Global AAC industry challenges and transformation opportunities

Since its industrialization in the 1980s, China’s AAC industry has experienced rapid expansion, and it now faces overcapacity and inefficiency. Over 70% of China’s 3,000+ AAC factories are more than a decade old, with average capacity utilization below 60% and steam consumption exceeding 200 kg/m³. Similarly, Europe faces aging equipment and tightening environmental regulations. The IEA reports that the building materials sector accounts for 11% of global carbon emissions, with energy and raw material consumption in AAC production being major contributors. Against this backdrop, UBlok transformed the Changxing Ytong plant into a high-efficiency, low-carbon benchmark, offering a practical model for global modernization of aging factories.

Current status and core challenges of China’s AAC industry

Comparative analysis of old vs. new factories

New factories with automated lines and advanced processes achieve daily outputs exceeding 3,000 m³ and steam consumption levels below 100 kg/m³. In contrast, ageing factories face the following challenges:

·     Low-capacity utilization: Inefficient workflows, slow production cycles, and poor mould turnover.

·     High energy consumption: Steam consumption >200 kg/m³, with 20% thermal loss.

·     Quality fluctuations: Cutting inaccuracies and uneven pore structures result in product qualification rates less than 95%.

·     High maintenance costs: Outdated equipment operates at <85% efficiency, with maintenance costs 2-3 times higher than those of new factories.

·     Import dependency: The procurement time for imported parts increased 4-8 times, with prices being 3-4 times higher.

Deep-rooted cost structure issues

Energy (30%), lime and cement (50%), and labour (12%) dominate costs in ageing factories. Steam consumption is concentrated in autoclave curing (80%), while traditional aluminium powder foaming wastes 15% of raw materials. The import dependency further escalates maintenance costs.

UBlok’s three-dimensional cost-reduction strategy: technical pathways and engineering practices

Energy optimization: reducing steam consumption from 200 to 100 kg/m³

Autoclave expansion and thermodynamic reconfiguration

Increased autoclave capacity, full-process insulation upgrades, and staged curing (gradient pressurization) raised thermal efficiency from 60% to 90%, shortening curing cycles by 20% and improving steam utilization by 40%.

Waste heat utilization

With the upgraded processes, 120°C condensate is recovered via flash tanks, saving 260 tons of steam annually. UBlok’s proprietary non-condensable gas separator boosted secondary steam reuse by 20%.

The steam trap system technology for the autoclave used in the AAC plant at the Changxing Ytong facility is specifically designed to enhance performance and efficiency. This system effectively addresses the challenge of timely discharge of low-pressure, large-flow condensate, ensuring smoother operation. Additionally, it resolves the issue of steam leakage during high-pressure drainage.

Process innovation: cutting lime and cement consumption by 50%

Formula optimization

In the course of the upgrade, the Ca/Si and water/material ratios were adjusted, reducing lime and cement consumption from 210 kg/m³ to 115 kg/m³. Simultaneously, the substitution rate of return slurry and recycled AAC waste was increased to 30%, reducing annual consumption of raw materials by 120,000 tons.

Table 1: Performance comparison of new and old formulations.

Water-based aluminium paste and foaming process innovation

Traditional aluminium powder is limited in application due to flammability. To address this, UBlok developed a proprietary water-based aluminium paste using microencapsulation emulsification coating technology. This innovation effectively reduces oxidation exposure between aluminium powder and air, mitigates flammability risks, decreases the standard deviation of pore diameter from ±0.5 mm to ±0.2 mm, and reduces raw material waste by 15%.

Product structure upgrade: transition from b06 blocks to b05 panels

Extension of low-density products: By optimizing porosity (increased from 75% to 82%), the dry density decreased from 650 kg/m³ (B06 grade) to 525 kg/m³ (B05 grade), while maintaining compressive strength values above 4.0 MPa (complying with EN 771-4 standards).

Panelization transition: Large-size AAC panels (6 m × 0.6 m, thickness 50-400 mm) were developed with built-in three-dimensional steel mesh cages, achieving cutting precision errors of less than 1 mm to meet the demands of prefabricated construction.

Automation upgrade

The automation upgrade led to a 30% reduction in staff while significantly boosting overall efficiency. Unmanned packaging systems enhanced stacking and packing performance by 30%, streamlining the end-of-line process. Meanwhile, the integration of PLC technology enabled real-time monitoring, which reduced ingredient errors to less than 0.5% and shortened fault response times to just 10 seconds.

Post-retrofit, per capita productivity surged from 4,000 m³/year to 12,500 m³/year.

Circular economy practices: from waste recycling to low-carbon production

Breakthrough in autoclaved bottom layer removal technology

UBlok’s self-developed autoclaved bottom layer removal equipment utilizes an automatic stripping system to achieve 100% waste recycling. This innovation saves 35,000 tons of sand annually, reduces carbon emissions by 1,200 tons, and has obtained EU CE certification.

As part of UBlok´s commitment to low-carbon pathways and alignment with EU sustainability initiatives, the plant has implemented innovative energy and emissions strategies. Steam waste heat is now utilized through cascade systems to support district heating, enabling integration into production heating networks and achieving thermal efficiency levels above 85%. In parallel, the carbon footprint assessment reveals a significant improvement: following retrofitting, the carbon intensity per cubic meter of AAC has been reduced from 120 kg CO₂e/m³ to 80 kg CO₂e/m³, meeting the compliance standards set by the EU Carbon Border Adjustment Mechanism (CBAM).

Changxing Plant: capacity leap and technology export

Dual enhancement in capacity and quality

Production cycle optimization has significantly enhanced output, with mould cycle times reduced from 6 minutes to just 3 minutes – doubling the daily production volume from 950 m³ to 1,900 m³. Looking ahead, further improvements aim to reduce cycle times to 2 minutes, targeting a daily capacity of 2,600 m³. In parallel, upgrades to the cutting process – specifically increasing the number of column pairs from 7 to 13 – have eliminated fracture defects in small-sized blocks and panels. As a result, product qualification rates have risen to over 99%.

Technology export and economic validation

Retrofits were successfully implemented for Shandong Lubi and Baowu Ma Steel, while technical licenses and management support were provided to Shaanxi Jingwei and the Philippines-based MVBC. These initiatives led to an average efficiency improvement of 35%, with a payback period of less than two years. Additionally, a localization rate exceeding 90% was achieved by replacing key components – such as electrical control systems, hydraulic systems, and autoclave valves – with domestically produced alternatives. This localization strategy contributed to a 30% reduction in maintenance costs.

Panel application cases

The company has established a strong international presence through the export and support of AAC panel technologies. In Southeast Asia, panel production technology and management support were provided to partners in Vietnam and the Philippines, enabling localized production where panels now account for 30% of the total capacity. In Australia and New Zealand, 75 mm thick panels were supplied for use in composite wall structures within residential projects. Meanwhile, in Hong Kong, large blocks and modular wall materials were delivered for premium developments in the city's central business district.

Conclusion and outlook: technology-driven global carbon neutrality pathways

UBlok’s practices demonstrate that modernizing ageing factories requires balancing technical, economic, and environmental benefits. Key insights include:

·       Scalability: Waste heat recovery and solid waste utilization solutions are adaptable to European regional systems.

·       Policy synergy: Governments must incentivize green transitions through tax relief and carbon pricing mechanisms.

Future research efforts will focus on several key areas aimed at enhancing sustainability and industrial efficiency. One priority is the development of low-carbon binders by replacing traditional cement with geopolymers or composite industrial waste, targeting a reduced carbon footprint of just 50 kg CO₂e/m³. In addition, work is underway to advance modular wall materials, specifically by designing large AAC panels exceeding 6 meters in length to support the shift toward construction industrialization. Another major focus is the innovation of smart production lines that combine low investment and space requirements with minimal maintenance and high operational efficiency.

The global AAC industry must leverage technological innovation, cross-border collaboration, and policy alignment to achieve carbon neutrality collectively.

References

[1] UBlok Group (2023), ‘Changxing Factory Technical Retrofit Report’.

[2] European Commission (2023), ‘Circular Economy Action Plan’.

[3] IEA (2022), ‘Global Carbon Emissions in Building Materials’.

[4] Smith, J. et al. (2021), ‘Energy Efficiency in AAC Production’, Journal of Sustainable Materials.