Tag Archives: CHRYSO SOUTHERN AFRICA (PTY) LTD

BRIDGE WITH LARGEST PRECAST BEAMS IN WESTERN CAPE RELIES ON CHRYSO

A range of CHRYSO products contributed to the success of a bridge project near the historic city of Paarl in South Africa, involving the largest precast beams cast to date in the Western Cape.

Weighing 64 t each, the 18 prestressed beams for the Val de Vie Berg River bridge project measured over 35 m long and two metres high. The large volume and tight spacing of the reinforcing steel, coupled with the presence of stressing cables, meant conventional concrete would not suffice and  the local CHRYSO Southern Africa team worked in conjunction with the precast contractor to design, test and submit a self-compacting concrete mix .

CHRYSO’s CHRYSO® Premia 310 superplasticiser and CHRYSO® Dem Bio 10 environmentally-friendly release agent formed part of the solution for the successful casting of these beams, and were also used in the project’s large facing panels, coping and culverts.

Once all the beam strands were evenly stressed, readymix concrete was placed and a combination of external and poker vibration was used for compaction. This provided a good surface finish with minimal blow holes. After pouring, a tarpaulin was placed over the mould and steam was injected under the cover to accelerate hydration. Using this method, a strength of 40 MPa was achieved in 20 hours, enabling the production of one beam a day. The final strength required was 60 MPa, and this was achieved within 28 days.

Before the casting process, CHRYSO® Retarder paste was applied at the end of each beam shutter and the concrete washed off with water the following day after the shutter was removed. This created a rough exposed aggregate finish that provided a good bonding surface for the assembly of the bridge. 

The facing panels were also steam-cured, and were cast with a glass-smooth finish. They were attached using ‘fingers’, eliminating the use of visual fixing on the front face. Some panels were curved, such as those used for cladding the central viewing cove.

Once all precast beams were in position, five diaphragm transverse beams were cast in-situ between the precast beams. Permanent deck shutters measuring 1,2 m by 300 mm by 50 mm closed the remaining gaps between the precast beams, resting on recesses cast into the beams for that purpose. Readymix concrete using CHRYSO’s water-reducing plasticiser CHRYSO® Plast Omega 126 was then poured onto the shutters to create the deck. 

CHRYSO SOLVES CONCRETE EFFLORESCENCE, ADDS DURABILITY

Preventing efflorescence on concrete is often a concern for contractors, but CHRYSO has a simple solution – CHRYSO® Alpha Color 600.

In fact, CHRYSO® Alpha Color 600 does more than reduce the appearance of efflorescence. It is a double-function admixture which simultaneously gives a durable water repellent property to concrete. Giving a beading effect to concrete, the admixture enables mortars and concrete to resist water penetration, by capillarity or by pressure.

It also improves the aesthetic characteristics of manufactured concrete products, considerably reducing the appearance of spots and rings due to efflorescence. This gives a homogeneous colour to the result, whether it is precast aesthetic concrete, light precast concrete or coloured concrete.

This high-performance efflorescence reducer is available in a range of packaging, including 25 litre jerry cans, 200 litre drums, 1,000 litre flow bins or bulk tanker loads. With a long shelf life of 12 months, it can be homogenised simply by some light agitation after extended periods of storage. It can even endure freezing, requiring only agitation after thawing to recover its properties. 

From a health and safety point of view, CHRYSO® Alpha Color 600 need not raise any concerns for contractors and their employees as it is classified as harmless.

AVOID CONCRETE CRACKING IN DRY CONDITIONS

Hot and windy conditions can lead to plastic shrinkage cracking on fresh concrete, but CHRYSO® ProFilm 19 can solve this problem, without the addition of extra water to the concrete mix. 

One of the dangers of working in low humidity conditions – even inside heated buildings during cold weather – is the rapid evaporation of surface moisture from the concrete. This can cause map cracking and plastic shrinkage, where cracks can penetrate to the full depth of a concrete slab.

According to the American Concrete Institute (ACI), plastic shrinkage cracking of concrete is likely to occur whenever the evaporation rate is more than 1 kg per square metre per hour. The ACI highlights that this rate of evaporation can be readily caused by many combinations of air temperature, relative humidity, concrete temperature and wind velocity. 

As an evaporation reducer, CHRYSO® ProFilm 19 prevents this cracking by protecting fresh concrete from the effects of excessive moisture loss in rapid drying conditions. Furthermore, it can achieve this result without increasing the bleed. By spraying this evaporation-reducing product onto fresh concrete surfaces, the user creates a continuous mono-molecular film over the concrete, which inhibits the rapid loss of bleed water. 

This film lasts as long as the concrete remains plastic, even where floating and trowelling operations must be conducted to create the required surface finish. CHRYSO® ProFilm 19 is a water based product which is compliant with guidelines on volatile organic compounds (VOCs).

The effectiveness of the mono-molecular film means that there is no need for water spraying on the surface of the concrete in order to slow the evaporation process. It can be used on a range of horizontal concrete pours where the evaporation rate may exceed the bleeding rate of concrete. These applications include industrial floors, roads, bridge decks, slabs, patios, driveways and sidewalks.

CHRYSO® ProFilm 19 is ideal in concrete applications that produce little or no bleed water, such as mixes with low water content.

CONCRETE WIND TURBINE TOWERS GET CHRYSO TREATMENT

In wind farms all over South Africa’s Eastern Cape and Western Cape provinces, CHRYSO Southern Africa is adding value to the precast concrete segments used to construct the 100 metre tall wind turbine towers.

The average concrete turbine tower comprises 18 precast segments, each with a height of between 18 to 20 metres and a diameter of between 600 mm and two metres. In the manufacture of these precast elements, the production speed and segment uniformity are essential. This demands high early strengths to ensure fast erection, while giving the towers an ability to withstand demanding fatigue loads. Wind turbines must also be able to perform in some of the country’s harshest working environments, making durability a key requirement for the concrete mixes used in precast units.

The CHRYSO® Fluid Premia range of plasticizers facilitates workability retention of between 30 and 45 minutes while achieving high early strengths. These early strengths allow for the fast erection of the towers owing to the quick turnaround time as the mould release and pre-stressing release can be done earlier. optimises early and late age strength development in concrete mixes.

The CHRYSO® Fluid Premia range maintains consistency in the manufacturing of reinforced concrete components, reducing the sensitivity of concrete to variations in water content.

Plastic shrinkage cracking and plastic settlement cracking can occasionally penetrate deep into a precast unit, causing significant cost in remedial measures and even replacement. Applying a curing compound from the CHRYSO® Cure Range to the precast segments reduces the incidence of shrinkage cracks and promotes better strength gain characteristics. Curing compounds also increase the impermeability of concrete, making it more durable.

Another important product gaining traction in this market is a.b.e.® duragrout. Developed especially for wind farm precast applications, this product which is proving popular is being used to level segment holders. The duragrout WF product is used for grouting and bedding of structural elements; it can be pumpable or gravity fed and has good cohesive properties without bleed or segregation. It is pre-blended and ready-to-use, requiring only clean water to be added.

In a related development, CHRYSO has partnered with Maturix to develop an innovative sensor solution with a digital cloud platform to monitor the maturity of concrete. It has been used worldwide on more than 350 in-situ and precast projects, and is being trialled on a wind farm project in South Africa. This cloud-based solution helps the construction industry to monitor concrete curing and hardening through hydration temperature measurements.

CHRYSO SOUTHERN AFRICA LEADS WITH FIBRE SOLUTIONS

CHRYSO Southern Africa offers outstanding solutions when it comes to fibre reinforced concrete. A mutually beneficial partnership with Oxyfibre has resulted in world class products being available locally, supported by expert fibre technology development and consultancy capabilities. 

Izak Louw, general manager at Oxyfibre, says that CHRYSO’s presence and established infrastructure in Southern Africa made them the partner of choice for making Adfil fibres available in Southern Africa.

CHRYSO® EasyFinish, as a macro fibre, optimises speed of construction by eliminating the need for costly placement of rebar and ensuring adequate cover to reinforcement. Added benefits include smooth surface finishes, maximum bond, greater tensile strength per fibre for enhanced residual flexural strength and toughness in the concrete. 

For micro fibre applications, CHRYSO® Fibrin XTserves as alternative to crack control mesh. The use of micro fibres in concrete product manufacturing has proved to enhance the surface properties and durability, significantly reducing the occurrence of plastic shrinkage and plastic settlement cracking.

Recent projects where these fibres have been used include the placing of 7000 m2 of concrete in very thick surface beds and several large warehouse floors. Other applications have been in coastal defence structures and shotcrete in the Western Cape, as well as for the construction of floors in the farming and food processing industries where harsh chemicals and other deleterious substances could potentially affect the concrete. All these projects reported noticeable cost and time savings. 

Louw says that ongoing research has resulted in new fibre solutions that will be available shortly. These include Ignis, a micro fibre specifically designed for its fire protection benefits, and a macro fibre that will address problem areas in the precast industry.

Fibre technology is used extensively in readymix concrete, but the ease of transport, storage and handling of these fibres also makes them ideal for smaller projects and on-site mixing.

The CHRYSO Southern Africa / Oxyfibre partnership has created a win-win solution for all stakeholders providing concrete reinforcement solutions for construction projects to be undertaken safely and rapidly with reduced waste and reduced impact on the environment.

CONCRETE FLOOR FINISHING MADE EASY WITH CHRYSO

Concrete is the ultimate, timeless solution for floors. The success of a durable and functional floor lies in the ability to produce a quality finish, typically characterised by a smooth and consistent surface, whether in an industrial or decorative setting.

With CHRYSO® FiniSafe, finishing concrete floors by troweling or floating has never been easier.

Spraying CHRYSO® FiniSafe on the surface just before the finishing operation commences, improves the finishability of the concrete surface. This makes it possible for the operator to finish the surface faster and with less effort, whether floating mechanically or manually. As this concrete aid allows the mechanical trowel to pass over the surface more efficiently, machine performance is optimised by reducing wear and tear on the blades.

The product is safe for application on all types of concrete surfaces that require troweling, including standard concrete and industrial flooring and precast products. It may be used safely on both indoor and outdoor concrete as it has no odour and contains no VOCs.

CHRYSO® FiniSafe does not affect the colour or the appearance of the concrete and may be used with confidence on all decorative concrete surfaces.

When using this product, no water is added during floating or troweling, minimising the potential for unsightly efflorescence appearing on concrete elements or weakened surfaces which will tend to dust, when put into use. Other surface treatments may be applied to the floated surface, without any additional preparation.

With the use of CHRYSO® FiniSafe, a smoother finish is achieved with better surface densification; exactly what is expected by clients and designers, when specifying a concrete floor.

CHRYSO Southern Africa’s sales and technical teams are on hand to discuss how CHRYSO® FiniSafe can save both time and money while achieving good quality surface finishes.

HOUSKEEPING ON-SITE MADE EASY BY CHRYSO

Good housekeeping on a construction site is not negotiable. When working with cement and readymix concrete it becomes even more critical that surrounding areas are free from spills and build-up, as well as keeping equipment and tools clean, to optimise functionality.  

CHRYSO® Green Decap 200 is a new generation concrete stripper, which allows for the easy cleaning of all equipment and surfaces, where both  hardened cementitious and readymix concrete residues need to be effectively removed. It is less aggressive in terms of its impact on both health and safety as well as the environment, when compared to traditionally used acids such as hydrochloric and nitric.

This synthetic concrete stripper dissolves nearly 15% more hardened cementitious based paste, than extremely aggressive substances such a nitric and hydrochloric acid. The special formulation may be used, where cement and concrete spills and stains need to be removed, without damaging surfaces such as paintwork, chrome, coated steel, plastic, aluminum, glass or insulated wiring.

The stripper can be applied with a brush or a spray and is typically left for 10 minutes to react before washing the surface or equipment with clean water. The operation may need to be repeated several times, to remove stubborn residues or stains. 

CHRYSO® Green Decap 200’s may also successfully be used to remove laitance and as a final cleaning of exposed aggregate surfaces.

This versatile product is an additional offering in CHRYSO Southern Africa’s comprehensive range of products designed to optimise the placing, performance and aesthetics of concrete.

CHRYSO Southern Africa’s sales and technical teams are on hand, to discuss how CHRYSO® Green Decap 200 can ensure that unsightly cementitious-based spills and stains, do not affect a concrete project, while also ensuring that tools and equipment remain clean and functional.

CHRYSO PRODUCTS USED IN AWARD WINNING BATTERY PARK PROJECT

CHRYSO’s significant contribution to the successful execution of the award-winning Battery Park project highlights its commitment to provide a comprehensive range of products which optimise the placing, performance and aesthetics of concrete.

Battery Park, a 12 000 m2 urban precinct at the entrance to the V&A Waterfront in Cape Town, comprises a park and piazza and well as a concealed multi-level parking facility and pedestrian routes. A winner of the CSSA 2019 Fulton Award in the category “Buildings greater than 3-storeys”, this project is a testimony to excellence in the use of concrete.

The use of different concrete elements displays the versatility of concrete. In many of these elements, CHRYSO products were used resulting in exceptionally detailed and finished concrete structures and elements.

CHRYSO® Plast Omega 122 W, a water reducing plasticiser, was incorporated in the concrete mix to optimise the workability characteristics. After placing the concrete, CHRYSO® Cure Acrylic, a water-based slightly viscous solution, was used as a curing compound to ensure colourless, stain-free surfaces.

A selection of formwork release agents from CHRYOS’s range was applied according to their special attributes. CHRYSO® Dem Oleo FW, a hydrocarbon-based, recycled delayed-release agent was used for the conventional concrete works, while CHRYSO® Dem Oleo SM, a mineral-based delayed-release agent was applied to the metallic and wooden formwork used during the wet precast processes.

For the construction and expansion joints, two products from a.b.e Construction Chemicals, part of the CHRYSO group, were used. Dowsil® 890 SL, a self-levelling silicone sealant, was used to seal irregular planes between concrete paving and asphalt surfaces, with the added benefit of providing fuel resistant seals. Doswil® 888, a non-sag silicone joint sealant, was applied to standard concrete pavement joints.

CHRYSO is proud to be associated with the Battery Park project in so many different applications. This is a true accolade not only for the quality of their products, but also for the CHRYSO sales and technical teams.

CHRYSO® DEM RANGE PLAYS CRUCIAL ROLE IN FORMWORK

CHRYSO Southern Africa’s commitment to provide quality solutions for the built environment, is evident in the CHRYSO® DEM range of application driven release agents.

Understanding the crucial role formwork plays in the production of quality concrete and similarly moulds in the manufacture of precast elements, the CHRYSO® DEM range has introduced much needed flexibility to the industry. Previously, it had been a case of one-size-fits-all when it came to release agents.

Discerning clients, developers, manufacturers and specifiers are increasingly particular about the aesthetics of concrete finishes. To achieve the desired texture and colour finish on the concrete’s surface it is imperative that formwork surfaces are adequately prepared in terms of cleanliness and that an optimal release agent is selected for the application.

As different form-face materials have varying longevity, absorbency and texture characteristics, specialised release agents are required to realise the full aesthetic potential of the formwork, eliminating wastage of time and materials.  

Not only will the optimal release agent reduce the likelihood of imperfections and surface defects (particularly blow holes) in the concrete, when applied correctly it will also ensure no staining or deviation from the specified colour finish.

The top quality release agents in the CHRYSO® DEM range provide greater coverage, are easy to use and add consistent quality, which is important on construction sites as well as in precast plants.

CHRYSO®Dem Bio 10 is a vegetable-based, bio-degradable and non-toxic release agent, which will not pollute the environment. It has a low odour and is therefore safe to use in confined spaces such as mining, tunneling and any poorly ventilated areas. It is suitable for use with all types of formwork: metal, wood, plastic, polystyrene and fibreglass.

Another product in the range is Elio VP, a hydrocarbon oil-based agent, which is suitable when producing concrete pipes with roller compacted pipe technology. The Elio VP significantly reduces surface defects. The low viscosity oil creates less surface tension against the sides of the pipe steel moulds which results in less outer concrete surface damage when demoulding.

CHRYSO® Dem Oleo WB is a wax-based delayed-release agent for wooden formwork used on conventional jobsites and for wooden pallets for cement-based brick manufacturing. This release agent temporarily protects and extends the life of veneer laminated shutter boards, decreasing the frequency of re-lamination. This release agent can also be used to coat pallets for protection, when stacking cement-based bricks on them.

CHRYSO® Dem Oleo FW is a hydrocarbon based, which is suitable for use with all types of formwork. It is however not suitable for precast applications. It ensures ease of formwork release and also temporarily protects and extends the life of metallic formwork from corrosion.

CHRYSO® DEM Oleo SM is a mineral-based delayed-release agent, ideal for use with metallic or wooden formwork for wet precast. It does not stain or affect the colour of the concrete when applied correctly. It is the perfect solution when white cement is used for specialised architectural finishes. CHRYSO® Dem Oleo SM can handle the high temperatures of steam curing and provides rust prevention. This release agent is a hydrocarbon oil-based delayed release agent, used for steam cured precast elements cast in steel formwork.

CHRYSO® Dem Oleo RT is a hydrocarbon oil-based, delayed-release agent for the roof tile industry, developed specifically for use with aluminum roof tile pallets.

This ready to use range of release agents reduces the likelihood of errors, which may occur in other release agents, where mixing of various components is required.

When applied correctly and for the specific purpose, the CHRYSO® Dem range does not modify cement hydration and as it is water repellent, it is not affected by rain.

These products are manufactured locally by CHRYSO Southern Africa at its production plant based in Jet Park, Johannesburg and comply with regulations for the transport and disposal of hazardous materials.

While generally regarded as a minor item on the bill of quantities, the specification and selection of an appropriate release agent and application method may prove to be critical to the success of the project, affecting both the quality and colour of the surface finish. A release agent is a low-cost item, yet vital in relation to the cost of formwork and moulds. It thus makes sense to use the appropriate release agent for the correct application and formwork substrate, in order to protect and extend the life of the formwork or mould, ultimately resulting in financial benefits.

As each release agent contributes differently to the off-form finish, care in the selection of the release agent is critical.

CHRYSO Southern Africa’s sales and technical teams are on hand to discuss the correct CHRYSO® DEM solution for any application, condition or aesthetic specification.

REFURBISH OLD CONCRETE SURFACE EASILY WITH TEXTURE TOP®

Texture Top® offers the ultimate decorative solution to save money and time by refurbishing old concrete surfaces.

Ageing, worn or surface damaged concrete no longer has to be demolished and recast at a cost to the customer and the environment. Instead, Texture Top®, a CHRYSO Southern Africa product, can be used to enhance existing surfaces through renovation and repair.

Texture Top® is a polymer-modified cementitious coating which could be applied either with a spray gun or trowel to obtain a specified finish. The spray technique allows coverage of large surfaces in a short time.

At an application thickness of merely 2 mm, this thin anti-slip coating offers excellent mechanical resistance. The product is available in a standard range of colours, and could be custom pigmented to complement various finishes.

Texture Top® can be applied to achieve any textured or smooth finish. This is a simple and durable solution to renovate and add aesthetic value to surfaces around swimming pools, paths, terraces, driveways, patios, floors and stairs, as well as interior and exterior walls.

CHRYSO Southern Africa’s technical and sales teams provide leading edge expertise in support of Texture Top® which makes it easy to achieve customised modern and trendy decorative finishes in a cost-effective and environmentally responsible way.