Development of Statistical Model, Mixture Design, Fresh and Hardened Properties of Furnace Slag - Lightweight Self Consolidating Concrete (FS-LWSCC)

A response surface method was carried out to model the influence of key mixtureparameters on properties affecting the performance of Expended Furnace Slag - LightweightSelf Consolidating Concrete (FS-LWSCC). Three key parameters that have significantinfluence on mixture characteristics of LWSCC were selected to derive mathematical modelfor evaluating the concrete fresh and hardened properties. Experimental levels of the variables(maximum and minimum) water/binder ratio (0.30 to 0.40), HRWRA (SP) (0.3 to1.2% bytotal content of binder), and total binder content (410 to 550kg/m3) were used for the designof Furnace Slag-LWSCC mixtures. A total of 18 mixtures were designed and produced. Theresponses of the derived statistical model were slump flow, V-funnel flow time, J-Ring flow,J-Ring height difference, L- box, filling capacity, bleeding, air content, initial and final settingtime, sieve segregation test, fresh unit weight, 28 days air dry unit weight, 28 days oven dryunit weight, and 7 and 28 days compressive strengths. It was seen that the proposed mixdesign model is a useful tool to understand the interactions between mixture parametersaffecting important characteristics of Expanded Furnace Slag - LWSCC. This understandingmight be simplified the mix design process and the required testing, as the model identifiesthe relative significance of each parameter, therefore providing important informationrequired to optimize the mix design. Consequently, minimize the effort needed to optimizeLWSCC mixtures ensuring balance between parameters affecting fresh and hardenedproperties

MAT-731: MECHANICAL & DURABILITY PROPERTIES OF ENGINEERED CEMENTITIOUS COMPOSITES WITH DIFFERENT AGGREGATES

This paper presents the outcome of a study conducted to exhibit the effect of micro-silica sand and mortar sand on fresh, mechanical and durability properties of Engineered Cementitious Composites (ECCs). ECC is a ductile concrete characterized by strain hardening and multiple-cracking behavior under tension and shear. This study used locally available aggregates instead of standard micro-silica sand to produce cost-effective, sustainable and green ECC mixtures to be used for construction applications. ECCs prepared by both types of sands exhibited almost similar behaviour in terms of fresh, mechanical and durability properties which indicated the viability of producing ECC mixtures with mortar sand. In addition, the behaviour of a standard ECC can still be achieved when producing ECCs made of high volume fly ash (up to 70% cement replacement) along with local mortar sand. By employing results of this research, correlations were derived between mechanical and durability properties

Use of spent foundry sand and fly ash for the development of green self-consolidating concrete

In the United States alone, the foundry industry discards up to 10 million tons of sand each year, offering up a plentiful potential resource to replace sand in concrete products. However, because the use of spent foundry sand (SFS) is currently very limited in the concrete industry, this study investigates whether SFS can successfully be used as a sand replacement material in cost-effective, green, self-consolidating concrete (SCC). In the study, SCC mixtures were developed to be even more inexpensive and environmentally friendly by incorporating Portland cement with fly ash (FA). Tests done on SCC mixtures to determine fresh properties (slump flow diameter, slump flow time, V-funnel flow time, yield stress, and relative viscosity), compressive strength, drying shrinkage and transport properties (rapid chloride permeability and volume of permeable pores) show that replacing up to 100% of sand with SFS and up to 70% Portland cement with FA enables the manufacture of green, lower cost SCC mixtures with proper fresh, mechanical and durability properties. The beneficial effects of FA compensate for some possible detrimental effects of SFS.Natural Sciences and Engineering Research Council (NSERC) of Canada, and the Canada Research Chair Progra

Size And High Temperature Effects On The Compressive Strength Of Self Compacting Concretes

The compressive strength behavior of concrete is one of the fundamental parameters of structural design as most load-bearing concrete elements, such as beams, columns and slabs. However, it was known that compressive behavior of the concrete elements alter depend on the element size and exposed temperature conditions. When the slenderness (height/diameter) of the concrete elements increased, compressive strength decreased relatively and this behavior known as size effect. In this study, compressive strength variation of the self compacting concrete specimens investigated taking in to account the different slenderness ratio and exposure temperatures. For this purpose, a self compacting mixture was prepared with water to cement ratio of 0.40 and 450 kg/m3 cement dosage. Cylindrical specimens with the diameter of 100 mm and slenderness of 2.0, 1.5, 1.0, and 0.5 were prepared and exposed to the different high temperatures (400, 600 and 800 oC) for an hour. For a control purpose, same size specimens were also tested under the laboratory conditions. The results show that high temperature exposure has severe strength loss effect on the concrete specimens irrespective of the slenderness ratio. Increasing the exposure temperature increased the strength loss of the specimens drastically. Moreover, it was seen that relative strength change (decrease) is evident when specimens' size increased

MAT-712: MICROSTRUCTURAL INVESTIGATIONS ON THE SELF-HEALING ABILITY OF ENGINEERED CEMENTITIOUS COMPOSITES INCORPORATING DIFFERENT MINERAL ADMIXTURES

The present study investigates the impacts that self-healing has on the microstructure characteristics of microcracked Engineered Cementitious Composites (ECC). These have two contrasting maturity levels and, furthermore, they involve three varying mineral admixtures that have very different chemical constituents. The impact of self-healing on the transport characteristics was examined by employing rapid chloride permeability tests (RCPT). The findings indicated that, if the appropriate mineral admixture type and conditioning were chosen, it would be possible to enhance the majority of the chloride ion penetrability levels following a 30-day period of water curing. As a result, the majority of the findings were in range of the low penetrability level over the 30 days, as set by ASTM C1202. The microstructural indications corroborated the findings from the experiments and provided weight to the notion that the causal factor of the healing was the appearance of calcium carbonate and C-S-H. These served to fill the crack owing to the hydration of the cementitious particles. In summary, the results indicate that the degree of self-healing is subject to variance in accordance with the contrasting chemical compositions that dominate within a certain infrastructure type over the course of its service life

Self-healing capability of large-scale engineered cementitious composites beams

YesEngineered Cementitious Composites (ECC) is a material which possesses advanced self-healing properties. Although the self-healing performance of ECC has been revealed in numerous studies, only small-scale, laboratory-size specimens have been used to assess it under fixed laboratory conditions and curing techniques. In order to evaluate the effect of intrinsic self-healing ability of ECC on the properties of structural-size, large-scale reinforced-beam members, specimens with four different shear span to effective depth (a/d) ratios, ranging from 1 to 4, were prepared to evaluate the effects of shear and flexural deformation. To ensure a realistic assessment, beams were cured using wet burlap, similar to on-site curing. Each beam was tested for mechanical properties including load-carrying capacity, deflection capacity, ductility ratio, yield stiffness, energy absorption capacity, and the influence of self-healing, by comparing types of failure and cracking. Self-healed test beams showed higher strength, energy absorption capacity and ductility ratio than damaged test beams. In test beams with an a/d ratio of 4 in which flexural behavior was prominent, self-healing application was highly successful; the strength, energy absorption capacity and ductility ratios of these beams achieved the level of undamaged beams. In addition, flexural cracks healed better, helping recover the properties of beams with predominantly flexural cracks rather than shear cracks.The authors gratefully acknowledge the financial assistance of the Scientific and Technical Research Council (TUBITAK) of Turkey provided under Project: MAG-112M876 and the Turkish Academy of Sciences, Young Scientist Award program. The second author would also like to acknowledge the financial support of TÜBITAK for the 2219 Scholarship

Contribution à l'étude du comportement non linéaire des plaques minces

On s'intéresse, dans ce travail, au comportement des plaques minces soumises à un chargement statique instantané. Le travail de recherche consiste à utiliser la méthode des éléments finis pour prédire la réponse à court terme des plaques et des panneaux pouvant être chargés dans le plan et/ou transversalement. Il s'agit, plus précisément, de développer un programme l'éléments finis approprié qui soit à la fois flexible et facile d'utilisation. Dans cette perspective, on développe d'abord un nouvel élément fini quadrilatéral pour a flexion des plaques minces homogènes. Ensuite, une formulation basée sur le principe du travail virtuel incrémental est implantée pour tenir compte de la non-linéarité géométrique. À l'issue de cette première partie, une série de tests numériques est réalisée sur des problèmes classiques de plaques minces et de coques peu profondes afin de prouver l'efficacité de l'élément développé et de démontrer la validité de la procédure incrémentale. Le deuxième volet de notre programme de recherche est consacré au développement d'un modèle numérique pour simuler le comportement des plaques et des panneaux faits en béton armé. La formulation élastique est étendue à l'étude du matériau composite "béton armé" en considérant un modèle hypoélastique en contraintes planes. En se basant sur les performances du modèle, on examine l'influence de divers paramètres sur la solution numérique obtenue

Analyse par éléments finis des plaques minces en béton armé

Un modèle mathématique est développé afin de simuler le comportement non linéaire, à court terme, des plaques minces en béton armé. La non-linéarité géométrique ainsi que celle due aux lois contrainte-déformation sont incorporées dans cette étude. Il s'agit, plus précisément, de développer un programme d'éléments finis approprié qui soit à la fois flexible et facile d'utilisation. Le programme mis au point utilise des éléments rectangulaires, en contrainte plane, à 4 noeuds et 6 degrés de liberté par noeud. Le programme ainsi développé est utilisé pour étudier l'influence de quelques paramètres définissant le modèle biaxial utilisé sur la stabilité et la flexion des plaques minces en béton armé. En plus, une étude comparative des plaques utilisant des bétons ordinaires et des bétons à haute performance est considérée

Contribution à l'étude du comportement non linéaire des plaques minces

On s'intéresse, dans ce travail, au comportement des plaques minces soumises à un chargement statique instantané. Le travail de recherche consiste à utiliser la méthode des éléments finis pour prédire la réponse à court terme des plaques et des panneaux pouvant être chargés dans le plan et/ou transversalement. Il s'agit, plus précisément, de développer un programme l'éléments finis approprié qui soit à la fois flexible et facile d'utilisation. Dans cette perspective, on développe d'abord un nouvel élément fini quadrilatéral pour a flexion des plaques minces homogènes. Ensuite, une formulation basée sur le principe du travail virtuel incrémental est implantée pour tenir compte de la non-linéarité géométrique. À l'issue de cette première partie, une série de tests numériques est réalisée sur des problèmes classiques de plaques minces et de coques peu profondes afin de prouver l'efficacité de l'élément développé et de démontrer la validité de la procédure incrémentale. Le deuxième volet de notre programme de recherche est consacré au développement d'un modèle numérique pour simuler le comportement des plaques et des panneaux faits en béton armé. La formulation élastique est étendue à l'étude du matériau composite "béton armé" en considérant un modèle hypoélastique en contraintes planes. En se basant sur les performances du modèle, on examine l'influence de divers paramètres sur la solution numérique obtenue

Structural Performance of Polymer Fiber Reinforced Engineered Cementitious Composites Subjected to Static and Fatigue Flexural Loading

This paper presents the influence of silica sand, local crushed sand and different supplementary cementing materials (SCMs) to Portland cement (C) ratio (SCM/C) on the flexural fatigue performance of engineered cementitious composites (ECCs). ECC is a micromechanically-based designed high-performance polymer fiber reinforced concrete with high ductility which exhibits strain-hardening and micro-cracking behavior in tension and flexure. The relative high cost remains an obstacle for wider commercial use of ECC. The replacement of cement by SCMs, and the use of local sand aggregates can lower cost and enhance greenness of the ECC. The main variables of this study were: type and size of aggregates (local crushed or standard silica sand), type of SCMs (fly ash “FA” or slag), SCM/cement ratio of 1.2 or 2.2, three fatigue stress levels and number of fatigue cycles up to 1 million. The study showed that ECC mixtures produced with crushed sand (with high volume of fly ash and slag) exhibited strain hardening behavior (under static loading) with deformation capacities comparable with those made with silica sand. Class F-fly ash combined with crushed sand was the best choice (compared to class CI fly ash and slag) in order to enhance the ECC ductility with slag–ECC mixtures producing lowest deflection capacity. FA–ECC mixtures with silica sand developed more damage under fatigue loading due to higher deflection evolution than FA–ECC mixtures with crushed sand