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Effect of Pre-wetting Lightweight Aggregates on the Mechanical Performances and Microstructure of Cement pastes

Journal of Wuhan University of Technology(Materials Science) 2020年第1期35卷 140-146页

作者：丁庆军向玮衡 ZHANG Gaozhan HU Cheng State Key Laboratory of Silicate Materials for Architectures Wuhan University of TechnologyWuhan 430070China School of Material Science and Chemical Engineering Anhui Jianzhu UniversityHefei 230601China The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081China

The water absorption and desorption processes of different types of lightweight aggregates were ***,the influences of pre-wetting lightweight aggregates on compressive strength,microhardness,phase composition,hydration parameters and micromorphology of the cement pastes were *** results showed that the water absorption and desorption capacities of the lightweight aggregates increased with the decrease of the densification *** the addition of pre-wetting lightweight aggregates,the compressive strength of the cement pastes would ***,the enhancement effect was more obviously with the desorption capacity of pre-wetting lightweight aggregates ***,sample S1 with pre-wetting red-mud ceramisites had the highest compressive strength,of which increased to 49.4 MPa after 28 d curing *** reason is that mainly because the addition of pre-wetting lightweight aggregates can promote the generation of C–S–H gels in the interfacial zone,and the hydration degree of the interfacial zone increases with the water desorption of pre-wetting lightweight aggregates *** is contributed to optimize the microstructure to enhance microhardness of the interfacial zone,resulting in the compressive strength of the cement-based materials ***,the pre-wetting lightweight aggregates with high porosity and strength are the potential internal curing agents for high-strength lightweight concretes.

关键词： pre-wetting lightweight aggregates cement pastes interfacial zone compressive strength microstructure

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Genotoxic Potential of Shrimp pastes (Belacan) Extracts Using <i>Umu</i>Test

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Food and Nutrition Sciences 2012年第4期3卷 522-525页

作者： Ahmad Rohi Ghazali Yvonne Sipain Nor Fadilah Rajab Siew Ee Ling Norain Ramli Rozaini Abdullah Zaliha Harun Firdaus Kamarulzaman Biomedical Science Program Faculty of Health Sciences School of Diagnostic and Applied Health Sciences Universiti Kebangsaan Malaysia Kuala Lumpur Malaysia Environmental Health Program Faculty of Health Sciences School of Diagnostic and Applied Health Sciences Universiti Kebangsaan Malaysia Kuala Lumpur Malaysia.

This study was conducted to observe the genotoxic effects of aqueous, methanol, hexane and dichloromethane extracts of “belacan” (shrimp paste) taken from three local districts in Melaka, Malaysia (Kelemak, Batang Tiga & Pantai Puteri). The umu test which was used as the screening test was conducted with and without the presence of metabolic activation system. Without the presence of metabolic activation system, aqueous extracts from Kelemak showed mutagenicity activity at 5 mg/ml with IR (Induction Rate) = 1.52 ± 0.57 and the methanol extracts showed mutagenic activities at 0.625 mg/ml and 5 mg/ml, which the IR was the highest at 5 mg/ml (2.08 ± 0.09). On the other hand, samples from Batang Tiga, Melaka showed mutagenic effects at all five concentrations for the dichloromethane extract, with IR = 2.09 ± 0.64 as the highest value at 1.25 mg/ml. Methanol extracts also showed positive results at 1.25 mg/ml and 2.5 mg/ml with IR = 1.70 ± 0.33 and IR = 2.12 ± 0.51 respectively, and aqueous extract at 0.625 mg/ml with IR = 1.54 ± 0.48 and 5 mg/ml with IR = 1.74 ± 0.50. There was a significant difference of the mean values of IR between the four different types of “belacan” extracts from Batang Tiga (p < 0.05). All four “belacan” extracts from Pantai Puteri, Melaka did not show any mutagenic effect. With the presence of metabolic activation system, there was no mutagenic effect observed in all four extracts from the three districts. Further study to analyze the contents in the food samples should be done in the future to determine the possible contents in the food samples that might be responsible for the mutagenic activities.

关键词： Shrimp pastes Mutagenicity Umu Test Melaka Genotoxicity

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Mechanical Properties of Micro-regions in Cement-based Material based on the PeakForce QNM Mode of AFM

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Journal of Wuhan University of Technology(Materials Science) 2019年第4期34卷 893-899页

作者： REN Mei SHI Tao College of Management Zhejiang University of Technology Hangzhou 310023China College of Civil Engineering and Architecture Zhejiang University of TechnologyHangzhou 310023China Key Laboratory of Civil Engineering Structures & Disaster Prevention and Mitigation Technology of Zhejiang Province Hangzhou 310023China Department of Civil and Environmental Engineering Northwestern UniversityEvanstonIL 60208USA

In this paper, the cement paste and the mortar were tested using the PF-QNM technique. It is shown that the PF-QNM technique is very powerful to characterize the mechanical properties of micro-and nanostructures in the cement-based materials. It does not have strict requirements for test environment and it does not damage the surface of the material. High-resolution images can be obtained very easily, and they can be analyzed statistically. The test results show that PF-QNM analysis can test not only the mechanical properties of the cement paste, but also investigate the interfacial regions in the cement-based material, including the variation in the mechanical properties of interface regions and the extension of the interfacial regions. During the test, care must be taken to choose the size of test area;indeed, a test area too small is not representative but too large leads to lack of stability. The recommended side is a square with a length of in the range 10-30 μm.

关键词： PF-QNM peakforce tapping AFM cement pastes mortar Young's modulus interface micro-and nano-structure nanoindentation

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