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Cement is undoubtedly a crucial material in our construction industry. Are you familiar with the history of cement? This article will take you through the evolution of cement. Additionally, handling cement can generate harmful silica dust, so wearing protective dust masks is necessary to safeguard lung tissues from damage due to prolonged exposure.
What is Cement?
Cement is a powdery substance that, when mixed with water, forms a paste that hardens both in air and underwater. It acts as a binding agent, holding together materials like sand and gravel.
History of Cement
The history of cement dates back to 1756, when British engineer J. Smeaton discovered that limestone containing clay produced a material that could harden underwater. This laid the theoretical foundation for modern cement.
In 1796, British inventor J. Parker produced a brownish cement from marble, known as Roman cement. This cement had excellent water resistance and quick-setting properties, making it ideal for underwater construction.
In 1813, French civil engineer Louis Vicat found that a mixture of lime and clay in a 3:1 ratio produced the best cement.
In 1824, British bricklayer Joseph Aspdin invented Portland cement and obtained a patent for it. He combined limestone and clay, burned them in a kiln, and ground the mixture into a fine powder. Named for its resemblance to the stone from the Isle of Portland, this cement revolutionized the construction industry with its superior properties.
In 1871, Japan built its first cement factory, marking the start of its cement industry. In 1877, British engineer Frederick Ransome improved the rotary kiln, further advancing cement production technology. By 1893, Japanese inventors Hideki Endo and Saburo Utsumi developed a sulfate-resistant Portland cement for use in seawater.
In 1907, Frenchman Jules Bied developed bauxite cement by substituting clay with bauxite, due to its high aluminum oxide content.
Throughout the 20th century, efforts to improve Portland cement led to the development of specialized cement like high-alumina and various other types for specific construction needs. By 2007, global cement production reached about 2 billion tons annually. In April 2023, scientists at Washington State University in the US created a new carbon-negative cement by incorporating eco-friendly biochar.
Composition of Cement
The primary chemical components of Portland cement are calcium oxide (CaO), silicon dioxide (SiO2), ferric oxide (Fe2O3), and aluminum oxide (Al2O3). The main mineral components include tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A), and tetracalcium aluminoferrite (C4AF).
Chemical Reactions in Cement
When cement is mixed with water, a series of chemical reactions occur, forming a solid structure. The main reactions are:
1. 3CaO·SiO2 + H2O → CaO·SiO2·H2O (gel) + Ca(OH)2
2. 2CaO·SiO2 + H2O → CaO·SiO2·H2O (gel) + Ca(OH)2
3. 3CaO·Al2O3 + 6H2O → 3CaO·Al2O3·6H2O (unstable)
3CaO·Al2O3 + 3CaSO4·2H2O + 26H2O → 3CaO·Al2O3·3CaSO4·32H2O (ettringite)
4. 4CaO·Al2O3·Fe2O3 + 7H2O → 3CaO·Al2O3·6H2O + CaO·Fe2O3·H2O
Setting and False Setting of Cement
Rapid setting of cement refers to an abnormal early hardening or premature stiffening. High temperatures can dehydrate gypsum, losing its ability to regulate setting time. False setting often occurs due to high temperatures during grinding, causing gypsum to dehydrate into hemihydrate. When mixed with water, hemihydrate reacts quickly to form a crystalline structure, causing the paste to set. High-alkali cement can also experience false settings due to the rapid formation of potassium sulfate and gypsum crystals. Unlike rapid setting, false setting releases minimal heat, and vigorous mixing can restore the paste’s plasticity without affecting strength.
Why do you need to wear a dust mask?
In cement, one of the main components, silica dioxide (SiO2), poses a risk to workers' health as it can be released in the form of dust during cement production and usage. Prolonged exposure to high concentrations of silica dioxide dust can lead to silicosis, a severe occupational lung disease. Silicosis damages lung tissues, causing permanent respiratory impairments and dysfunction.
Therefore, when handling cement, workers need to wear appropriate masks to prevent inhalation of silica dioxide dust. This is especially crucial in environments where cement requires cutting or grinding, as dust concentrations may be higher, necessitating additional precautions to protect respiratory health. Choosing the right type of mask and ensuring proper mask fit is essential to effectively filter dust particles from the air, reducing the potential impact on workers' health.
The reason why BASE CAMP MASK's masks are suitable for cement work lies in several key features:
1. Effective Filtration of Dust and Particles:
The BASE CAMP filter has a double layer of melt-blown layers with electrostatic adsorption electrons that effectively filter up to 99.6% of solid particles and dust. This allows the mask to provide efficient protection from particle filtration, making it a construction filtration face mask mask, suitable for cement work.
2. Reduction of Odors and Gases:
The activated charcoal in the filter can adsorb some gases and odors, helping to improve the air quality in the working environment. Cement work may produce certain odors or harmful gases, and the activated charcoal in the mask can act as a cleaner, providing a more comfortable breathing environment.
3. Comfort and Adaptability:
BASE CAMP MASKS are designed with comfort in mind, our new design BASE CAMP M Pro mask features a fully adjustable head strap and nose clips to ensure a snug fit. This design provides excellent adaptability, allowing the mask to be worn for extended periods during cement work without causing discomfort and keeping it snugly secure.
New Carbon-Negative Eco-Friendly Concrete
Scientists at Washington State University have developed a new carbon-negative concrete by incorporating eco-friendly biochar. This concrete maintains the strength of traditional concrete and offers better insulation, reducing energy consumption and carbon emissions. Given that the global cement industry emits about 2.8 billion tons of CO2 annually, this new concrete could significantly cut carbon emissions, offering both environmental and economic benefits.
Published in the latest issue of "Materials Letters," this innovation has garnered widespread attention and praise from global environmental organizations. This carbon-negative cement is expected to be widely adopted in the future, driving sustainable development in the cement industry and contributing to global carbon reduction efforts.
