The utilization of two kinds of iron slag in the production of pozzolanic cement is introduced. A... more The utilization of two kinds of iron slag in the production of pozzolanic cement is introduced. A series was created with a fixed percentage of OPC (30%) and varying amounts of imported granulated blast-furnace slag (IGBFS) and air-cooled slag (ACS) at which imported IGBFS was substituted by ACS with the mass ratios of 10, 20, and 30%. Physico-mechanical properties and hydration parameters of the hardened pastes were examined at different time intervals. Furthermore, the aggressive attack of seawater on chosen specimens was studied for up to one year of immersion. The hardened composite cement pastes were tested in terms of weight loss, compressive strength, bulk density, total porosity, and free lime at different thermally treated temperatures starting at 105 °C and ending at 800 °C for 2 h of a socking period to investigate its thermal characteristics. XRD, IR, and DTA/TGA techniques were used to examine some chosen samples. The results revealed that the incorporation of ACS reduc...
h i g h l i g h t s Increase of CKPD%, W n content increases upto 50mass%. Wn content of SSFCKD20... more h i g h l i g h t s Increase of CKPD%, W n content increases upto 50mass%. Wn content of SSFCKD20 increases than with specimen without-MS (SCKD20 mix). Replacement of GBFS with 20 and/or 30 mass% CKPD uncommonly increases the CS. The precipitation of geopolymer reduces the attainable of SO 4 2anion which give rise to the deterioration. GBFS-CKPD-MS geopolymers are not easily breaking in by attacker Clanions. 20mass% CKPD is the suitable mix design composition, which gives high values of CS, BD and Wn contents.
Abstract This work focuses on the individual impact of nano- and ultrafine micro magnesia (N–MgO ... more Abstract This work focuses on the individual impact of nano- and ultrafine micro magnesia (N–MgO and UM-MgO, respectively) on the early performance of high volume fly ash (FA)-blended-cement mortar (CM). N–MgO and UM-MgO were synthesized using a thermal treatment of lightweight hydromagnesite at 550 and 1100 °C, respectively. Different contents of MgOs (1, 3, and 5 wt% by weight of powder) were individually added to FA-blended-CM. The results revealed that the N–MgO exhibits higher efficiency in the acceleration of early PC-FA system hydration compared to UM-MgO at all addition levels. The addition of 1, 3, and 5 wt% N–MgO to FA-blended-CM has resulted in the enhancement of 3-days compressive strength value by ~26, 94, and 103%, respectively; whereas the UM-MgO shows a modest effect. The small particle size, low crystallinity, and high hydration reactivity are the dominant features of N–MgO, which reflect on the enhancement of FA-pozzolanic activity accompanied by the acceleration of strength-giving-phases formation at early ages of hydration. To achieve the sustainability, we have recommend the use of N–MgO, as it contributes to cost minimization, energy saving, and the mitigation of carbon footprint.
The present work aims to investigate the influence of clay nanoparticles (CNP) on the mechanical,... more The present work aims to investigate the influence of clay nanoparticles (CNP) on the mechanical, physical and microstructure cement pastes composites. The cement paste composites were formulated by adding 20-60 mass % fly ash (FA), fine blast furnace slag (FBFS) and/or 6 mass % clay nanoparticles. The physico-chemical properties of the cement paste composites (CPC) were improved by the substitution of 6 % CNP in instead of OPC (ordinary Portland cement) in the consistence of the superplasticiser (SP). The physico-mechanical properties and hydration characteristics were investigated by the determination of the setting times (STs), the consistency (W/C, %), the free lime (FL), the combined water (Wn), the gel/ space ratio (X), the total porosity (TP), the compressive strength (CS) and the bulk density (BD). The compressive strength values of the cement-CNP hybrid were higher than those of the cement paste composites without CNP. The STs of CPC-pastes containing CNP were accelerated. The CNP showed synergetic effect with the FA and FBFS to enhance the performance of pozzolanic reaction to form supplementary CSH, CAH and CASH, these phases are responsible for bridging, producing a rigid closed compact structure; hence the compressive strength, gel/space ratio, bulk density and chemically combined water increased, whereas the porosity decreased.
h i g h l i g h t s Herein, characteristics of corrosion events in fixed FA-CCP-matrix have been ... more h i g h l i g h t s Herein, characteristics of corrosion events in fixed FA-CCP-matrix have been explored. Rebar immersed in pure cement extract showed higher corrosion resistance. The results confirmed that spinach extract is a typical eco-friendly corrosion inhibitor. At first 6 h, the increased of passive-film thickness followed by decrease corrosion rate. Significant increase in CS and X was obtained up to 90 days in the 10% FA-CCP mix. With prolonged hydration, dense crystalline-CSH products were formed in CCP-matrix.
The beneficial use of alkali-activation/sintering process in the fabrication of open-celled cellu... more The beneficial use of alkali-activation/sintering process in the fabrication of open-celled cellular materials and lead solidification/stabilization (S/S) is the biggest challenge of the present work. Waste glass (WG), red-clay brick waste (RCBW), and lead-bearing-sludge (LBS) were used as silicate-rich-wastes in the foaming process. Porous materials with porosity ranging from 50 to 89% accompanied by low bulk density (0.73e0.27 g/cm 3), low thermal conductivity (0.3e0.14 W/mK), and high compressive strength (3.4e14.2 MPa) were obtained when alkali activated WG, WG-RCBW, and WG-LBS fired at different elevated temperatures (700-900 C). The results revealed that comparing with WG-foamed materials, the heating of WG activated by 4M-NaOH at 800 C has resulted in the formation of foamed-glass with higher porosity, lower thermal conductivity, and lower bulk density. The use of RCBW, as a partial substituent of WG, represents the potential impact on the enhancement of foamed-material homogeneity. The dominant feature of the foamed-WG-LBS set is the formation of a porous structure with the biggest pore size and the lowest thermal conductivity. The leaching test proved that the applied alkali activation/sintering process has high efficacy on the Pb-stabilization.
A cleaner production of one-part alkali activated cement (AAC) was implemented by mixing chemical... more A cleaner production of one-part alkali activated cement (AAC) was implemented by mixing chemically treated concrete waste (CTC) with slag. The treatment process was conducted by the addition of NaOH to concrete waste (CoW) at NaOH to CoW weight ratios of 0.2, 0.1, and 0.05 (namely, CTC-1. CTC-2, and CTC-3, respectively), followed by mixing with water and drying. The solidified material was ground then dry-mixed with slag to create one-part alkali AAC powder with fixed particle size. The amount of CTC was varied to achieve constant Na 2 O content (2 wt. %) in all mixtures. The results indicated that the prepared one-part AACs can react with water to yield hardened materials with acceptable compressive strength. Comparing with CTC-1 and CTC-3, the CTC-2 was found to have a dominant impact on the activation of slag
h i g h l i g h t s Urea and urease enzyme were used for the removal of Ca 2+ and Mg 2+ from grou... more h i g h l i g h t s Urea and urease enzyme were used for the removal of Ca 2+ and Mg 2+ from ground water. Nano-magnesium calcite (NMC) waste is a byproduct of ground water treatment. NMC was mixed with cement mortar to enhance its engineering properties and durability. NMC showed a positive effect on the performance of cement mortar in sulfate medium.
The hybrid-NS/NC-nano-particles enhance the hydration-kinetic of composite cement. NS:NC hybrid s... more The hybrid-NS/NC-nano-particles enhance the hydration-kinetic of composite cement. NS:NC hybrid system has a remarkable impact on compressive strength. Increase in gel/space ratio reduces porosity yielding high compaction of hardened cement matrix. Microstructure of hybrid-nano-particles densified the matrix with the absence of portlandite. 3%NS:3%NC hybrid-nano-particles is the optimum composite which gave the highest performance.
h i g h l i g h t s Composite cement paste containing 25-50 mass% GBFS gives higher compressive s... more h i g h l i g h t s Composite cement paste containing 25-50 mass% GBFS gives higher compressive strength. The compressive strength increases with thermally treated OPC-NS cement pastes up to 400°C. 25-50% GBFS in the presence of silica-nanoparticles improve the fire resistance up to 650°C. SEM shows a massive nanocrystalline C-S-H deposits without micro-cracks at 650°C. The total porosity of M25S and M50S mixes has lower values of total porosity up to 950°C.
Indian Journal of Engineering and Materials Sciences
Pozzolanic activity of tired clay bricks (Homra) was studied using hydrated lime as an activato r... more Pozzolanic activity of tired clay bricks (Homra) was studied using hydrated lime as an activato r. Three diffe rent mixes of Homra/hyd rated lime were hydrated in a paste fo rm for vari o us time intervals up to 90 days. The hydrati o n characteristi cs of the hydrated pastes were followed by thermal analysis (TGA and DTA) at various times of hydrati on. The resul ts obtained from thermal analysis of the formed hydrates were rel ated as mu ch as poss ibl e to th e pozzo lamc acti vit y as determined by chemical analysis. The results indi cated that Homra, as a waste product o f clay bri cks industry , can be used in the production of low cost filled pozzolani c cements. Clays and shales are not able to produce appreciable hardening with lime unless the crystal stuctures of the clay mineral s present are destroyed by heat treatment in an industrial furnace to enhance their pozzolanic property. The pozzolanic activity of the product is mainly due to the formation of an amorphous or disordered aluminosilicate sturcture as a result of calcination process. Clay bricks made from 70% natural clays and 30% sand, then mixed with each other by water to give a suitable workability, compressed, dried and fired between 900-1 100°e. Wi Id et al. 1.2 showed that ground calcined clay bricks at 600-1 OOO°C exhibit a significant pozzolanic activity equivalent to that of fly ash.
The utilization of two kinds of iron slag in the production of pozzolanic cement is introduced. A... more The utilization of two kinds of iron slag in the production of pozzolanic cement is introduced. A series was created with a fixed percentage of OPC (30%) and varying amounts of imported granulated blast-furnace slag (IGBFS) and air-cooled slag (ACS) at which imported IGBFS was substituted by ACS with the mass ratios of 10, 20, and 30%. Physico-mechanical properties and hydration parameters of the hardened pastes were examined at different time intervals. Furthermore, the aggressive attack of seawater on chosen specimens was studied for up to one year of immersion. The hardened composite cement pastes were tested in terms of weight loss, compressive strength, bulk density, total porosity, and free lime at different thermally treated temperatures starting at 105 °C and ending at 800 °C for 2 h of a socking period to investigate its thermal characteristics. XRD, IR, and DTA/TGA techniques were used to examine some chosen samples. The results revealed that the incorporation of ACS reduc...
h i g h l i g h t s Increase of CKPD%, W n content increases upto 50mass%. Wn content of SSFCKD20... more h i g h l i g h t s Increase of CKPD%, W n content increases upto 50mass%. Wn content of SSFCKD20 increases than with specimen without-MS (SCKD20 mix). Replacement of GBFS with 20 and/or 30 mass% CKPD uncommonly increases the CS. The precipitation of geopolymer reduces the attainable of SO 4 2anion which give rise to the deterioration. GBFS-CKPD-MS geopolymers are not easily breaking in by attacker Clanions. 20mass% CKPD is the suitable mix design composition, which gives high values of CS, BD and Wn contents.
Abstract This work focuses on the individual impact of nano- and ultrafine micro magnesia (N–MgO ... more Abstract This work focuses on the individual impact of nano- and ultrafine micro magnesia (N–MgO and UM-MgO, respectively) on the early performance of high volume fly ash (FA)-blended-cement mortar (CM). N–MgO and UM-MgO were synthesized using a thermal treatment of lightweight hydromagnesite at 550 and 1100 °C, respectively. Different contents of MgOs (1, 3, and 5 wt% by weight of powder) were individually added to FA-blended-CM. The results revealed that the N–MgO exhibits higher efficiency in the acceleration of early PC-FA system hydration compared to UM-MgO at all addition levels. The addition of 1, 3, and 5 wt% N–MgO to FA-blended-CM has resulted in the enhancement of 3-days compressive strength value by ~26, 94, and 103%, respectively; whereas the UM-MgO shows a modest effect. The small particle size, low crystallinity, and high hydration reactivity are the dominant features of N–MgO, which reflect on the enhancement of FA-pozzolanic activity accompanied by the acceleration of strength-giving-phases formation at early ages of hydration. To achieve the sustainability, we have recommend the use of N–MgO, as it contributes to cost minimization, energy saving, and the mitigation of carbon footprint.
The present work aims to investigate the influence of clay nanoparticles (CNP) on the mechanical,... more The present work aims to investigate the influence of clay nanoparticles (CNP) on the mechanical, physical and microstructure cement pastes composites. The cement paste composites were formulated by adding 20-60 mass % fly ash (FA), fine blast furnace slag (FBFS) and/or 6 mass % clay nanoparticles. The physico-chemical properties of the cement paste composites (CPC) were improved by the substitution of 6 % CNP in instead of OPC (ordinary Portland cement) in the consistence of the superplasticiser (SP). The physico-mechanical properties and hydration characteristics were investigated by the determination of the setting times (STs), the consistency (W/C, %), the free lime (FL), the combined water (Wn), the gel/ space ratio (X), the total porosity (TP), the compressive strength (CS) and the bulk density (BD). The compressive strength values of the cement-CNP hybrid were higher than those of the cement paste composites without CNP. The STs of CPC-pastes containing CNP were accelerated. The CNP showed synergetic effect with the FA and FBFS to enhance the performance of pozzolanic reaction to form supplementary CSH, CAH and CASH, these phases are responsible for bridging, producing a rigid closed compact structure; hence the compressive strength, gel/space ratio, bulk density and chemically combined water increased, whereas the porosity decreased.
h i g h l i g h t s Herein, characteristics of corrosion events in fixed FA-CCP-matrix have been ... more h i g h l i g h t s Herein, characteristics of corrosion events in fixed FA-CCP-matrix have been explored. Rebar immersed in pure cement extract showed higher corrosion resistance. The results confirmed that spinach extract is a typical eco-friendly corrosion inhibitor. At first 6 h, the increased of passive-film thickness followed by decrease corrosion rate. Significant increase in CS and X was obtained up to 90 days in the 10% FA-CCP mix. With prolonged hydration, dense crystalline-CSH products were formed in CCP-matrix.
The beneficial use of alkali-activation/sintering process in the fabrication of open-celled cellu... more The beneficial use of alkali-activation/sintering process in the fabrication of open-celled cellular materials and lead solidification/stabilization (S/S) is the biggest challenge of the present work. Waste glass (WG), red-clay brick waste (RCBW), and lead-bearing-sludge (LBS) were used as silicate-rich-wastes in the foaming process. Porous materials with porosity ranging from 50 to 89% accompanied by low bulk density (0.73e0.27 g/cm 3), low thermal conductivity (0.3e0.14 W/mK), and high compressive strength (3.4e14.2 MPa) were obtained when alkali activated WG, WG-RCBW, and WG-LBS fired at different elevated temperatures (700-900 C). The results revealed that comparing with WG-foamed materials, the heating of WG activated by 4M-NaOH at 800 C has resulted in the formation of foamed-glass with higher porosity, lower thermal conductivity, and lower bulk density. The use of RCBW, as a partial substituent of WG, represents the potential impact on the enhancement of foamed-material homogeneity. The dominant feature of the foamed-WG-LBS set is the formation of a porous structure with the biggest pore size and the lowest thermal conductivity. The leaching test proved that the applied alkali activation/sintering process has high efficacy on the Pb-stabilization.
A cleaner production of one-part alkali activated cement (AAC) was implemented by mixing chemical... more A cleaner production of one-part alkali activated cement (AAC) was implemented by mixing chemically treated concrete waste (CTC) with slag. The treatment process was conducted by the addition of NaOH to concrete waste (CoW) at NaOH to CoW weight ratios of 0.2, 0.1, and 0.05 (namely, CTC-1. CTC-2, and CTC-3, respectively), followed by mixing with water and drying. The solidified material was ground then dry-mixed with slag to create one-part alkali AAC powder with fixed particle size. The amount of CTC was varied to achieve constant Na 2 O content (2 wt. %) in all mixtures. The results indicated that the prepared one-part AACs can react with water to yield hardened materials with acceptable compressive strength. Comparing with CTC-1 and CTC-3, the CTC-2 was found to have a dominant impact on the activation of slag
h i g h l i g h t s Urea and urease enzyme were used for the removal of Ca 2+ and Mg 2+ from grou... more h i g h l i g h t s Urea and urease enzyme were used for the removal of Ca 2+ and Mg 2+ from ground water. Nano-magnesium calcite (NMC) waste is a byproduct of ground water treatment. NMC was mixed with cement mortar to enhance its engineering properties and durability. NMC showed a positive effect on the performance of cement mortar in sulfate medium.
The hybrid-NS/NC-nano-particles enhance the hydration-kinetic of composite cement. NS:NC hybrid s... more The hybrid-NS/NC-nano-particles enhance the hydration-kinetic of composite cement. NS:NC hybrid system has a remarkable impact on compressive strength. Increase in gel/space ratio reduces porosity yielding high compaction of hardened cement matrix. Microstructure of hybrid-nano-particles densified the matrix with the absence of portlandite. 3%NS:3%NC hybrid-nano-particles is the optimum composite which gave the highest performance.
h i g h l i g h t s Composite cement paste containing 25-50 mass% GBFS gives higher compressive s... more h i g h l i g h t s Composite cement paste containing 25-50 mass% GBFS gives higher compressive strength. The compressive strength increases with thermally treated OPC-NS cement pastes up to 400°C. 25-50% GBFS in the presence of silica-nanoparticles improve the fire resistance up to 650°C. SEM shows a massive nanocrystalline C-S-H deposits without micro-cracks at 650°C. The total porosity of M25S and M50S mixes has lower values of total porosity up to 950°C.
Indian Journal of Engineering and Materials Sciences
Pozzolanic activity of tired clay bricks (Homra) was studied using hydrated lime as an activato r... more Pozzolanic activity of tired clay bricks (Homra) was studied using hydrated lime as an activato r. Three diffe rent mixes of Homra/hyd rated lime were hydrated in a paste fo rm for vari o us time intervals up to 90 days. The hydrati o n characteristi cs of the hydrated pastes were followed by thermal analysis (TGA and DTA) at various times of hydrati on. The resul ts obtained from thermal analysis of the formed hydrates were rel ated as mu ch as poss ibl e to th e pozzo lamc acti vit y as determined by chemical analysis. The results indi cated that Homra, as a waste product o f clay bri cks industry , can be used in the production of low cost filled pozzolani c cements. Clays and shales are not able to produce appreciable hardening with lime unless the crystal stuctures of the clay mineral s present are destroyed by heat treatment in an industrial furnace to enhance their pozzolanic property. The pozzolanic activity of the product is mainly due to the formation of an amorphous or disordered aluminosilicate sturcture as a result of calcination process. Clay bricks made from 70% natural clays and 30% sand, then mixed with each other by water to give a suitable workability, compressed, dried and fired between 900-1 100°e. Wi Id et al. 1.2 showed that ground calcined clay bricks at 600-1 OOO°C exhibit a significant pozzolanic activity equivalent to that of fly ash.
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