Cement News tagged under: belite

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Belite-based low-carbon clinker cements

10 March 2020, Published under Cement News

While Portland cement is expected to remain the most-used cement type in concrete production, alternative cements are gaining importance. This has seen the continued development of alternative clinkers, such as belite-based low-carbon clinkers with a belite content of more than 40 per cent, in China over the last two decades. By Tongbo Sui, Sinoma Research Institute, China, Hao Sui, Monash University, Australia, and Bin Wang, Sinoma Research Institute, China. Clinker used in the produ...

Belite in Portland clinker

22 July 2019, Published under Cement News

While belite is often represented as a pure dicalcium silicate, in practice the phase contains a range of impurities. Arthur Harrisson highlights the differences in belite composition and examines the causes of such impurities. Type I belite crystals with dark laminations containing exsolved matter The belite phase in Portland cement clinker is often characterised as dicalcium silicate or C 2 S, implying a lime-to-silica ratio of 2:1. The ratio refers to the number of CaO units ...

Belite appearance in clinkers

11 April 2019, Published under Cement News

This month Arthur Harrisson looks at the second-most abundant constituent of cement – belite – and its appearance in clinkers. Figure 1: Type I belite with multiple sets of parallel laminations. The blue crystals are alite Of the four main constituents of cement clinker, the tricalcium silicate known as alite is the most abundant and is the one that is conventionally maximised to react with water to produce calcium silicate hydrate, the material required to achieve strength in a...

Crystal clusters in clinker

13 December 2017, Published under Cement News

With increasing use of alternative fuels, short homogenisation times in precalciner kiln systems and the requirement for high alite cement, the presence of crystal clusters is not expected to be a thing of the past. While the impact of crystal clusters in clinker on quality is not always clear, some effects can be seen.  Figure 1: brown and lighter blue belite crystals surrounding liquid phase Cement clinker for general-purpose Portland cement is composed essentially of four...

C2S solid solution reactivity in high-belite cement

28 November 2017, Published under Cement News

The key cause of the high energy intensity in the cement production process is the high heat required to form alite, the main constituent of Portland cement. One option is to lower the alite content, which leads to a higher share of belite. However, such high-belite cement often has a lower early strength, impacting on the quality of the final product. To address this issue, achieving a suitable control of belite reactivity is essential. By Dr Eng Daisuke Kurokawa and Shun Niijima, Taiheiyo...

Crystal inclusions in Portland cement clinker

10 August 2016, Published under Cement News

The nature of inclusions in clinker crystals provides clues about the burning environment and are therefore important indicators of clinker quality. Figure 1: blue belite inclusions in alite crystals Of the four main crystalline compounds that are found in Portland cement clinker, two are produced as solids and two are present in the burning zone of the cement kiln as a liquid, which then crystallises on cooling. Microscopic examination of clinker has been employed as a quali...

How much alite?

18 May 2015, Published under Cement News

The content of alite and other cement phases such as belite, aluminate and ferrite can have significant effects on the strength of the final mortar. This article looks at the correlation between alite and other cement phases on the 28-day strength of cement as well as some of the production conditions required to produce high-quality cement in these circumstances. Figure 1: quantity of alite and 28-day strength from seven cement plants It is well known that the four main phases ...

A is for alite

18 June 2012, Published under Cement News

The characteristics of clinker minerals when viewed under the microscope reveal key information about the cement production process. Arthur Harrisson explains their importance, mineral non-equilibrium and mineralogy in practice. He also takes a closer look at the key mineral alite. Optical microscope can reveal a wealth of information about clinker manufacturing processes and clinker properties Cement clinker contains four main minerals, all of which are usually identifiab...