Solutions For Precast Concrete From MAPEI
The precast concrete industry is continuously innovating, driven by shifts in global markets, increasing customer expectations and pressures from increasing labour costs. Producers are constantly searching for ways to improve productivity, increase quality and maximize their bottom line. Further, heightened environmental awareness and an emphasis on project life-cycles has placed a higher demand on sustainable construction practices, especially on reducing waste, greenhouse gas emissions and energy consumption. As concrete is the most common constituent construction material and the most abundant manufactured material in the world, this has had a major propulsive effect on the development of better concrete technologies in general, and for the precast market.
This led to the development of a variety of concretes in the form of, among others, fibre reinforced concrete, polymer concrete, ferrocement, sulphur concrete, lightweight aggregate concrete, autoclaved cellular concrete, high-density concrete, ready-mixed concrete, self-compacting concrete, roller compacted concrete, high strength concrete, super high-strength concrete, high performance concrete, high-volume fly ash concrete, self-curing concrete, floating concrete and smart concrete.
MAPEI offers globally proven products and systems for the demanding production and repair of various precast concrete elements, including hollow-core planks, concrete pipes, burial vaults, septic tanks and double tees, as well as other specialized precast members. Whether it is repairing a ‘cull’ or injecting a ‘crack’, MAPEI can provide the correct product or system for the customers’ needs. The products for Precast Concrete from Mapei, are discussed below.
Mapei Admixtures like Dynamon SX626, Dynamon SX628 and Dynamon SX550 are hyperplastisicing admixtures, based on new generation of Polycarboxylate Ether for high performance concrete mixes with very low water cement ratio and high early compressive strength, specially designed to improve the rheology of precast concrete.
Dynamon SX 626/Dynamon SX550 is mainly used for:
- waterproof and durable concrete with exposure class in compliance with EN 206-1
- ready-mixed concrete with high mechanical performance and good acceleration in the development of mechanical strength
- concrete that is pumpable
Dynamon VM is a liquid admixture specifically developed to produce vibro-compressed and extruded concrete components, made using a dry or slightly damp mix. Dynamon VM increases the compacting grade of the concrete when vibrated. The plasticising action of Dynamon VM, alongside its property of increasing mechanical strength after short curing times, allows manufactured components to be made using the vibro-compression and extrusion technique, which have considerably reduced curing times and, therefore, handling times.
Also, the performance characteristics are improved, such as mechanical strength and indirect traction. Further, the components are more durable due to the reduced water absorption and have higher resistance to abrasion. Dynamon VM does not excessively modify the rheology of the fresh concrete and may be introduced into the production cycle without taking any precautions.
Dynamon VM is particularly suitable for:
- production of vibro-compressed components, such as blocks, self-locking pieces, kerbs, manholes, etc.
- production of extruded components, such as honey-comb floor slabs and large diameter pipes
- production of components which require quick stripping of formwork and/or reduced curing times
Fibre Reinforced Concrete
MAPEI offers Mapefibre NS12/NS18 – Polypropylene fibres for concrete that is 12 mm/18 mm long. Mapefibre NS12/NS18 are 100% virgin mono-filament polypropylene fibres, which are resistant to alkalis and do not absorb water. They have been specially developed to reduce the formation of cracks induced by hygrometric shrinkage of the concrete at the fresh and hardened stages. The special ‘mono-filament’ formation makes their distribution and position within the concrete mix easier, so that they are distributed uniformly, to create a particularly strong matrix, which is resistant to the stresses induced by the setting and hardening process.
Mapefibre NS12/NS18 are particularly suitable for the following:
- production of concrete used for industrial floors, airport forecourts and multi-storey carparks
- production of pre-cast reinforced concrete panels, pipes and concrete sections
- production of fire-resistant concrete
It is also necessary to ensure that the design of the concrete mix is correct to prevent cracking phenomenon, and that curing of the concrete is carried out accordingly, to avoid sudden evaporation of the water from the surface of the cast concrete.
Mapefibre NS12/NS18 are compatible with other admixtures used in the production of high-quality concrete, and especially with:
- Acrylic-based super-plasticising agents from the Dynamon range, for an improved mix design, consistency and maintenance of workability
- Mapecure range curing surface films, for correct curing of the concrete
- Mapecrete System’s innovative technology, used in the production of concrete with volumetric stability
- Mapeform Eco and DMA stripping compounds, used for stripping concrete from moulds
Form Releasing Agents
Mapeform 1600 is a universal form release agent with chemical and physical action. It owes its efficacy to physical action of conventional form release agents, which counter-act adhesion of concrete to forms, and to chemical reactions with cement paste in contact with forms, which creates a very thin insulating film. Mapeform 1600 chemical property absolutely guarantees efficient separation of the two elements.
Mapeform 1600 features the following benefits:
- better surface finish
- no surface dusting
- no grease stains, even with white cements
- less cleaning of forms
- simple low-cost application
- Typical applications of Mapeform 1600 include facilitation of form release of:
- precast concrete
- steam-cured concrete
- concrete cast in plastic forms
- concrete cast in cement or gypsum forms
- concrete cast in metal forms
Mapecure 101 is a white pigmented Acrylic resin-based film-forming, curing, sealing and protective compound in water emulsion for concrete. Mapecure 101 protects fresh concrete from rapid water evaporation caused by wind or sunlight, and reduces surface cracking. Removal of film is not required; it acts as primer for coating, bitumen and plastering.
Mapecure 101 offers the following advantages:
- less surface dusting
- less plastic shrinkage cracking
- elimination of traditional protection methods, such as spraying water, wet burlap sacks, wet sand
- fast and easy application
- lower labour costs and more efficient job-site management
Mapecure 101 is especially recommended for protecting concrete structures, such as industrial floors, exterior paving (roads, parking lots), airport runways, renders, dam faces, bridges, canals, buildings and reservoirs.
Planiseal 88 is a one component polymer modified cementitious coating for waterproofing concrete and masonry surfaces.
Planiseal 88 is used for:
- waterproofing horizontal, vertical and overhead surfaces
- interior or exterior concrete applications, such as walls, retaining walls, wet rooms, pools, planters, irrigation canals, culverts, concrete jersey, barriers, beams, columns, building facades, overpasses and piers exposed to positive or negative hydrostatic pressure.
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