Durability of steel reinforced concrete in chloride environments: An overview

A design scheme for self-reinforced cementitious composites to be used for building-scale 3D printing processes is introduced. The design is based on that of engineered cementitious composites, which include dispersed short polymer fibers to generate robust tensile strain-hardening. The mechanical property profile of these printable ECC materials is meant to eliminate the need for steel reinforcement in printed structures, providing more freedom and efficiency for building-scale 3D printing processes. The fresh state rheological properties have been systematically manipulated to allow printability. Effects on fresh state workability of several compositional ingredients and processing parameters are investigated herein. To maintain consistent printing performance with a batch mixing approach, thixotropy in the fresh state is exploited to temporarily decouple hardening behavior from the processing timeline. Minimal workability loss under continued shear agitation is achieved. Mechanical properties of the printable materials are characterized and the printability of the materials is demonstrated.

A self-reinforced cementitious composite for building-scale 3D printing

An exploratory study on high-volume fly ash concrete incorporating silica fume subjected to thermal loads

High-performance concrete strength prediction based on ensemble learning

In the present scenario to fulfill the demands of sustainable construction, concrete made with multi-blended cement system of OPC and different mineral admixtures, is the judicious choice for the construction industry. Silica fume (SF) and fly ash (FA) are the most commonly used mineral admixtures in ternary blend cement systems. Synergy between the contributions of both on the mechanical properties of the concrete is an important factor. This study reports the effect of replacement of OPC by fly ash (20, 30, 40 and 50 % replacement of OPC) and/or silica fume (7 and 10 %) on the mechanical properties of concrete like compressive strength and split tensile strength, with three different w/b ratio of 0.3, 0.4 and 0.45. The results indicate that, as the total replacement level of OPC in concrete using ternary blend of OPC + FA + SF increases, the strength with respect to control mix increases up to certain replacement level and thereafter decreases. If the cement content of control mixes at each w/b ratio is kept constant, then as w/b ratio decreases, higher percentage of OPC can be replaced with FA + SF to get 28 days strength comparable to the control mix. A new method was proposed to find the efficiency factor of SF and FA individually in ternary blend cement system, based on principle of modified Bolomey’s equation for predicting compressive strength of concrete using binary blend cement system. Efficiency factor for SF and FA were always higher in ternary blend cement system than their respective binary blend cement system. Split tensile strength of concrete using binary and ternary cement system were higher than OPC for a given compressive strength level.

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Effect of Relative Levels of Mineral Admixtures on Strength of Concrete with Ternary Cement Blend

Portland cement is a highly energy intensive material. Therefore, considerable effort is being made to find substitutes for partial replacement of cement in concrete. This paper reports the results from experimental studies on the compressive strength and resistance to chloride ion penetration of concrete containing ternary blends of Portland cement, silica fume (SF) and wide range of fly ash (FA) Class C fly ash is used in this study in various proportions (i.e.) 30%, 40% and 50% and that of silica fume by 6% and 10% by weight of cement. The mix proportions of concrete had constant water binder ratios of 0.4 and super plasticizer was added based on the required degree of workability. The concrete specimens were cured on normal moist curing under normal room temperature. The compressive strength was determined at various ages and the resistance to chloride-ion penetration was measured at different ages up to 90 days. The results indicate that the concrete made with these proportions generally show excellent fresh and hardened properties since the combination is somewhat synergistic. The addition of silica fume with fly ash was found to increase the compressive strength of concrete at early age when compared to concrete made with fly ash alone. Moreover the incorporation of fly ash and silica fume in concrete increases the resistance to chloride ions and produced concrete with low permeability.

Effect of Ternary Cementitious system on compressive strength and resistance to Chloride ion penetration

This paper presents the results of an experimental investigation carried out to evaluate the compressive strength of High Strength Concrete. High Strength Concrete is made by partial replacement of cement by fly ash (FA) and silica fume (SF). In this study the Class C fly ash used in various proportions 30%, 40% and 50% and that of silica fume by 6% and 10% by weight of cement. The mix proportions of concrete had a constant water binder ratio of 0.4 and super plasticizer was added based on the required degree of workability. The total binder content was 450 kg/m. The concrete specimens were cured on normal moist curing under normal atmospheric temperature. The compressive strength was determined at various ages up to 90 days. The results indicate the concrete made with these proportions generally show excellent fresh and hardened properties since the combination is somewhat synergistic. The addition of silica fume shows a early strength gaining property and that of fly ash shows a long term strength. The ternary system that is Portland cement-fly ash-silica fume concrete was found to increase the compressive strength of concrete on all age when compared to concrete made with fly ash and silica fume alone.

Study on Strength Development of High Strength Concrete Containing Fly ash and Silica fume

This research paper presents the use of wasteful supplementary cementitious materials like fly ash and silica fume to conserve the cement used in concrete. The cement industry is one of the major producers of greenhouse gases and an energy user. In this study, Portland cement was used as a basic cementitious material. Fly ash and silica fume were used as the cement replacements by weight. The replacement levels of fly ash were 30%, 40% and 50%, and silica fume were 6% and 10%. The water binder ratio was kept constant as 0.4 and super plasticizer was added based on the required workability. Results of the binary and ternary concrete mixtures compressive strength, split tensile strength and flexural tensile strength were taken for studyup to 90 days. Based on the experimental results of compressive strength, prediction models were developed using regression analysis and coefficients were proposed to find the split tensile strength and flexural strength of binary-ternary concrete mixtures at 28 and 90 days.

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A R Hariharan

Papers

Effect of Ternary Cementitious system on compressive strength and resistance to Chloride ion penetration

Study on Strength Development of High Strength Concrete Containing Fly ash and Silica fume

Statistical model to predict the mechanical properties of binary and ternary blended concrete using regression analysis