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• Novel analysis of attenuation the growth of Aspergillus tamarii on concrete using radiation in the field of conservation of heritage building. • UVC and gamma irradiation decreased the leaching of calcium ions from concrete when infected with A. tamarii. • Increase in compressive strength of concrete cube was observed to be the most in irradiated cubes. • Effect of A. tamarii and low dose radiation led to less deterioration of concrete (except higher dose) than only exposure to A. tamarii. The conservation of concrete-based deteriorated heritage buildings is a big challenging issue worldwide including in India. This study focused on to prevent fungal biodeterioration in concrete using UVC and gamma radiation. M20 graded concrete cubes (5 cm × 5 cm × 5 cm) were infected with Aspergillus tamarii , which was isolated from a 200 years old historic heritage building. M20 signifies a mixture of cement, sand and aggregate (1:1.5:3), made in such a way that the concrete cube has a compressive strength of 20 N/mm2 when examined after 28 days of curing. The fungal growth appeared clearly as calcium oxalate crystals in the Scanning Electron Microscope (SEM) photographs. Several doses of UVC and gamma radiation were applied on concrete cube. The changes in concrete properties were examined after 30 days in terms of weight, compressive strength, Fourier Transform Infrared Spectroscopy (FTIR) and micro Energy Dispersive X-ray Fluorescence (EDXRF). The results exhibited that compressive strength of control (non-infected and non-irradiated), biodeteriorated (infected), UVC (625 µw/cm² × 300 s) and gamma (0.5 KGy) irradiated infected (inhibition) concrete cubes were 19.74 ± 0.46, 18.88 ± 0.43, 20.20 ± 0.34 and 19.93 ± 0.20 N/mm2 respectively whereas negligible weight losses were observed for inhibition cubes compared to biodeteriorated ones. Calcite (1400, 874 and 705 cm−1), one of the major functional band present in concrete became weak after getting infected by Aspergillus tamarii and strong for inhibition samples irradiated with the above doses. The EDXRF analysis exhibited that mass percentage of calcium ions of the biodeteriorated concrete cubes (49.88 ± 0.65%) was lower than that of UV (75.75 ± 0.16%) and gamma (70.95 ± 0.30%) irradiated infected or inhibition concrete cubes. Altogether, the efficacy of the recommended inhibitory dose of ultraviolet and gamma radiation against concrete deterioration in the field of conservation of heritage building was observed to be positive. [Display omitted] [ABSTRACT FROM AUTHOR]

• Indian finely grounded waste glass powders (GP) recycling in M30 and M40 grade concretes. • GP as cement replacement from 0 to 40%, steps of 10% • Workability, compressive strength and durability indicators improved with the increased of GP content. • Increased drying shrinkage with GP content, still within standard limits. • 30% GP as cement replacement provides optimal engineering properties for conventional concretes and paver concrete blocks. Waste glass is a significant concern in India, and management solutions seek. Finely ground waste glass (GP) presents pozzolanic properties, which make it potential for concrete applications as cement replacement. The main feature of the present work lies in the simultaneous incorporation of two GPs with different fineness, generated from consumer scrap in India, as cement replacement in equal proportions, from 0 to 40 %, in two concrete grades, M30 and M40. An experimental programme was carried out, including fresh, shrinkage, mechanical and durability properties. GP concrete specimens showed compressive strength and a slight improvement for both concrete grades compared to reference concrete specimens (0 % GP incorporation). The durability indicators, namely, water absorption, sorption, chloride-ion penetration and moisture movement in GP concrete, improved with the increase of GP content. The drying shrinkage increased with the rise in GP content; however, the results still fit the permissible standard limits. Optimal concrete mixtures were selected to further study GP incorporation in concrete paver blocks. Four concrete paver block types were produced, including M30 and M40 with no GP (0 %GP) and M30 and M40 with 30 % GP as cement replacement (15 % GP1 + 15 % GP2). The compressive strength of the concrete paver blocks with GP significantly improved. Thus, the concrete with 30 % partial cement replacement by GP is a potential option for the construction industry while providing a management waste solution and contributing to a circular economy. [ABSTRACT FROM AUTHOR]

Coal fired thermal plants in India produce about 131 million tons of coal ash, which comprises about 25 million tons of coal bottom ash. Utilization of coal bottom ash has environmental advantages also which are of great importance in the present context of sustainability of natural resources. The replacement of river sand with industrial by-products such as coal bottom ash in concrete can prove both technically and economically beneficial to the construction industry. In this study, laboratory tests were conducted to assess the possibility of the use of coal bottom ash as a substitute material of river sand in concrete. River sand was substituted with coal bottom ash by mass in concrete at 0, 30, 50, 75 and 100% replacement level. The test results show that 28 d compressive strength and pulse velocity through concrete were not affected on the use of coal bottom ash in concrete. Water absorption and initial rate of absorption of water by capillary action increased on incorporation of coal bottom ash in concrete manufacturing. However, the secondary rate of absorption of water was constant for all concrete mixtures. Water absorption varied between 4.68 and 5.56% for all concrete mixtures at curing period of 28 d. With increasing age, bottom ash concrete mixtures showed significant reduction in permeable pore space and water absorption. Abrasion resistance was measured in terms of average depth of wear. Bottom ash concrete mixtures displayed marginally lesser resistance to abrasion than control concrete. All the concrete mixtures showed decrease in the average depth of wear with increasing age, in other words increase in resistance to abrasion. [ABSTRACT FROM AUTHOR]

Abstract: A novel hot spring bacterial strain was isolated and characterized from Bakreshwar, West Bengal, India. Phylogenetic analysis of partial 16 S-rRNA gene sequence (697 nucleotides) suggested that the isolate was affiliated with the family ‘Firmicutes’ and 99.8% homologous with Thermoanaerobactor thermohydrosulfuricus. A unique thermostable and high pH tolerant protein (28kDa) secreted by the bacterium was isolated whose N-terminal partial sequence (25 AA) suggested that the protein was similar to mammalian carbonic anhydrase-II. This bacterium or its unique protein both increase the compressive (>25%) and tensile (>20%) strengths, hardness and elastic modulus of cementitious material when incorporated to the cement/cement–sand mixture. The protein (named as bioremediase) possesses silica leaching activity, which is increased by calcium ions. No esterase and/or proteolytic activities are present in the protein. The use of such isolated bacterium or its protein in concrete technology develops new construction material that may be used for self-healing concrete in future. [Copyright &y& Elsevier]

The mining of natural material such as sand on large scale for use in construction of infrastructure in developing countries like India is posing threat to the environment. To save the environment, therefore, it becomes obligatory on the part of researcher to explore the utilization of industry by-products in place of natural material. In this study utilization of saw dust generated by wood industry in concrete has been explored. This article presents properties of concrete using different percentage of water and sodium silicate treated saw dust as replacement of sand. Saw dust passing through 4.75 sieve was treated with water and sodium silicate for 24 h before using in concrete. Natural sand was replaced with 5, 10,15 and 20% water treated saw dust in concrete mixture. The effect of silica fume on properties of concrete containing 5% water treated saw dust was also studied by replacing 4, 8 and 12% cement with silica fume in concrete. It was observed that concrete made with 5% water or sodium silicate treated saw dust displayed compressive strength comparable to that of control concrete. However, for 10% replacement level, compressive strength and split tensile strength decreased by 30.30% and 32.19% respectively, at 28 days. Total charge passed, water penetration and capillary water absorption increased by 224%, 153% and 117.4%, respectively, on use of 10% treated saw dust. The concrete mixture modified with sodium silicate treated saw dust showed remarkable improvement in respect of resistance to chloride ion penetration. As expected, the results showed considerable decrease in density of concrete with the use of saw dust as replacement of sand. Addition of sodium silicate treated saw dust resulted in ettringite formation in large quantity in concrete. • Sand in concrete was replaced with 5, 10, 15 and 20% water treated saw dust. • The optimum quantity of water or sodium silicate treated saw dust is 5%. • Density of concrete decreased on use of saw dust. • Strength properties of concrete modified with 5% saw dust is comparable. • Chloride ion permeability improved on silica fume in saw dust modified concrete. [ABSTRACT FROM AUTHOR]