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cement and cement clinker cement and cement clinker

spanish cement and clinker productions co2 emissions fall in 2020 - cement industry news from global cement

spanish cement and clinker productions co2 emissions fall in 2020 - cement industry news from global cement

Spain: The total CO2 emissions of cement and clinker production in Spain fell by 14% year-on-year in 2020. The El Economista newspaper has reported that a report by the Sustainability Observatory recorded that 10 Spanish companies were responsible for emitting 51Mt of CO2 in 2020 or 56% of the national total.

what is cement clinker? composition, types & uses - civil engineering

what is cement clinker? composition, types & uses - civil engineering

Clinker is a nodular material produced in the kilning stage during the production of cement and is used as the binder in many cement products. The lumps or nodules of clinker are usually of diameter 3-25 mm and dark grey in color. It is produced by heating limestone and clay to the point of liquefaction at about 1400C-1500C in the rotary kiln. Clinker, when added with gypsum (to control the setting properties of cement and ensure compressive strength) and ground finely, produces cement. Clinker can be stored for long periods of time in a dry condition without degradation of quality, hence it is traded internationally and used by cement manufacturers when raw materials are found to be scarce or unavailable.

The raw materials entered into the kiln are taken at room temperature. Inside the kiln, the temperature continues to rise and when it reaches its peak, clinker is produced by rapid cooling. Though the reaction stages often overlap, they can be expressed in a sharply-defined sequence as follows:

The most common type of clinker is produced for Portland cement and its blends. The types of clinker vary depending on the type of cement for which the clinker is produced. Aside from the Portland cement blends, some special types of cement clinker are listed below:

It contains 76% alite, 5% belite, 2% tricalcium aluminate, 16 % tetracalcium aluminoferrite, and 1% free calcium oxide. Its production has decreased in recent years because sulfate resistance can easily be obtained by using granulated blast furnace slag in cement production.

It contains 29% alite, 54% belite, 2% tricalcium aluminate and 15 % tetracalcium aluminoferrite, with very little free lime. It is no longer produced because cement produced from ordinary clinker and ground granulated blast furnace slag has excellent low heat properties.

It contains 76% alite, 15% belite, 7% tricalcium aluminate, no tetracalcium aluminoferrite, and 2% free lime, but the composition may vary widely. White clinker produces white cement which is used for aesthetic purposes in construction. The majority of white cement goes into factory-made pre-cast concrete applications.

Reduction of alkali content in clinker is done by either replacing the raw-mix alumina source with another component (thus obtaining a more expensive material from a more distant source), or installing an "alkali bleed", which involves removing some of the kiln system's high temperature gases (which contain the alkalis as fume), resulting in some heat wastage.

This concept is used in producing a type of clinker with up to 30% less carbon dioxide emission. Energy efficiency improves and the electricity costs for the manufacturing process are about 15% lower as well.

Clinker, combined with additives and ground into a fine powder, is used as a binder in cement products. Different substances are added to achieve specific properties in the produced cement. Gypsum added to and ground with clinker regulates the setting time and gives the most important property of cement, compressive strength. It also prevents agglomeration and coating of the powder at the surface of balls and mill wall. Some organic substances, such as Triethanolamine (used at 0.1 wt.%), are added as grinding aids to avoid powder agglomeration. Other additives sometimes used are ethylene glycol, oleic acid, and dodecyl-benzene sulphonate. The most notable type of cement produced is Portland cement, but certain active ingredients of chemical admixtures may be added to clinker to produce other types of cement, such as:

Clinker is primarily used to produce cement. Since it can be stored in dry condition for several months without noticeable deterioration, it is traded internationally in large amounts. Cement manufacturers buy clinker for their cement plants in areas where raw materials for cement are scarce or unavailable.

Please note that the information in Civiltoday.com is designed to provide general information on the topics presented. The information provided should not be used as a substitute for professional services.

italcementi to invest euro5.0m to restart clinker production at trentino cement plant - cement industry news from global cement

italcementi to invest euro5.0m to restart clinker production at trentino cement plant - cement industry news from global cement

Italy: HeidelbergCement subsidiary Italcementi has announced a planned investment of Euro5.0m to restart clinker production at its Trentino cement plant in Sarche di Madruzzo. The plant will have an integrated production capacity of 0.25Mt/yr when it resumes full operation from January 2022. The company aims to establish a reference plant for the Northeast at the facility. It will begin hiring 30 new staff in late 2021. The unit has been operating as a grinding plant since 2015.

Technical director Agostino Rizzo said, The cement plant is equipped with the technologies necessary to guarantee high level environmental performance. To this will be added a landscape integration. The relationship with the region and local communities is of great importance for us.

difference between clinker and cement - civil engineering

difference between clinker and cement - civil engineering

Cement and clinker are not the same material. Cement is a binding material used in construction whereas clinker is primarily used to produce cement. The main differences between clinker and cement are given below.

Please note that the information in Civiltoday.com is designed to provide general information on the topics presented. The information provided should not be used as a substitute for professional services.

difference between clinker and cement | compare the difference between similar terms

difference between clinker and cement | compare the difference between similar terms

Earlier, people did not have sophisticated homes; therefore, they used simple things found in the environment to build houses. But today there are many advanced materials and equipment, which assist in constructions. Cement is a marvellous material among them. Before developing high standard cement, which is in the market today, there were primitive types of cement made out from limestone. Earlier, types of cement were not that stable, and they were not a great binding agent. However, today cement has evolved in such a way it has become a reliable building material.

Clinker is the material that we use as the binder of cement, and it is a nodular material. Usually, the lumps or nodules of clinker has its size in the range of 3 millimetres to 25 millimetres in diameter and are dark grey in colour. This material forms during the cement production, inside the kiln. There, clinker forms as a result of sintering limestone and aluminosilicates such as clay during the cement kiln step. Above all, we produce cement via adding gypsum to clinker and grinding finely.

Furthermore, we can store this material for a long period in a dry condition. There, the storing does not degrade the quality of clinker. When considering the composition of this material, there are two major groups as mineral components and chemical components. There, the four major components are alite, belite, aluminate and ferrite.

Cement is an important substance that we use in constructions as a binder to adhere materials to other materials. Often we use cement along with sand and gravel rather than using it alone. We can use this material mainly in two purposes, as mortar in masonry and as concrete; there, we can produce mortar by mixing cement with fine aggregates whereas we can produce concrete by mixing cement with sand and gravel.

The cement that we use in construction purposes is inorganic; manufacturers use lime or calcium silicate in producing this type of cement. We can characterize this material as either hydraulic and non-hydraulic cement, depending on the ability of this material to set in the presence of water or the absence of water respectively. Therefore, non-hydraulic cement sets as it dries and reacts with carbon dioxide. Moreover, it is chemical resistant after setting.

Cement is an important substance that we use in constructions as a binder to adhere materials to other materials. Clinker is a component in cement. It is the active binding component in cement. Therefore, the key difference between clinker and cement is that clinker appears as marble-like nodules, whereas cement is a very fine powder. Moreover, particles in clinker size are in the range of 3 millimetres to 25 millimetres in diameter while in cement there are very fine particles. Apart from that, clinker forms inside the kiln during the cement manufacturing whereas we can produce cement via adding gypsum to clinker and grinding finely.

Cement is a major building material that we use in constructions. Clinker is a major component in cement. The key difference between clinker and cement is that clinker appears as marble-like nodules, whereas cement is a very fine powder.

Madhu is a graduate in Biological Sciences with BSc (Honours) Degree and currently persuing a Masters Degree in Industrial and Environmental Chemistry. With a mind rooted firmly to basic principals of chemistry and passion for ever evolving field of industrial chemistry, she is keenly interested to be a true companion for those who seek knowledge in the subject of chemistry.

cement clinker and cement market analysis: the transformative impact due to covid-19, leading brands: anhui conch cement, jidong cement, heidelbergcement, cemex the manomet current

cement clinker and cement market analysis: the transformative impact due to covid-19, leading brands: anhui conch cement, jidong cement, heidelbergcement, cemex the manomet current

GlobalCement Clinker and Cement Marketresearch report 2021 is a comprehensive, professional report delivering market research data that is relevant for new market entrants or established players. The research study covers significant data which makes the document a handy resource for managers, analysts, industry experts, and other key people to get ready-to-access and self-analyzed study along with graphs and tables to help understand market trends, drivers, and market challenges. Combining the data integration and analysis capabilities with the relevant findings, the report has predicted the strong future growth of the Cement Clinker and Cement market in all its geographical and product segments.

Whats more, the Cement Clinker and Cement industry development trends and marketing channels are analyzed. Industry analysis has also been done to examine the impact of various factors and understand the overall attractiveness of the industry. Also, a six-year (2012 to 2020) historic analysis is provided for Cement Clinker and Cement markets.

Market Research Storeis the best marketplace where research teams working on all types of market facts and factors which are important for developingthe industry. We have multiple kinds of product research reports like Software, Chemicals, Consumer Goods, Technology, Retails, Cloud Computing, Bitcoin or Cryptocurrency, Agricultural, Aerospace, Healthcare, Medicines, Biotechnology, Business Financial Services, Defense & Security, IT, Electronics and Semiconductors, Pharmaceuticals, Luxury Goods, Media and Entertainment and many more.

Geographically, this report is segmented into several key Regions, with production, consumption, revenue (million USD), and market share and growth rate of Cement Clinker and Cement in these regions, from 2012 to 2023 (forecast), covering North America, Europe, China, Japan, Southeast Asia, India and its Share (%) and CAGR for the forecasted period 2019 to 2024.

Top Manufacturers Analysis in Cement Clinker and Cement Market:Taiwan Cement, Chhatak Cement Factory Ltd, China Resources Cement, CRH, Jidong Cement, HC Trading, Buzzi Unicem, InterCement, Eurocement, HeidelbergCement, Shun shing, UltraTech Cement, SsangYong Cement, Dangote Cement, LafargeHolcim, Cemex, Anhui Conch Cement, China National Building Materials (CNBM), Votorantim

This report also presents product specification, manufacturing process, and product cost structure, etc. Production is separated by regions, technology, and applications. Other important aspects that have been meticulously studied in the Cement Clinker and Cement market report are Demand and supply dynamics, import and export scenario, industry processes and cost structures, and major R&D initiatives. In the end, the report includes Cement Clinker and Cement new project SWOT analysis, investment feasibility analysis, investment return analysis, and development trend analysis.

The manufacturing cost of products and the pricing structure adopted by the market are also evaluated in the report. Other parameters crucial in determining trends in the market such as consumption demand and supply figures, cost of production, gross profit margins, and selling price of product and services is also included within the ambit of the report.The report is all around made with a combination of the basic information relying upon the important data of the worldwide market, for instance, the key point responsible for fluctuation in demand with services and products.

In conclusion, it is a deep research report on theGlobal Cement Clinker and Cement industry.Here, we express our thanks for the support and assistance from Cement Clinker and Cement industry chain related technical experts and marketing engineers during Research Teams survey and interviews

cement clinker - an overview | sciencedirect topics

cement clinker - an overview | sciencedirect topics

Cement clinker dust (CKD) is a problematic waste derived from the cement industry which may cause some problems in clinkering kiln operations and cement performance. CDW has to be discarded despite its hydraulic properties due to high content of chlorine, sulphur and alkalis. Wang et al. (2004) analysed CKD/FA blends activated with NaOH. 50%/50% CKD-FA system activated with 2% of NaOH showed the best mechanical behaviour (27MPa) when cured for 56 days at 38C. Badanoiu et al. (2011) also studied this CKD/FA system and found that the decrease of liquid/solid ratio (from 0.25 to 0.15) led to improving the strength in 98200%. Good behaviour also was found for 20% CKD systems when cured for 28 days at 85C (Cabrera-Fuentes et al., 2011). A comparison between different mineral additions was carried out by mixing CKD and slag, FA, inert calcite filler and MK (Buchwald and Schulz, 2005). The best results were observed for 1:1 CKD/slag system, finding a compressive strength higher than 20MPa. Geopolymer bricks were manufactured by activation with NaOH (10 to 15M) of a mixture of CKD and copper mine tailings (Ahmari and Zhang, 2013).

Spent FCC catalyst was studied as a precursor for geopolymer synthesis. This residue is composed of a mixture of Al2O3 and SiO2. Tashima et al. (2012b) discovered the high reactivity of FCC by mixing with NaOH/Na2SiO3 solutions. Fig. 13.19 shows that applying 1.19 SiO2/Na2O molar ratio, 68MPa were reached after curing for 3 days at 65C. Different studies were carried out in order to find optimum dosage (silica modulus, water/binder ratio) for different curing conditions (thermal curing, room temperature) (Tashima et al., 2013c, 2014; Rodriguez et al., 2013; Trochez et al., 2015). Very good strength development was found for mortars cured at room temperature, for both sodium- and potassium-activated systems (Tashima et al., 2014). Cellular concrete was prepared by alkali activation of FCC in 0.2% of metallic powdered aluminium presence (Font et al., 2017a,b).

Residue from calcium carbide (CCR) produced in the acetylene production was also used as a co-precursor. CCR contains Ca(OH)2 and when mixed with FA and blast furnace slag yielded appropriate binding characteristics (Arullrajah et al., 2016). Crushed bricks and RA concrete (RAC) were geopolymer stabilised and the systems could be used for pavement base/sub-base applications. CCR was also used for stabilising water treatment sludge by means the alkali activation with NaOH/Na2SiO3 (Suksiripattanapong et al., 2017). The best dosage of CCR was for 10% by mass of sludge. FA/CCR systems (0%30% CCR content) were studied by Hanjitsuwan et al. (2018). The partial replacement of FA by CCR showed an improvement in strength properties and in mortars durability when exposed to sulphate solutions (sulphuric acid and magnesium sulphate) as can be seen in Fig. 13.20.

Figure 13.20. Compressive strength values of alkali-activated FA mortars with CCR after immersion in H2O, 5% MgSO4, and 5% H2SO4 solutions (Hanjitsuwan et al., 2018). FA, Fly ash; CCR, Calcium carbide residue.

Li et al. (2016) demonstrated that calcined paper sludge (PS) can be alkali-activated. The ash contained mainly SiO2, Al2O3 and CaO. The geopolymers produced with these ashes showed a great porosity (swelling was observed before curing) probably due to the presence of metallic aluminium particles. A study of PS and bottom coal FA in a 1:2 mass ratio was carried out by Boca-Santa et al. (2013). Yan and Sagoe-Crentsil (2016) analysed the behaviour of FA systems in which the PS replacement was in the range 0%40% by mass. They described that the PS reduced both the flow of fresh mortar and the setting time. The 7-day compressive strength was highly improved for PS containing mortars and the shrinkage was reduced in the first 91 days of curing.

PS was also combined with FA for geopolymerisation (Yan and Sagoe-Crentsil, 2012). The sludge contained a high fraction of organic matter (58.8% loss on ignition (LOI), 51.8% cellulosic matter). The addition of 10% of the sludge reduced the flow of mortars and diminished the compressive strength by 50%. The drying shrinkage values of alkali activated mortars incorporating 2.5% and 10% PS were 34% and 64% less if compared to the reference mortar, demonstrating the shrinkage-reducing role of this dry PS additive (Fig. 13.21).

Silica rich waste (89.2% SiO2) produced in the flue gas scrubbing treatment of chlorosilane production was studied by Gluth et al. (2013). A mixture (4:3 ratio) with sodium aluminate was carried out by mixing with water (0.6 water to solid ratio). After curing 7 days at 70C, the samples yielded 7MPa in compressive strength.

The cement clinker manufacturing process traditionally involves intimate mixing and the subsequent heat treatment of a blend of calcareous rock, such as chalk or limestone, and argillaceous rock, such as clay or shale. A series of chemical reactions of calcium, silicon, alumina and iron oxides present leads to the formation of the clinker material with main compounds tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A) and tetracalcium aluminoferrite (C4AF). After cooling and storage, the clinker is ground into a fine cement powder and gypsum is added, as a source of calcium sulphate, to improve the future setting behaviour of the cement.

This process places a high demand on natural resources, and a large amount of CO2 emissions are generated from the energy needed to convert the calcium carbonate (CaCO3) in limestone into calcium oxide (CaO), which is commonly known as lime. As such, this has sparked an interest in bringing in recycled and secondary materials such as blast furnace slag, cement kiln dust and fly ash as alternative sources of the required calcium (without the conversion process from CaCO3), silicon, alumina and iron oxides.

As is evident from the oxide composition analysis in Chapter 4, SSA appears to be another potentially suitable candidate for exploitation as raw feed in the cement clinker manufacturing process, with average contents of 32% SiO2, 14% CaO, 14% Al2O3 and 11% Fe2O3. The vast size of the cement industry also adds to the appeal of this application, as the use of SSA even at low proportions to some degree of regularity on the world scale could amount to large quantities overall.

The use of SSA as raw feed for cement clinker production has been explored at rather low contents, ranging from 1% to 11%, and as is evident from the experimental blends in Table 5.2, the material has been incorporated with a range of other secondary materials such as fly ash, copper slag, ferrate waste, water purification sludge ash (WPSA) and industrial wastewater sludge ash, along with the traditional limestone, clay and sand materials. To ensure that the desired main clinker phases are formed, the contents of many of the constituents are continuously adjusted to satisfy the requisite oxide requirements. These variations make it difficult to precisely quantify the direct impact of SSA, though there are certain trends that can be discerned from the results.

In the assessment of the oxide composition and mineral phases of the clinkers produced, results for selected key parameters for the aforementioned SSA blends (outlined in Table 5.2) are presented in Table 5.3, along with a brief description of findings from the respective studies, including for some the setting times and compressive strength performance. Results for the ordinary Portland cement clinkers (denoted by PC) are also provided. It should be noted that the data from Kikuchi (2001) was not included in the results, as SSA had been used in a solitary blend at only a mere 1%.

The incorporation of SSA into the manufacturing process has been found to significantly increase the P2O5 and SO3 contents in the resultant cement clinker. At the higher end of the tested SSA levels, these oxide contents become excessively high and this generally appears to suppress the formation of C3S, which is the mineral phase primarily responsible for setting behaviour and early strength development. However, when limiting the SSA content to around 5%, setting behaviour and compressive strengths comparable to those of the control PC blends have been achieved.

As an alternative solution, an integrated approach involving the pretreatment of SSA to extract the phosphorus fraction (which is a valuable resource in the agricultural industry) and subsequently use of the processed material in cement clinker production appears to be a promising and complementary option.

Of additional interest, the use of the original sewage sludge in the cement clinker manufacturing process is another possible approach, though this is not the specific focus of this work. With the organic fraction present, the sludge has a much higher calorific value than the ash (average of 15MJ/kg, determined in Chapter 3) and, after drying, could serve as a beneficial fuel source and lessen the energy requirements involved in the heat treatment process.

The leaching characteristics of cement clinker containing CS have been investigated since the beginning of the 2000s. The cement clinker in these studies contained a small amount of CS, ranging from 0.3% to 2.5%, and possibly in combination with other waste materials such as ashes from sewage sludge, municipal incineration and coal combustion, sewage dry powder and aluminium dross that together amounted to around 840% of the total raw feed composition, as provided in Table 8.2.

NR, not regulated; Neg., negligible amount; TCLP, toxicity characteristic leaching procedure; w/c, water/cement ratio; PFA, pulverised fly ash; SSA, sewage sludge ash; MIBA, municipal incinerated bottom ash; MIFA, municipal incinerated fly ash.

NR, not regulated; Neg., negligible amount; TCLP, toxicity characteristic leaching procedure; w/c, water/cement ratio; PFA, pulverised fly ash; SSA, sewage sludge ash; MIBA, municipal incinerated bottom ash; MIFA, municipal incinerated fly ash.

The leaching results of cement clinker containing CS (1) measured in the ground form or (2) obtained from the cast cement paste and mortar specimens are given in Table 8.2. These results show that the amounts of leached heavy metals of the samples containing CS, with or without other waste materials, are all well within the US EPA (2012) regulatory levels for the TCLP tests. When measured from the cast mortar specimens, the results appear to show that their leaching behaviour is independent of the maturity of mortar, for which the specimens were tested at the ages of 1, 3 and 7days (Kikuchi, 2001). It should be noted that the US EPA (2012) does not provide regulatory limits for Cl, CN, Co, Cu, Ni and Tl.

Apart from the leaching test, the chemical analysis of the exhaust gases emitted during the manufacture of cement clinker can also be important in determining environmental impact. Kikuchi (2001) showed that the values of sulphur oxide, nitrogen oxide, dust and dioxins in the exhaust gases of cement clinker made with CS and other waste materials are well below the permissible levels recommended by the Japanese standards (JIS Z 8808 and JIS K 0107). However, it would have further helped to evaluate the environmental impact if such results were provided together with cement clinker made with natural materials, for comparison purposes.

The optimization of cement clinker volume in the mix composition leads to a significant reduction in the environmental impact compared with the reference concrete mixtures. This improvement is specifically based on the use of fly ash, slag, and limestone powder. It has to be kept in mind that an allocation of environmental impacts to byproducts such as fly ash and slag can change this conclusion noticeably. In this case, the results depend significantly on the allocation criteria for the SCM. The allocation burdens can be associated with both the relative mass and current economic values of products and byproducts [17]. Every allocation has the effect that the calculated impact of the used waste (SCM) is in some cases and for different impact categories much higher than the replaced material (Portland cement clinker). This leads to problematic results and potentially prevents the use of byproducts that cannot be used for other applications in a reasonable way. However, the allocation procedure supports the efficient use of fly ash and slag in the mix design.

The GWP, which considers the distinctive effect of different greenhouse gases, was calculated using the environmental performance evaluation based on data for the constituents according to kobau.dat 2010 and the GaBi database [29], Netzwerk Lebenszyklusdaten [16], and the European Federation of Concrete Admixture Associations [30]. In a first step, no allocations were considered for slag and fly ash except for the secondary process. Also the reabsorption of carbon dioxide was not considered, due to the fact that the degree of carbonation in concrete members over the life cycle and the life cycle itself is uncertain.

Fig. 4.9 shows the GWP of selected concretes without allocation to SCM and with economic allocation according to Ref. [17]. For a comparable concrete strength the GWP without allocation was reduced by approximately 35% by using fly ash and limestone and by approximately 60% when using slag as cement clinker replacement. According to the environmental performance evaluation, other impact factors as well as primary energy consumption are also reduced significantly [8]. If the economic allocation to SCM is considered, the reduction of the GWP is only 1525% and 3545% using slag as a replacement. For other environmental categories (e.g., for acidification, photochemical oxidation) the calculated impact of the cement-reduced concretes based on the allocation to SCM is even higher.

To consider the performance of the concrete, the GWP was also related to the compressive strength. The results without allocation to SCM are shown in Fig. 4.10 for appropriate mixtures. The reduction of water and cement clinker leads to a relative GWP of approximately 3kg CO2-eq/(N/mm) notwithstanding the compressive strength. It can be further noticed that the reduction of environmental impact in comparison to conventional concrete was more remarkable for low- and medium-strength concrete.

The process of cement clinker manufacturing involves intimate mixing and subsequent heat treatment of a blend of calcareous rocks, such as chalk or limestone, and argillaceous rocks such as clay or shale. The calcium, silicon, alumina and iron oxides present in these materials undergo a series of chemical reactions that leads to the formation of a clinker material with main compounds tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A) and tetracalcium aluminoferrite (C4AF). After cooling and storage, the clinker is ground into a fine cement powder and gypsum is added, as a source of calcium sulphate, to improve the future setting behaviour of the cement.

Cement clinker production places a high demand on natural resources and large amounts of CO2 emissions are also generated from the energy needed to convert the calcium carbonate (CaCO3) in limestone into calcium oxide (CaO) (commonly known as lime). As such, this has sparked an interest in bringing in recycled and secondary materials such as blast furnace slag, cement kiln dust and fly ash as alternative sources of the required calcium (without the conversion process from CaCO3), silicon, alumina and iron oxides.

The chemical composition of MIBA suggests that it can also potentially serve as a valuable resource in cement clinker production. Based on the previous analysis of the materials characteristics in Chapter 4, it was established that MIBA had average SiO2, CaO, Al2O3 and Fe2O3 contents of 37.4%, 22.2%, 10.2% and 8.3%. The huge size of the cement manufacturing market is another reason this outlet is very appealing, as the use of MIBA at even very low percentages to some degree of regularity on the world scale could amount to large quantities overall.

The work carried out and the emerging results on the use of MIBA as part of the raw feed in cement clinker production are described in Table 5.6. Bottom ash has been used at relatively low contents ranging up to 15%, incorporated alongside other waste materials such as copper slag, iron slag and fly ash, along with the traditional limestone and sand constituents. It should be noted that the last two studies in Table 5.6 deal with the use of a combined municipal solid waste ash, including both bottom ash and fly ash fractions, but are still given in the table for the readers interest.

To ensure that the same main clinker phases are produced in the cement clinkers incorporating MIBA, the sum of SiO2, CaO, Al2O3 and Fe2O3 from all the constituents has to be tightly controlled. As such, when MIBA is incorporated into the raw feed, the contents of all the other constituents (limestone, sand and others) also generally have to be adjusted. This makes it more difficult to isolate and analyse the specific effects of MIBA, when comparing the trial mixes with the control mixes.

Based on the aforementioned mix design procedure, it was not surprising to find that chemical compositions of the cement clinkers produced using MIBA were very similar to those of the control mixes (Table 5.6). However, using the upper end of the tested MIBA replacement levels, the contents of some of the more minor oxides present in MIBA, such as P2O and SO3, began to build up to a level that started to suppress C3S formation. As a result, this led to reductions in the compressive strengths of the MIBA cement clinkers and increases in the setting times, though the susceptibility to sulphate expansion was lessened. The chloride content of MIBA was also identified as another key parameter to consider, as the presence of this element in the raw feed can eventually lead to corrosion of the equipment in the cement kiln in the long term, if not properly controlled. One solution to pre-empt this problem is to subject MIBA to a washing treatment before its use, as has been done by Pan etal. (2008).

There was one study (Shih etal., 2003) that simply used MIBA, after magnetic separation treatment, as a direct replacement of certain percentages of the raw feed (from 1% to 15%), though it did not seem to adjust the contents of the other constituents to preserve the same overall oxide composition. With MIBA contents up to 5%, compressive strengths comparable to those of the control were achieved; however, at the higher 10% and 15% replacement levels, large strength losses were incurred owing to the deficiencies in the CaO in the feed, arising from replacing the traditional limestone, clay and shale materials with MIBA. However, after using a conditioning treatment involving the addition of CaO to meet the hydraulic modulus and lime saturation factor quotas, satisfactory strengths were achieved with the clinkers produced using 10% and 15% MIBA.

Based on the overall data, it is expected that MIBA could be suitable for use in cement clinker raw feed at low contents, suggested at up to around 5%, without any compromising effects on the performance of the resultant products. Higher contents could also possibly be incorporated depending on the contents of certain minor constituents present in the ash such as P2O5, SO3, Cl and metallics. Magnetic separation treatment to reduce the metallic fraction and washing to lessen the chlorides content are potential options to further improve the prospects for MIBA use. However, because of the vast size of the cement manufacturing industry, which was reported to produce 250million tonnes of cement clinker in the European Union countries in 2015 (Cembureau, 2016), it is projected, as an example, based on the ash production figures, that close to 80% of the total MIBA generated in these countries would be expended with this use alone, if the material was adopted at this 5% content across the board in cement kilns.

The aforementioned erosion mechanism shows that calcium hydroxide and hydrated calcium aluminate in set cement is the internal cause leading to set cement failure; thus, the C3A content should first be controlled for corrosion prevention. The expansion ratio of set cement in CaSO4 solution is gradually increased with the increase of C3A content. The C4AF in the cement clinker can inhibit expansion reaction to a certain extent. The appropriate increase of C3AF content (total content of C3AF and 2 C3A in high-sulfateresistant cement up to 24%) can enhance sulfate erosion resistance).

The activated SiO2-rich material (such as silica flour or microsilica, volcanic ash, and slag) can react with Ca(OH)2 and generate a new hydrated calcium silicate C-S-HII when added to cement composition, thus increasing erosion resistance of set cement.

Enhancing set cement tightness for preventing corrosive media from invadinga.Microsilica is appropriately added to cement composition. Impermeable tight set cement structure is formed due to good size grading between microsilica and cement particles, thus preventing corrosive media from further erosion.b.A latex cement system is used. Set cement pores are filled with polymer films or gel particles so that set cement permeability is decreased, and erosion resistance is increased. A further satisfactory result can be achieved with the combined use of latex and microsilica or fly ash.

Microsilica is appropriately added to cement composition. Impermeable tight set cement structure is formed due to good size grading between microsilica and cement particles, thus preventing corrosive media from further erosion.

A latex cement system is used. Set cement pores are filled with polymer films or gel particles so that set cement permeability is decreased, and erosion resistance is increased. A further satisfactory result can be achieved with the combined use of latex and microsilica or fly ash.

Developing and adopting a hydrogen sulfide corrosion-resistant oil well cement can intrinsically enhance corrosion resistance and are of great significance to sour gas well cementing, cement plug building, sour gas well plugging and abandoning, and so on.

This type of cement slurry system includes channeling-resistant compressible cement slurry system (such as KQ series), latex cement slurry system (such as PCR168 and PCR169), slightly expanding latex cement slurry, and so on. Gas-channeling inhibiting measures include rationally using separable setting cement slurry, and acting annulus backpressure during curing.

Without gypsum, cement clinker can condense immediately by mixing with water and release heat. The major reason is that C3A in the clinker can dissolve in water quickly to generate a kind of calcium aluminate hydrate, a coagulant agent, which will destroy the normal use of cement, the retardation mechanism of gypsum is: when cement is hydrated, gypsum reacts with C3A quickly to generate calcium sulfoaluminate hydrate (ettringite) which deposits and forms a protection film on the cement particles to hinder the hydration of C3A and delay the setting time of cement.

If the content of gypsum is too little, the retardation affect will be unobvious. Too much gypsum will accelerate the setting of cement because gypsum can generate a coagulating agent itself. The appropriate amount of gypsum depends on the content of C3A in the cement and that of SO3 in gypsum, and it also related to the fineness of cement and the content of SO3 in clinker. The amount of gypsum should account for 3%~5% of the cements mass. If the content of gypsum exceeds the limit, it will lower the strength of cement and it can even lead to poor dimensional stability, which will cause the expanded destruction of cement paste. Thus, the national standard requires that the content of SO3 should not be more than 3.5%.

CEM I is ground cement clinker with a proportion of a gypsum and anhydrite mix or an alternative sulfate source (the amount limited by the SO3 content of the cement) and is allowed to contain up to 5% of a Minor Additional Constituent (MAC). A MAC is defined in EN 197 as, Specially selected, inorganic natural mineral materials, inorganic mineral materials derived from the clinker process or constituents as specified in 5.2 unless they are included as main constituents in the cement. Section 5.2 of the Standard defined the main constituents allowable as in Table 4.28. The MAC may therefore take many possible forms but is most commonly either ground limestone or a combination of this with cement kiln dust (CKD) from the final filter of the kiln or bypass dust both of which qualify as inorganic materials derived from the clinker process.

Within the definition of CEM I is white cement, manufactured from especially pure chalk or limestone, with china clay (low in iron) and white sand as sources of silica. Such an unreactive mix requires power-consuming sand grinding, and very high clinkering temperatures (~1600C).

In terms of properties, CEM I cement produces the best combination of early (2 days) and late (28 days) strengths with a typical setting time of up to 2 h. The colour of the product varies depending primarily on the quantity of iron present in the cement clinker.

In terms of workability and flowability, CEM I is susceptible to false set if the mill temperatures have been high and a high proportion of gypsum to anhydrite has been used in the mill. Water demand is dependent on the fineness and the sulfate type in the finished cement. In terms of durability, CEM I is susceptible to sulfate attack unless the C3A component is kept within the limits set out for sulfate resisting cement. In the United Kingdom it is considered susceptible to alkali aggregate reaction with reactive aggregates if the alkali content is sufficiently high to produce more than the quantity of alkali per cubic metre of concrete prescribed in Concrete Society report TR30,88 BRE IP1/0289 and BRE Digest 33090 which is 3.5 kg/m3 for most cements and 3.0 kg/m3 for high alkali cements (Na2O equivalent > 0.75%). It is generally susceptible to chloride ion penetration, with consequent potential for corrosion of reinforcement steel.

From examining the required minerals for cement clinkers it is obvious that the major raw material for the clinker product is a strong source of calcium (Ca). The main minerals readily available are limestone or chalk (calcium carbonate, CaCO3). Materials rich in calcium such as degraded coral have also been used in the past but such materials are now considered environmentally unacceptable.

The calcium carbonate is then blended with a second material containing a source of alumino-silicate such as clay or shale. Secondary raw materials (materials in the kiln raw feed other than limestone) depend on the purity of the limestone. Some of the second raw materials used are clay, shale, sand, iron ore, bauxite, fly ash and slag. Coal used to fire the rotary kiln should also be considered a secondary raw material as it contributes its ash to the mix.

A growing source of raw materials for cement manufacture comes from industrial by-products. The use of by-product materials to replace natural raw materials is a key element in reducing costs and achieving sustainable development.

As silicate cement clinker has higher content of tri-calcium silicate and tri-calcium aluminate, it has the features such as fast setting and hardening and higher strength, especially higher early strength, which makes it available for important structures requiring high-strength, pre-stressed and high early strength concrete projects, and for concrete projects in cold and freezing regions suffering frequent freezing and thawing cycles; due to its higher anti-carbonization performance, it is applicable to concrete projects requiring carbonization; as silicate cement has strong wear resistance, it is also applicable for cement projects in the construction of roads and airfield runways.

As silicate cement clinker has greater content of tri-calcium silicate and tri-calcium aluminate and its hydrated product contains a lot of calcium hydroxide and hydrated tri-calcium aluminate which are easy to catch corrosion, silicate cement is not applicable for the long term use in environments with varieties of corrosive media; with high hydrated heat and intense heat release, it is inapplicable to massive-concrete construction and inapplicable to concrete constructions with heat-resistance requirements due to its weak heat-resistance.

Measures should be taken in the transportation and storage to prevent silicate cement from water or moisture. When cement reacts with water, it will set and harden, and lose part of its cohesive force. The strength is weakened and even worse it may become inapplicable to construction.

Cement is stored based on difference types, strength levels as well as the date of production, and should be labeled. Bulk cement should be stored in different warehouses; the piling height of sacked cement should be no more than 10 sacks. Generally come-first-go-first rule should be followed in use. The strength of cement stored for a long time should be re-tested and it should be used based on its current strength. Cement stored in normal conditions tends to decrease in strength by 10%-20% after 3 months, 15%-30% after 6 months and 25%-40% after 1 year. Generally, cements validity storage period is 3 months.

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