China
Africa
Explore chapters and articles related to this topic
Overview on Valorization of Dredged Materials as Cementitious Resource
Published in Amine El Mahdi Safhi, Valorization of Dredged Sediments as Sustainable Construction Resources, 2022
Amine El Mahdi Safhi, Abdelhadi Bouchikhi, Hassan Ez-Zaki, Patrice Rivard
It was revealed that DMs used as SCMs are mainly composed of 35–76% SiO2, 0.1–26% CaO, 1.6–23% Al2O3, and 0.4–13% Fe2O3. The LOI of the raw DMs was about 15–38%, which decreases after treatment to lower than 5.5%. The sum of SiO2, Al2O3, and Fe2O3, was about 38–59% for the raw DMs and reached 54–97% after the treatment, which classified the treated DMs as a highly pozzolanic material. Their reported pozzolanic reaction makes them suitable materials to be used as a cementitious addition. The high SiO2 content in DMs enables the pozzolanic reaction, with the addition of CaO producing additional C–S–H gels. However, DMs found to have a retarding effect on the setting time can either alter or accelerate the early hydration kinetics. PSD, chemical properties, and the rate of incorporation were found to be the critical factors influencing this effect.
Effect of fly ash in Southeast Asia on the properties of mortar
Published in Hiroshi Yokota, Dan M. Frangopol, Bridge Maintenance, Safety, Management, Life-Cycle Sustainability and Innovations, 2021
T.T. Win, R. Wattanapornprom, W. Pansuk
The compressive strength results at 7 days, 28 days and 91 days of the mortar containing MFAF, TFAF, TFAC, IFAF and IFAC are summarized in Figure 6. The strength development of OPC mortar is rather good at 7 days. The 7 days, 28 days and 91 days strengths of OPC are 37.02, 42.64 and 43.95 MPa, respectively. As a result, the fly ash from different sources did not completely react for the first 7 days. However, the strength of mortar with 15% fly ashes significantly increased at the age of 28 days except the strength of MFAF. From the test results, it can be seen that the maximum strength was observed for the replacing source IFAC, followed by IFAF, TFAC, TFAF and MFAF at 91 days strength. The trend of increasing compressive strength with replacing fly ash from different sources was remarked significantly at the curing age of 91 days. The low early strength and later age strength improvement are the common characteristic of pozzolanic materials due to the pozzolanic reaction (Sakai et al., 2005).
Alkali-activated lime-pozzolan cements
Published in Caijun Shi, Pavel V. Krivenko, Della Roy, Alkali-Activated Cements and Concretes, 2003
Caijun Shi, Pavel V. Krivenko, Della Roy
Elevation of curing temperatures accelerates the pozzolanic reaction, especially at early ages (Shi and Day 1993a). The microstructure of Na2SO4− activated lime-pozzolan cement pastes at 35°C is similar to that at 23°C. However, in addition to needle-like crystals, there are some hexagonal
Potential pozzolanic reactivity of recycled aggregates and waste powders as cement mortar component
Published in Journal of the Chinese Institute of Engineers, 2023
Chung-Hao Wu, Wei-Chien Wang, Chou Hsuan Jung
On the other hand, a lot of researches also engaged in enhancing the properties of RCA by using finer waste powder to partly substitute the cement. The common ceramic materials, such as brick and tile, in the construction waste are manufactured by high-temperature sintering process. Such a production process is fairly similar to that of producing fly ash and slag. If these materials are ground finer to replace cement, it is likely to trigger a pozzolanic reaction which is favorable to reduce hydration heat, improve concrete workability, effectively increase long-term strength, and enhance the durability of concrete (Asensio et al. 2016; Xiao et al. 2018; Liu et al. 2020). Liu et al. (2020) investigated the activities of various particle size of waste powders obtained from aerated concrete block and clay brick. The results indicated that the finer the waste powder is, the more intensive pozzolanic reaction will occur. Duan et al. (2020) reported from the research of ultrafine waste powders that the brick powder and clay brick powder had the relative positive impact on the mechanical properties of the resulted mortar at later age. Zhu and Zhu (2020) indicated that it is possible to partly replace cement with sintered clay brick powder to improve the mechanical properties of the concrete. Karthikeyan and Dhinakaran (2017) studied the strength and durability of high-strength concrete using ceramic waste powder. The results presented that concrete incorporating 15% ceramic waste powder gained the relative positive performance.
Glass powder replacement in self-compacting concrete and its effect on rheological and mechanical properties
Published in Journal of Sustainable Cement-Based Materials, 2022
Samia Tariq, Allan N. Scott, James R. Mackechnie, Vineet Shah
The modulus of elasticity of glass powder mixes followed similar trends to that found for compressive and tensile strength. Figures 14 and 15 compare the elastic modulus value of PC, FAF30% and glass powder concrete mixes at different ages. With the increase in particle size and replacement level of glass the elastic modulus of the concrete decreased. Due to the non-destructive nature of the test at low load levels, the same three cylinders for each mix were used for measuring modulus at different ages. In general, a reduction in modulus of elasticity has been reported on replacing cement with SCMs. The elastic modulus of 10G30% concrete mix was higher or similar than FAF30% at all ages whereas for 20G30% concrete mix the higher difference in elastic modulus at early ages decreased with continued hydration and reached similar value at 545 days of curing. The continuing pozzolanic reaction assists in strengthening the bond between cement paste and aggregate, thereby the overall concrete performance [40, 41].
Accelerated curing potential of cold mix asphalt using silica fume and hydrated lime as filler
Published in International Journal of Pavement Engineering, 2022
In order to compare the performance of cement-treated mixes, the ambient and accelerated curing regimes were investigated. The stability of cement-treated CMA (CMA-CT) containing different filler compositions tested for Marshall stability at different curing temperatures is presented in Figure 10. It is easily observed that curing temperature increases the performance of all of the cement-treated mixes. The excessive cement hydration phrases could explain this phenomenon at higher curing temperatures Rojas and Cabrera (2002). Higher temperature accelerates the hydration mechanism and helps in faster pozzolanic reaction in the presence of premixing water. The presence of Quartz in SF filler and cement composition helps in the formation of C2S and C3S that also imparts strength in mixes Debbarma et al. (2020). CMA3-CT had the highest stability among others which increased from 16.78% to 20.59% than HMA after the addition of cement.