High Perormance SY-G Type Anti-cracking Expansive Agent

The ‘UJOIN’ brand high efficiency SY-G type anti-crack expansive agent is the fourth generation new expansive agent that is developed by our company using advanced techniques at home and abroad. The product with dominantcompositions of Calcium Aluminate-Sulfo (CAS) and Calcium Aluminate, together with appropriate amount of natural anhydrite and our company’s appropriative activating agent, which are grinded up according to the strict and precise dosage ratio, is a new generation high efficiency concrete anti-crack expansive agent with reasonable gradation.

1. The reaction mechanism of high efficiency SY-G type anti-crack expansive agent

The CA in high efficiency SY-G anti-crack expansive agent product has high activity and high speed of hydration, and can react with CaSO4 (calcium sulfate) to the ettringite (C3A·3CaSO4·32H2O) as early expansive source, which can compensate hardening concrete’s autogenously shrinkage early , thermal contraction attributed to the hydration heat and parts of drying shrinkage. However, the ettringite (C3A·3CaSO4·32H2O) that generated from the chemical reaction with CA2 and CaSO4 is mainly used for compensating concrete’s medium-term drying shrinkage, so as to reduce shrinkage loss.

CA+3CaSO4+2Ca(0H)2+32H2O= C3A·3CaSO4·32H2O

CA2+6 CaSO4+5 Ca(0H)2+59 H2O =2(C3A·3CaSO4·32H2O)

C4A3S+8CaSO4+6Ca(0H)2+90H2O=3(C3A·3CaSO4·32H2O)

The both generated ettringite (C3A·3CaSO4·32H2O) can efficiently fill the concrete’s pores, and cause the formation dense cement structures. Under the restrain from rebar and adjacent position, it generates pre-stressing force ranges from 0.2MPa~0.7MPa. In different ages of the concrete, different expansive minerals generated, and cause the coordination of the expansive growth curve and the strength curve of the concrete, which are good for the efficient exertion of expansive ability and efficiently compensate concrete shrinkage. So it can be ensured that in all ages the concrete net shrinkage value is less than the concrete limit extension value, so as to reach the goal of anti-crack and anti-seepage.

2.Technical Features:

(1) Efficient expansion: The special clinker with expansive mineral of CA,CA2,C4A3S can produce ettringite to improve the expansion effect at different time by different way.

(2) Stable expansion process: the hydration reaction cycle is short with high activity and stable expansion ability. The later concrete strength can be enhanced though there is no obvious effect on early strength.

(3) Peculiarity of anti-crack and anti-seepage:The feature of synchronous compensation shrinkage can be exposed during the application process, namely that when SY-G type high efficiency anti-crack expansive agent was dosed to the concrete, the generated expansion and concrete’s shrinkage were developed in the same time. Under different periods, different amount and different mineral crystals individual mechanisms, generates the pre-stressing force ranged from 0.2 MPa to 0.7 MPa generated by concurrent concrete expansion , will compensate and reduce concrete shrinkage and then ensure that in all ages the concrete net shrinkage value less than the concrete limited extension value, so as to effectively reach the anti-crack and anti-seepage goal.

(4)Safe and environment-friendly: This produce don’t contain chloride ion and have no rust-eaten harm to reinforcing steel bar. The resistance to carbonization, wearing and chemical attack is much better than normal concrete. This high efficient expansive agent is nontoxic, water pollution-free and environment-friendly.

3.Technical Characteristics:

(1)Fineness:Retained percentage on 1.18mm sieve≤0.5%. Specific surface area, 250m2/kg-350m2/kg;

(2)Restrained expansion rate:≥0.030% in water for 7d, and ≥-0.02% in air for 21d.

(3)Compressive Resistance: 7d≥20.0MPa,28d≥40.0MPa;

(4)Setting Time: Initial Setting≥45min,Final Setting≤10h;

(5)Compatibility:Good adaptability to chemical agent, less alkali content, and remarkable ability of reducing concrete’s hydration heat;

(6)Durability:The dosed concrete has obviously seepage-proofing and frost resisting abilities, no corrosion to rebar, and better abilities of chemical corrosion resistance, abrasive resistance, and carbonation resistance than normal concrete.

4.Product Testing Standard:GB 23439-2009;

5.Notices:

(1)Dosage:The normal dosage is 6%~8% by the weight of waterproof concrete, 8%~10% of compensating shrinkage concrete, and 10%~12% of filling concrete.

(2)Material inputting: Input materials should be strictly accordance with the volume of each material, or else the function of concrete will be out of expected effect. So dedicated should be arranged to be in charging of input at the concrete batching plant to guarantee accurate inputting.

(3)Mixing: It is suggested that the mixing time should extend for 60s to guarantee that the SY-G distribute evenly in the concrete.

(4)Pouring: Comparing with normal concrete, the SY-G shrinkage compensating concrete demands more plastering before final setting and take film curing in time to prevent early plastic crack. Detail construction please refer to JGJ/T178-2009<Technical specification for application of Shrinkage-compensating concrete>.

(5)Maintenance:The maintenance of concrete structure is particularly important for the large water demand of the process SY-G slight expansion components generating expansive sources, only sufficient water curing can maxing the function of SY-G. So lay out film and watering in time after final setting. The slab structure should take water curing for 14 days if condition permits. For side walls, set up pipes on their top, loose the split bolt in 3 days after pouring, and take shower curing for 14 days.

6.Package and Storage:

(1)This product is packaged in complex membranes woven bags or in the bulk. The product should be placed in the dry place, and handle it gently preventing damage and damp, and the stack amount should not be exceeded by 10 bags.

(2)The unused product should be sealed in time, preventing damp and metamorphism. The product’s quality guarantee period is 6 months in the sealed situation, and the product should not be retested and ensure its quality before utilization unless exceeding the quality guarantee period.

7.Applications:

Maximum length of the foundation is 266m, maximum width is 65m. This construction has realized structure self-waterproof by using shrinkage compensating agent of SY-G high efficient expansion cracking agent.