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Volume 34, SIPMO 2019
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Proceedings, 2019, SMASCO 2019

The 1st International Conference on Smart Materials for Sustainable Construction

Luleå, Sweden | 10–12 December 2019

Volume Editors: Andrzej Cwirzen, Karin Habermehl-Cwirzen, Carina Hannu, Magdalena Rajczakowska, Ilda Tole, Thanyarat Buasiri, Ankit Kothari and Vasiola Zhaka


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Cover Story (view full-size image) This issue of Proceedings gathers abstracts presented at SMASCO 2019, the 1st International [...] Read more.
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Open AccessAbstract
Fayalite Slag as Binder and Aggregate in Alkali-Activated Materials—Interfacial Transition Zone Study
Proceedings 2019, 34(1), 1; https://doi.org/10.3390/proceedings2019034001 - 18 Nov 2019
Viewed by 215
Abstract
Alkali-activated materials (AAMs) are an environmentally friendly option for Portland cement mortars and concretes. Many industrial residues such as blast furnace slag and coal fly ash have been extensively studied and applied as AAM precursors but much less focus has been on the [...] Read more.
Alkali-activated materials (AAMs) are an environmentally friendly option for Portland cement mortars and concretes. Many industrial residues such as blast furnace slag and coal fly ash have been extensively studied and applied as AAM precursors but much less focus has been on the use of fayalite slags. Water-cooled fayalite slag comes in granular form, which is then milled into fine powder (d50 ~10 microns) prior to its alkali activation. In addition, the un-milled granular fayalite slag can be used as an aggregate to replace sand in mortar. The alkaline solution utilized for the study was a mix of 10 M sodium hydroxide solution and commercial potassium silicate solution. A liquid to solid ratio of 0.15 was held constant for all the mixes. The particle size distributions of the binder and the aggregates were optimized, and the microstructure and chemical composition of the interfacial transition zone (ITZ) was studied using scanning electron microscope coupled with energy dispersive X-ray spectroscopy. ITZ is a region that exists between the aggregate and the binder and this can influence the mechanical and transport properties of the construction materials. The results showed that the mechanical properties of mortar having fayalite slag as aggregate and binder was significantly higher than one with standard sand as aggregate. No distinct ITZ was found in the samples with fayalite slag as aggregate. The outer rim of the fayalite slag aggregate participated in the hardening reaction and this significantly contributed to the bonding and microstructural properties of the mortar samples. In contrast, an ITZ was observed in mortar samples with standard sand aggregates, which contributed to its lower strength. Full article
Open AccessAbstract
Plastic Shrinkage Cracking in Concrete
Proceedings 2019, 34(1), 2; https://doi.org/10.3390/proceedings2019034002 - 18 Nov 2019
Viewed by 163
Abstract
Plastic shrinkage cracking in concrete is mainly a physical process, in which chemical reactions between cement and water do not play a decisive role. It is commonly believed that rapid and excessive moisture loss, due to evaporation is the primary cause of the [...] Read more.
Plastic shrinkage cracking in concrete is mainly a physical process, in which chemical reactions between cement and water do not play a decisive role. It is commonly believed that rapid and excessive moisture loss, due to evaporation is the primary cause of the phenomenon. Once the concrete is cast, its solid particles start to settle due to gravity, causing an upward water-flow from the concrete interior and through its pore system to the surface, i.e., bleeding regime. When the amount of the evaporated water exceeds the amount of the water accumulated at the concrete surface, i.e., bleed water, concrete enters the so called drying regime, during which water menisci form inside the pores causing a build-up of a negative pore pressure, also known as capillary pressure. The progressive evaporation gradually decreases the radii of the menisci, which causes a further increase of the pore pressure and solid particles consolidation. Eventually, the skeleton of the concrete becomes stiff enough to resist the gravitational forces, which means that the vertical deformation of the concrete either completely stops or continues at a much lower rate. At this point, the capillary pressure is no longer able to further consolidate the concrete and move the pore water towards the surface. Instead, the developed tensile forces reduce the inter particle distances and the horizontal deformation continues. If the concrete member is restrained (e.g., due to reinforcement, variation in sectional depth, the friction of the form, etc.), the shrinkage can lead to tensile stresses accumulation. Once the tensile stresses exceed the early age tensile strength of the concrete, cracks start to form, preparing passageways for ingress of harmful materials into the concrete interior, which eventually may impair the durability and serviceability of the structure. This abstract reports the findings of a PhD research, carried out at Luleå University of Technology (LTU) to investigate the impact of parameters such as, admixtures, water-cement ratio (w/c), cement type, dosage of superplasticizer (SP), and steel fibers, on concrete’s cracking tendency while in plastic state. The results show that presence of accelerators, retarders, coarser cement particles, high w/c, and more SP increases the cracking risk, while stabilizers, air entraining agents (AEA), shrinkage reducing admixtures (SRA), and steel fibers notably decrease the cracking potential. Based on the findings of the above mentioned investigation a new model is proposed to estimate the severity of plastic shrinkage cracking, based on the initial setting time and the amount of the evaporated water from within the concrete bulk. The experimental results of the PhD research, alongside those reported by other researchers, were utilized to check the validity of the proposed model. According to the outcomes, the model could predict the cracking severity of the tested concretes with a good precision. Full article
Open AccessAbstract
Reuse of Urban Soils as Earthworks Material: Geotechnical and Environmental Specifications
Proceedings 2019, 34(1), 3; https://doi.org/10.3390/proceedings2019034003 - 18 Nov 2019
Viewed by 161
Abstract
In the context of urban extension, the depletion of natural resources for construction constitutes a crucial issue. Specifically, in the field of earthworks, the amounts of materials can be massive and pose the crucial problem of resource shortage. Therefore, the reuse of excavated [...] Read more.
In the context of urban extension, the depletion of natural resources for construction constitutes a crucial issue. Specifically, in the field of earthworks, the amounts of materials can be massive and pose the crucial problem of resource shortage. Therefore, the reuse of excavated urban soils from foundation layers as new earthwork construction materials appears to be a sustainable and promising solution. Two questions are thus asked: (1) Are urban soils relevant from a geotechnical point of view? (2) Are they relevant from an environmental point of view? To answer those issues, two urban soils from the suburb of Paris (France) have been studied. Geotechnical approach and environmental approach exhibit that both soils have common features. Specifically, they are bearer of several pollutant phases like metals, organic carbon and sulphates. Interestingly, those materials, when treated with few percent of hydraulic binders reach required mechanical performances for a use in road structure despite the occurrence of pollutants that are known to have deleterious effects on soil stabilization with lime and cements. However, even if permeability of materials is reduced when they are treated with cement, leaching tests under neutral pH (7) and alkaline pH (12) show, that treatment could have inhibitor effects or activating effects on pollutants release. Full article
Open AccessAbstract
Restoration of Deteriorated Concrete Columns by Wrapping with an Ecological UHPC
Proceedings 2019, 34(1), 4; https://doi.org/10.3390/proceedings2019034004 - 18 Nov 2019
Viewed by 172
Abstract
Ultra high performance concrete (UHPC) is self-compacting, reaching compressive strength over 200 MPa and flexural strength exceeding 30 MPa material. The used very low W/C ratio and high amount of Portland cement often exceeding 900 kg/m3, addition of up to 30% [...] Read more.
Ultra high performance concrete (UHPC) is self-compacting, reaching compressive strength over 200 MPa and flexural strength exceeding 30 MPa material. The used very low W/C ratio and high amount of Portland cement often exceeding 900 kg/m3, addition of up to 30% of silica fume produces a very dense and nearly impermeable binder matrix. In this research, cement was substituted with limestone filler to lower the effective CO2 footprint. Prepared concrete mixes had high slump flow of 850 mm and reached the compressive strength of 150 MPa after 28 days. Full-scale columns having dimension of 30 × 30 × 250 cm were produced using self-compacting concrete (Figure 1a,b), having the 28 days compressive strength of 40 MPa. External surfaces of the 3 months old columns were water jetted to simulated real case scenario (Figure 1c). For the test, the columns were surrounded by a plywood formwork leaving less than 3 cm of spacing between the concrete surface and the formwork (Figure 1d). The concrete was poured from top of the column and with no segregation reached the bottom and perfectly filled the mold. Test included determination of basic mechanical properties, bond strength between UHPC and “old” concrete, crack formation and frost durability. All results exceeded expectations. Full article
Open AccessAbstract
Dissolution Studies of Glass Wool and Stone Wool at Alkaline pH
Proceedings 2019, 34(1), 5; https://doi.org/10.3390/proceedings2019034005 - 18 Nov 2019
Viewed by 211
Abstract
Mineral wools—a general term for stone wool and glass wool—are the most common insulation materials in the world. Consequently, 2.5 million tons of mineral wool waste is generated globally which is mainly landfilled. Recently, it was found that mineral wool waste can be [...] Read more.
Mineral wools—a general term for stone wool and glass wool—are the most common insulation materials in the world. Consequently, 2.5 million tons of mineral wool waste is generated globally which is mainly landfilled. Recently, it was found that mineral wool waste can be used as cementitious material by alkali activation. In alkali activation, dissolution is the primary process as it involves the breakage of bonds and release of ionic species from the surface of the material upon interaction with the reacting solution. Dissolution plays a significant role in the strength development and micro/nano-structural morphology of the final cementitious material. Here, we study the dissolution of stone wool (depicting chemistry of Al-Ca-Mg-Fe silicate glass) and glass wool (depicting chemistry of soda lime silicate glass) in sodium hydroxide solution to provide a better understanding of their reactivity under alkali activation.
Experimental studies were carried out at two different liquid to solid ratio (L/S) conditions: high L/S (1000) and low L/S (50) in an N2 glove box. High L/S conditions give information on the early stages of the dissolution whereas low L/S provides later stages of the process.
The ICP results show that under both L/S conditions glass wool releases increasing amount of Si, Al and B reaching 39–45 wt.%, 23–26 wt.% and 34–44 wt.% extent of dissolution with time respectively. However, in stone wool the release rate of Si and Al increases initially but becomes constant after certain time period. In both mineral wools, release rate of Ca and Mg varied with time. These changes in the release rate was observed to be due to precipitation of dissolved species. XRD results revealed that three crystalline phases-hydrotalcite, calcite, and calcium silicate were present on both glass and stone wool fibers after 25 days of dissolution. SEM results revealed that the morphology varies at different dissolution times and experimental conditions for both the mineral wools depicting the change in the reaction path. From these studies, we conclude that the dissolution rate and mechanism are controlled by both chemical composition of the fiber and the reacting solution conditions. Full article
Open AccessAbstract
Self-Healing Potential of Geopolymer Concrete
Proceedings 2019, 34(1), 6; https://doi.org/10.3390/proceedings2019034006 - 18 Nov 2019
Viewed by 240
Abstract
Waste management is emerging as one of the most troublesome and critical problems of the upcoming decades. Therefore, the utilization of industrial by-products as building materials components has been widely studied in recent years. Geopolymer concrete, with binder entirely substituted by slag or [...] Read more.
Waste management is emerging as one of the most troublesome and critical problems of the upcoming decades. Therefore, the utilization of industrial by-products as building materials components has been widely studied in recent years. Geopolymer concrete, with binder entirely substituted by slag or fly ash, is one of the materials, which combines positive environmental impact with satisfying mechanical parameters. Although various properties of geopolymers have been examined, the autogeneous self-healing potential of this alternative binder has not been thoroughly verified yet. This paper aims to validate whether geopolymer concrete made of alkali activated slag is capable of self-repair. Four different mortar mixes with two types of slag and varying activation parameters were investigated. The polyvinyl alcohol (PVA) fibers were added in order to control the crack width. The 1.2 × 1.2 × 6 cm beams were pre-cracked with the use of three point bending test at 7 days after casting to achieve crack opening of approximately 300 µm. The effects of various exposure conditions on the healing process were examined, i.e., lime water, different sodium silicate solutions and water. The self-healing efficiency as well as the evolution of the crack recovery was assessed by the observation of the crack surface with the use of digital optical microscope. The healed area of the crack was calculated and compared for all the specimens by applying the image processing techniques. The morphology of the healing products as well as their chemical composition were examined with the use of Scanning Electron Microscope with Energy Dispersive Spectroscopy. Full article
Open AccessAbstract
Physical Characterization of Dutch Fine Recycled Concrete Aggregates: A Comparative Study
Proceedings 2019, 34(1), 7; https://doi.org/10.3390/proceedings2019034007 - 18 Nov 2019
Viewed by 196
Abstract
In the Netherlands, yearly 20 Mt Construction- and Demolition waste (CDW) is being produced mainly consisting of concrete and masonry rubble. This is two third of the yearly production of concrete (33 Mt). Currently, less than 1 Mt/year of the 20 Mt/year CDW [...] Read more.
In the Netherlands, yearly 20 Mt Construction- and Demolition waste (CDW) is being produced mainly consisting of concrete and masonry rubble. This is two third of the yearly production of concrete (33 Mt). Currently, less than 1 Mt/year of the 20 Mt/year CDW is recycled in new concrete (mainly as coarse recycled concrete aggregates). This preliminary study being part of a larger study, is aiming to increase that amount, amongst others by focusing on use of the fine recycled concrete aggregates. Fine recycled concrete aggregates (fRCA) appear promising for (partial) replacement of natural fine aggregates (sand) and cement in new concrete. Nevertheless, they can be expected to have adverse properties and components that may reduce the performance of the concrete. Their physical, chemical and mechanical properties, which thus may significantly differ from that of natural sand, are still far from being fully investigated. The present paper focusses on characterization of physical properties of fRCA for finding the most critical indicators for fRCA quality. The tests include particle size distribution, morphology, BET surface area, solid density and water absorption of individual and total fractions (0–0.25 mm, 0.25–4 mm and 0–4 mm). The tests are performed on three fRCAs with different origin. Natural river sand with 96 wt.% of SiO2 was also studied to provide a baseline for comparison. Experimental results showed that, on the one side, the particle size distribution, surface area and amounts of individual fractions of fRCAs are significantly different from that of natural sand and that there is a large difference between each other. This is caused by variations of the parent concrete properties and by the type of recycling technique and processes (one step or multiple steps crushing). On the other side, fRCAs have comparative solid densities, which were still lower than that of natural sand. It was also shown that difference in water absorption between fractions 0.25–4 mm and 0–4 mm is very small in all three fRCAs groups. The results of this study will be used for future correlations between investigated properties of fRCAs with properties of concretes with fRCAs. This will be investigated in the next stage of the project, such that these correlations can enable production of durable concretes with fRCAs and assist recyclers in optimization of their production processes based on quality control of fRCAs. Full article
Open AccessAbstract
Valorization of Inert Part of Construction and Demolition Wastes for the Production of Fired Bricks
Proceedings 2019, 34(1), 8; https://doi.org/10.3390/proceedings2019034008 - 18 Nov 2019
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Abstract
Green routes to prepare or manufacture sustainable building materials have been attracting a lot of attention over the years targeting sustainability issues. In this investigation, for the first time, sludge from the inert mineral part of the construction and demolition waste (RA-S) is [...] Read more.
Green routes to prepare or manufacture sustainable building materials have been attracting a lot of attention over the years targeting sustainability issues. In this investigation, for the first time, sludge from the inert mineral part of the construction and demolition waste (RA-S) is used as main raw material in the fabrication of fired bricks for building purposes. Fired bricks fabricated with different dosages of RA-S and earth material (i.e., 0%, 30%, 50%, 70% and 100% by weight) were prepared and evaluated in terms of their properties. The RA-S was characterized and the results showed that it can be classified as a clayey material and richly graded silty sand whereas brick soil can be classified as clayey sand according to the French Standards. XRD analysis revealed that the addition of the RA-S into raw earth material did not cause big changes in the final mineralogical properties of the fired bricks. The compressive strength (CS) test results indicated that the strength of the brick samples (fired at 800°C) increased with the addition of the RA-S from 30% to 70%. The CS of bricks fired at 800°C were 10.2 MPa, 13.2 MPa, and 16.7 MPa after incorporating 30%, 50% and 70% RA-S, respectively. The density of the fired brick slightly reduced with the RA-S addition. The highest strength was attained at the firing temperature of 800°C in relation to the firing temperature of 1000°C. The RA sludge can be used in combination with earth material to fabricate fired bricks, which can meet the requirements of many Standards all over the world. In the light of these results, it is possible to say that the RA-S generated from recycling inert mineral part of construction and demolition waste plant is a promising material to prepare efficient fired bricks that can be successfully employed in the real construction sector. Full article
Open AccessAbstract
Monitoring of Early and Late Age Hydration Products of Volcanic Ash Blended Cement Paste
Proceedings 2019, 34(1), 9; https://doi.org/10.3390/proceedings2019034009 - 18 Nov 2019
Viewed by 244
Abstract
One of the major concerns of concrete industries is to develop materials that consume less natural virgin resources and energy to make sustainable construction practices. Efforts have been made and even implemented to use the waste/by product materials such as fly ash, slag, [...] Read more.
One of the major concerns of concrete industries is to develop materials that consume less natural virgin resources and energy to make sustainable construction practices. Efforts have been made and even implemented to use the waste/by product materials such as fly ash, slag, silica fume, and natural pozzolana as a partial or complete replacement for Portland cement in concrete mixtures. The deterioration of concrete structures in the existing hot and cold climates of Gulf Cooperation Council countries, along with chloride and sulphate attack, demands the use of pozzolanic materials for concrete construction. Volcanic ash incorporated cement based concretes are known for its better performance in terms of strength and durability in harsh marine environments. Understanding the cement hydration process and characterizing the hydration products in microstructural level is a complex and interdependent process that allows one to design complex mix proportions to produce sustainable concrete materials. In this paper, the early and late age hydration behavior along with micro- and pore structure of cement paste samples prepared with locally available ordinary Portland cement (OPC) and volcanic ash (VA) obtained from Saudi Arabia was monitored using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric (TGA) and N2-Adsorption analysis. The hydration progress of cement paste samples with different combinations of OPC and VA (0%, 15%, 25%, and 35%) at a w/c ratio of 0.45 after 14, 28, and 90 days were discussed. The qualitative XRD and SEM of cement paste samples showed no new phases were formed during the course of hydration. The disappearance of portlandite with increase in VA content was due to both pozzolanic effect and dilution effect. This was further confirmed quantitatively by the TGA observations that the samples with VA contain less Ca(OH)2 compared to the control specimens. N2 adsorption experiments after 90 days of curing showed larger hysteresis as the VA content increases. The studies show that the incorporation of volcanic ash certainly contributes to the generation of C-S-H and hence the cement hydration progress, especially in the later ages through pozzolanic reactions. A 15–25 % volcanic ash blended cement paste samples showed compact and denser morphological features, which will be highly detrimental for the durability performances. Full article
Open AccessAbstract
Alkali Activation of Silicate Mine-Tailings: Response to Different Activator Sources
Proceedings 2019, 34(1), 10; https://doi.org/10.3390/proceedings2019034010 - 18 Nov 2019
Viewed by 169
Abstract
To attain sustainability in construction industries, it is important to explore industrial side-streams as a potential replacement for traditional construction materials. This will avoid the depletion of natural resources and helps in preserving the environment. In this way, mining industry attracts the attention [...] Read more.
To attain sustainability in construction industries, it is important to explore industrial side-streams as a potential replacement for traditional construction materials. This will avoid the depletion of natural resources and helps in preserving the environment. In this way, mining industry attracts the attention of scientific community for the huge volume of tailings generated along with the problem of disposal. This paper mainly focuses on silicate tailings (MT) from two different mining sources with high magnesium (HM) and high alumina (HA) content. To study the possibility of using these tailings as precursors in alkali activation, different activators such as, sodium silicate (Na2SiO3), sodium sulphate (Na2SO4) and sodium carbonate (Na2CO3) were employed. It was noted that the mine tailings took longer time to set in case of activators other than sodium silicate. The milled tailings were co-grinded with the respective solid activators (10%) and mixed with 30% of sodium silicate solution (accelerates setting), to make cylindrical paste specimens. The specimens were cured at 60 °C for 24 h. The results shown that tailings rich in magnesium (MT-HM) activated with sodium carbonate gives high early age strength i.e., 60% increase in average strength compared to other activators. Whereas, sodium silicate helped in achieving 10% increase in early age strength of high alumina tailings (MT-HA). However, this was not the case for the later ages. At 7th day of testing, sodium silicate activated MT-HM shown a strength improvement from 2 MPa to 6 MPa with the formation of magnesium silicate hydrate and hydrotalcite. MT-HA activated with sodium sulphate resulted in a maximum strength of 8.5 MPa due to the ettringite and zeolite in the system. Sodium carbonate does not show comparable results at 7th day of testing though it shown improvement in strength with age. It is also important to consider that there are other oxides like calcium and iron present in these tailings which could also have impacted the results. Full article
Open AccessAbstract
Impact of Artificial Waste on the Strength of Cementitious Composites
Proceedings 2019, 34(1), 11; https://doi.org/10.3390/proceedings2019034011 - 18 Nov 2019
Viewed by 157
Abstract
Every year number of municipal wastes increases. Despite of belonging to the countries with landfill ban, over 35% of municipal wastes in Poland were disposed to landfills in 2018. Abandoned artificial wastes can endanger whole environment including human. Scientists and students try to [...] Read more.
Every year number of municipal wastes increases. Despite of belonging to the countries with landfill ban, over 35% of municipal wastes in Poland were disposed to landfills in 2018. Abandoned artificial wastes can endanger whole environment including human. Scientists and students try to reduce arising number of artificial wastes by turning it into construction materials. Plastic waste material can replace natural aggregate in cementitious composites. Addition of artificial wastes decreases density of composites, but also affects their strength significantly. Properties of cementitious composites containing artificial wastes depend on the amount of added plastic material and its type. In the article different types of artificial wastes substituted natural aggregate in mortar. Alternative aggregate were PET flakes, PET pellet, powdered PVC and shredded HDPE. Aggregate was replaced in the amount of 2%, 5% and 10% of volume of sand. Control sample consisted of Portland cement CEMI 42,5R with water/cement/aggregate ratio 0.5:1:3. Samples were cured in water until the examination and weighed before the test. Compressive and flexural strength tests were conducted after 2 and 28 days. Mortars containing artificial wastes presented similar results to control sample after 2 days of curing. The difference was more significant after 28 days, the compressive strength decreased up to 30% for mortars containing 10% of artificial wastes. After flexural strength test mortars containing PET flakes were difficult to divide into two parts. Additionally, the impact resistance of mortar containing 5% PET flakes was examined. According to the assumption, the results were higher for samples containing PET flakes in comparison to control mortar. The addition of different artificial wastes led to compressive and flexural strength decrease. However, the results of impact resistance test are higher for samples containing PET flakes in comparison to control mortar. The results show that addition of artificial wastes could improve some properties of mortar; still further tests need to be conducted in order to qualify artificial wastes as valuable component of cementitious composite. Full article
Open AccessAbstract
Feasibility of Using Biomass Fly Ash in Cementitious Materials
Proceedings 2019, 34(1), 12; https://doi.org/10.3390/proceedings2019034012 - 18 Nov 2019
Viewed by 184
Abstract
In recent years, numerous studies focused on the development of sustainable cement-based binders through the use of supplementary cementitious materials such slag, fly ash, metakaolin, silica fume, pozzolan, etc. The use of wood biomass for power generation is increasingly common which lead to [...] Read more.
In recent years, numerous studies focused on the development of sustainable cement-based binders through the use of supplementary cementitious materials such slag, fly ash, metakaolin, silica fume, pozzolan, etc. The use of wood biomass for power generation is increasingly common which lead to an important amount of waste produced in the combustion process such as fly ash, which must be transported to landfills for deposition, or used as sludge in farming. Depending on their chemical and physical characteristics, wood biomass fly ashes could be reuse in blended cements as supplementary cementitious material. Different sources of biomass fly ashes have been selected to evaluate their potential for use as a cement replacement. Their chemical and mineralogical compositions, as well as their morphology were first evaluated via X-ray and laser diffraction (XRD), inductively coupled plasma (ICP) and scanning electron microscopy (SEM coupled with energy-dispersive X-ray spectroscopy (EDX). Fly ashes showed variable physicochemical characteristics but some present interesting compositions for the intended use. One fly ash present a high content of CaO and minors of SiO2 and Al2O3. The chemical composition does not allow to categorize this fly ash as a pozzolan material but it may have a latent hydraulic behaviour, which could be interesting as cement substitution. This fly ash has been incorporated into a cement paste by progressive replacement of Portland cement (from 0 to 70%). It has been observed that biomass fly ash has a higher water demand compared to Portland cement. This additional water demand was evaluated by the Vicat consistency test and by an evaporometry method. The setting time and kinetic hydration of the biomass fly ash pastes were also assessed with the standardized Vicat test and by isothermal calorimetry. Full article
Open AccessAbstract
Possible Effects of Sea Ice on Concrete Used in Arctic Conditions
Proceedings 2019, 34(1), 13; https://doi.org/10.3390/proceedings2019034013 - 18 Nov 2019
Viewed by 167
Abstract
The Arctic region is receiving an increasing attention due to the diminishing area of the permanent ice and easing access to various natural resources including especially oil, gas and rare metals. The nearest future will require building a significant number of new harbors [...] Read more.
The Arctic region is receiving an increasing attention due to the diminishing area of the permanent ice and easing access to various natural resources including especially oil, gas and rare metals. The nearest future will require building a significant number of new harbors and other structures related to sea operations and exploration. Harsh weather conditions including especially extreme freezing temperatures, snowfall and ice formation impose demanding requirements, which must be taken into account while designing, building and maintaining those structures. Concrete is the main construction material used for harbor structures. Unfortunately, the usage of Portland cement, which is the main cementitious binder used for concrete, it involves hardening processes, which are controlled by the hydration reactions. The hydration needs water and temperatures above freezing point, which impose serious limitations in the arctic environment. Furthermore, later exposure to the arctic conditions and especially to ice may impair its long-term durability and thus the sustainability of built structures. The present work focuses on characterization of properties of sea ice forming in harbors located in the Arctic region and on identification of possible implications on concrete material during the construction phase but also in long-term exploitation. Full article
Open AccessAbstract
Sustainability Aspects of New Admixtures and Supplementary Cementitious Materials for Durable Concrete
Proceedings 2019, 34(1), 14; https://doi.org/10.3390/proceedings2019034014 - 18 Nov 2019
Viewed by 219
Abstract
s the global population is growing and changing the globalization direction towards large city areas the needs for the development of infrastructure and housing will increase. In order to have a safe and sustainable construction the infrastructure needs to be not only sustainable [...] Read more.
s the global population is growing and changing the globalization direction towards large city areas the needs for the development of infrastructure and housing will increase. In order to have a safe and sustainable construction the infrastructure needs to be not only sustainable but also durable. In some cases, the concrete is subjected to severe environments, e.g., elevated or high temperatures, de-icing salts, seawater exposure or acidic environment, which means increased demand to extend the service life beyond what is prescribed in the design codes. The sustainability of concrete infrastructures is highly dependent on the durability. A longer service life with low repair work reduces the greenhouse gas emissions. Various admixtures and cement supplementary materials may increase the durability of the concrete. However, it is also important to consider the embodied impact and safety issues concerning innovative nanomaterials as well as application of slag and fly-ash in concrete and their future availability on the market. Here we present an overview on the latest developments on the durability and sustainability of climate-optimized concrete. Full article
Open AccessAbstract
Optimization of the Process Parameters Controlling the Degree of Amorphization during Mechanical Activation of Clay Using the Taguchi Method
Proceedings 2019, 34(1), 15; https://doi.org/10.3390/proceedings2019034015 - 18 Nov 2019
Viewed by 184
Abstract
Mechanical activation in a planetary ball mill (BM) is an environmentally friendly process able to enhance the chemical and pozzolanic activity of natural clays. Those materials can be used as supplementary cementitious materials (SCMs) to partially replace Portland cement in concrete. The process [...] Read more.
Mechanical activation in a planetary ball mill (BM) is an environmentally friendly process able to enhance the chemical and pozzolanic activity of natural clays. Those materials can be used as supplementary cementitious materials (SCMs) to partially replace Portland cement in concrete. The process parameters of the BM are directly related to the degree of amorphization and thus to the enhancement of the chemical activity. Design of experiments (DOE) is a well-known statistical tool, which can assist in selecting optimized conditions and in obtaining systematic data. However, full factorial design requires a large number of experiment. Taguchi method is based on the use of an Orthogonal Array (OA) to evaluate optimization of the selected factors but with less required experiments. In this study, three factors, each on 2 levels, were selected: ball to powder ratio (B/P) with level 3 and 25, time of grinding with level 5 and 20, and water to powder ratio (W/P) with level 0 and 1. The degree of amorphization (DOA) was selected as the main response for the Taguchi method. DOA was calculated as the ratio between the integral intensities of the main peak of the kaolinite [001] before and after grinding. For dry grinding, the predicted optimized value of DOA complied with the experimental results. Maximized DOA value was achieved for B/P equal to 25 and the grinding duration of 20. This method can be a valuable tool to predict the amorphization degree of minerals present in the natural clay, leading to the optimization of the mechanical activation process. Full article
Open AccessAbstract
Phase Change Material Used for Masonry Joints: Numerical Simulation and Scale Test
Proceedings 2019, 34(1), 16; https://doi.org/10.3390/proceedings2019034016 - 18 Nov 2019
Viewed by 190
Abstract
In order to effectively improve the thermal performance of the thermal insulation masonry wall, the thermal bridge effect of the grey joint on the heat transfer of the wall structure was studied. A brand-new form of phase change material walls, which used phase [...] Read more.
In order to effectively improve the thermal performance of the thermal insulation masonry wall, the thermal bridge effect of the grey joint on the heat transfer of the wall structure was studied. A brand-new form of phase change material walls, which used phase change materials in the wall parts to build ash joints, was carried out. The application of phase change material mortar, which was different from conventional "Hamburger" phase change material walls, was demonstrated to be a useful tool to reduce the thermal coefficient of the masonry wall. Furthermore, the scale-down test and numerical simulation of the heat transfer coefficient of the phase change material wall with different distribution of ash joints were experimented and discussed, and the feasibility of the new-form phase change material wall within the error range was verified. Full article
Open AccessAbstract
Damage and Stress Detection (Self-Sensing) in Concrete with Multi-Walled Carbon Nanotubes
Proceedings 2019, 34(1), 17; https://doi.org/10.3390/proceedings2019034017 - 18 Nov 2019
Viewed by 170
Abstract
Within EU project LightCoce (Building an Ecosystem for the upscaling of lightweight multi-functional concrete and ceramic materials and structures), RISE will be running a Pilot Line to allow the design and development of materials, elements of Cellular Lightweight Concrete (CLC) and/or lightweight composite [...] Read more.
Within EU project LightCoce (Building an Ecosystem for the upscaling of lightweight multi-functional concrete and ceramic materials and structures), RISE will be running a Pilot Line to allow the design and development of materials, elements of Cellular Lightweight Concrete (CLC) and/or lightweight composite elements with improved functionalities. One of these functionalities is self-sensing (damage and stress detection), achieved by reducing the natural concrete’s resistance with incorporation of the multi-walled carbon nanotubes (MWCNTs). By applying a small electric current in the outer electrodes attached to the concrete and measuring voltage on the inner electrodes the resistivity of the material can be easily calculated. The resistivity changes may indicate cracking and changing stress levels. In our study concrete was enhanced with various amounts of MWCNTs and tested in cyclic compression. The change of stress levels was clearly visible on the resistivity changes. After that, ultrahigh-performance concrete (UHPC) panels with two types of textile reinforcement (GFRP and CFRP) were tested in cyclic 4-point bending to investigate concretes sensitivity for multiple cracking. The resistivity measurement was able to capture multiple discrete cracks and the material degradation at micro-level due to fatigue. Full article
Open AccessAbstract
A Modular Reactor for Thermochemical Energy Storage Examination of Ettringite-Based Materials
Proceedings 2019, 34(1), 18; https://doi.org/10.3390/proceedings2019034018 - 18 Nov 2019
Viewed by 253
Abstract
More attention on renewable energy has been attracted after the achievement of Paris Agreement against climate change. Solar-based technology is supposed to be one of the most promising green energy technologies for residential buildings since its wide thermal usage for hot water and [...] Read more.
More attention on renewable energy has been attracted after the achievement of Paris Agreement against climate change. Solar-based technology is supposed to be one of the most promising green energy technologies for residential buildings since its wide thermal usage for hot water and heating. However, the seasonal mismatch between its energy-production and consumption makes buildings need an energy storage system to improve the efficiency of renewable energy use. Indeed, even if different kinds of energy storage systems using sensible or latent heat already exist, thermochemical energy storage can be then recommended by considering the problems of energy dissipation during storage and low energy density for the first two methods. As potential thermochemical storage materials, ettringite (3CaO∙Al2O3∙3CaSO4∙32H2O) based materials possess high energy densities (~500 kWh/m3), low material cost (<1000 €/m3) and low storage temperature (~60–70°C), compared to salt hydrates of similar energy density like SrBr2·6H2O (42 k€/m3, ~80°C), LaCl3·7H2O (38 k€/m3, ~100°C) and MgSO4·7H2O (5 k€/m3, ~150°C). Therefore, ettringite-based materials have the possibility to be largely used in building sector by being coupled to normal solar collector systems via reversible chemical reactions (Equation (1)): (i) charging mode: hot air or hot water (>70°C) from solar collectors dehydrates ettringite to meta-ettringite, and consequently store heat to chemical energy; ii) discharging mode: humid air is pumped to material container to rehydrate meta-ettringite, and consequently release stored chemical energy as heating. However, the lack of extensive examination leads to poor knowledge on their thermal properties and limits maturity of this technology. Therefore, the aim of this work is to characterize the capacity of an ettringite-based material (named C80P20, containing ~70 wt.% ettringite) in terms of thermal energy storage by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Besides, a modular reactor adapting to thermal characterizations of C80P20 particles has been developed for various weights (up to 300 grams). In our case, the energy density of pure ettringite is around 1012 J/g while 708 J/g for C80P20 powder in TGA-DSC. First preliminary results from modular reactor demonstrate a general energy density of 150 kWh/m3 released by the hydration process of C80P20 grains (pre-dehydrated at 80 °C) at 25 °C and 85% relative humidity. Moreover, the reactor is intended to study the durability of the energy storage material over time, and also as function of the number of charging/discharging cycles.CaO∙Al2O3∙3CaSO4∙32H2O ettringite+heat↔3CaO∙Al2O3∙3CaSO4∙32-XH2Ometa-ettringite+XH2O Full article
Open AccessAbstract
Load Sensing Capability of Cementitious Matrixes—Nanomodified Cement Versus Carbon Nanotube Dispersion
Proceedings 2019, 34(1), 19; https://doi.org/10.3390/proceedings2019034019 - 18 Nov 2019
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Abstract
A cement-based matrix incorporating conductive materials such as carbon nanotubes and carbon nanofibers can have self-sensing capability. Both nanomaterials are characterized by excellent physical, mechanical and electrical properties. A disadvantage is that due to their hydrophobic nature it is very difficult to ensure [...] Read more.
A cement-based matrix incorporating conductive materials such as carbon nanotubes and carbon nanofibers can have self-sensing capability. Both nanomaterials are characterized by excellent physical, mechanical and electrical properties. A disadvantage is that due to their hydrophobic nature it is very difficult to ensure uniform dispersion throughout the cementitious matrix. To overcome this problem a new nanomodified cement containing in-situ attached CNFs was developed leading to a very homogenous and conductive binder matrix. This study aimed to compare the piezoresistive responses of two types of matrixes, one based on the nanomodified cement and the second containing multi-walled carbon nanotubes. Several mortars were prepared containing either MWCNTs or the nanomodified cement, which partially replaced the untreated cement. The effective amount of the carbon nanomaterials was the same for both types of mixes and ranged from 0 wt.% to 0.271 wt.%, calculated by the all binder weight. Changes in the electrical properties were determined while applying compressive load. The results showed that the binders based on the nanomodified cement have significantly better load sensing capabilities and are suitable for applications in monitoring systems. Full article
Open AccessAbstract
Self-Healing of Cracked Textile Reinforced Concrete Layers
Proceedings 2019, 34(1), 20; https://doi.org/10.3390/proceedings2019034020 - 18 Nov 2019
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Abstract
Sustainable maintenance of existing steel-reinforced concrete structures becomes more important. Using non-reinforced sprayed mortar to maintain these structures often leads to cracks in this repair layer due to the alteration of crack widths in the ordinary structure. The water impermeability as well as [...] Read more.
Sustainable maintenance of existing steel-reinforced concrete structures becomes more important. Using non-reinforced sprayed mortar to maintain these structures often leads to cracks in this repair layer due to the alteration of crack widths in the ordinary structure. The water impermeability as well as the durability of the sprayed mortar will be reduced due to the described cracks. This presentation shows a solution for the described problem. The use of carbon yarns with a special inorganic coating as reinforcement in sprayed mortars leads to a self-healing of the arising cracks. Due to the inorganic coating applied on carbon yarns the excellent bond between mortar and yarn results in a fine distributed crack image with crack width below 0.1 mm. It is shown that these cracks heal themselves. Consequently we can provide a mainly mineral protection layer for existing steel reinforced concrete structures which is impermeably to water based solutions. The presentation focuses on the material development and characterization. Full article
Open AccessAbstract
The Effect of SAP and POSS Additives on the Durability of Concrete in Artic Environments
Proceedings 2019, 34(1), 21; https://doi.org/10.3390/proceedings2019034021 - 18 Nov 2019
Viewed by 143
Abstract
In an on-going European project LORCENIS, which focus on the development of durable concrete structures, different types of innovative additives have been tested for use in concrete. As a part of this project the effect of super absorbent polymers (SAP) and polyhedral silsequioxanes [...] Read more.
In an on-going European project LORCENIS, which focus on the development of durable concrete structures, different types of innovative additives have been tested for use in concrete. As a part of this project the effect of super absorbent polymers (SAP) and polyhedral silsequioxanes (POSS) on different durability issues was investigated in laboratory tests. In this study the focus was on the application for large concrete structures in arctic environments, e.g., hydro power dams. The purpose was to investigate the effect of the additives on two durability issues: the combination of leaching and freeze-thaw and the self-healing of cracks under hydro static water pressure. In addition, the influence of the additives on the fresh and hardened properties of the concrete was also investigated, this included e.g., flow characteristics, compressive strength and volume stability. As basis for the tests, a concrete mix suitable for use for large concrete structures was developed within the project. In this paper, the results and conclusions from the laboratory tests will be presented. Full article
Open AccessAbstract
Elaboration and Characterization of Composite Materials Based on Plaster-Gypsum and Mineral Additives for Energy Efficiency in Buildings
Proceedings 2019, 34(1), 22; https://doi.org/10.3390/proceedings2019034022 - 18 Nov 2019
Viewed by 179
Abstract
The building sector is one of the largest energy consumers in the world, prompting scientific researchers to find solutions to the problem. The choice of appropriate building materials presents a considerable challenge for improving the thermal comfort of buildings. In this scenario, plaster-based [...] Read more.
The building sector is one of the largest energy consumers in the world, prompting scientific researchers to find solutions to the problem. The choice of appropriate building materials presents a considerable challenge for improving the thermal comfort of buildings. In this scenario, plaster-based insulating materials have more and more interests and new applications, such as insulating coatings developing the building envelope. Several works are being done to improve energy efficiency in the building sector through the study of building materials with insulation quality and energy savings. In this work, new composite materials, plaster-gypsum with mineral additives are produced and evaluated experimentally to obtain low-cost materials with improved thermo-physical and acoustic properties. The resulting composites are intended for use in building walls. Plaster-gypsum is presented as a high-performance thermal material, and mineral additives are of great importance because of their nature and are environmentally friendly. Measurements of thermal properties are carried and measurements of acoustic properties. The results show that it is possible to improve the thermal and acoustic performance of building material by using plaster as a base material and by incorporating thermal insulators. The thermal conductivity of plaster alone is greater than that of plaster with mineral additives, offer interesting thermal and acoustic performance. By varying the additives, the thermal conductivity changes. Finally, comparing the results, plaster with mineral additives is considered the best building material in this study Full article
Open AccessAbstract
Response of Nano-Reinforced Cementitious Composites Using Natural and Commercial Dispersants
Proceedings 2019, 34(1), 23; https://doi.org/10.3390/proceedings2019034023 - 18 Nov 2019
Viewed by 208
Abstract
An efficient and promising approach from economy point of view to effectively disperse Multi-walled carbon nanotubes (MWCNTs) in cementitious environment has been devised. The natural organic extract from species of indigenously known ‘keekar’ trees scattered along tropical and sub-tropical countries; is found as [...] Read more.
An efficient and promising approach from economy point of view to effectively disperse Multi-walled carbon nanotubes (MWCNTs) in cementitious environment has been devised. The natural organic extract from species of indigenously known ‘keekar’ trees scattered along tropical and sub-tropical countries; is found as an exceptional replacement to the non-natural commercial surfactant. In the initial phase ideal content of surfactant was explored in relation with the added content of MWCNTs using ultra-violet spectroscopy. The experimental investigations were then extended to five formulations containing 0.0, 0.025, 0.05, 0.08 and 0.10 MWCNTs by weight percent of cement. It was observed that the natural surfactant produced efficient dispersion at much reduced cost (>14% approx.) compared with the commercial alternate. The estimated weight efficiency factor ‘ϕ’ was found 6.5 times higher by the proposed sustainable replacement to the conventional with remarkable increase of 23% in modulus of rupture on 0.08 wt% addition of MWCNTs. Besides, strength enhancement the dispersed MWCNTs also improved the first crack and ultimate fracture toughness by 51.5% and 35.9%, respectively. The field emission scanning electron microscopy of the cryofractured samples revealed efficient dispersion of MWCNTs in the matrix leading to the phenomenon of effective crack bridging and crack branching in the composite matrix. Furthermore, the proposed scheme significantly reduced the early age volumetric shrinkage by 39% to mitigate early age micro-cracks encouraging long lasting deteriorations from durability prospects. Full article
Open AccessAbstract
Are Shrinkage and Creep Prediction Models Developed for Portland Cement also Valid for Alkali-Activated High-MgO Blast Furnace Slag?
Proceedings 2019, 34(1), 24; https://doi.org/10.3390/proceedings2019034024 - 18 Nov 2019
Viewed by 148
Abstract
Alkali-activated slag (AAS) based materials is one. [...]
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