, plasticizer-concrete waterproofing admixture (according to the ASTM C-494 specification). Certified with the CE marking as high range water reducing – concrete superplasticizing admixture according to EN 934-2: T3.1 and T3.2, certificate number: 0906-CPD- 02412007.
These admixtures offer the following advantages:
When added during the preparation of concrete, they reduce the quantity of the mixing water needed and consequently the water/cement ratio, resulting in a significant increase of its initial and final strength.
When added to ready-mixed concrete, they plasticize it (increasing flow) without requiring additional water, therefore, without reducing its strength.
They contribute to better moisturizing of the cement, resulting to the highest possible level of performance.
They act against segregation and significantly improve workability and pumpability.
They significantly reduce contractions during setting (avoiding cracks).
They significantly improve the concrete’s watertightness, contributing to its proper condensation.
They do not have air-entraining action.
They do not include chlorides or other corrosive components.
They are compatible with all types of Portland cement.
They are indispensable aids for the preparation of high-strength concrete, exposed concrete, pumpable concrete etc.
Directions of use
The plasticizing admixtures may be added to:
The mixing water, during the preparation of concrete or mortar, in order to reduce the quantity of the mixing water required (drastic reduction of the water/cement ratio).
The ready-made mixture slightly before its use, in order to increase its flow, significantly.
In this case, in order to achieve uniform mixing of the plasticizer into the mixture’s mass, 4-5 minutes of good mixing with a rotating mixer is recommended.
Classification – Consumption
BEVETOL-SPL acts as:
Type G superplasticizer (ASTM C-494), when the dosage is 0,6%-0,8% by cement weight.
As a type A or D plasticizer, (ASTM C-494), in smaller dosages (0,3%-0,5% by cement weight).
REOTOL-SPL acts as:
Type F superplasticizer (ASTM C-494), when the dosage is 1,2%-1,7% by cement weight.
Type Α plasticizer (ASTM C-494) in smaller dosages (0,6%-0,9% by cement weight).
PLASTIPROOF acts as:
Type A plasticizer (ASTM C-494) and is used in a proportion of 0,2-0,5% by cement weight.
Consumption of plasticizers, when they are added to ready-mixed concrete depends on the workability of the concrete when it arrives at the work site, and on its desired final workability.
When plasticizers are added to the concrete by the time it is delivered in site, in order to increase it’s flow, then they should be added shortly before concreting, because the working time for these admixtures is approx. 30 minutes.
An excessive dose may prolong setting time, but without negative effects on the concrete’s final strength.