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Chloride ingress in concrete leads to deterioration of reinforcement and subsequent distress in concrete. The focus of the present study was to determine the amount of chloride ingress in concrete with and without supplementary cementitious materials (SCM) using Rapid Chloride Penetration Test (RCPT) and Rapid Chloride Migration Test (RCMT). A comparison of chloride ingress was made of Control concrete with six other mixtures having varying percentages of fly ash (20% & 30%), ground granulated blast furnace slag (GGBFS) (30% & 40%), silica fume (5%) as replacement of cement. Compressive strength, RCPT and RCMT tests were evaluated for all the mixtures after 28 and 90 days respectively. A correlation between RCPT and RCMT tests was established. Mixtures containing fly ash as SCM had lesser initial compressive strength compared to mixtures with GGBFS and silica fume. Chloride permeability of concrete mixture with silica fume as SCM has a significant decrease in chloride permeability in both RCPT and RCMT tests at both ages compared to concrete without SCM. Estimation of service life was carried out using Life-365TM software. It was observed that the service life of concrete without SCM was estimated to be 14.8 years while in the concrete with 5% silica fume expected service life was 24.9 years. Thus, the incorporation of supplementary cementitious material in concrete enhances the service life and is a boon to the construction industry.

One of the sustainable alternatives to Portland cement is geopolymer concrete consisting of industrial waste. Practical application of geopolymer concrete is restricted as it requires the use of high temperature to develop compressive strength. This study aims to develop a mixture design for geopolymer prestressed concrete specifically designed to take prestressing force using ambient curing technique and compare its performance with the same grade of Portland cement concrete mix. As ambient curing technique is used for geopolymer concrete hence a combination of blast furnace slag and fly ash is taken as source materials and due to ease of availability and economy, sodium hydroxide and silicate are chosen as activators. After several trial mixtures, M 40 grade of geopolymer concrete is developed using an equal proportion of fly ash and ground granulated blast furnace slag (GGBFS) as source material. GGBFS provides early strength at ambient curing in geopolymer concrete and hence was incorporated with fly ash. 3 ply of 3 mm diameter bars were used as pre-tensioning wire. Load v/s deflection graph for non-prestressed geopolymer concrete beams and beams with same grade Portland cement concrete show that the load-carrying capacity of both beams was at par. It was also observed that prestressed geopolymer concrete beams which were cured under ambient curing developed sufficient strength and were equally capable of carrying the load as compared to Portland cement concrete beams. Load carrying capacity increased in prestressed Portland cement concrete beams increased by 78% while in prestressed geopolymer concrete beams the increase was 83% and also the deflection of both prestressed beams was more compared to non-prestressed beams. This indicates that sustainable material can be effectively utilized in prestressing work without comprising on strength.

Manual inspection of cracks on concrete surfaces requires wholesome knowledge and depends entirely on the expertise and capabilities of the inspector. This study proposes the use of a simple Convolutional Neural Network (CNN) for automatic crack detection. A comparative approach for Automated Crack Detection is presented between Feed-Forward Fully Connected Neural Networks and CNN, focusing on the primary hyperparameters affecting the accuracy of both systems. An inclination towards CNN is concluded due to its simplicity and computational efficiency. For the purpose of this study, the input data is extracted from an open-source platform. In the second step, the images are pre-processed for obtaining lowpixel density images with the aim to get better accuracy at lower computer power. The CNN proposed uses Max Pooling and appropriate optimization techniques. The model is trained to detect and segregate cracked and non-cracked concrete surfaces through input images. The proposed model predicts and labels images with cracks on concrete surfaces and images with no cracks using pixel-level information. The final accuracy achieved is 97.8% by the proposed CNN model. The proposed model is a novel approach to detecting cracks on low pixel density images of concrete surfaces for its economic and processing efficiency and thus eliminates the need for high-cost digital image capturing devices. This study signifies and confirms the impact of Artificial Intelligence in the Civil Engineering field where using simple techniques like a simple four-layered Neural Network is capable of carrying automatic inspection of cracks which can be further developed for other applications. [ABSTRACT FROM AUTHOR]

Concrete is one of the widely used building material in the world and chief agent which does the binding of all the compounds is cement. Deterioration of concrete structure takes place due to cracks in the concrete. In order to minimize the crack formation an attempt is made to incorporate self-healing compound. Few of the self-healing compounds that can be introduced are urea, calcium formate and calcium acetate. Various dosage of urea was added and its effect on three parameters consistency, setting time and compressive strength was evaluated. Optimum dosage of urea was found to be 2.5% beyond which incorporation in cement paste will lead to decrease in compressive strength. Similarly, when 2.5% of cement is replaced by calcium formate and calcium acetate it will lead to significant change in compressive strength. [ABSTRACT FROM AUTHOR]

Waste management generated by industries is one of the major problems faced by world. Majority of the waste generated by industries fall in non-biodegradable category like plastic, rubber, glass, fly ash and ceramic waste. Being generated in large quantity and as it is non-biodegradable, its disposal possesses huge challenge, ceramic waste being one of them. As these kinds are generally dumped as landfilling it pollutes land and water. Mostly ceramic waste is generated from wastage of tiles and have silica (SiO2) and alumina (Al2O3) ions. In present study, three concrete mixtures were prepared for M 25 grade of concrete. Mix A with 0% replacement, Mix B with 20% replacement and Mix C with 20% replacement of ceramic fine powder with cement. Mechanical properties were evaluated for all three-mixture design. It was observed that, the compressive strength and flexural strength of mix B which is partial replacement of 10% with cement have nearly gives same results compare to mix A. The density of mix B is decreased compare to Mix A due to fineness of ceramic powder. [ABSTRACT FROM AUTHOR]

Sustainable development and preservation of environment for future generation are the need of the hour. It is very much essential to have an alternative to cement due to its disadvantage of large emission of carbon dioxide into atmosphere and highly energyintensive process. Geopolymer concrete is an alternative to conventional concrete. This paper presents a study carried out on the combination of industrial waste fly ash and slag as source materials and the factors affecting the compressive strength of oven cured specimen. The ratio of alkaline liquid to source material was kept at 0.4, the rest period at 1 day and temperature at 90 °C. The density of geopolymer concrete was kept approximately equal to 2400 kg/m3 equivalent to conventional Ordinary Portland Cement (OPC) concrete. It was found that compressive strength of geopolymer concrete increased with increase in curing duration. Increase in strength was also observed with increase in molarity and increase in alkaline solution ratio. Also, if dosage of superplasticizer increased, workability also increased, and it led to increase in compressive strength. [ABSTRACT FROM AUTHOR]

The article presents a discussion of the article "Plastic Hinge Lengths in High-Rise Concrete Shear Walls," by Alfredo Bohl and Perry Adebar from the March-April 2011 issue as well as a response from the authors. Various elements of the empirical equations presented in the original article are reviewed, including the definition of loading conditions, ductility values, and maximum curvature demand.