Concrete operation: Al Ghurair Construction Readymix
Al Ghurair Construction Readymix has concrete batching plants working round the clock everyday to deliver ready mix concrete on time to construction sites in the UAE. PMV Middle East visits the company's manufacturing facility in Dubai to find out more about its plant configurations and operations
If the volume of ready-mix concrete production is a good indicator of construction activity, then construction in Dubai is as busy as ever. It’s the peak summer season in Dubai, and Al Ghurair Construction Readymix has three concrete plants working round the clock at its manufacturing facility in Al Quoz Industrial Area, dispatching mixer trucks every few minutes to construction sites across Dubai.
The centralised operation of the plants combined with the company’s fleet of over 90 mixer trucks with 9 m3 and 12 m3 capacities ensure that ready-mix concrete is delivered anywhere in Dubai within one hour, providing sufficient time on sites for pouring of the concrete. The three concrete plants are stationary batching plants with horizontal configurations and mixer capacities up to 3 m3.
“There’s sufficient demand from contracting companies in Dubai as well as individuals to keep our plants operational for 24 hours every day. A large amount of the ready-mix concrete we produce is delivered to residential construction sites, particularly villas, and commercial projects such as building towers. Every villa requires a certain quantity of concrete over a period of 2–3 months, and villa projects in Dubai generally have several villas under construction, simultaneously. This ensures steady demand for ready-mix concrete throughout the year,” says Frederick Fernandes, production manager, Al Ghurair Construction Readymix.
All three plants at Al Ghurair Construction Readymix have integrated cement silos, aggregate bins, admixture storage tanks, as well as flake ice plants, chilling plants and water storage tanks for concrete cooling. The ice plants are put into operation in the summer season to replace chilled water to lower the temperature of concrete to around 32°C. The largest plant among the three, a Schwing Stetter batching plant has a 3m3 twin-shaft mixer and five 250-tonne cement silos, two each for ordinary Portland cement (OPC) and ground granulated blast-furnace slag (GGBS), and one for microsilica. The other two plants are from Schwing Stetter and Liebherr. In addition to cement, the main ingredients used by Al Ghurair for concrete production are dune sand, crushed sand, 10-mm and 20-mm aggregate, admixture or additives, and water. All ingredients are sourced from local suppliers.
“These ingredients are sufficient for the demands of this region. The demand for GGBS has been increasing with Dubai’s evolving environmental standards and regulations. Currently, most batches have requirements of a certain percentage of both OPC and GGPBs. Microsilica is required for construction work that demand higher durability, such as towers and infrastructure,” says Fernandes.
Cement silos of the concrete plant labelled to identify their contents
Fernandes indicates that automation and preventive maintenance ensure smooth operations of the plants. As ready-mix concrete cannot be stored as inventory, production is not scheduled unless there’s an order confirmation.
“The entire process, from feeding the aggregate to mixing them in the right composition with the other ingredients and loading the truck mixers is automated. From the time of receiving an order, it takes 5-7 minutes to produce a batch of concrete and dispatch it through a mixer truck from our largest plant. In addition, we do preventive maintenance to avoid plant downtime. The three plants serve as back up for each other to enable us to achieve our production targets,” says Fernandes.
The plant operations are managed through control systems, the MC500 control system developed by Schwing Stetter for its plants and the Simma Electronic concrete management system for the Liebherr plant. The control systems are integrated with other administrative and accounting functions such as preparation of quotations, planning of orders, fleet management and invoicing. Each plant is controlled from its own control room adjacent to the plant and manned by operators working in two shifts. Operators control the plant functions and its various parameters via a software user interface as well as a hardware control panel for additional manual settings.
The concrete plant control system
The quality control process includes concrete cube testing to evaluate the characteristics of the concrete in compliance with BS EN standards. This step involves inspection of samples of concrete from a loaded truck before it leaves the plant. The concrete is poured into cube moulds and labelled to identify their sources. They are then cured and tested after 7, 14 and 28 days to determine the gain in comprehensive strength of the concrete over time. The same process is repeated on the site so that the supplier and customer maintain the same samples and can evaluate the quality of the concrete, independently.
Fernandes points out that operational challenges do arise from time to time as a result of customer delays or other unforeseen circumstances, which affect production schedules. If a truck breakdown occurs or concrete delivery is rejected from a site, Al Ghurair minimises waste by either recycling the unused material for concrete production or using it for block manufacturing.
“Delays often occur when customers do not adhere to concrete pouring schedules. For example, if a customer announces a time for pouring concrete and then delays it due to poor planning, it overlaps with our subsequent production schedules during the day for other customers. In such cases, we reschedule production or use one of our other plants. We ensure that the transit time of concrete mixtures from batching to pouring does not exceed 120 minutes, although technically, it can be extended by several hours, and in extreme cases by up to 24 hours, by using admixtures or chemical additives. In case of unforeseen delays, our technicians prolong the life of the concrete onsite by using additives,” says Fernandes.
Al Ghurair Construction Readymix is expanding its operations to cater to Dubai Expo 2020 projects. Last year, the company set up two plants in DIC, both of them stationary, horizontal batching plants with 2m3 mixer capacities, from Schwing Stetter.
Loading of the mixer truck
Schwing Stetter is finding increasing demand in the Middle East for its concrete plants. The manufacturer also offers customised plant configurations for different customer requirements in the Middle East. Its product portfolio includes stationary plants with horizontal and vertical configurations, twinned configurations, and mobile plants. They are offered as standalone solutions or as a combination, depending on the scale of a project. For example, large projects may require two high-performance 3m3 stationary plants working in parallel or in a twinned configuration to provide a combined output of 240 m3/h. This set up is useful when a large production capacity is required in a given amount of time. Additionally, the plants serve as backup for one another. Mobile plants such as the M1 model with 60m3/h output capacity are preferred for smaller projects in remote areas. Certain applications require a combination of stationary and mobile plants.
Karsten Hausmann, head of sales-Middle East region, Schwing Stetter, points out that the biggest advantage Schwing Stetter has over its competitors is that the company designs and manufactures its plants, mixers and control systems in Germany, which enables full control of the performance and quality of its hardware and software. This also enables the manufacturer to play the role of a consultant during the engineering and design process to help evaluate the customer’s production requirements and markets and then recommend the appropriate size and configuration of the plant, components, number of cement silos, and storage requirements for other ingredients.
"Schwing Stetter is the only manufacturer that offers the entire range of products and services required to run a concrete ready-mix business. We design plants to run 24x7 with high performance and low maintenance. We also design them with the provision for future expansion and upgradation. As we develop integrated solutions, the control systems are offered as part of the package. We also supply the plant, mixer and control system, separately,” says Hausmann.
Schwing Stetter ships its plants from Germany to customers worldwide. After delivery, the installation and commissioning of the plant and operator training is completed in 2–3 weeks.
“The plant installation, operator training and after sales support is equally important to us. When a concrete plant is delivered to a site, we request the entire team including the operations manager, operators, mechanics, electricians and helpers to be present while the plant is installed. This group exercise provides sufficient initial training to the staff. Once the installation is over, we provide operator training for an additional week. In less than three weeks, we ensure that a plant is operational in full swing,” he adds.
The quality of the mixer and control system are at the core of Schwing Stetter's product development because both elements are critical to the performance and longevity of a plant. Schwing Stetter uses both twin staft and pan mixers for its 1 m3, 1.5 m3, 2 m3, 2.25 m3 models. For mixers with capacities above 2.25 m3, Schwing Stetter uses only twin shaft mixers because they are twice as fast as pan mixers in delivering a similar mixing quality.
"Mixer capacities ranging from 3–4 m3 are popular in the Middle East because the truck mixers available in this market have capacities of 9 m3 and 12 m3. A 3m3 mixer will fill a 9m3 truck in three batches and a 12m3 truck in 4 batches. This enables optimum utilisation of the plant and truck," says Hausmann.
Currently, the most popular configuration among Schwing Stetter customers in the Middle East is the horizontal plant with 3 m3 (120 m3/h) mixer, inline silo compartments and belt conveyor equipment.
Vertical plant configurations are yet not common in the region as they require more than double the investment of horizontal plants. However, this trend could change with a new customer in Oman, the Duqm Port and Drydock, which has ordered a vertical plant that has a capacity of 320 m3/h with two 4m3 mixers. This will be Schwing Stetter’s second vertical plant installation in the Middle East, after its first vertical plant was installed in Kuwait 20 years ago.
“We provided a customised design with two mixers in one plant. We call this the ‘super twin’ mixer configuration. We see increase in demand for such high-performance plants. With a new refinery project coming up, the Duqm Port plans to install at least five concrete batching plants in the future. Oman is among our best performing markets in the region, including Saudi Arabia and UAE,” says Hausmann.
Hausmann announces that the company will launch its biggest mobile plant by the end of 2018, specifically for the Middle East market. The M3 will have an output capacity of 120 m3/h.
“The design of M3 will be similar to the M2 model, but it will have a bigger mixer providing a 20% increase in output. We developed this model considering the output and delivery capacities of the plants and truck mixers in this region,” says Hausmann.