A Contribution towards a More Sustainable Cement: Synergy of Mill Scales, Greek Wet Fly Ash, Conventional Raw Materials and Clinkering Temperature

Abstract

Portland cement is the most common type of cement and one of the most important ingredients in concrete. Concrete, on the other hand, is the most used building material worldwide just behind the water with an increasing usage trend in infrastructure for the upcoming years. During the production process of cement, massive CO2 emissions are released into the environment, while large amounts of raw materials and energy are consumed. In the present study, Portland type cement was prepared in laboratory-scale by Greek Wet Fly Ash and Mill Scales, as well as conventional raw materials such as limestone, shale and lava. The experiments were conducted at 1450 °C and 1340 °C. The fired compositions were characterized by XRD, Q–XRD, optical microscopy, SEM/EDS and the concrete specimens were tested for their compressive strength. The results indicated that formation of cement clinker at lower temperatures (1340 °C) is feasible with the combined use of natural raw materials and industrial byproducts following the standard production route of cement industries. Finally, the so-obtained cement presented compressive strength values comparable to the conventional ones fired at 1450 °C.

Physico-Chemical Study of the Possibility of Utilization of Coal Ash by Processing as Secondary Raw Materials to Obtain a Composite Cement Clinker

“…In accordance with the results of the XRD analysis of limestone, Figure 9 shows that the limestone sample consisted mainly of calcite (d = 3.89; 3.09; 2.30; 2.078; 1.93; 1.910; 1.626; 1.512A) with admixtures of quartz (d = 4.44; 3.40; 2.595; 2.30A). This result was confirmed by a similar study [64]. The results of the differential thermal analysis of the limestone are shown in Figure 10.…”

“…Thus, the results obtained during the research support the use of coal ash as a secondary raw mineral product for the manufacture of clinker, which complements the previously performed investigations of a number of researchers [63][64][65][66][67][68][69], and have all the necessary indications for industrial testing and implementation of this method to obtain cement clinker by ash disposal at cement plants.…”

“…It is known that the process of dusting due to the influence of wind can lead to contamination of the soil, surface, and groundwater with toxic compounds. In particular, investigators found that ash components were detected in the superficial stratum of soil at a distance of several kilometers to several hundred kilometers from ash storage facilities, depending on the granulometric composition [64]. Additionally, the concentration of ash elements turned out to be increased in growing grasses and harvested forage studied near ash dumps and storage facilities.…”

New Types and Dosages for the Manufacture of Low-Energy Cements from Raw Materials and Industrial Waste under the Principles of the Circular Economy and Low-Carbon Economy

“…The total CO 2 emissions produced by the cement industry account for approximately 8% of global CO 2 emissions [ 7 ]. These CO 2 emissions are released in two main ways: 60% of emissions is due to the thermal decomposition of CaCO 3 into CaO and CO 2 , while 40% is due to the consumption of thermal energy required for the production process [ 8 , 9 , 10 , 11 ]. Depending on the raw materials and the production process, 60 to 130 kg of fuel oil, or its equivalent, is required for each tonne of cement produced, as well as about 110 kWh of electricity [ 12 ].…”