M. Shanmugasundaram’s research while affiliated with Chennai Institute Of Technology and other places

Magnesium oxychloride cement (MOC) has recently garnered considerable research attention as an environmentally sustainable building material. Nevertheless, the mechanical characteristics of MOC have effectively hindered its extensive implementation in engineering structures owing to their inefficient water resistance. In this regard, this study investigates the novel application of steatite to MOC to augment the water resistance of paste. First, steatite was thermally processed to improve the reactivity of the particle and was introduced as a metasteatite with rich magnesium silicate. Furthermore, metasteatite is substituted for MgO in the MOC paste by varying the replacement level from 0 % to 25 % with an interval of 5 %. Thus, metasteatite's effect on MOC paste water resistance is investigated in terms of compressive strength, strength retention under water exposure, and microstructural characterization. Compressive strength results revealed that the influence of metasteatite deteriorated the strength of the matrix with an increased dosage of metasteatite. Moreover, the compressive strength of MOC paste susceptible to water enhanced the strength retention coefficient to 42.9 % for MS10 compared to control specimens. FE-SEM analysis exhibits the formation of M-S-H gel that leads to dense microstructure and contributes to water resistance. In addition, the porosity of the paste is decreased owing to the reaction of Phase 5 with SiO2. The EDS analysis and mapping showed the occurrence of hydration products and the binding affinity between Mg and Si, which improved the continuity of microstructure and water resistance of MOC paste. Therefore, the optimum enhancement is observed for the MOC paste with 10 % metasteatite, demonstrating its efficacy in bolstering water resistance. Finally, this investigation elucidates the feasibility of using metasteatite as a supplementary material for MgO in MOC for developing water resistant MOC.

This study aims to investigate the behavior of alkali activated mortar, which is made of naturally available magnesium silicate as source material. For magnesium silicate, ultrafine natural steatite powder (UFNSP) is used as the primary source of binder, and the activation is initiated through the alkali liquid which is proportioned in various combinations of silicate to hydroxide ratio (Na2SiO3/NaOH) ratio, and this ratio in this study varies from 1 to 3. The UFNSP is calcined at two different temperatures, 700 and 1 000 °C. The mortar mix is proportioned as 1:3 between powder and the fine aggregate, and the mortar is prepared with hydroxide molarity (M) of 10 M. The mortar is cured for 48 hours at 60 °C and the compressive strength was studied. All the mix were studied for its microstructural behavior along with compressive strength. The mix proportion of the mortar, and the results obtained through microstructural characterization were combinedly formed as input for artificial neural network(ANN) predictive modelling. The model is designed to predict the compressive strength, which is trained through Bayesian regularization algorithm with varying hidden neurons of 7 to 10. This experimental and predictive study shows that the strength is influenced by both Na2SiO3/NaOH ratio and calcination process. And the ANN is influenced by mainly calcination temperature and uncorrelation occurs in selected samples of 1 000 °C calcined UFNSP mix.

This research examines the effects of using a combination of Ground Granulated Blast furnace Slag (GGBS) and Hydrated Lime (HL) as alternative cement ingredients on the mechanical and microstructural properties of ternary mixed concrete (Ordinary Portland Cement (OPC)+GGBS+HL). The OPC was replaced with GGBS in increments of 10% from 10% to 70%, while HL was substituted at levels ranging from 0% to 20% in increments of 10%. The results showed that the highest compressive strength (56.20 MPa), split tensile strength (4.25 MPa), and flexural strength (5.58 MPa) were observed for the ternary concrete mixture containing 60% OPC, 30% GGBS, and 10% HL with 0.36 water binder ratio after 28 days of curing.

This work enunciates the effect of Multi-Walled Carbon Nanotubes (MWCNTs) as an addition to concrete subjected to normal environment and adverse environment. The MWCNTs are dispersed in water in the range of 0 to 0.25 % by weight of cement. The dispersed MWCNTs are added in concrete during its manufacturing process, and get cured for 28 days. Then portion of the samples are tested for its compressive strength, further samples are placed in exposed conditions, such as 5% concentrated sodium chloride solution and 5% concentrated sulphuric acid solution for a period of 4 weeks and 8 weeks respectively. The effect of this exposure is studied through changes in the weight density and compressive strength of the samples. All the exposed and unexposed samples were studied for its microstructural behavior through scanning electron microscopy. Ultimately, this work elucidates the influence of MWCNTs in the resistance of concrete under adverse environmental condition

Alkali activated binders are emerging sustainable binders in the construction sector due to their higher strength and superior resistance against aggressive environments than cement concrete. Steatite powder is obtained as a by-product from soapstone processing and disposed of as waste in large quantities. Studies on the reuse of steatite powder in alkali-activated concrete are highly narrow. Hence, the current research majors on the influence of ultra-fine steatite powder on the mechanical as well as durability properties of slag and fly ash-based alkali-activated concrete. Six replacement levels (10, 20, 30, 40, 50, and 60%) of slag and fly ash with steatite powder were adopted and activated using sodium-based activator. Heat curing and ambient curing were performed for fly ash-steatite concrete and slag-steatite concrete, respectively. From the test results, 30% steatite powder is optimum in slag and fly ash-based alkali-activated concretes. Lesser water absorption and higher resistance against acid exposure are observed for steatite used alkali-activated concrete specimens.

Ultrafine graded fly ash (UFGFA) is a well‐graded pozzolanic material among silica‐rich reactive pozzolans that contributes to the improvement of the early pozzolanic reactivity of cement paste, mortar, and concrete at early ages. The purpose of this article is to demonstrate the effect of UFGFA on the development of compressive strength in M20, M25, and M30 grade concretes with a partial replacement of cement ranging from 0% to 40% by weight at various water‐binder (W/B) ratios of 0.43–0.53. Compressive strength development was examined at ages 7, 14, 28, and 56 days. Additionally, three machine learning (ML) models (linear regression, ANN, and GEP) were used to predict the compressive strength of the concretes using different predictive classifications. According to the investigations, experimental studies indicate that a lower W/B ratio and a minimum amount of UFGFA replacement result in an increase in strength at an early age of 7 days. At 14, 28, and 56 days, higher strength results were obtained when 15%–30% UFGFA was replaced with a W/B ratio less than 0.5, whereas a reduction in strength was observed when more than 30% UFGFA was replaced with cement and with W/B ratio greater than 0.5. All machine learning models produced good predictions of compressive strength, with LR models having least performance and ANN has the more accurate fit. ANN models outperformed the other three machine learning models, but GEP models performed identically near to the ANN model, with expressions generated, that can be used for further development of predictive model.

The industrial adoption is wide spread in present scenario because of this generation of waste increasing enormously. Reuse and recycling of it is very crucial to safeguard the environment. Through recycling of waste materials and the reduction in carbon emissions geopolymer concrete has the considerable capability to firmly come up with environmental sustainability in industrial sector as well as in construction sectors. Past two decades substantial amount of research has been performed to know the ability of geopolymer and to mitigate the use of ordinary Portland cement. However, geopolymer industry has to face number of challenges to adopt it in construction. Most amount of research was carried and also continuing for wide variety of waste as procures and as aggregates in geopolymer concrete. In this paper construction and demolition, energy production, metal industry, mining and enrichment of ore waste utilization in geopolymer concrete is discussed .Various properties of geopolymer concrete such as their rheology, fresh properties and hardened properties, their environmental susceptibility for aggressive conditions such as chloride and sulphate attack and also to various hazards salts because of which it losses in its strength are discussed. The main agenda of this paper is to review the research into various industrial waste-integrated Geopolymers and specify the difficulties to adopt it in industrial production with an observation to pointing the path for further research.KeywordsGeopolymerAlkali activated concreteSustainable materialReuseIndustrial waste

Self-compacting concrete (SCC) is a highly stabilized flowable concrete that can be used in both dynamic and static states without segregation. Additionally, the exceptional homogeneity of the material contributes to its strength and durability. To produce sustainable SCC, it is necessary to incorporate appropriate supplementary cementitious materials (SCMs) to enhance mass construction applications. Thus, this review of SCC examines the stages of development and adoption, with a particular emphasis on the role of various calcium-rich, silica-rich, and engineered/reactive silica-rich SCMs as blends in achieving sustainable concrete. By summarising and comparing the properties of SCC in the plastic and hardened states in terms of workability, segregation, strength, and durability. According to the annotations in this review, researchers proposed that during the early stages of developing studies on SCC, the limits of constituent material proportioning be designed with the influence of ultra-fine fly ash (UFFA), an improved reactive supplementary material with a more appropriate particle size that is engineered from high silica-rich fly ash. Additionally, prior research indicates that an artificial neural network (ANN) is a more effective prediction tool for conducting and validating SCC experiments. However, no comprehensive study has been conducted on the effect of ultra-fine fly ash (UFFA) on SCC in the plastic and hardened states; additionally, the ANN can be an excellent tool for validating those properties, which is the novel scope of this review.

The water used in preparation of cement composite is going to be altered through magnetization. When the water is kept in magnetic field the additional hardness elements i.e., Ca, Mg and Fe get separated from water. But this separation cannot be done through normal magnetic field. Hence high electromagnetic diffuser or high-end magnets are needed. In this study Neodymium (Nd) - N52 magnets were used which has an atomic number 60. The water kept under the magnetic field for various time periods. The strength variation and development will be studied for mortar on various edges.

This paper predicts the compressive strength of reinforced cement concrete with different pozzolan having different biproducts such as flyash, GGBS, silica fumes and rice husk on 28 days with multiple regression analysis (MRA) and artificial neural network (ANN) and compares them. The model prepared uses the data from the previously published papers; the data collected from the papers are cement content, coarse aggregate, fine aggregate, water/cement ratio, replacement of cement with pozzolan materials like GGBS, flyash, silica fumes, rice husks, S i O 2 , Al 2 O 3 , Fe 2 O 3 , CaO, MgO, SO 3 quantities are taken in the form of input for the models and the respective compressive strength obtained from the literature is taken as the target strength or parameter. The result shows that this the model made with these parameters produces a valid model through MRA and ANN.