Indian Concrete Journal

Sorptivity test on quaternary blended concrete Seshadri Sekhar T., P. Srinivasa Rao, V. Kiran Kumar

The growing importance of high-strength/high-performance concrete necessitates using alternatives to cement as binding materials. The making of high-strength/performance concrete may be met by the addition of supplementary cementitious materials which are byproducts/waste products of other industries. The cement is partially replaced by these supplementary cementitious materials (SCMs) and some of the SCMs are very fine in size densifies the pore structure thereby improving strength and durability. The concrete performance is greatly affected by the penetration of water into the concrete structures. The penetrated water or harmful liquids into the inner part of concrete structures through interconnected voids leads to the deterioration of concrete. Some of the commonly used SCMs are fly ash, ground granulated blast furnace slag (GGBS), micro silica, rice husk ash, metakaolin, etc. The recent trend in research shows that the use of nanomaterials in combination with above SCMs showing greater performance in durability and mechanical aspects. The current study compares the sorptivity of quaternary blended concrete with that of control concrete by utilizing several SCMs, including fly ash, nano silica, and metakaolin. Owing to its compact structure and improved particle refinement, the quaternary blended concrete outperforms the control concrete in terms of water resistance. The increased performance was due to the addition of SCMs which led to dense and uniform microstructure and also due to a compact interfacial transition zone. The addition of these SCMs like fly ash decreases the emission of greenhouse gases and also solves the problem of disposal.

Effect of mineral admixtures on compression and aggregate type on infiltration of pervious concrete: A review Khandare Manish A., Agarwal Anil L.

Pervious concrete known as no fine concrete, porous concrete, gap-graded concrete, or draincrete has lesser density and a high percentage of interconnected voids in comparison with conventional concrete. Voids in the pervious concrete allow water to pass and help in groundwater recharge. The high percentage of voids in the pervious concrete is responsible for strength reduction and hence its application is limited to low volume traffic. This paper examines how mineral admixtures affect compressive strength and how aggregate type affects infiltration of the pervious concrete. The physical and chemical properties of fly ash, metakaolin, rice husk ash, granulated blast furnace slag, and silica fume are examined. We address the studies on the effect of various mineral admixtures with different dosages on the compressive strength of pervious concrete. The effect of aggregate type and size on infiltration rate is also examined. Partial replacement of cement with mineral admixtures increases the compression of pervious concrete. The combination of SF and fibers improves compressive strength up to 41.2 MPa and the replacement of cement by ground granulated blast furnace slag (GGBS) enhances compressive strength upto 42 MPa. This paper also observes how biopolymers including cellulose, starch, alginate, pectine, and carrageenan improve the properties of conventional concrete. The compression of hemp concrete is improved by 53 and 92 % with the addition of 3 and 5 % Gum Arabic. Since limited studies on the effect of biopolymers on the mechanical properties of pervious concrete are available, the authors propose to identify the effect of biopolymers on the mechanical properties of the pervious concrete.

Impact of grounded low calcium fly ash on the strength of geopolymer concrete Avinash Ojha, Unnati S. Agrawal, Rahul Daiya, Aman Jain, Aman Ahlawat, Praveen Aggarwal

This research investigates the influence of the fineness of lowcalcium fly ash on the compressive strength of geopolymer concrete. Fly ash was procured from two different thermal power plants and subjected to grinding in a Los Angeles Abrasion Testing Machine for 250 and 500 revolutions to achieve finer particle sizes. Geopolymer concrete was synthesized by activating these fly ashes with a 14M sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) solution mixed in the ratio of 1:2.5, respectively, to produce the alkaline activator solution. The activated fly ash was then combined with fine and coarse aggregates and water to form the concrete mix. Specimens were heat-cured at 80°C for 24 hours to enhance geopolymerization. Compressive strength tests revealed that increased fly ash fineness led to a significant enhancement in strength, with improvements of approximately 7 % for chabra low calcium fly ash (CLCF)-based concrete and 9 % for kota low caclium fly ash (KLCF)-based concrete. These findings highlight the importance of fly ash fineness in enhancing geopolymer concrete’s mechanical properties, confirming its potential for sustainable construction Future research could explore the impact of varied curing conditions, different fly ash sources, and long-term durability tests to further enhance the understanding and applicability of geopolymer concrete.

Performance evaluation of alternative fine aggregates in concrete Shashank B. S., Praveen Kumar K.

Shortages of river sand impede the construction industry’s ability to procure high-quality fine aggregates for concrete. This problem compels scholars to explore alternatives to river sand for construction purposes. Despite the widespread utilization of M-sand, it is not a viable alternative. The construction business is progressively pursuing alternatives. The main objective of the study is to investigate sustainable alternative fine aggregates that can substitute M-sand. A comparative investigation on the strength properties of concrete incorporating M-sand, pond ash, and steel slag has been conducted. The study showed that steel slag possesses greater angularity, a rougher surface, and a larger total specific surface area, in comparison to pond ash, which is inherently smoother. For conventional M25 grade concrete in comparison to M-sand, these alternative aggregates exhibit superior strength and enhanced concrete properties. Fine particles diminish the workability of concrete across diverse mix patterns. Concrete formulated with only pond ash exhibits a 60 % increase in compressive strength for 30 % replacement, and a mixture containing 10 % pond ash and 50 % steel slag demonstrates approximately 49 % enhanced strength due to the angular and rough particles that augment the strength of alternative fine aggregate combinations, albeit without improving workability. Steel slag and pond ash can substitute for M and river sand. This study may address the deficiency of river sand and M-sand in the market.

State-of-the-art review on axial behavior of frp-concrete-steel double-skin tubular columns P. Praneet Sai Kumar, Shamsher Bahadur Singh, Sudhirkumar V. Barai

Over the last twenty years, there has been considerable focus on the use of fibre-reinforced polymer (FRP) composites as confinement substances. The hybrid double-skin tubular column (DSTC) represents an innovative construction approach, comprising an external fibre-reinforced polymer (FRP) tube, an inner steel tube, and a concrete infill. These columns are primarily designed to offer corrosion and seismic resistance, DSTCs have gained popularity in bridges and offshore structures applications. This paper aims to provide an unbiased evaluation of the experimental research efficiency of hybrid FRPconcrete-steel double-skin tubular columns subjected to axial compression while exploring various critical parameters, as well as numerical and analytical studies. The examined parameters include the buckling behavior of the inner steel tube, the diameter of the inner steel tube, FRP tube thickness, the orientation of fibres, failure modes, axial load-strain behavior, FRP hoop rupture strain, concrete strength and concrete type, the interaction between steel and FRP tubes, filling the inner steel tube, stiffened DSTCs, and cross-sectional form. The review findings emphasize the importance of future research in areas such as non-circular column members, the use of natural fibres for the outer FRP tube, and numerical and analytical studies. These insights are valuable for researchers, practitioners, and decision-makers involved in designing, constructing, and retrofitting efficient and resilient structures as hybrid DSTCs.