Journal Sep 2023

Versatile concrete with limestone calcined clay cement Manu Santhanam, Smrati Jain, Shantanu Bhattacherjee

Limestone calcined clay cement (LC3) is a mixture of clinker, calcined clay, limestone powder, and gypsum. The special blend of ingredients gives unique characteristics to this cement, which leads to improved performance of the concrete apart from lowering the sustainability impact as compared to ordinary Portland cement (OPC) concrete. While the durability in chloride environments is a major plus of LC3, there are issues with the achievement of workability and its retention. Different strategies can be employed to improve the workability characteristics of such systems. This paper describes the versatility of concrete with LC3 using three case studies – (i) achievement of durability in chloride environment even with poor quality control during the concreting process, (ii) use of limestone calcined clay binder in combination with Portland pozzolana cement (PPC) for the manufacture of tetrapods for breakwater purpose, and (iii) use of LC3 in 3D printed concrete that results in taking advantage of its difficult rheology.

Development and application of environmentally friendly concrete in Japan - energy·CO2 minimum (ECM) concrete Masaro Kojima, Daijiro Tsuji

Energy·CO2 Minimum (ECM) concrete, one of Japan’s leading environmentally friendly concrete products, achieves a reduction of 60-70 % in CO2 emissions compared to conventional concrete by utilizing a significant amount of ground granulated blast furnace slag and using a binder that optimizes the type and dosage of gypsum, all while maintaining high quality. In this paper, slump retention, exothermic characteristics, strength development, shrinkage cracking resistance, durability and fire resistance are discussed as the properties of ECM concrete. In addition, examples of application to structures using these characteristics are described.

Impact of addition of fly ash (as sand replacement) and polypropylene fibers on shrinkage and thermal characteristics of foam concrete Chandrashekhar D. Wagh, Indu Siva Ranjani Gandhi, Kasi Venkatesh Neti

Foam concrete (FC) has recently received a lot of attention owing to its excellent properties such as high workability, low density, and low thermal conductivity (TC). The aggregate requirements of FC being different from conventional concrete, the fly ash (FA), the most commonly used industrial residue has great potential to serve as filler in FC. Thus, this work quantifies the effects of FA, (as filler replacement) and polypropylene (PP) fibers on shrinkage, thermal, and mechanical properties of FC made with natural hingot surfactant. In this study, three FC densities were used to test four FA replacement levels (0, 25, 45, and 65 %) and four PP fiber addition levels (0, 0.1, 0.2, and 0.3 % by weight of solids). Results show that increasing FA percentage improves FC’s pore structure, increasing compressive strength and lowering TC. Addition of PP fibers reduced FC shrinkage by 40 % in this study. Despite the stated benefits, adding more PP fiber (0.3 %) caused uneven distribution, decreasing FC compressive strength. Hence the experimental outcomes of present study have proved that addition of optimum levels of FA and PP fibers are sustainable measures to enhance the performance of FC produced with hingot surfactant without affecting the foam stability.

A comparative study of life cycle embodied energy of precast vs cast-in-place concreting in the Indian context Ashwin Mahalingam, Anisha Picardo

Buildings consume energy in their life cycle right from construction to demolition. Calculating the embodied energy provides a good indicator of the environmental impact of any structure. This paper compares the embodied energy from cradle to handover stage, of precast and cast-in-place floor slabs for an upcoming sports complex at a Indian Institute of Technology, Madras. The findings show that the energy expended for the precast floor slab is 10 % less than the cast in place floor slab, with manufacturing embodied energy of raw materials accounting for more than 90 % of the energy use. Although transportation of the slabs required greater energy in precast construction, it was more sustainable given the lower quantity of materials and the more efficient manufacturing and construction practices. As we work on ways to develop more sustainable buildings, precast construction may prove to be a very effective option.

Strength and impact behavior of paving concrete incorporating discarded coconut coir fibers Raul Zerbino, Juan Vivas, Ronald Cruz, Felipe, María Celeste Torrijos, Francisco Hours, Graciela Giaccio, Someen Khute, Surender Singh

With the aim to explore the potential contributions of discarded coconut fibers (DCF) as reinforcement in concrete the hardened properties of coir concrete of similar slump, with different fiber lengths and dosages are analysed in this paper, including compressive strength and stiffness, flexural response, and mainly the resistance to impact loading using two tests, that proposed by the ACI Committee 544 and a new method based on the application of Growing Impact Loads. It was found that DCF yields similar effects as synthetic microfibers in fresh and hardened properties of concrete but the incorporation of longer DCF shows improvement in terms of impact resistance

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