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The combination of sticky rice pulp and tabia is a building material in ancient China, while the concrete preparation with sticky rice pulp instead of water is a new concept, and exploratory experimental study on its working and mechanical properties is indispensable. Therefore, on the basis of concrete substrates of Chinese C25, sticky rice pulp with different concentrations was used to replace water to complete the preparation of concrete, and its slump and compressive strength test under different ages was carried out. The results showed that sticky rice pulp could be a retarder and reduce the water‐cement ratio to a certain extent, and amylopectin in sticky rice pulp could also play the role of template. In addition, there is cementation of coarse and fine aggregate by adhesive components in sticky rice pulp. These effects cause the compressive strength of concrete to decrease at the early stage and increase at the later stage, and in terms of strength alone, the optimal concentration of sticky rice pulp that replaces water is about 1%. According to the test results, the influence functions of cube compressive strength of concrete with sticky rice pulp at 3d and 28d ages, as well as the correlation function of cube compressive strength and two variables about concentration and age of sticky rice pulp were also fitted. The results of the above series of exploration provide basis for the engineering application of concrete with sticky rice pulp in future, which is an environmentally friendly building material. [ABSTRACT FROM AUTHOR]

The durability of recycled concrete is susceptible to degradation from both chloride salt attack and carbonation when exposed in service environment. The depth of carbonation in recycled concrete subject to chloride salt attack was studied here. This investigation assessed the effects of mineral admixture, replacement rate of recycled coarse aggregate, and quality of recycled coarse aggregate on the carbonation depth. The carbonation depth Recycled concrete was studied through accelerated simulated carbonation in the laboratory for 7d, 14d and 28d. Based on the results, the correlation analysis was conducted to investigate the relationship between depth of carbonation, mineral admixture, recycled coarse aggregate replacement rate, recycled coarse aggregate quality and the presence of chloride ions. The objective of this study was mainly to investigate the effect of internal chloride ions on the depth of carbonation of recycled concrete subjected to chloride salt attack. The study referred to previous academic research on carbonation in recycled concrete that had not been affected by chloride salts, and conducted a comparative analysis to identify the carbonation depth pattern in recycled concrete influenced by chloride salt exposure. The study discovered a negative correlation between the replacement rate of mineral admixture and recycled coarse aggregate and the carbonation resistance of concrete. Moreover, enhancing the quality of recycled coarse aggregate positively impacted the carbonation resistance of concrete. An improved model was developed that considers the effect of internal chloride salts on the carbonation depth of recycled concrete, in reference to the empirical prediction model presently available. The model demonstrated a high level of agreement with experimental outcomes, displaying an error range of between −4.32% and 8.27%. It enables an in-depth comprehension of the carbonation behavior of recycled aggregate concrete in an environment exposed to chloride salt attack. Based on the model, the service life of recycled concrete structures can be more accurately forecasted, which can provide a theoretical direction for enhancing the durability of engineering structure. • This study aims to investigate the impact of chloride salts on carbonation in recycled aggregate concrete. • The influence of recycled aggregate on carbonation of recycled aggregate concrete has been studied. • The carbonation depth of recycled concrete is reduced due to the presence of chloride ions. • An empirical prediction carbonation model of recycled aggregate concrete with embedded chloride ions has been developed. [ABSTRACT FROM AUTHOR]

In order to explore the interactional relations of internal chloride and external chloride-binding amongst the cementitious materials, the chloride-binding capacity of mortars composed of marine sand (MS) or washed marine sand (WMS) were investigated. Results indicate that more external chloride can penetrate and diffuse more deeply into the WMS mortar than that in the MS mortar. This phenomenon suggests that the external chloride migration resistance due to WMS is lower than that caused by MS. The distribution trends of the bound chloride content in the two types of mortars are the same at different immersion times. However, a significantly decreased area of the bound chloride content exists at the border of the external penetration area (EPA) and the external unaffected area (EUA) at the immersion ages of 3 and 7 d, and then it disappears gradually with immersion time. The WMS mortar can bind more external chloride, whereas the MS mortar can bind more internal chloride, at different immersion times. The distributions of bound chloride conversion rate in the EPAs of the two types of mortars differ across immersion times. The distribution firstly decreases, and then it increases at the immersion ages of 3 and 7 d. The distribution was from increase, then decreases, and increase again at the immersion ages of 28 and 56 d. The bound chloride conversion rate in the WMS mortar is affected more greatly by external chloride penetration than that in the MS mortar. The amounts of the Friedel's salt tend to increase with prolonged immersion time. Finally, the penetration of external chloride can increase the amount of fine capillary pores smaller than 100 nm in the WMSmortar exposed for 56 d in the chloride salt solution (WMS-E) specimen. [ABSTRACT FROM AUTHOR]

• Treated and non-treated SNS flakes enhanced the mechanical and fracture properties of the cementitious composites. • The SNS strengthening and toughening mechanisms in the cementitious composites are crack bridging and crack deflection. • The SNS induced performance enhancement similar to that of graphene-based materials. This paper examines the mechanical and fracture properties of cementitious composites doped with a new type of 2D bio-nanoplatelets sheets, synthesized from sugar beet pulp waste. The sugar beetroot nanosheets (SNS) were added to the cement pastes at different concentrations. The influence of SNS treatment and water-to-cement (w/c) ratio on the performance of the cementitious composites was elucidated. The experimental results showed that 0.2- wt% and 0.35 were the optimal SNS concentration and w/c ratio for increasing the compressive, splitting tensile and flexural strength, flexural modulus, fracture energy and fracture toughness. These properties were enhanced by as much as 12.15%, 36.87%, 39.91%, 32.69%, 69.01% and 49.06%, respectively. This enhancement was due to crack deflection and crack bridging mechanisms in the cementitious composites as a result of the high specific surface area of SNS and the strong chemical and physical bonding of SNS with the hydration phases. The SNS materials offers strong advantages over graphene-based materials on improving the engineering properties of cementitious materials and reducing their cost and CO 2 emissions. [ABSTRACT FROM AUTHOR]

Antimony (Sb) is a trace element applied widely in modern industry. A large number of tailing solid wastes are left and accumulated in the mining area after purifying the precious antimony from the antimony ores, causing serious pollution to the environment. The major aim of this study is to investigate the feasibility of utilizing antimony tailing coarse aggregate (ATCA) as a complete substitute for natural coarse aggregate (NCA) in high-strength concrete. Concrete specimens with 25%, 50%, 75%, and 100% ATCA replacing the NCA in conventional concrete were prepared for evaluating the performance of ATCA concrete. The investigators find that ATCA concrete has good workability, and the mechanical properties and long-term behavior (shrinkage and creep) of ATCA concrete with all replacement levels are superior to those of NCA concrete. The durability indices of ATCA concrete, such as the frost-resistant, chloride permeability, and resistance to carbonation, are better than those of NCA concrete. While the alkali activity and cracking sensitivity behavior of ATCA concrete seem to be decreased, nevertheless, the difference is not significant and can be neglected. The researchers demonstrate that all of the control indices of ATCA concrete meet the requirements of the current industry standards of China. Overall, ATCA can be used in concrete to minimize environmental problems and natural resources depletion. [ABSTRACT FROM AUTHOR]