18 research outputs found
Utilization of fly ash in concrete
Fly ash, a by-product of coal burning power plants, is produced in large quantities each year. It is commonly known that fly ash possesses pozzolanic behavior which can enhance the properties of concrete. Due to a lack of proper understanding on the formation of fly ash and its performance in concrete, the question of quality assurance has frequently been a major concern of engineers using fly ash in their construction projects. As a result, much fly ash is disposed of as waste material in landfills. Recent environmental concerns and a shortage of landfill space have rapidly escalated the disposal cost of fly ash and therefore, the need to seek better utilization of fly ash in concrete is then critical.
The objective of this investigation is to study the effect of fly ash on the strength development of mortar and concrete and to develop models to predict its performance in these cementitious composites. The fly ash used was carefully selected and defined as to its origination, formation, physical and chemical compositions, and the storage condition. The original fly ash was fractionated into six particle size ranges, each having a relatively uniform particle size, with maximum sizes ranging from 5 to 300 microns. The rate of strength gain of these fly ash concretes was monitored from 1 to 180 days. The compressive strength for each series was correlated to the conditions of fly ash used to determine the major parameters affecting the performance of fly ash in mortar and concrete.
The results from this study show that the particle size of fly ash has a significant effect on the strength development of concrete. The combustion condition in the boiler has some influence on the performance of fly ash in cementitious composites. Of particular importance is the finding that certain portions of fly ash when used as cement replacement can improve the strength of concrete beyond normal cement as early as 14 days. A correlation to predict the compressive strength of fly ash concrete is proposed and provides good agreement with experimental results both from this study as well as from other investigators
Influence of Palm Oil Fuel Ash and W/B Ratios on Compressive Strength, Water Permeability, and Chloride Resistance of Concrete
This research studies the effects of W/B ratios and palm oil fuel ash (POFA) on compressive strength, water permeability, and chloride resistance of concrete. POFA was ground until the particles retained on sieve number 325 were less than 5% by weight. POFA was used to partially replace OPC at rates of 15, 25, and 35% by weight of binder. The water to binder (W/B) ratios of concrete were 0.40 and 0.50. The compressive strength, water permeability, and chloride resistance of concrete were investigated up to 90 days. The results showed that POFA concrete with W/B ratio of 0.40 had the compressive strengths ranging from 45.8 to 55.9âMPa or 82â94% of OPC concrete at 90 days, while POFA concrete with W/B ratio of 0.50 had the compressive strengths of 33.9â41.9âMPa or 81â94% of OPC concrete. Furthermore, the compressive strength of concrete incorporation of ground POFA at 15% was the same as OPC concrete. The water permeability coefficient and the chloride ion penetration of POFA concrete were lower than OPC concrete when both types of concrete had the same compressive strengths. The findings also indicated that water permeability and chloride ion penetration of POFA concrete were significantly reduced compared to OPC concrete
Properties of concrete made from industrial wastes containing calcium carbide residue palm oil fuel ash rice husk-bark ash and recycled aggregates
āļāļāļāļąāļāļĒāđāļāļāļāļāļāļĢāļĩāļāļāļĩāđāļāļđāļāļāļģāļāļķāđāļ āđāļāļĒāđāļāđāļ§āļąāļŠāļāļļāđāļŦāļĨāļ·āļāļāļīāđāļāļāļļāļāļŠāļēāļŦāļāļĢāļĢāļĄāļāļąāđāļāđāļāļ§āļąāļŠāļāļļāļāļĢāļ°āļŠāļēāļāđāļĨāļ°āļĄāļ§āļĨāļĢāļ§āļĄāļāļēāļāđāļāļĨāđāļāļĩāļĒāļĄāļāļēāļĢāđ-āđāļāļāđ (CCR) āļāļŠāļĄāđāļĒāļāļāļąāļāđāļāđāļēāļāļēāļĨāđāļĄāļāđāļģāļĄāļąāļ (PA) āđāļĨāļ°āđāļāđāļēāđāļāļĨāļāđāļāļĨāļ·āļāļāđāļĄāđ (RA) āļāļģāļĄāļēāđāļāđāđāļāđāļāļ§āļąāļŠāļāļļāļāļĢāļ°āļŠāļēāļāđāļāļāļāļĩāđāļāļđāļāļāļĩāđāļĄāļāļāđāđāļāļŠāđāļ§āļāļāļŠāļĄāļāļāļāļāļĢāļĩāļ āļāļāļāļāļēāļāļāļĩāđāļĄāļ§āļĨāļĢāļ§āļĄāļĢāļĩāđāļāđāļāļīāļĨāļāļđāļāļāļģāļĄāļēāđāļāđāđāļāļāļāļĩāđāļĄāļ§āļĨāļĢāļ§āļĄāļāļĢāļĢāļĄāļāļēāļāļīāđāļāļ·āđāļāļāļĩāđāļŦāļĨāđāļāļāļąāļ§āļāļĒāđāļēāļāļāļāļāļāļĢāļĩāļ (āļāļāļāļāļĢāļĩāļ CCR-PA āđāļĨāļ° CCR-RA) āļŠāļĄāļāļąāļāļīāļāļāļāļāļāļāļāļĢāļĩāļ āđāļāđāđāļāđ āļāļģāļĨāļąāļāļāļąāļ āļāļēāļĢāđāļāļĢāļāļāļķāļĄāļāļāļāļāļĨāļāđāļĢāļāđ āđāļĨāļ°āļāļēāļĢāļāļķāļĄāļāļāļāļāđāļģāļāđāļēāļāļāļāļāļāļĢāļĩāļāđāļāđāļĢāļąāļāļāļēāļĢāļāļĢāļ°āđāļĄāļīāļāđāļĨāļ°āđāļāļĢāļĩāļĒāļāđāļāļĩāļĒāļāļāļąāļāļāļāļāļāļĢāļĩāļāļāļ§āļāļāļļāļĄ (āļāļāļāļāļĢāļĩāļ CON) āļāļĨāļāļēāļĢāļ§āļīāļāļąāļĒāļāļāļ§āđāļēāļ§āļąāļŠāļāļļāļāļĢāļ°āļŠāļēāļ CCR-PA āđāļĨāļ° CCR-RA āļŠāļēāļĄāļēāļĢāļāļāļģāļĄāļēāđāļāđāđāļāđāļāļŠāļēāļĢāļĒāļķāļāđāļāļēāļ°āđāļāļāļāļāļāļĢāļĩāļāļāļĩāđāđāļāđāļĄāļ§āļĨāļĢāļ§āļĄāļĢāļĩāđāļāđāļāļīāļĨ āđāļĄāđāļ§āđāļēāļ§āļąāļŠāļāļļāļāļĢāļ°āļŠāļēāļ CCR-PA āđāļĨāļ° CCR-RA āļĄāļĩāļŦāļĢāļ·āļāđāļĄāđāļĄāļĩāļāļđāļāļāļĩāđāļĄāļāļāđ āļāļēāļĢāļāļąāļāļāļēāļāļģāļĨāļąāļāļāļąāļāļāļāļāļāļāļāļāļĢāļĩāļ CCR-PA āđāļĨāļ° CCR-RA āļāļĨāđāļēāļĒāļāļąāļāļāļāļāļāļĢāļĩāļ CON āļāļāļāļāļēāļāļāļĩāđāļ§āļąāļŠāļāļļāļāļĢāļ°āļŠāļēāļ CCR-PA āđāļĨāļ° CCR-RA āļŠāļēāļĄāļēāļĢāļāļāļĢāļąāļāļāļĢāļļāļāļāļēāļĢāđāļāļĢāļāļāļķāļĄāļāļāļāļāļĨāļāđāļĢāļāđāđāļĨāļ°āļāļēāļĢāļāļķāļĄāļāļāļāļāđāļģāļāđāļēāļāļāļāļāļāļĢāļĩāļāđāļāđāļāļĒāđāļēāļāļĄāļĩāļāļĢāļ°āļŠāļīāļāļāļīāļ āļēāļ āļāļĨāļāļēāļĢāļ§āļīāļāļąāļĒāļĒāļąāļāļāļĩāđāđāļŦāđāđāļŦāđāļāļ§āđāļēāļāļāļāļāļĢāļĩāļ CCR-PA āđāļĨāļ° CCR-RA āļŠāļēāļĄāļēāļĢāļāđāļāđāđāļāđāļāļāļāļāļāļĢāļĩāļāļāļĩāđāđāļāđāļāļĄāļīāļāļĢāļāđāļāļŠāļīāđāļāđāļ§āļāļĨāđāļāļĄāļāļāļīāļāđāļŦāļĄāđ āđāļāļĢāļēāļ°āļāļāļāļāļĢāļĩāļāđāļŦāļĨāđāļēāļāļĩāđāļŠāļēāļĄāļēāļĢāļāļĨāļāļāļēāļĢāļāļĨāđāļāļĒāļāđāļēāļāļāļēāļĢāđāļāļāļāđāļāļāļāļāđāļāļāđāđāļĨāļ°āļĨāļāļāļąāļāļŦāļēāļŠāļīāđāļāđāļ§āļāļĨāđāļāļĄAbstractThis concrete was made by using several industrial wastes in both binder and aggregates. Calcium carbide residue (CCR) mixed separately with palm oil fuel ash (PA) and rice husk-bark ash (RA), and was used as a binder instead of Portland cement in the concrete mixture. Furthermore, recycled aggregates were fully replaced natural aggregates in order to cast concrete specimens (CCR-PA and CCR-RA concretes). Concrete properties namely compressive strength, chloride migration, and water permeability of CCR-PA and CCR-RA concretes were evaluated and compared with the conventional concrete (CON concrete). The results indicated that CCR-PA and CCR-RA binders could be used as a new cementitious material in recycled aggregate concrete, even though the CCR-PA and CCR-RA binders contained no Portland cement. The characteristic compressive strength of CCR-PA and CCR-RA concretes developed similar to CON concrete. Moreover, CCR-PA and CCR-RA binders in the mixtures were effectively improving the chloride migration and water permeability of recycled aggregate concretes. These results also suggested that CCR-PA and CCR-RA concretes can be used as a new environmental friendly concrete because of these concretes can reduce as much as CO2 emissions and environmental problems
Effect of Fly Ash on Chloride Penetration and Compressive Strength of Reclycled and Natural Aggregate Concrete under 5-year Exposure in Marine Environment
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Enhanced durability of concrete with palm oil fuel ash in a marine environment
This research aimed to enhance the durability of concrete at a marine site by using ground palm oil fuel ash (GPOFA). Portland cement type I had been replaced by GPOFA at various replacement levels of 0â50% by weight of binder, with three different strength grades. Cubical concrete specimens with embedded steel bars at various covering depths were cast to determine chloride ingression and steel corrosion. After curing for 28 days, the concrete specimens were placed in a marine environment. The compressive strength, total and free chloride ingress, and embedded steel corrosion of the specimens were determined after subjecting them to tidal zone conditions for 7 years. The results show that the concrete specimens containing GPOFA at replacement levels of 15â35% by weight of binder provided the best durability performances at the marine site, with lower compressive strength loss and higher chloride and steel corrosion resistances than ordinary Portland cement concrete. This indicates that GPOFA in a replacement levels of 15â35% by weight of binder, with a maximum W/B ratio of 0.45, can be used efficiently in concrete to enhance the service life of marine concrete structures
Evaluation of Heat Evolution of Pastes Containing High Volume of Ground River Sand and Ground Granulated Blast Furnace Slag
This paper investigated the heat evolution of pastes containing inert and active materials with different particle sizes. Ground river sand was used as an inert material while ground granulated blast furnace (GGBF) slag was used as an active material. Ground river sand (GRS) and GGBF slag were ground to have the same particle size and were used separately as a replacement of Portland cement type I at rates of 50 â 70 % by weight of the binder. Heat evolution of pastes containing GRS and GGBF slag was measured using an isothermal conduction calorimeter up to 72 h. The results showed that GRS with different particle sizes had a slight effect on the heat evolution of pastes. GGBF slag with median particle size d50 of 4.4 Ξm and d50 of 17.8 Ξm had a small effect on the heat evolution of pastes during the first 24 h, and the pastes also had very low heat evolution for up to 72 h. At the same replacement rate of Portland cement, however, the heat evolution due to the slag reaction was slightly increased when the particle size of the GGBF slag was decreased. Finally, the higher is the cement replacement by GGBF slag, the higher is the slag reaction
āļāļēāļĢāļāļĢāļ°āļĒāļļāļāļāđāđāļāđāļāļĩāđāļāļāļāļĨāļīāđāļĄāļāļĢāđāļāļēāļāđāļāđāļēāđāļāļĨāļāđāļāļāļāļāļāļĢāļĩāļāļāļĨāđāļāļāļāļāļīāļāļĢāļąāļāļāđāļģāļŦāļāļąāļUtilization of Rice Husk Ash-based Geopolymer in Hollow Load-bearing Concrete Masonry Block
āļāļēāļāļ§āļīāļāļąāļĒāļāļĩāđāļĻāļķāļāļĐāļēāļāļĨāļāļāļāļāļĢāļīāļĄāļēāļāļĄāļ§āļĨāļĢāļ§āļĄāļāļ§āļēāļĄāđāļāđāļĄāļāđāļāļāļāļāļŠāļēāļĢāļĨāļ°āļĨāļēāļĒāđāļāđāļāļĩāļĒāļĄāđāļŪāļāļĢāļāļāđāļāļāđ (NaOH) āđāļĨāļ°āļāļļāļāļŦāļ āļđāļĄāļīāļāđāļĄāļāđāļāļāļģāļĨāļąāļāļāļąāļ āđāļĨāļ°āļāļēāļĢāļāļđāļāļāļķāļĄāļāđāļģāđāļāļāļāļāļāļĢāļĩāļāļāļĨāđāļāļāļāļāļīāļāļĢāļąāļāļāđāļģāļŦāļāļąāļāļāļēāļāļāļĩāđāļāļāļāļĨāļīāđāļĄāļāļĢāđāļāļēāļāđāļāđāļēāđāļāļĨāļāļāļēāļāđāļĢāļāļāļēāļāđāļāļĒāļāļĢāļ āđāļāļĢāļĩāļĒāļĄāļāļĩāđāļāļāļāļĨāļīāđāļĄāļāļĢāđāļāļāļāļāļĢāļĩāļāļāļĨāđāļāļāļāļēāļāļāļēāļāđāļāđāļēāđāļāļĨāļāļāļĩāđāđāļĄāđāļāđāļēāļāļāļēāļĢāļāļāđāļĨāļ°āđāļāđāļēāļāđāļēāļāļŦāļīāļ (āđāļāđāļēāđāļāļĨāļ : āđāļāđāļēāļāđāļēāļāļŦāļīāļ āđāļāđāļēāļāļąāļ 50 : 50 āđāļāļĒāļāđāļģāļŦāļāļąāļ) āļŠāļēāļĢāļĨāļ°āļĨāļēāļĒāđāļāđāļāļĩāļĒāļĄāļāļīāļĨāļīāđāļāļ (Na2SiO3) āđāļĨāļ°āļŠāļēāļĢāļĨāļ°āļĨāļēāļĒāđāļāđāļāļĩāļĒāļĄāđāļŪāļāļĢāļāļāđāļāļāđ (NaOH) āđāļāļĒāđāļāđāļāļ§āļēāļĄāđāļāđāļĄāļāđāļāļāļāļāļŠāļēāļĢāļĨāļ°āļĨāļēāļĒāđāļāđāļāļĩāļĒāļĄāđāļŪāļāļĢāļāļāđāļāļāđ āđāļāđāļēāļāļąāļ 12, 14, 16 āđāļĨāļ° 18 āđāļĄāļĨāļēāļĢāđ āđāļĨāļ°āđāļāđāļāļĢāļīāļĄāļēāļāļŦāļīāļāļāļļāđāļāđāļāđāļāļĄāļ§āļĨāļĢāļ§āļĄāđāļāļāļāļĩāđāđāļāļāļąāļāļĢāļēāļŠāđāļ§āļ (āđāļāđāļēāđāļāļĨāļāļāļŠāļĄāđāļāđāļēāļāđāļēāļāļŦāļīāļ) : āļŦāļīāļāļāļļāđāļ āđāļāđāļēāļāļąāļ 1 : 4, 1 : 6 āđāļĨāļ° 1 : 8 āđāļāļĒāļāđāļģāļŦāļāļąāļ āļŦāļĨāļąāļāļāļēāļāļāļąāđāļāļāļģāļāļēāļĢāļāļąāļāļāļĩāđāļāļāļāļĨāļīāđāļĄāļāļĢāđāļāļāļāļāļĢāļĩāļāļāļĨāđāļāļāđāļāđāļāļĢāļ·āđāļāļāļāļąāļāļāļāļāļāļĢāļĩāļāļāļĨāđāļāļ āđāļāļĒāļāđāļĄāļāļĩāđāļāļāļāļĨāļīāđāļĄāļāļĢāđāļāļāļāļāļĢāļĩāļāļāļĨāđāļāļāđāļāļāļēāļāļēāļĻāļāļĩāđāļāļļāļāļŦāļ āļđāļĄāļŦāđāļāļ (25°C) āđāļĨāļ°āļāđāļĄāđāļāļāļđāđāļāļāļāļĩāđāļāļļāļāļŦāļ āļđāļĄāļī 65°C āđāļāđāļāđāļ§āļĨāļē 24 āļāļąāđāļ§āđāļĄāļ āļāļēāļāļāļąāđāļāļāđāļĄāđāļāļāļēāļāļēāļĻāļāļĩāđāļāļļāļāļŦāļ āļđāļĄāļīāļŦāđāļāļāļāļāļāļķāļāļāļēāļĒāļļāļāļāļŠāļāļ āđāļāļĒāļāļāļŠāļāļāļāļģāļĨāļąāļāļāļąāļāļāļĩāđāļāļēāļĒāļļ 7, 14, āđāļĨāļ° 28 āļ§āļąāļ āļāļĨāļāļāļāļāļāļāļŠāļāļāļāļēāļĢāļāļđāļāļāļķāļĄāļāđāļģāļāļĩāđāļāļēāļĒāļļ 28 āļ§āļąāļ āļāļĨāļāļēāļĢāļĻāļķāļāļĐāļēāļāļāļ§āđāļē āļāļēāļĢāđāļāđāļāļ§āļēāļĄāđāļāđāļĄāļāđāļāļāļāļāļŠāļēāļĢāļĨāļ°āļĨāļēāļĒ NaOH āļāļĩāđāļŠāļđāļāļāļķāđāļ āļŠāđāļāļāļĨāđāļŦāđāļāļĩāđāļāļāļāļĨāļīāđāļĄāļāļĢāđāļāļāļāļāļĢāļĩāļāļāļĨāđāļāļāļĄāļĩāļāļģāļĨāļąāļāļāļąāļāļŠāļđāļāļāļķāđāļāđāļĨāļ°āļāļēāļĢāļāļđāļāļāļķāļĄāļāđāļģāļĄāļĩāļāđāļēāļĨāļāļĨāļ āđāļāļĒāđāļŦāđāļāļāļĨāļāļąāļāđāļāļāđāļāļāļĩāđāļāļāļāļĨāļīāđāļĄāļāļĢāđāļāļāļāļāļĢāļĩāļāļāļĨāđāļāļāļāļĩāđāđāļāđāļĄāļ§āļĨāļĢāļ§āļĄāļāļĢāļīāļĄāļēāļāļāđāļģāļĄāļēāļāļāļ§āđāļēāļāļĢāļīāļĄāļēāļāļŠāļđāļ āļāļēāļĢāđāļāđāļĄāļ§āļĨāļĢāļ§āļĄāļāļŠāļĄāđāļāļāļĩāđāļāļāļāļĨāļīāđāļĄāļāļĢāđāļāļāļāļāļĢāļĩāļāļāļĨāđāļāļāđāļāļāļĢāļīāļĄāļēāļāļāļĩāđāļĄāļēāļāļāļķāđāļ āļŠāđāļāļāļĨāđāļŦāđāļāļģāļĨāļąāļāļāļąāļāļāļāļāļāļĩāđāļāļāļāļĨāļīāđāļĄāļāļĢāđāļāļāļāļāļĢāļĩāļāļāļĨāđāļāļāļĨāļāļĨāļ āļāļĨāļāļāļāļāļāļēāļĢāđāļāđāļāļļāļāļŦāļ āļđāļĄāļīāđāļāļāļēāļĢāļāđāļĄ 65°C āđāļāđāļāđāļ§āļĨāļē 24 āļāļąāđāļ§āđāļĄāļāļŠāđāļāļāļĨāđāļŦāđāļāļģāļĨāļąāļāļāļąāļāļāļāļāļāļĩāđāļāļāļāļĨāļīāđāļĄāļāļĢāđāļāļāļāļāļĢāļĩāļāļāļĨāđāļāļ āļŠāļđāļāļāļ§āđāļēāļāļĨāļļāđāļĄāļāļĩāđāļāđāļĄāđāļāļāļļāļāļŦāļ āļđāļĄāļīāļŦāđāļāļ 25°C āļāļĒāđāļēāļāļāļąāļāđāļāļ āđāļāļĒāļāļļāļāļŦāļ āļđāļĄāļīāļāđāļĄāļāļĩāđāļŠāļđāļāļāļķāđāļāļĄāļĩāļāļĢāļ°āļŠāļīāļāļāļīāļ āļēāļāļāđāļāļāļēāļĢāđāļāļīāđāļĄāļāļģāļĨāļąāļāļāļąāļāđāļāļāļĨāļļāđāļĄāļāļĩāđāđāļāđāļāļ§āļēāļĄāđāļāđāļĄāļāđāļāļāļāļāļŠāļēāļĢāļĨāļ°āļĨāļēāļĒ NaOH āļāđāļģāļĄāļēāļāļāļ§āđāļēāļāļ§āļēāļĄāđāļāđāļĄāļāđāļāļāļāļāļŠāļēāļĢāļĨāļ°āļĨāļēāļĒ NaOH āļŠāļđāļThis research aims to study the effects of aggregate content, sodium hydroxide (NaOH) concentration and curing temperature on compressive strength and water absorption of load-bearing geopolymer concrete block. Original coarse rice husk ash blended with fly ash at the percentage by weight of 50 : 50 was used as a binder. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solutions were also mixed with the binder to produce geopolymer concrete block. NaOH solution concentrations were varied at 12, 14, 16, and 18 molars. Dust limestone was also used as an aggregate in the mixture at various weight ratios between the binder (rice husk ash blended with fly ash) to aggregate of 1 : 4, 1 : 6 and 1 : 8. The geopolymer concrete blocks were produced by using the Cinva-Ram machine. The specimens were then arranged into two groups at the temperatures of 25°C (room temperature) and 65°C for the first 24-hour curing and then all the specimens were cured in room temperature until the testing ages. The geopolymer concrete block specimens were tested for compressive strength at 7, 14, and 28 days and its water absorption was tested at 28 days. The results showed that higher NaOH solution concentration led to higher compressive strength and lower water absorption of geopolymer concrete block. These effects were evidently found in geopolymer concrete blocks with low aggregate content than in those with high aggregate content. Increase of aggregate content in the mixture also decrease compressive strength of geopolymer concrete block. In addition, geopolymer concrete blocks, which were cured at 65°C for 24 hours apparently yielded higher compressive strength than those cured at 25°C (room temperature). Besides, high curing temperature has a greatter effect to increase compressive strength of geopolymer concrete block with lower NaOH concentration than that with higher NaOH concentration
Solidification of heavy metal sludge using cement, fly ash and silica fume
405-414In this paper, the properties of solidified waste
using ordinary Portland cement (OPC) containing silica
fume (SF) and fly ash (FA) as a binder
are reported. Silica fume and fly ash are used to partially replace ordinary
Portland cement by 10% and 30% by weight, respectively. Plating sludge is used of 40, 50 and 60% by
weight of the binder. A water to binder (w/b) ratio of 0.40 is used for all of
the mixtures. The compressive strength of the solidified wastes is
investigated. The leachability of heavy metals is determined by TCLP and XRD,
and XRF is used to study the chemical properties, while the fractured surfaces
are studied by SEM, and the pore size distribution is studied by MIP. The test
results show that the setting time of the blended
cement increased as the amount of plating
sludge in the mix increased. In addition, the compressive strength of
the blended cement increased with increasing curing duration time but at a
decreasing rate. The compressive strengths at 28 days of the SF solidified
waste mixes are 12.4, 2.7, 1.34 MPa and those of FA solidified waste mixes are
1.1, 1.0, 0.5 MPa at the plating sludge
of 40, 50 and 60% by weight of the binder, respectively. The quality
of the solidified waste containing SF and FA is better than that with OPC alone
in terms of the effectiveness in reducing the leachability. The concentrations
of heavy metals in the leachates are within the limits specified by the US EPA.
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Evaluation of Strengths from Cement Hydration and Slag Reaction of Mortars Containing High Volume of Ground River Sand and GGBF Slag
This paper investigates the cement hydration, and the slag reaction contributes to the compressive strengths of mortars mixed with ground river sand (GRS) and ground-granulated blast furnace (GGBF) slag with different particle sizes. GRS (inert material) and GGBF slag (reactive material) were ground separately until the median particle sizes of 32âÂąâ1, 18âÂąâ1, and 5âÂąâ1 micron and used to replace Portland cement (PC) in large amount (40â60%) by weight of the binder. The results showed that, at the early age, the compressive strength obtained from the cement hydration was higher than that obtained from the slag reaction. The results of compressive strength also indicated that the GGBF slag content and particle size play important roles in the slag reaction at the later ages, whereas cement hydration is more prominent at the early ages. Although the results could be expected from the use of GGBF slag to replace PC in mortar or concrete, this study had presented the values of the compressive strength along with ages and the finenesses of GGBF slag that contributed from cement hydration and from GGBF slag reaction
Development of Concrete Paving Blocks Prepared from Waste Materials without Portland Cement
This experiment used three types of waste materials: calcium carbide residue, fly ash, and recycled concrete aggregate to develop concrete paving blocks. The blocks had calcium carbide residue and fly ash as a binder without ordinary Portland cement (OPC) and combined with 100Â % of recycled concrete aggregate. The concrete paving blocks were 10Â ÃÂ 10Â ÃÂ 20Â cm and were formed using a pressure of 6 or 8Â MPa. The binder-to-aggregate ratio was held constant at 1:3 by weight, while the water-to-binder ratios were 0.30, 0.35, and 0.40. The effects of the water-to-binder ratios and fineness of the binder on the compressive strength, flexural strength, abrasion resistance, and water absorption of the concrete paving blocks were determined and compared with those of TIS 827 and ASTM C1319 standards. The results revealed that by applying this procedure, we were able to produce an excellence concrete paving block without using OPC. The compressive strength of the concrete paving blocks made from these waste materials was 41.4Â MPa at 28 days and increased to 45.3Â MPa at 60Â days. Therefore, these waste materials can be used as raw materials to manufacture concrete paving blocks without OPC that meet the requirements of 40Â MPa and 35Â MPa specified by the TIS 827 and ASTM C1319 standards, respectively.DOI: http://dx.doi.org/10.5755/j01.ms.24.1.17566</p