From burlap sacks to valved paper bags: An industrial history of cement packaging

Stacks of neatly arranged square-bottomed valve bags, resembling books, circulate on a modern production line. Behind this seemingly ordinary assembly line lies a revolution in packaging materials and technology spanning more than a century.

From open-air storage and manual loading and unloading to today's automated packaging lines, the evolution of cement packaging reflects the progress of industrial civilization. Early cement packaging used wooden barrels and burlap sacks, with loading and unloading primarily done manually, resulting in high labor intensity and low efficiency.

In 1939, Jinan Jingzhi Cement Co., Ltd. pioneered the manufacture of fixed and mobile packaging machines, initiating the era of paper bag packaging for cement in China. This transformation not only improved efficiency but also marked a crucial step in the mechanization of cement packaging from purely manual labor.

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1. Initial Exploration

The earliest forms of cement packaging were far more primitive than what we see today. In the early 20th century, the transportation and storage of cement faced significant challenges. The earliest packaging containers were Japanese-made tin drums , each weighing approximately 170.5 kilograms.

While these tin drums provided basic protection, they were heavy, expensive, and unsuitable for large-scale transportation. Meanwhile, wooden drums also found a place in cement packaging.

Germany, as one of the countries with the fastest development of the cement industry in the early years, started its cement bag industry in the late 19th and early 20th centuries, initially using kraft paper imported from Northern Europe.

Early cement packaging in China also faced the predicament of scarce packaging materials and outdated technology. According to records, Huaxin Cement Plant only began to use paper bags for packaging in the late 1940s after introducing the world's most advanced wet-process cement production line, and wooden barrels gradually disappeared from the historical stage.

From tin drums to wooden barrels, and then to the earliest paper bags, the packaging explorations of this period reflect the arduous adaptation process of the cement industry in its early stages. The lack of standardized packaging methods led to significant transportation losses and storage difficulties, not to mention the absence of modern moisture-proof and leak-proof functions.

Although these early packaging forms were primitive, they accumulated valuable experience for subsequent technological innovations.

2. The Paper Packaging Revolution

In the mid-20th century, paper packaging gradually became the mainstream choice in the cement industry. In 1958, Jinan Cement Plant began using a two-nozzle fixed packaging machine , which could package up to 30 tons of cement per hour.

During the same period, the factory also manufactured its own cement bag stacking machine, which significantly improved work efficiency and reduced labor intensity. However, at that time, the loading and unloading of finished products in many local cement plants still relied mainly on manual operation, which was inefficient, had harsh working conditions, and was labor-intensive.

The application of paper cement bags was not achieved overnight. Cement packaging has extremely strict requirements for paper, and Professor Herzberg made significant contributions to the development of the cement bag industry in Germany.

The quality of cement bags only improved significantly after paper was standardized. After World War II, due to import controls and increased demand for paper, Germany faced a shortage of domestically produced kraft paper, necessitating the extensive use of sulfite pulp, which led to a decline in paper quality.

In China, the promotion of paper packaging also faces challenges. In the late 1950s, enterprises at the county level and above generally used fixed single-nozzle packaging machines, packaging 15-20 tons of cement per hour.

By the 1960s, more and more companies were adopting double-nozzle and four-nozzle packaging machines. In the 1970s, larger companies such as Shandong Aluminum Plant, Shandong Cement Plant, and Shandong Cement Experimental Plant began to use rotary 14-nozzle standard packaging machines , with a packaging capacity of 96 tons of cement per hour.

3. Transition from woven plastic bags

With the development of the chemical industry, plastic woven bags gradually entered the cement packaging field in the late 20th century. In 1982, plastic woven bags began to be used for cement packaging on a trial basis.

This period coincided with the peak of China's import of packaging machinery, with hundreds of plastic weaving production lines being introduced, including a dozen or so with complete sets of bag-making equipment. Domestically produced equipment also began to be installed one after another.

Compared to traditional paper bags, woven plastic bags offer greater strength and weather resistance , exhibiting superior performance, especially in humid environments. This shift is not a simple material replacement but involves adjustments to the entire production chain.

In 1995, Huaxin Cement introduced a paper-plastic composite cement bag production line with an annual output of 20 million bags, changing the more than 40-year history of paper cement bag production.

By 2001, Huaxin had completely phased out paper-plastic cement bags and began producing only all-plastic cement packaging bags . The use of woven plastic bags in the cement packaging industry continued for a considerable period, becoming an important transitional form connecting traditional paper packaging with modern valve bags.

4. Modern valve bag technology

In the 21st century, square-bottomed valve bags have gradually become the mainstream choice for cement packaging. This new type of packaging bag is made of multi-layered paper or woven plastic materials and uses heat-sealing welding technology to achieve a seal. Its structural features allow for top valve inlet feeding and automatic sealing.

The square-bottom valve bag design allows for neat stacking, forming a regular cubic stack, which greatly improves the utilization rate of storage and transportation space.

2009 became a pivotal year for technological innovation in cement packaging. In that year, Huaxin Cement adopted then-internationally leading technology to produce square-bottom valve bags.

In the same year, Huaxin Packaging Company boldly introduced the first heat-sealing machine in China and began to explore the production technology of square-bottom valve bags. At that time, the domestic market generally used plastic woven bottom bags, and there was no experience to draw on, making market expansion difficult.

The technological advantages of square-bottom valve bags are obvious: First, they are made of PP (polypropylene) material or paper-plastic composite material. The base material includes a three-layer paper-one-film composite layer or a multi-layer paper bag structure. The surface is coated to improve printing effect and waterproof performance.

Secondly, the square bottom design, combined with the top valve structure, makes it compatible with automated filling equipment. Finally, this packaging method offers excellent breathability, is environmentally friendly, and effectively reduces dust emissions.

5. Standardization process

The standardization process of cement packaging bags is an important force driving technological progress in the industry. China's cement packaging bag standard was first formulated in 1988, and subsequently revised several times in 1996, 2002, 2010, and 2020.

The GB/T 9774-2020 standard for cement packaging bags , released on September 29, 2020, officially came into effect on April 1, 2022, replacing the original GB/T 9774-2010 standard.

This new standard requires the complete elimination of sewn-bottom bags, limiting them to square-bottom valve bags using adhesive or heat-sealing processes. The standard specifies detailed technical requirements: laminated woven plastic bags must have a warp tensile load of no less than 500N and a weft tensile load of no less than 450N, with a unit area mass of no less than 75g/m².

For the moisture-proof performance test, the humidity should be adjusted to 80%±5%, the filling speed of a single bag should not exceed 15 seconds/bag, and the weight loss of the bag after 6 drop tests should not exceed 40g.

As a technology leader in the industry, Huaxin Packaging Company actively participates in the formulation of national standards and holds 11 related patents . The company not only participated in the revision of the national standard for "Cement Packaging Bags," but also led the drafting of the group standard for "Easily Recyclable Plastic Woven Bags for Packaging" and several industry standards for carbon peaking and carbon neutrality in the building materials sector.

6. Globalization trend

The evolution of cement packaging is not only a phenomenon in China, but also a microcosm of the global building materials industry. Different countries and regions have chosen unique packaging technology paths based on their own industrial development stages and resource conditions.

Nepal, as a developing country, notified the "Technical Regulations for 50kg Cement Packaging PP Woven Laminated Bags" on August 5, 2024, stipulating that 50kg of cement should be packaged in PP woven laminated bags in accordance with relevant standards. This indicates that developing countries are also keeping up with international trends in cement packaging standardization.

As a pioneer in the early development of the cement industry, Germany's cement bag industry started as early as the late 19th century, initially relying on kraft paper imported from Northern Europe.

In a 1947 technical document, Japan detailed the development experience of the German cement bag industry, hoping to encourage the development of domestic cement bag manufacturers in Japan.

Globally, technological exchanges and cooperation in cement packaging are becoming increasingly frequent. Advanced valve bag production line equipment has been imported from countries such as Germany, and production technology is being disseminated and improved worldwide.

With the advancement of the Belt and Road Initiative, cement packaging bags produced in China have been exported to many countries and regions in Central Asia and Africa.

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In the workshop of Shaanxi Baihong Ouli Plastics Co., Ltd., the valve bag production line is running at a rapid pace, producing tens of thousands of brightly colored cement packaging bags per hour.

These bags are neatly stacked together and are about to be sent to construction sites in Xinjiang, Gansu, Qinghai, and even as far as Kazakhstan and Mozambique.

From heavy tin buckets to cleverly designed square-bottomed valve bags, from dusty manual packaging to clean automated production lines, every crease in cement packaging bags records the progress of industry .