Abstract:In order to explore the influence of curing time on the surface permeability of concrete, 10 groups of high content fly ash and slag concrete with two kinds of water-binder ratio were designed. There were cured under five curing methods, respectively. The influence of curing time on the surface permeability of concrete was studied. The mechanism was explained by hydration heat and mercury intrusion porosimetry. The results show that inadequate curing time leads to insufficient hydration of cementitious materia… Show more
“…The percentage reduction in the initial rate of water absorption of concrete exhibited a substantial increase with curing age, in contrast to the secondary rate of water absorption that is dependent on the initial rate of absorption. These findings align with the research conducted by (Kotwa, 2015;Liu et al, 2022).…”
Concrete production and waste generation are among human activities that negatively impact the environment. This study investigated the effects of fly ash on compressive strength and durability properties of lean concrete using appropriate standard methods. The results showed that the compressive strength of the control mix is higher than those of fly ash concrete mixes. The compressive strength of the fly ash blended mixes decreased as the replacement level increased. However, the strength increased with hydration time, and the optimal replacement level being 5%. While the chloride ion penetration and water absorption rate decreased, the sulfate resistance increased with hydration time and replacement level. The fly ash mixes exhibited better durability properties than the control mix in all durability tests conducted. The SEM-EDX analysis showed that mixes with well-packed microstructures exhibited favorable compressive and durability properties. In conclusion, Class C fly ash is recommended for lean concrete mixes at a replacement level of up to 15% when compressive strength is the primary concern, while mixes with a replacement level of 25% or more are recommended in areas susceptible to sulfate attack.
“…The percentage reduction in the initial rate of water absorption of concrete exhibited a substantial increase with curing age, in contrast to the secondary rate of water absorption that is dependent on the initial rate of absorption. These findings align with the research conducted by (Kotwa, 2015;Liu et al, 2022).…”
Concrete production and waste generation are among human activities that negatively impact the environment. This study investigated the effects of fly ash on compressive strength and durability properties of lean concrete using appropriate standard methods. The results showed that the compressive strength of the control mix is higher than those of fly ash concrete mixes. The compressive strength of the fly ash blended mixes decreased as the replacement level increased. However, the strength increased with hydration time, and the optimal replacement level being 5%. While the chloride ion penetration and water absorption rate decreased, the sulfate resistance increased with hydration time and replacement level. The fly ash mixes exhibited better durability properties than the control mix in all durability tests conducted. The SEM-EDX analysis showed that mixes with well-packed microstructures exhibited favorable compressive and durability properties. In conclusion, Class C fly ash is recommended for lean concrete mixes at a replacement level of up to 15% when compressive strength is the primary concern, while mixes with a replacement level of 25% or more are recommended in areas susceptible to sulfate attack.
“…The strength gain is due to increased cement hydration products such as C–S–H gels, which are known to reduce porosity and improve the cohesion of CTB 48 . The formation of hydration products is high at an early age, thus, contributing to the high growth of UCS 49 . Figure 5 The effect of the curing period and cement content on the UCS of CTB samples 50 .…”
The behaviour of a stratified backfilled stope in terms of strength development and stress distribution has not been well established in the field of rock engineering. Yet, the mining industries with massive ore bodies are looking into high production with a high standard of safety which is mainly governed by large excavation with backfill as a support system. It is difficult to fill these large excavations at one time. Therefore, a subsequent backfilling of the stope layer by layering is adopted, which results in a layered backfill structure. The purpose of this study was to explore the strength development, stress distribution and deformation across the stope supported by both layered and non-layered backfill. It has been observed that the backfill support system gain its strength with time, however, the layered backfill support system loses its strength when more layers are introduced, this is due to the shearing effect around the interfaces of the backfill layers. The impact of layering was validated by 3D numerical simulation. It is therefore concluded that non layered backfill support system are more suitable for stoping mining methods rather than layered support system.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
