Physico-chemical, morphological and thermal analysis for the combined pozzolanic activities of minerals additives

Ashraf, Muhammad; Khan, Akhtar Naeem; Ali, Qasair; Mirza, Jahangir; Goyal, Ajay; Anwar, Ahmed M.

doi:10.1016/j.conbuildmat.2008.12.008

Cited by 67 publications

(32 citation statements)

References 5 publications

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“…The SEM image of the fracture surface of NS10 after 7 days illustrates a very condensed mortar structure and a good dispersion of NS clusters throughout the entire surface of hydrated cement products. The CH grains of NS10 are less visible than those of OPC, SF10 and FA10 [49,52,[59][60][61] . The SEM images of the fracture surfaces of OPC, NS10, SF10 and FA10 after 28 days of curing are given in Figure 8.…”

Section: Characterization Of the Mortar Specimensmentioning

confidence: 90%

“…The dehydration of water molecules in hydrates such as C-S-H and ettringite took place within the range from room temperature to 200 °C [29,[49][50][51][52][53][54][55] . The second step of thermal degradation occurred between 325-550 °C, and the corresponding mass loss was associated with the dehydroxylation of free CH produced during curing 29,[49][50][51][52][53][54][55] . When the mortar specimens were cured, calcium hydroxide forming in them gradually combined with carbon dioxide of the surrounding air to form calcium carbonate 46 .…”

Section: Characterization Of the Mortar Specimensmentioning

confidence: 99%

“…When the mortar specimens were cured, calcium hydroxide forming in them gradually combined with carbon dioxide of the surrounding air to form calcium carbonate 46 . The third decomposition step happened between 550-740 °C was due to decomposition of calcium carbonate and escape of CO 2 from the cement matrix 46,[49][50][51][52][53][54][55][56][57] . Table 3 presents the mass percent of free CH, and the mass percent of CaCO 3 which were calculated by multiplying the mass loss percent of the second and third steps of TG curves, given in Figure 5a and 5b, with the stoichiometric molar mass ratios of Ca(OH) 2 / H 2 O and CaCO 3 /CO 2 , respectively, as mentioned in the literature 46,56,57 .…”

Section: Characterization Of the Mortar Specimensmentioning

confidence: 99%

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Comparative study of the characteristics of nano silica - , silica fume - and fly ash - incorporated cement mortars

2014

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The structural characteristics of cement mortars, impregnated with nano silica (NS), silica fume (SF) and fly ash (FA), were comparatively studied using Fourier transform infrared spectrometer (FTIR), thermogravimeter-differential thermogravimeter (TG-DTG) and scanning electron microscope (SEM). The mechanical strengths of the specimens were determined at early (7th day) and standard (28th day) curing ages. The compressive strengths and flexural strengths developed in the mortar specimens containing NS particles were found considerably higher than those of the corresponding specimens of SF and FA over and above the control at both ages. FTIR, TG-DTG and SEM analyses results were consistent with the remarkable increase in the mechanical strength of the mortars with NS. These increases in the strengths of the mortars with NS are attributable to the nano sized particles and extensive surface area of NS. The nano sized particles, as nucleating agents, promoted the hydration of C 3 S and C 2 S and the formation of C-S-H phase. Plenty of active sites on the surface of NS particles induced their pozzolanic reactivity and the extent of bond formation between NS particles and free CH.

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Section: Characterization Of the Mortar Specimensmentioning

confidence: 90%

Section: Characterization Of the Mortar Specimensmentioning

confidence: 99%

Section: Characterization Of the Mortar Specimensmentioning

confidence: 99%

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Comparative study of the characteristics of nano silica - , silica fume - and fly ash - incorporated cement mortars

2014

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“…This result reveals that no pozzolanic reaction between CH and quartz silica took place under stand- Journal of Civil Engineering and Management, 2014, 20(1): 32-37 ard curing and DS acted as a filler material. Ashraf et al (2009) found similar peaks of CH at similar positions in the cement paste mixture cured under standard curing. Figure 7 shows the XRD pattern of the same mixture but cured under autoclave condition.…”

Section: Morphological Investigationmentioning

confidence: 52%

Use of Fine Ground Dune Sand as a Supplementary Cementing Material

Alhozaimy

Alawad

Jaafar

et al. 2014

Journal of Civil Engineering and Management

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Abstract. The process of Portland cement production is associated with high consumption of energy and resources. Therefore, there is a need to replace the Portland cement with environmental friendly materials. This study was conducted to determine the feasibility of using ground dune sand as cement replacement materials under different curing conditions. Portland cement was replaced by ground dune sand at five levels of replacement (0-40% by weight). The compressive strength of mortar under standard and autoclave curing conditions and the influence of different autoclave temperatures and durations were investigated. The microstructure of selected mixtures was analyzed by XRD and SEM. Results showed that the compressive strength under the standard curing decreased as the level of replacement increased. However, under autoclave curing compressive strength increased as the content of ground dune sand increased. XRD and SEM revealed the absence of calcium hydroxide and the formation of secondary calcium silicate hydrate. The improvement of compressive strength and the absence of calcium hydroxide under autoclave curing indicated that the pozzolanic reaction between silica of dune sand and calcium hydroxide occurred.Keywords: dune sand, autoclave curing, pozzolanic materials, compressive strength, XRD, SEM.

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“…Thermal analysis has been defined by the International Confederation of thermal analysis (ICTA) as a general term, which covers a variety of techniques that record the physicochemical changes occurring in a substance as a function of temperature [20] . Specimens at the ages of 28 and 56 days were prepared to evaluate the hydration activity by TGA.…”

Section: Thermal Gravimetric Analysis (Tga)mentioning

confidence: 99%

Effects of sugar cane bagasse ash as a cement replacement on properties of mortars

Chi

2012

Science and Engineering of Composite Materials

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Sugar cane bagasse ash (SCBA), a by-product of sugar and alcohol production, is one of the potential pozzolanic material that can be blended with Portland cement. In this study, SCBA with particle sizes < 45 μ m was used to replace type I ordinary Portland cement with various dosages (10 % , 20 % , and 30 % ) by weight of binder. The water/cementitious material (w/cm) and sand/binder ratios were kept at constants of 0.55 and 2.75, respectively. Composites were mixed, and effects of SCBA on properties were investigated by conducting flow test, water absorption test, initial surface absorption test, drying shrinkage test, compressive strength test, rapid chloride penetration test (RCPT), thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). Experimental results show that the flow spread of fresh mortars would decrease with an increase of SCBA replacement. The specimens with 10 % SCBA have the superior performance on compressive strength, drying shrinkage, water absorption, initial surface absorption, and chloride ion penetration, TGA, and SEM at the age of 56 days. It indicates that 10 % cement replacement of SCBA may be considered as the optimum limit.

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Physico-chemical, morphological and thermal analysis for the combined pozzolanic activities of minerals additives

Cited by 67 publications

References 5 publications

Comparative study of the characteristics of nano silica - , silica fume - and fly ash - incorporated cement mortars

Comparative study of the characteristics of nano silica - , silica fume - and fly ash - incorporated cement mortars

Use of Fine Ground Dune Sand as a Supplementary Cementing Material

Effects of sugar cane bagasse ash as a cement replacement on properties of mortars

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