Abstract. The use of recycled concrete aggregate (RCA) in concrete as partial and full replacements of natural coarse aggregate is growing interest in the construction industry, as it reduces the demand for virgin aggregate. In addition, the use of RCA leads to a possible solution to the environmental problem caused by concrete waste and reduces the negative environmental impact of the aggregate extraction from natural resources. This paper presents a comprehensive review on the use of RCA in concrete based on the experimental data available in the published research. The most important physical, mechanical, and chemical properties of RCA are discussed in this paper. However, more emphasis has been given to discuss the effects of RCA on the fresh and hardened properties and durability of concrete. This paper also identifies the gaps existing in the present state of knowledge on RCA and RCA concrete and provides some recommendations for future research. Keywords: concrete; natural coarse aggregate; recycled concrete aggregate; fresh properties; hardened properties; durability.
Field experiments were conducted to study the effect of intercropping of mustard (Brassica napus, Var. Bari Sarisha-7) with onion (Allium cepa L.) and garlic (Allium sativum L.) on aphid [Lipaphis erysimi (Kaltenbach)] population and yield. Intercropped with these two medicinal as well as spice crops reduced the aphid population significantly (P<0.05). Mustard blocks intercropped with garlic gave highest cost-benefit ratios (1:2.07 and 1: 2.96) than onion intercropped blocks. Sole mustard blocks produced lowest cost-benefit ratios (1:1.65 and 1:2.06).
The antibacterial activity of methanol extract from the root bark of Akanda (Calotropis gigantea L.) and its petroleum ether, chloroform and ethyl acetate fractions were investigated. Both of methanol extract and its chloroform fraction showed activity against Sarcina lutea, Bacillus megaterium and Pseudomonas aeruginosa. Petroleum ether fraction showed activity against Bacillus subtilis and Shigella sonnei whereas ethyl acetate fraction showed activity against Pseudomonas aeruginosa and Escherichia coli at 20µg/disc, 30µg/disc and 40µg/disc doses. Among the tested materials, methanol extract and its chloroform fraction showed comparatively better results. Minimum inhibitory concentration (MIC) for methanol extract and each fraction were also determined by serial dilution technique.
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.