Tag Archives: CHRYSO SOUTHERN AFRICA (PTY) LTD

CHRYSO GROWS ITS LABS TO PUSH CEMENT TECHNOLOGY

In its quest to help customers generate more sustainable construction materials, CHRYSO Southern Africa has continued to enhance its laboratory facilities – even during the disrupted years following the onset of the Covid-19 pandemic.

The latest expansion within its Centre of Excellence in Jet Park near Johannesburg has been a cement laboratory, in which the company has invested extensively. According to research and development (R&D) manager Mpume Mlalazi, these investments will continue into 2022 to ensure the latest tools are available.

“Much of our work in the cement laboratory is focused on the growing global concern to reduce carbon dioxide emissions from cement manufacturing,” says Mlalazi. “We are also now fully equipped to align with international standards in cement testing.”

CHRYSO Southern Africa’s other facilities include a research and development laboratory for new product formulation and evaluation, a concrete laboratory conducting physical tests to evaluate concrete properties, a quality control laboratory and a colour laboratory.

There are also satellite laboratories at the company’s Cape Town, Port Elizabeth and Kwa-Zulu Natal branches to support customers. Amongst the equipment recently acquired is an isothermal calorimetry and permeability tool; in addition to basic tools for cement setting time, specific surface Blaine, pycnometry and cement compressive strength determination auxiliary equipment.

“Our cement laboratory works closely with cement industry players, and supports our customers with product development to find solutions for their ever-changing applications,” she says. “Of course, cement is the main contributor to concrete performance, so it is vital that we understand exactly what impacts are achieved by the changes we can make.”

This is why CHRYSO Southern Africa’s wide breadth of facilities – combined with its depth of expertise – is so effective, with its cement and concrete laboratories under one roof, she explains. Whatever is achieved in the cement laboratory can be closely assessed and tested in the concrete laboratory.

“As experts in the field of admixtures, we have the necessary chemistry knowledge and products to help customers drive their sustainability agendas and meet their carbon reduction targets,” says Mlalazi.

She highlights that CHRYSO Southern Africa re-invests at least 4% of its sales revenues into R&D each year, emphasising that the laboratory capacity has a strategic role in supporting customers’ key concerns into the future. These include carbon emissions, clinker factors, cement performance and energy saving. The exciting projects underway in its cement laboratory include research into the potential for limestone calcined clay cement (LC3) to drastically reduce carbon dioxide emissions during the manufacturing process.

NEW-GENERATION PLASTICISER USED ON MUSINA BRIDGE PROJECT

An advanced new-generation water reducing plasticiser – CHRYSO® Plast Omega 174 – has notched up another successful application. The product has been used in the concrete mixes for the new Nancefield bridge, which forms part of SANRAL’s Musina Ring Road Project in Limpopo Province. The R640 million project, which allows the N1 to bypass Musina, is due for completion in Q2 2022.

The N1 will pass under the 77 metre long bridge. SANRAL wanted visitors from Zimbabwe and South Africa travelling on the N1 to experience a feeling of being welcomed and the bridge therefore features a prominent pair of 13 metre high ‘hands’ – which are essentially extensions of the centre piers – which express this message. The deck is supported by the columns of the hands and the bridge is aesthetically held on the palms of the hands. 

One of the main reasons CHRYSO Plast Omega 174 plasticiser was selected for the project was that it countered the problem of slump loss.  Due to the available aggregate, ambient temperature and distance from site, CHRYSO Plast Omega 174 was tested and found to be the most suitable admixture. Mix designs were conducted by Matthew Barker, general manager at CHRYSO for technical, mining and export at CHRYSO’s centre of excellence.  

Another challenge was presented by the hot temperatures – up to 45°C – typical of Musina in summer. The concrete temperature needed to be kept under 30°C to prevent thermal cracking. This was achieved by a combination of measures, which included keeping the concrete under shade and cooling it with sprayers, which involved installing a cooling tower to keep the water cool. CHRYSO Plast Omega 174 allowed the mix designs to be optimised, giving more open time on the fresh mix concrete.

CHRYSO Plast Omega 174 was the primary product supplied for the Nancefield bridge and was used for the bridge decks, balustrades and the bridge piers with hands.

Just over 3 000 m3 was required for the concrete of the bridge. The use of CHRYSO admixtures for the mix design was implemented by Jacques Marais, senior plant foreman for the production of concrete at OMV, part of the Raubex Group. The consulting engineers for the project were KBK Engineers.

CHRYSO Southern Africa’s personalised technical service offering and logistics were the deciding factor in OMV using CHRYSO as the main admixture supplier for the project. 

According to Ben Myburg, technical consultant at CHRYSO Southern Africa, “CHRYSO Plast Omega 174 is a multi-dose admixture, which allows concrete to exhibit extended workability characteristics. It improves the cohesion and lowers the viscosity of a concrete mix, which results in an improved homogeneity and compaction, allowing for superior off-shutter finishes thereby eliminating the risk of repairs. By reducing the need for extra water, it increases the durability of concrete by reducing permeability.”

CHRYSO Plast Omega 174 is part of the wider CHRYSO Plast Omega range. Products in the range are ideal for applications such as underwater concrete, pumped concrete, large pours and flowing concrete.

MAKING PERVIOUS CONCRETE EASIER TO TRANSPORT AND PLACE

A stabiliser specifically designed for pervious concrete, CHRYSO® EasyDrain  is perfectly adapted to concrete with low fluidity.

This technology eliminates the constraints traditionally associated with batching, transporting and placing of pervious concrete, while improving performance and quality. By controlling hydration reaction, CHRYSO® EasyDrain extends the workability of concrete, while also fluidising the pervious concrete to facilitate its placement. 

Key benefits to customers include improved cost effectiveness, as trucks can be loaded faster to full capacity making transport more affordable as well as reducing the CO2 footprint associated with the delivery of concrete to construction sites.  Concrete is also easier to handle and place, being more fluid and homogenous. In addition, there is greater durability, with less risk of cracking and aggregate ravelling. 

CHRYSO® EasyDrain allows customers to take full advantage of the outstanding qualities of pervious concrete, which are its high performance and high drainage capacity of rainwater. 

As well as achieving full truck loads, concrete suppliers can discharge concrete trucks faster with no need for water reducers or cohesion agents. Contractors enjoy the faster discharge and easier placing that CHRYSO® EasyDrain  provides as well as the improved surface finish that is possible with high workability. Contractors can also install curing membranes quicker and significantly reduce associated costs that includes time and labour cost benefits. 

Project owners in turn will appreciate the greater drainage that their pervious concrete achieves, along with its enhanced aesthetic finish and improved durability. 

CHRYSO® EasyDrain can contribute to a wide range of pervious concrete applications, including light traffic roads, car parks, terraces, garden paths, swimming pool surrounds, cycle paths and pedestrian ways. 

The CHRYSO® EasyDrain solution involves specific concrete mix design criteria with the use of complementary admixtures that improve the quality and performance of pervious concrete. 

Project reference includes the WBHO Vlakfontein reservoir project where the use of CHRYSO EasyDrain was specified to improve the quality of pervious concrete. Several other admixture solutions were also supplied by CHRYSO  to this project site including CHRYSO Serenis (shrinkage reducing admixture) and  CHRYSO CWA 10 (crystalline water proofing admixture) as well as CHRYSO Omega 178 new generation admixture to improve the water reduction properties as well as achieve the concrete strength requirements of the specific concrete mix design.

BEAT CONCRETE CRACKING AND CURLING WITH CHRYSO® SERENIS

For concrete applications with an elevated risk of cracking – like floors, screed and precast panels with large surface-to-volume ratios – CHRYSO® Serenis brings peace of mind.

Contractors and manufacturers alike need to be confident that they can prevent their concrete structure from cracking or curling, to ensure the success of their applications. Cracks can weaken concrete, compromise its durability and allow ingress of corrosive elements like water, chlorides and ice. They can also spoil the appearance of concrete. 

These outcomes are the result of shrinkage, which happens at all ages in the life of concrete; a length of concrete cast can shrink by as much as 0,08 %. While concrete has excellent plasticity when fresh and high mechanical strength once set, it can only withstand minor deformation. When shrinkage comes up against a mechanical constraint, the concrete may crack. 

As a ready-to-use shrinkage-reducing admixture for concrete and mortars, CHRYSO® Serenis can reduce shrinkage by up to 80% depending on the conditions and concrete mix design. This makes it ideal for all applications requiring minimal shrinkage, including injection grouting, high and ultra-high performance concrete and special structures.

The phenomenon of curling or bending in fine concrete parts or elements can also be addressed by CHRYSO® Serenis. As evaporation takes place mainly from the surface of concrete, there is always more shrinkage in the surface. As the concrete shrinks, therefore, the edges rise. 

This action is more or less pronounced depending on the surface-to-volume ratio, but even the slightest curling is a risk. It can endanger an element’s integrity, leading to breakage during transport, unloading or even under its own weight. By reducing the amount of shrinkage, CHRYSO® Serenis is able to reduce the possibility of curling.

Another important benefit of CHRYSO® Serenis is that it can allow users to increase the distance between shrinkage joints. Industrial floors made from concrete, for instance, are normally divided into areas of 5 metres by 5 metres, bordered by shrinkage joints sawn into the surface of the concrete. More distance between shrinkage joints means time saved on laying floors, reduced maintenance costs and improved overall appearance.

CHRYSO® Serenis works by reducing the capillary tensions, therefore impacting the most important mechanism at the origin of shrinkage. It does not have a spreading effect, and does not modify the water demand of concrete nor impact the water-to-cement ratio. It is compatible with new generation superplasticisers as well as traditional plasticisers and superplasticisers.

CHRYSO ADMIXTURES SUPPORT WATER-SAVING BY CONTRACTORS

Responsible contractors have realised the growing strain on South Africa’s scarce water resources, and CHRYSO is supporting their conservation efforts with its water-reducing admixtures for concrete.

A recent example of this was in the construction of the Vlakfontein Reservoir near Standerton in the province of Mpumalanga. This is probably one of the largest cylindrical post-tensioned concrete reservoirs in the world, with an inner diameter of 154 metres and a heavily reinforced 11,8 metre high wall.

According to Patrick Flannigan, technical manager : concrete business unit at CHRYSO Southern Africa, the project made use of several CHRYSO® admixtures to reduce water and improve workability. 

“One of these is CHRYSO® Plast Omega 178 plasticiser which, when used in a concrete mix, permits a reduction in water content without affecting the consistency, also referred to as the workability,” says Flannigan. “It can also increase the slump – or flow – without affecting the water content of the mix.”

The Vlakfontein Reservoir has a ground water drainage system constructed with three layers of 5 MPa no-fines concrete. The 8 000 m3 of no-fines concrete comprises a 50 mm thick layer of 9,5 mm stone mix, followed by a 245 mm and 125 mm layer of 19 mm aggregate. 

CHRYSO® Easydrain was introduced to these mixes to facilitate consistency and ensure the aggregate would bind mechanically and hydraulically to the cement paste. This specialised admixture fluidises the concrete, assists with a homogenous mix and improves curing to reduce the chance of cracking. The bonded aggregates, once dried, will not loosen. An additional drainage layer of around 2 200 m3 of no-fines concrete will be poured around the reservoir. 

Once the no-fines concrete was completed, a layer of 200 mm 35 MPa concrete was pumped in 13 pours of approximately 250 m3 each. This mix included CHRYSO® Serenis, a shrinkage reducing admixture. This, together with CHRYSO® Omega 178 superplasticiser, reduces water and assists with workability. 

CHRYSO® CWA 10 crystalline waterproofing agent will provide integral waterproofing and reduce permeability in the concrete. The crystals prevent water penetration and protect the concrete against corrosive ground water and chemicals. 

CHRYSO’s water-reducing admixtures were also used in the Khutsong Reservoir near Carletonville in Gauteng. Due to the danger of sinkholes in this region, and the possibility of ground movement, the reservoir is the first to be constructed with a pre-tensioned concrete floor. 

The scale of the work required 212 truckloads of concrete for the floor, successfully poured within a day. The 1,267 m3concrete floor used pumped mixes at 35 MPa at a thickness of 450 mm. In this demanding contract, the concrete mix included CHRYSO® ZA 1559, a new generation, multi-dose water-reducing plasticiser. 

“This admixture allows a wide range of dosages to be applied, without any excessive retardation at the higher dosages,” he says. “The multi-dose characteristic of CHRYSO® ZA 1559 also gives concrete extended workability characteristics.”

Flannigan notes that it improves the cohesion and lowers the viscosity of a concrete mix. This results in an improved homogeneity and compaction, allowing for superior off-shutter finishes. With less need to add extra water, CHRYSO® ZA 1559 reduces the permeability of concrete, thereby improving is durability.

“The product may be used in mixes extended with limestone or commonly used supplementary cementing materials (SCMs) like ground granulated blast furnace slag (GGBS), fly ash and silica fume,” he says. “At the same time, it does not undermine the early age strength of concrete. In fact, in certain cases, it may be used to improve it.”

CHRYSO® ZA 1559 has applications in readymix concrete and mechanically mixed site concrete, as well as conventionally placed, pumped and highly reinforced concrete. It conforms to the requirements of SANS 50934-2 (EN 934-2) standards, which are approximate equivalents of ASTM C494 Type A.

Water evaporation was successfully controlled with CHRYSO® Profilm 19 evaporation reducer, while shrinkage of the reservoir floor was reduced using CHRYSO® Serenis shrinkage reducing agent. A minimum of 180 litres of water per m3 had to be used and fly ash was added as the heat of hydration had to be controlled due to the mass pour. The end strength did not exceed 45 MPa.

SMART MONITORING OF CONCRETE WITH MATURIX

Contractors need to know when their concrete has reached a certain strength, to move ahead with the next stage of construction, but this has never been very easy to find out – until now. 

Having insight into the strength of concrete helps contractors determine when the concrete can be walked on or when formwork can be removed, so that there are no unnecessary delays in the construction schedule. However, concrete strength can be difficult to estimate, as it does not always develop at the same speed. Temperature and weather conditions will affect how fast or slow the strength of a structure develops.

CHRYSO’s Maturix software solution now makes it possible to measure the maturity of concrete on site or in precast element production. Maturix monitors the curing process of concrete, gathering data from in-situ sensors and processing this information on an intuitive software platform. It is able to make real-time maturity calculations, as well as future projections on concrete strength, based on machine learning.

While concrete maturity alone does not show how strong the concrete is, the maturity method can determine the relationship between maturity and strength development. Concrete maturity is a concept that relates temperature, time and strength development. The maturity method is therefore an easy way to estimate the early-age strength development of a concrete mix. Maturix achieves this by providing all relevant insights for concrete monitoring, including temperature, humidity and ambient climate.

Maturix works through a concrete sensor cable which is mounted to the reinforcement before the wet concrete is poured. The thermocouple is connected to the Orbit K transmitter and the monitoring is initiated on a smartphone or computer. Data is continuously transmitted using the Internet of Things (IoT) network Sigfox for accurate real-time data.

The user can track the strength and maturity of the concrete from anywhere and at any time, and can receive a notification when the curing is complete. They can be notified by SMS, e-mail, app notification or on a customised dashboard. This facilitates better scheduling on site, as the user is given exact insights into the concrete behaviour – allowing the project workflow and timelines to be adjusted based on real-time data. This flexibility helps to streamline the construction process, saving time and money.Maturix also makes it easy to document processes for quality assurance reporting, as all monitored data is automatically saved as online reports, which can be shared, exported and downloaded.

ADMIXTURES TO REDUCE CONTRACTORS’ CARBON FOOTPRINT

A new range of admixtures from CHRYSO will further support South African contractors in their efforts to transition towards a low-carbon economy.

The new CHRYSO® EnviroMix range of tailor-made admixtures allows for reduced environmental impact from concrete mix designs. While CHRYSO® EnviroMix delivers a reduction in CO2 emissions of up to 50%, CHRYSO® EnviroMix ULC (Ultra Low-Carbon) can achieve reductions of even more than 50% in the carbon footprint of concrete. 

A key feature of this admixture range is that it allows better utilisation of mixes that incorporate high volumes of pozzolans such as fly ash. It is able to achieve this while still ensuring superior levels of technical performance. Among other important benefits are an improved quality of concrete – due to a lower water-cement ratio for a given workability – and increased early and ultimate compressive and flexural strengths.

As part of this offering, CHRYSO also supplies customers with dedicated services such as EnviroMix® Impact. This allows the environmental impact of a concrete mix design to be calculated, so that formulation strategy can be set up for the customer to meet their specific carbon-reduction targets. CHRYSO also offers a digital solution for real-time monitoring of CHRYSO® Maturix concretes, which provides on-site concrete temperature, strength and maturity, humidity and climate monitoring.

The last 15 years has seen CHRYSO strengthening its expertise in the field of concrete admixtures with low-carbon impact. The innovative technology in the company’s portfolio of cement additives underpins its specialist knowledge in the chemistry of new low-carbon cements. Its solutions are based on many scientific collaborations and industrial partnerships, reinforcing its expertise in these new binders including geopolymers and calcined clay cements.

The CHRYSO® EnviroMix range also provides superior finishability, while improving surface quality and reducing cracking potential. The admixtures provide better workability and pumpability of concrete, as well as ease of placement and consolidation. 

Through these innovations, CHRYSO is developing solutions that produce the cements of tomorrow, as industry stakeholders search for technological opportunities to forge a low-carbon future.

SOLAR ENERGY ADDS TO CHRYSO’S SUSTAINABILITY JOURNEY

Cement additive manufacturing company CHRYSO Southern Africa has installed a solar electricity generating system at its Jet Park premises in Gauteng, as part of its efforts to lower its carbon footprint.

According to CHRYSO Southern Africa CEO Norman Seymore, the system will generate almost 240 MWh each year to serve the company’s production facility.

“This output will make up about 70% of our energy requirements, with the rest sourced from the national grid,” says Seymore. “One of our three sustainability pillars at CHRYSO is the reduction of energy consumption, and this installation goes a long way in reducing our dependence on South Africa’s notoriously carbon-producing electricity.”

A total of 393 solar panels – each with a capacity of 400 W – were installed on the roof of CHRYSO Southern Africa’s premises in January this year. They will collectively generate a kilowatt peak of 157 kWp through five 27.6 kW inverters. 

“Our investment in solar energy generation is an important contribution to the company’s global commitment to a more sustainable construction sector,” Seymore says. “Our CHRYSO admixture products themselves play a valuable role in driving down the carbon emissions related to construction materials.”

He highlights that these admixtures can help to reduce the cement component of concrete – cement being among the world’s most significant carbon-generating products. CHRYSO Southern Africa is also active in other environmental initiatives, such as ensuring that its packaging materials and containers are recyclable and reusable. The company delivers much of its product range in bulk, but uses recyclable material where products are delivered in 200-litre drums or 1,000-litre containers.

“We have, in addition to our solar installation, also implemented a series of wastewater treatment systems at our plant to reduce and recycle the volumes of wastewater we produce,” he says. “We constructed several wastewater catchment areas to ensure that any discharged wastewater was first treated to an acceptable standard.”

CHRYSO IS PARTNER IN PIONEERING HARDSTAND LAUNCH

An innovation in concrete pavement construction was recently launched in Johannesburg, pointing the way to the future of external hardstands, according to Hannes Engelbrecht, Concrete Unit Business Director at CHRYSO Southern Africa.

The pioneering solution – Optipave VRS – is a collaboration between leading players in the field. It combines the volumetric retraction stability (VRS) additive Link EVR from RCR Industrial Flooring, thin concrete paving (TCP) short-slab design technology and fibre-reinforced concrete.

“CHRYSO® EasyFinish is a macro monofilament fibre that is engineered to replace steel mesh or steel fibres in concrete,” says Engelbrecht. “It is specially designed for concrete reinforcement and is shaped to create a smooth concrete surface finish, improving durability and mechanical properties.”

Link EVR reduces shrinkage and curling in concrete slabs, and also prevents superficial micro cracks known as crazing. It makes concrete less porous, improving its freeze-thaw behaviour as well as its resistance to liquid spillage and abrasion. 

The Monofloor TCP design ensures that only one set of wheels can load each slab at any one time, reducing the flexural stress and changing the failure mode. The result of this is that a thinner slab can be cast for the same loading. 

“Together, these technologies solve recurring problems in conventional external concrete pavements and hardstands,” he says. “Optipave VRS, a technology from the RCR Industrial Flooring Group) reduces tensile stress in the slab, eliminates the negative effects of curling and pumping, reduces slab thickness, and allows minimal joint opening and maintenance.”

The Optipave system is also environmentally friendly as it has a low carbon footprint, absorbing just 500 g/m2 of carbon dioxide. It is recommended for a wide range of applications including highways, industrial pavements, low-traffic roads and parking lots.

“We believe that the Optipave system has a bright future due to its competitive construction costs and ease of installation,” says Engelbrecht. “The optimised load distribution system and latest technologies in concrete also give Optipave a longer lifespan. This further enhances its cost effectiveness.”

The launch, which took the form of a practical demonstration where sample panels were cast, raised the interest of contractors, property developers and consulting engineers alike. 

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.