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A comparative study of mechanical properties of RCC trial mix using two different cementitious materials (fly ash and natural pozzolan)
Published in L. Berga, J.M. Buil, C. Jofré, S. Chonggang, Roller Compacted Concrete Dams, 2018
A.I. Husein Malkawi, H. Shaia, S. Mutasher, M. Aridah
The selection of pozzolanic material suitable for RCC should be based on its conformance with applicable standards (ASTM C 618). Two types of pozzolanic materials were used in the mixtures proposed, these are: Jordanian natural pozzolan and fly ash class F material.
Constituent Materials
Published in Ganesh Babu Kodeboyina, High Performance Self-Consolidating Cementitious Composites, 2018
In general, these mineral admixtures are called as pozzolans. According to ASTM C 618 (1994), a pozzolan is defined as “a siliceous or siliceous and aluminous material which, in itself, possesses little or no cementitious value but which will, in its finely divided form and in the presence of moisture, react chemically with calcium hydroxide at ordinary temperature to form compounds possessing cementitious properties.” Pozzolans can be broadly divided into two major types, namely natural pozzolans and artificial pozzolans. Natural pozzolans include volcanic ash (glass), volcanic tuft, calcined clay or shale, and raw or calcined opaline silica. Calcined as well as uncalcined clays like kaolin, (metakaolin), zeolite, and so on are also a part of these. The artificial pozzolans include fly ash, silica fume, GGBS, and RHA. The use of natural pozzolans as binders in combination with lime and other additives was known for such a long time that in fact we do not have any information on the excellent cementitious recipes that were used in several of the monuments of yesteryears that have defied the effects of the environment for centuries if not millennia. In recent years, the use of artificial pozzolans as supplementary or complimentary cementitious materials in concrete is increasing because of the fact that their presence in concrete improves the properties both in the green and hardened states. Also the use of these materials represents eco-friendliness while being economical.
Soil Pollution and Its Control
Published in Danny D. Reible, Fundamentals of Environmental Engineering, 2017
Often a bulking agent is added to the mixture to reduce the volume of cementing agent needed to perform a particular solidification. This reduces costs and in some cases a bulking agent exhibits pozzolanic activity. A pozzolan is defined as a material that exhibits cementing ability when mixed with other materials. A pozzolan will encourage solidification as well. The cementing agents that are appropriate for a solidification process and the effectiveness of the solidified product must be evaluated by experimentation with the actual contaminated materials requiring solidification.
Surface application of multifunctional compound to prevent and control combined chloride and carbonation corrosion in concrete
Published in European Journal of Environmental and Civil Engineering, 2023
Ashish Kumar Tiwari, Shweta Goyal, Vijay Luxami
The use of pozzolanic cement in the construction industry is increasing from the past few years due to its sustainability and structural benefits. The incorporation of fly ash modifies the mechanical properties, permeation characteristics, and chemical composition of concrete. In corrosive environment, addition of fly ash improves the chloride diffusion coefficient, electrical resistivity and chloride binding capacity of concrete (Andrade & Buják, 2013; Angst, 2018; Florea & Brouwers, 2014; Hu & Poon, 2022; Jung et al., 2018; Thomas et al., 2012), but the rate of carbonation becomes 2–4 times higher in PPC concrete than OPC based concrete (Justnes et al., 2020; Lye et al., 2015, 2016; Morandeau et al., 2015; Stefanoni et al., 2018; Younsi et al., 2013). Thus, making the embedded rebar more vulnerable to corrosion (Aguirre-Guerrero et al., 2016; Hren et al., 2021). The severity of this problem increases when PPC concrete is exposed to combined environment as it decreases the steel resistivity (Aguirre-Guerrero et al., 2016) and increase the available chloride concentration (Montemor et al., 2002). The rate of corrosion is bound to increase in PPC based concrete after being subjected to combined environmental condition irrespective to their sequence of exposure (Hren et al., 2021; Ye et al., 2016).
Role of recycling fine materials as filler for improving performance of concrete - a review
Published in Australian Journal of Civil Engineering, 2019
Paul O. Awoyera, Adeyemi Adesina, Ravindran Gobinath
Based on the criteria established by the American Society for Testing Materials (ASTM C618 2008), a pozzolanic material must have the summation of its silica, alumina and ferric oxides greater than or equal to 50%. In Table 1, nano silica, silica fume (SF), metakaolin (MK), granite dust, ground clay bricks (GCB), and fly ash (FA) that fell into the category of pozzolanic materials. So, apart from the ability of the materials to fill pores in a cement based matrix, they can also trigger a pozzolanic reaction in concrete which will improve its strength. Studies (Laukaitis, Žurauskas, and Kerien≐ 2005; Hanzic and Ho 2017; Joudi-Bahri et al. 2012) have shown that fillers with larger specific surface tend to be more functional than those having small surface. A cement matrix having fillers of larger specific surface are more compacted with no major pores than the matrix having fillers with smaller specific surface. The hydration modulus (HM) and the basicity index (BI) of the fillers listed in Table 1 were determined by following (Leong et al. 2016)’s method in equations 1 and 2. The HM and BI of the materials are presented in Table 3.
Compressive strength and durability properties of pozzolan obtained from co-fired clay and rice husk
Published in Cogent Engineering, 2020
Mark Bediako, Albert A. Adjaottor, Simon K.Y Gawu, Eric Opoku Amankwah
Table 5 presents the estimated embodied carbon values per cubic meter of the control and the blended cement mortars. The embodied carbon (EC) content of the control mortar was approximately 516.00 kgCO2eq whereas the blended mortar (30RH1) was also approximately 369.23 kgCO2eq. The incorporation of 30% content of pozzolan reduced the greenhouse gases by approximately 29%. In essence, the inclusion of the pozzolan could be a means of decarbonizing mortar which could be very beneficial to the environment since it is already known that greenhouse gases are the major cause of global warming.