The innovative Motus building system comes with a number of advantages, including affordable housing, new architectural highlights and high earthquake resistance. Its range includes not only solid and sandwich walls but also three-dimensional hollow-core slabs in many shapes and designs. EGI, an Uzbek construction contractor, relies on automated manufacturing processes and the expertise provided by Vollert, the German equipment manufacturer, for the industrial prefabrication of this building system.
Nowadays, urban architecture has to meet a large number of different needs, such as applying sustainable and resource-efficient construction methods while ensuring the quick completion of low-cost, affordable housing projects for the growing number of people living in mega-cities. Other important factors include quality of life, living comfort and attractive architectural features, as well as an effective response to the increasingly severe climate- and weather-induced changes and geophysical natural disasters. Currently, 1,300 earthquakes of magnitude 5 to 6 occur each year, causing severe damage and a death toll of 50,000 worldwide.
This is where innovative building systems come into play. Since the 1980s, there has been a growing demand for industrially prefabricated concrete elements, which has become the leading construction method particularly in Europe. Yet building systems are also increasingly being used in Russia and the CIS countries. Particularly during the last decade, construction technology has evolved significantly, including enhanced materials and improved production processes. “However, up to now, it has been virtually impossible to construct high-rise residential buildings in seismically active regions while increasing the load-bearing capacity of walls and floors and combining these structural features with attractive architectural highlights such as intricate designs and color schemes,” explains construction engineer and building designer, Roman Kusmichev.
Motus building system provides earthquake resistance and many other benefits
Kusmichev has been one of the driving forces behind preparing initial drawings and architectural designs in order to implement the new building system developed by the construction engineering team at Vollert, the German equipment manufacturer. He contributed his comprehensive hands-on expertise as well as a huge amount of data and statistics stemming from his previous career in the former USSR.
Novel prefabrication method for reinforced-concrete hollow-core slabs
Vollert developed an innovative production process in order to respond to all these practical needs. Instead of employing an extrusion or slipforming method, the new hollow-core slabs are produced on a pallet circulation system. Each prestressed concrete hollow-core slab is manufactured exactly to the specified shape and dimensions in a waste-free process, rather than cutting the continuous floor slab to the required size after concrete pouring. The production line includes a newly designed machine with cylinders to create the hollow cores. These cylinders are inserted into the slab form only temporarily during concrete pouring. The number and shape of the voids can be varied very flexibly, which would not be possible in an extrusion process on long casting beds. In addition, the new process makes it possible to insert cable conduits, utility ducts for water supply and ventilation, and custom embedded parts, thus opening up completely new options for structural or technical designers. A single-strand prestressing unit ensures the application of the specified tensioning forces. For this purpose, the production pallets were designed such that the maximum possible prestressing forces can be transferred to the precast element.
A complete system for landmark construction projects in Uzbekistan
Orient Group had previously used the Vollert equipment technology to successfully complete construction projects in Uzbekistan. In 2017, the company engaged in initial talks with Euro Global Invest (EGI), which has been doing business in the construction sector since 2016. This Uzbek construction material supplier produces materials for the city of Tashkent and the neighboring regions, including granite chippings and sand but also ready-mixed concrete for large-scale construction projects within the city limits, such as the rapidly growing Tashkent City mega-project. Together with Ipoteka Bank, the company decided to strategically expand its construction portfolio. “Already in the initial discussions, we got convinced of Igor Chukov, the entire Vollert project team and the Motus building system,” explains the CEO of Euro Global Invest, Djamchid Inagamov. “Right from the start, our aim was to manufacture the complete building system on a single, consistently designed production line.”
The ground-breaking ceremony for the precast plant in a Tashkent suburb followed almost six months after the final contractual negotiations. “The Motus prestressed concrete hollow-core slabs and the solid and sandwich walls required for completing the building system are manufactured simultaneously, plus a number of other structural precast elements including columns, beams and stairs, as well as conventional, slipformed hollow-core slabs for industrial construction,” says Inagamov. “This output is equivalent to an annual formwork area of just under 700,000 m².” Vollert, the equipment specialist, took care of the complete transfer of knowledge and expertise, particularly in relation to the Motus building system, and assumed a general contractor role for the complete production equipment and machinery as well as automation, software design and implementation.
“In this process, we cooperated very closely with our trusted system suppliers Liebherr, Elticon, EVG, and Nordimpianti. We thoroughly discussed many options, always with a view to the requirements imposed by the Motus building system. The Vollert construction engineers and project managers coordinated all related processes and work steps,” describes Roman Burau, head project manager at Vollert. The plant design excels with its high degree of automation, efficient production sequences and state-of-the-art equipment technology. “Just like in the automotive industry, we have implemented processes that are standardized to a great extent. Highly efficient robots and machines and the cycle-based manufacture of wall panels and floor slabs on a circulation system make it possible to achieve maximum productivity in the production process.” For instance, smart-cast automated concrete spreaders ensure optimal concrete cycle times as well as precise concrete batching in accordance with the zero-error strategy in the manufacture of both the Motus hollow-core slabs and the solid wall panels. A central Elticon bucket conveyor distribution line was installed for supplying concrete directly to pouring. The Vario Cure curing chambers, state-of-the-art storage and retrieval units and reliable transport and loading sequences all use cutting-edge technology. Electrically driven Vario Smooth troweling machines are used for surface finishing. “This is how we produce high-quality walls and floors that conform to architectural concrete standards,” explains the EGI CEO, Djamchid Inagamov. “We also installed a smart-set shuttering robot in the solid wall production line, a latest-generation multifunctional robot that combines innovative technology with high advance rates in terms of travel speed and acceleration. Depending on the type of wall or floor, a CAD/CAM system is used for positioning the stop-end formwork and plotting the contours of embedded parts and reinforcement components.”
The mesh welding unit and the lattice girder production line supplied by the Austrian manufacturer EVG are also fully automated. They utilize state-of-the-art robotics and are fully integrated into the control system.
Partnerships with EVG, Elticon, Nordimpianti and Liebherr
The reinforcement production line was installed centrally as the core piece between the hollow-core slab and solid wall production lines. A sophisticated Vario Safe safety concept ensures that hazards are kept to a minimum.
A Liebherr concrete mixing unit was installed as the central source for supplying structural and ready-mixed concrete to all in-house concreting processes and external sites. The integrated ring-pan mixer allows for an output of 2.25 m³ of concrete per batch.
Vollert Control Center as the “brain” of precast element production
The automated production equipment used at EGI ensures a consistently high quality standard, but the implemented production control system is just as important for achieving maximum productivity. The Vollert Control Center (VCC) is the central interface for transferring the structural data taken from the architect’s designs to the ERP system and the production equipment. Cycle times and automated pallet allocation are optimized continuously while controlling all machines, automatically tracking and processing relevant data, managing retrieval sequences and curing times, and providing a large number of statistics. “This is why the VCC is often referred to as the brain of the modern precast plant,” adds Igor Chukov of Vollert. “At EGI, the challenge was to integrate the production equipment of all system partners into the control system. For us, both factors – the integrated production equipment and
the smart control system – provided the cornerstones for optimizing the precast element production launch at EGI.”
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