Effects of graphite nanoplatelets (GNPs) and carbon nanofibers (CNFs) on mechanical properties of ultra-high-performance concrete (UHPC) are investigated. A non-proprietary UHPC mixture composed of 0.5% steel micro fibers, 5% silica fume, and 40% fly ash was used. The content of the nanomaterials ranged from 0 to 0.3% by weight of cementitious materials. The nanomaterials were dispersed using optimized surfactant content and ultra-sonification to ensure uniform dispersion in the UHPC mixture. As the content of nanomaterials is increased from 0 to 0.3%, the tensile strength and energy absorption capacity can be increased by 56% and 187%, respectively; the flexural strength and toughness can be increased by 59% and 276%, respectively. At 0.2% of GNPs, the UHPCs exhibited “strain-hardening” in tension and in flexure.

Mechanical Properties of Ultra-High-Performance Concrete Enhanced with Graphite Nanoplatelets and Carbon Nanofibers

Cracks in cement concrete composites, whether autogenous or loading-initiated, are almost inevitable and often difficult to detect and repair, posing a threat to safety and durability of concrete infrastructures, especially for those with strict sealing requirements. The sustainable development of infrastructures calls for the birth of self-healing concrete composites, which has the built-in ability to autonomously repair narrow cracks. This paper reviews the fabrication, characterization, mechanisms and performances of autogenous and autonomous healing concretes. Autogenous healing materials such as mineral admixtures, fibers, nanofillers and curing agents, as well as autonomous healing methods such as electrodeposition, shape memory alloys, capsules, vascular and microbial technologies, have been proven to be effective to partially or even fully repair small cracks. As a result, the mechanical properties and durability of concrete infrastructure can be restored to some extent. However, autonomous healing techniques have shown a better performance in healing cracks than most of autogenous healing methods that are limited to healing of cracks having a width narrower than 150 μm. Self-healing concrete with biomimetic features, such as self-healing concrete based on shape memory alloys, capsules, vascular networks or bacteria, is a frontier subject in the field of material science. Self-healing technology provides concrete infrastructures with the ability to adapt and respond to the environment, exhibiting a great potential to facilitate the creation of a wide variety of resilient materials and infrastructures.

Self-healing cement concrete composites for resilient infrastructures: A review

Effect of Graphite Nanoplatelets and Carbon Nanofibers on Rheology, Hydration, Shrinkage, Mechanical Properties, and Microstructure of UHPC

Recycled powder (RP) is the main by-product in the reclamation of construction and demolition (CD in addition, improvement methods and a benefit evaluation of RP concrete are further introduced. Based on statistical data that describe the activity index of RP and the compressive strength of RP concrete, the median diameter and replacement ratio of RP in concrete preparation should be below 30 μm and 30%, respectively. The use of RP improves the durability of concrete when the RP fineness is superior to the cement fineness. Increasing the RP fineness is an effective approach to improving the properties of RP concrete, and a CO2-curing treatment of RCP is an eco-friendly modification method. Furthermore, the use of RP in concrete has good economic and environmental benefits. Therefore, one expects that this review helps the further use of RP in concrete.

The utilization of eco-friendly recycled powder from concrete and brick waste in new concrete: A critical review

Potential use of brick waste as alternate concrete-making materials: A review

There has been a persistent drive for sustainable development in the concrete industry While there are series of encouraging experimental research outputs, yet the research field requires a standard framework for the material development In this study, the strength characteristics of geopolymer self-compacting concrete made by addition of mineral admixtures, have been modelled with both genetic programming (GEP) and the artificial neural networks (ANN) techniques The study adopts a 12M sodium hydroxide and sodium silicate alkaline solution of ratio to fly ash at 033 for geopolymer reaction In addition to the conventional material (river sand), fly ash was partially replaced with silica fume and granulated blast furnace slag Various properties of the concrete, filler ability and passing ability of fresh mixtures, and compressive, split-tensile and flexural strength of hardened concrete were determined The model development involved using raw materials and fresh mix properties as predictors, and strength properties as response Results shows that the use of the admixtures enhanced both the fresh and hardened properties of the concrete Both GEP and ANN methods exhibited good prediction of the experimental data, with minimal errors However, GEP models can be preferred as simple equations are developed from the process, while ANN is only a predictor

Estimating strength properties of geopolymer self-compacting concrete using machine learning techniques

This article discusses the use of high per cent by-products (ie marble powder, brick powder) in green concrete to develop a procedure which construction industry can use This current study, ther

Fresh and hardened properties of green binder concrete containing marble powder and brick powder

Advancements in mechanical and physical properties for marble powder–cement composites strengthened by nanostructured graphite particles

Strength gain mechanisms of blended-cements containing marble powder and brick powder were investigated in the presence of chemical composition changings of cement pastes. Blended Cements (BC) were prepared blending of 5% gypsum and 6%, 20%, 21% and 35% Marble Powder (MP) or 6%, 20%, 21% and 35% Brick Powder (BP) for CEMI42.5N cement clinker and grinding these portions in ball mill at 30 (min). Pastes and mortars were also drawn up with these cements. Chemical compositions of pastes, Compressive Strength (CS) and Flexural Strength (FS) of mortars were determined at 7th-day, 28th-day and 90th-day according as standard methods. Experimental results indicated that fluctuation of SiO2, Na2O and alkali at Marble Powder-Blended Cement Paste (MP-BCP) and continuously increasing of SiO2 at Brick Powder-Blended Cement Paste (BP-BCP) positively induced strength gain mechanism of BCM since MP up to 6% or BP up to 35% were blended for cement.

Strength gain mechanisms of blended-cements containing marble powder and brick powder

This is a full article that overcomes such some negative side effects as rapid coagulation and reduced early strength in class F fly ash-substituted cement (FFA-SC) by serving nano graphite particle (nG) This study uses class F fly ash (FFA), nG, and ASTM type I cement as constituent materials to prepare proper pulverized fly ash–Portland cement combinations (35% FFA + 65% ASTM I + 11% nG ie) Pastes include lime and/or lime + nG, and tap water to examine ups and downs in Ca(OH) 2 content Mortars also contain these prepared cements, tap water and/or tap water + super plasticizer (SP), and mortar sand in order to measure fluidity, flexural strength, and compressive strength according to present standard methods Results indicate for FFA-SC system that the nano graphite particle increases the reduced early strength gain at early age, and the SP reduces the rapid coagulation The use of nG also shows to be favorable in terms of the Ca(OH) 2 content, the fluidity and the flexural strength gain, and compressive strength gain in FFA-SC system when compared to the pure Portland cement with and without nano graphite particle

Mehmet Serkan Kirgiz

Papers

Estimating strength properties of geopolymer self-compacting concrete using machine learning techniques

Fresh and hardened properties of green binder concrete containing marble powder and brick powder

Advancements in mechanical and physical properties for marble powder–cement composites strengthened by nanostructured graphite particles

Strength gain mechanisms of blended-cements containing marble powder and brick powder

Advance treatment by nanographite for Portland pulverised fly ash cement (the class F) systems