Cement News tagged under: cement chemistry
Alite hydration with alkalis15 September 2014, Published under Cement NewsThe continued drive to optimise the use of cement in concrete mixes has sparked an interest in the hydration of alite in an alkaline environment. Research has shown that the presence of alkalis such as Na and K during alite hydration results in a higher amount of hydrated products and matrix densification. By Carolina Giraldo Torres, Ariel Berrío, Cementos Argos & Oscar Mendoza Reales, Jorge Iván Tobón, Universidad Nacional de Colombia. R&D at Cementos Argos, Colombia Almost two... |
Alite size16 July 2014, Published under Cement NewsThe practical implications following microscopic examination discussed in the April 2013 issue of ICR showed that the interpretation of alite size is not a simple matter. We take a closer look at the relationship between burning conditions, alite crystal size and cement quality. Figure 1: alite crystals averaging 35µm Several factors come into play when considering alite size including flame length and temperature, nucleation, production and kiln conditions, chemical factors, si... |
Problems with cement17 June 2014, Published under Cement NewsThere are many causes for complaints about cement quality from customers, some more justified than others. A brief review of some common perceived issues indicates that a deeper look at the potential causes for problems may help reduce the incidence of complaints. Problems with concrete cracking Over a six-month period the complaints from customers of a single cement plant were categorised and 69 per cent of the complaints were found to relate to service matters, typically late ... |
Alternative fuel characteristics20 January 2014, Published under Cement NewsMost microscopic analysis is based on classic studies carried out when single natural (traditional) fuels were the norm. How has the use of alternative fuels affected the microstructures observed? These observations start with a view on what differences new fuels can bring to the clinker. Figure 1: a belite cluster (150µm across) after the presence of coarse fly ash in the kiln feed Reducing conditions occur where there is an absence of oxygen such as at the bottom of an ocean o... |
Microscopy & practice08 April 2013, Published under Cement NewsIn this article Arthur Harrisson connects microscopy observations with the practical issues on the cement plant and in the market. He also identifies the benefits which are obtained by regular microscopic examination of cement clinker. Figure 1: effect of coarse silica in kiln feed. Oversized belite crystals are very difficult to combine with free lime In a previous article concerning microscopy (ICR July 2010) as a demonstration of the complexity of clinker mineralogy I took th... |
Making more of hotmeal14 February 2013, Published under Cement NewsReferences to hotmeal are common in cement plants and the concept is relatively simple – hotmeal is the kiln feed after drying and before clinkering. There is a considerable amount of information available from hotmeal which is not always collected and used. Therefore, this article takes a closer look at the useful findings that may help to steer the cement production process in the right direction. In the hotmeal a preformed cluster around belite is difficult to combine Hotmeal... |
Free lime reduction08 October 2012, Published under Cement NewsThe occurrence of high free lime can result in poor clinker quality and inefficient burning. Chemical variance in the raw materials and changes to the burning conditions can also upset the kiln balance, which can lead to other problems such as the formation of snowballs. So what are the main factors that will help to reduce high free lime? Figure 1: cluster of early-formed C2S crystals (field of width 750µm) As in most walks of life, cement manufacturing has developed a degre... |
Flame shape and quality30 January 2012, Published under Cement NewsArthur Harrisson investigates how burning and temperature in various types of kilns has an effect on the clinker produced and discusses different aspects of the burning process such as heating rate, maximum burning temperature, the burning time and the cooling rate to show their importance to clinker quality. Optical microscopy offers visual assessment of clinker quality In the cement manufacturing industry, people still tend to refer to the burner at the front-end of the kiln a... |