Chemical building materials
Green building materials
ⅠProduct functions and use
The composite admixture is developed by our company for concrete use. It is ground materials composed of more than two kinds of mineral materials for cement production, volatilized silica and other functional components. It is one of the mineral admixtures stipulated in JGJ 55-2011 "Design Discipline of Mixing Ratio of Ordinary Concrete" that can be used .The composite admixture can completely replace the admixture of fly ash, granulated blast furnace slag powder, steel slag powder, phosphate slag powder, volatilized silica and other cementing materials, thus cement will be saved, with significant technical and economic benefits.
Composite admixture is one of the main materials for preparing high strength autoclaved concrete components of high-speed railway and subway. Also it is an important admixture for preparing high strength and high performance concrete. Its application in ordinary concrete is an important means to solve the shortage problems of granulated blast furnace slag powder, volatilized silica and fly ash, cut down water consumption, reduce hydration heat, prepare high strength and high performance concrete, ensure the stability of concrete quality, and reduce the cost of manufacturing concrete. In production, composite admixture will simplify the mixing ratio of concrete, make the measurement more accurate and the storage facilities more optimized. This material is called auxiliary cementing material in foreign countries. It has already become the sixth component of concrete. Composite admixture will be the development direction of green concrete, high strength and high performance concrete in the future.
The function of the composite admixture is to optimize the various functional materials by compound gelatinization effect, induced activation effect, surface micro crystallization effect, interface coupling effect and micro aggregate effect, stack effect and filling effect. It will improve the working performance of concrete. Meanwhile the mechanical properties and durability of concrete will be significantly improved. Especially in mass concrete construction, applying the composite admixture will lower the internal temperature of concrete by 10 ~ 200℃. Furthermore reduce the hydration heat and decrease the crack of concrete.
Ⅱ. Product properties
1. The composite admixture can completely replace single mineral admixtures such as mineral powder, fly ash, volatilized silica and some of cement, reduce the types of cementing materials in the mix ratio, and comprehensively reduce the cost of concrete.
2. This product can improve the workability and coherence of concrete, prevent bleeding and segregation, improve the construction performance and pumpability of concrete.
3. This product can reduce the hydration heat, decrease the cement content, lower the internal temperature of concrete and reduce the concrete cracks. It is suitable for mass concrete construction.
4. Applying the admixture by activating micro aggregate, the late strength of concrete can be significantly improved.
5. Improve the durability of concrete. The ultrafine particles in the composite admixture can fill the capillary pores of concrete, replace the free water, and the concrete structure will be more compact. Thus the freeze resistance, impermeability and sulfate resisting of concrete will be improved.
Ⅲ. Operative standards
Q/GXGH 01-2014 <Composite Admixture for Ordinary Concrete >and JGJ 55-2011 <Design Rules of Proportion of Ordinary Concrete >put on record by Quality and Technical Supervision Bureau of Guangxi Zhuangzhu Autonomous Region.
Ⅳ. Usage and dosage
1. This product, due to its fine particles, after replacing the mineral powder, fly ash, volatilized silica or some cement in the cementing material, should be fully mixed, and the mixing time should be extended 1 minute so as to achieve the best mixing effect.
2. In use of composite admixture, lower water-binder ratio should be kept, water consumption reduced, with the additives optimization, thus to meet the need of the working ability of concrete.
3. Portland cement and ordinary Portland cement should be used for concrete with composite admixture. When other kinds of cement are used, the variety and amount of the blended material in cement should be known, and the mixing amount of composite admixture should be determined after experiments.
4. Concrete mixed with composite admixture should be mixed with additive simultaneously. The admixture and cementing material adaptability and reasonable mixing amount of additive should be determined after experiments, meeting the relevant stipulations of national standards.
5. The substitution amount of mixed composite admixture should be determined through the trial mixing experiments, and comply with JGJ55-2011<Design Rules of Proportion of Ordinary Concrete>.
V. Precautions for use:
1. Mixing proportion of concrete mixed with composite admixture should conform to JGJ55-2011<Design Rules of Proportion of Ordinary Concrete>.
2. The premixing concrete mixed with composite admixture shall conform to GB/T14902 <Premixing Concrete>.
3. The construction of concrete mixed with composite admixture shall conform to GB 50666 <Construction Norm for Concrete Structural Engineering> and GB 50164<Concrete Quality Control Standard>.
4. The composite admixture should be mixed with other cementing materials simultaneously and conform to GB 9142 "Concrete Mixer".
5. The concrete mixed with composite admixture should be mixed throughly. The homogenization of the same plate of concrete shall conform to GB/T50164 <Standard for Concrete Quality Control>.
6. The slump of concrete mixed with composite admixture should meet the construction requirements in its transportation and concrete placement . When the slump loss of the mixture cannot meet the construction requirements, high efficient water reducer should be added for secondary fluidization. Adding water to the mixtures is forbidden.
7. After the placement of concrete mixed with composite admixture, it should be timely moisture-retentive cured by water spraying, covering and spraying curing compound. The curing method will be determined by site conditions, environmental temperature and humidity, properties of constructional elements, technical requirements, construction operation and other factors. The moisture-retentive curing time of concrete should not be less than 7days. The moisture-retentive curing time of concrete with requirements of shrinkage compensating, permeability resisting or retarding setting should not be less than 14 days. The curing time should be extended when the temperature is low or curing in dry environment. In the construction of composite admixture concrete, on concrete finishing at least two rubbing pressure should be made. The last rubbing pressure should be made before the end of bleeding and initial setting. Then moisture-retentive curing should be maintained.
8. Winter construction shall comply with JGJ/T104 <Winter Construction Regulations for Construction Projects>.
9. The quality inspection and evaluation of concrete with composite admixture should be conducted in accordance with the provisions of GB/T50107, the current national standard <Standard for Inspection and Assessment of Concrete Strength>, GB50204 <Norm for Acceptance of Construction Quality of Concrete Structure Engineering>. Other mechanical performance tests should meet the design requirements and the provisions of the current national standards.
10. The acceptance strength age of concrete with composite admixture shall meet the GB/T50107 provisions of the current national standard <Concrete Strength Inspection and Evaluation Standard>. 60d, 90d or other acceptance strength age should be adopted for the acceptance strength age of mass concrete with composite admixture.
11. The inspection for the long-term properties of concrete with composite admixtures can be implemented in accordance with the relevant provisions of the durability test in JGJ/T 193 <Concrete Durability Test Evaluation Standard>.
12. The composite admixture must be stored in closed containers and prevent from mixing with other substances. Stored separately and prevent from moisture. The storage period should not exceed 50 days.
Early strength type
of sieve）( mass fraction)/%
Index of activity
Compressive strength growth ratio of colloidal mortar
Water content(mass fraction)/%
Chloride ion content( mass fraction)/%
Sulphur trioxide content(mass fraction)/%
Expansion in autoclave test less than 0.50%
Shandong Zhongsen Science and Technology Co., Ltd.