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The study explores the potential of recycling construction and demolition waste into recycled coarse aggregates (RCA) to decrease waste generation and carbon footprint, using a standard compacting effort to calculate compressive strength and particle packing density in a specific cylindrical volume. This study investigates the impact of RCA on concrete’s workability, compressive strength, flexural, split tensile, drying shrinkage, electrical resistivity, rapid chloride penetration, and microstructural characteristics using XRD, SEM, and EDAX. Test findings showed that increasing the replacement percentage beyond the optimum value (RCA 25) had detrimental effects on the strength and microstructure of the concrete. RCA 25 has a higher compressive, flexural, and split tensile strength in the order of 11.56%, 3.06%, and 5.17% respectively compared to reference concrete, as well as 5.23% increase in drying shrinkage, 8.79% higher electrical resistivity, and 4.68% higher resistance to chloride penetration than reference concrete.

The use of recycled aggregates instead of natural aggregates used in concrete reduces environmental pollution and concrete costs. Recycled Asphalt Pavement (RAP) aggregate used as recycled aggregate has a lower water absorption than natural aggregate due to its bituminous structure, which reduces the water requirement of fresh concrete. In this study, it was aimed to determine the optimum use of RAP particles as aggregate in concrete for read pavements and to determine their durability properties. For this purpose, RAP was used instead of crushed stone aggregate used in concrete road construction. RAP was used by replaced aggregate 0%, 25%, 50% and 100% of the crushed stone aggregate used on the concrete road. The dose of the produced concrete was 350 kg/m3 and the water/cement ratio was kept constant as 0.45. The fresh workability and air content of concretes containing RAP were determined. Compressive strength, splitting tensile strength, electrical resistivity value, accelerated corrosion test of hardened concretes were subjected to corrosion resistance, water absorption and porosity percentage, acid resistance, ultrasonic pulse rate and Scanning Electron Microscope (SEM) and X-ray Diffractometer (XRD) analyzes were determined. In the experimental results, it has been observed that the use of RAP ratio of 25% and 50% remains within the limit values for concrete pavement. It is recommended to be used on reinforced concrete roads that will be exposed to adverse environmental conditions with its high corrosion resistance, thanks to its anti-corrosion feature.

This research investigated the bond properties at high temperatures and with hybrid fiber addition between basalt fiber reinforced polymer (BFRP) bars and hybrid fiber-reinforced concrete (HFRC). The tensile strength and appearance morphology of BFRP bars were analyzed. Used scanning electron microscopy (SEM) to examine the microscopic morphology and used the bond-slip constitutive model to fit the bond-slip curves. When BFRP bars after exposed to 300 °C, their tensile strength dropped by 42%. With the increasing temperature, the bond strength and stiffness of normal concrete (NC) specimens decreased by 27.3 % and 67.5 %, respectively, while HFRC specimens decreased by 20.8 % and 55 %, respectively. Hybrid fibers increased the bond strength and stiffness of HFRC specimens by 27.1 % and 49.1 %, respectively. The best fitting models were the Malvar model and the Continuous Curve model.

Rice husk residues are generated within the rice industry. In this research, the environmental impact of the use of rice husk ash is evaluated as a replacement for cement in the production of concrete in the city of Ibagué (Colombia). The environmental criteria of cement and concrete production alternatives were evaluated through life cycle analysis methodology, using SimaPro 9.3.3 software and the Recipe 2016 Midpoint (H) evaluation method. The economic cost of each of these production alternatives was included. To carry out the study, surveys and interviews had to be undertaken with rice-producing plants, aggregates, cement and concrete plants in Tolima. It was corroborated that rice husk ash (RHA) generated during the rice husk (RH) gasification process for electricity and heat production was beneficial from an environmental and economic perspective when it was used in cement and concrete in the city of Ibague (Colombia).

This paper presents an experimental study on a set of 30 specimens, tested on three-point bending, divided into two categories. With the insertion of geogrids and cathodic emulsions, the first category consists of 14 prismatic beams and the second of 16 pre-cracked and reinforced slab specimens. In situ tests were carried out using a heavy deflectometer (HWD) on a flexible runway of an airfield located in the city of Ouragla (800 km south-east of Algiers), before and after its reinforcement. This work showed, with a numerical calibration, that the geogrid with emulsion, improves the displacements and the stresses approximately 30% and increases the modulus of elasticity and the modulus of rupture (MOR) by 60% and 20%, respectively. The damping coefficient (k) can reach the value of 2 to 5, which increases the longevity of a reinforced flexible pavement.

The aim of this paper is to evaluate the influence of a crystallizing chemical admixture on precast micro concretes with two water contents (7% and 11%, by dried mass) and two different conditions of exposure. Thus, precast micro concretes with a composition of 1:3 (cement: fines) with and without crystalline chemical admixture were evaluated on compressive strength (at the age of 28 and 154 days) and water absorption by immersion (at the age of 154 days). Statistical analysis showed that the only significant factor was the effect of the water content on the compressive strength. Besides that, the most significant factors for the water absorption and voids index properties were the water content, followed by the exposure conditions, and the interaction between the water content and the presence of the chemical admixture. The crystalline admixture was insignificant in the conditions of this research.

The paper analyses the degradation process of commercial ultramarine blue pigments in cementitious materials. For this purpose, two commercial pigments (with and without a protective coating) in different solutions and cement pastes are studied incrementally. The results show that pigment degradation occurs due to an ion exchange phenomenon; during hydration high ion contents are released, calcium and potassium being the most aggressive for the pigment. Calcium distorts the unit cell; between the sodium of the pigment and the potassium in the medium a cation exchange phenomenon takes place. Both processes lead to the diffusion of sulphate and sulphide ions from the pigment to the medium causing loss of colour and the formation of ettringite.

This article presents the experimental outcomes of the shear strength and microstructural characteristics of high-volume fly ash self-compacting concrete (HVFYA-SCC) containing recycled concrete aggregates and coal bottom ash as partial replacements for natural coarse aggregates and natural fine aggregates. A total of ten numbers of mixes were produced, including HVFYA-SCC made without recycled concrete aggregates and coal bottom ash (as control) along with HVFYA-SCC mixes made with recycled concrete aggregates (from 25% to 50%) and coal bottom ash (from 10% to 30%). The compressive and shear strength of the HVFYA-SCC mixes were improved by 7% and 4%, respectively, with the incorporation of 20% coal bottom ash and 25% recycled concrete aggregates after 120 days of curing. On the other hand, scanning electron microscopic analysis revealed that incorporating coal bottom ash exhibited the pozzolanic reactions with fly ash densified the binder-aggregate matrix of the resulting HVFYA-SCC.

The application of various Fiber Reinforced Polymer (FRP) composite materials is very widespread in the world. The use of recycled materials in concrete, can improve some of the mechanical properties of concrete. In this laboratory research, the behavior of reinforced concrete beams with composite rebars with glass fibers made of concrete containing recycled materials such as glass, rubber and micro-silica with different mixing plans has been investigated. These mixing plans are such that recycled glass and rubber aggregates have replaced a percentage of fine and coarse concrete aggregates, and glass powder and micro-silica have also replaced a percentage of concrete cement. The results showed that the replacement of coarse rubber, glass powder, and micro-silica in concrete materials increases the bending strength and ductility of concrete beam. In examining the microstructure of concrete by Scanning Electron Microscope (SEM) the adhesiveness of the rubber Interfacial Transition Zone (ITZ) in concrete was suitable.

Limestone Calcined Clay Cement (LC3) Technology is a low carbon cement that combines limestone, calcined clay, and clinker, aiming to reduce CO2 emissions by 40%-50% during production. In this study, large-scale investigations were conducted to explore LC3 as a potential substitute for conventional cement (CC). Mechanical and durability tests were performed on LC3, comparing results with CC and Pozzolana Cement (PC) concretes. The findings revealed that LC3 concrete exhibited promising early-stage strength similar to CC concrete. However, at 90 days, LC3 showcased a 10% higher strength compared to CC concrete. Additionally, LC3 displayed a remarkable 45% increase in resistance to moisture ingress, indicating improved durability over CC concrete. These results highlight the efficacy of low carbon cement in developing ternary blended cements that offer early strength and enhanced durability, making it a viable eco-friendly alternative in the construction industry.

In this study is explored the use of construction and demolition waste as fine aggregate in mortars. The addition of nano-graphene oxide (0.1%wt) has also been evaluated. Tests were conducted to determine their density, humidity content, water absorption capacity and open void porosity (using water absorption) and the micro and nano-porosity using Hg intrusion and N2 absorption techniques, as well as their flexural and compressive strength and resistance to acid attacks. The mechanical properties of mortars manufactured with standard sand were better (30%) than made with waste aggregate. Mortars with both aggregates can be classified as M20. Nano-Graphene oxide acts as a filler, reducing the volume of macro and micro pores, thereby increasing the mechanical performance, especially when recycled aggregates are used (30% the flexural strength for recycled aggregates and 4% for standard sand). The addition of nano-graphene oxide reduces the transmission channels of acid within mortar.

This study presents the preparation of steel-fiber reinforced concretes (SFRCs) using straight navicular fibers with annular-sector-shaped sections and corrugated fiber with rectangular-shaped sections, respectively. The flexural and splitting tensile strengths of both the respective SFRCs increase with increasing fiber volume fraction, whereas their compressive strengths initially increase, then decrease, and then increase again. For the same fiber volume fraction, the mechanical properties of the navicular fiber-reinforced concrete are superior to those of the corrugated fiber-reinforced concretes. The introduction of steel fiber changes the failure mode of the plain concrete during bending from a typical brittle mode to a bimodal ductile failure mode. As compared to the corrugated fiber, the navicular fiber has stronger interface bonding to concrete and a higher friction resistance to fiber sliding and subsequent pullout. Furthermore, navicular fiber has a higher load-bearing capacity, which makes it more favorable for improving the mechanical properties of plain concrete.

This study aims to evaluate the effect of RCP from a precast concrete plant on rheological and mechanical properties of cementitious pastes. In the study, Portland cement was replaced by RCP in 10, 20, and 30% (in mass). The hydration kinects of cement with RCP was studied through isothermal calorimetry. The fresh properties were assessed using mini-slump test and rotational rheometry. The mechanical properties were evaluated through compression tests and the microstruture was studied using Scanning Electron Microscopy. RCP reduces fluidity of the pastes, by increasing both yield stress and plastic viscosity. The addition of RCP accelerates the hydration of cement, while reducing the released heat. RCP also reduces the compressive strength and elastic modulus of the pastes. The use of RCP as partial substitute for cement is viable, due to its size distribution and specific surface area.

High water absorption is a typical characteristic of recycled coarse aggregate and is often used to explain the loss of performance of concrete when replacing natural coarse aggregate with recycled coarse aggregate. Extensive attention has been paid to the mean value of the water absorption of recycled coarse aggregate, but not to the standard deviation. This paper aims to assess whether recycled coarse aggregates with the same mean water absorption but different standard deviations will perform equally in high-performance concrete (HPC). The resulting HPC mixtures exhibited very similar compressive strength. Even so, it was hypothesised that as the standard deviation of the water absorption of recycled coarse aggregate increases over a wide range, the compressive strength of HPC will first increase due to local variations in the water/cement ratio, then decrease due to the presence of weak particles, and finally remain constant due to the role of the surrounding new mortar.

The energy deficiency in rural housing in the Andes of Peru is recurrent. In this context, local and low environmental impact materials present an opportunity. This research evaluated the properties of five panels composed of totora and gypsum for ceiling applications. Firstly, the physical and durability properties were obtained. Then, impact and fire resistance were evaluated. Finally, thermoacoustic properties were assessed. The results showed a moisture level of 10.25%, water absorption of 354.85% which is considered high, and a dry density of 292.84 kg/m3. Adequate durability to fungus with resin on both sides. The panels’ fire resistance is superior to 60 minutes, with a safe impact criterion for 10 N and a functionality criterion for 5 N. The average values for the panels were 0.061 W/m·K for thermal insulation and 0.54 for NRC. Therefore, it is possible to produce an insulating material for thermoacoustic improvement.

The main aim of this work is to study two relevant experimental setups designed for studying shear fracture and see if any of them allows studying the evolution of fracture under Mode II conditions, not only inducing a shear stress state at the onset of fracture. Two tests have been selected, a standardised test described by a Japanese standard, here referred to as the JSCE test, and the push-off test. These tests have been carried out on fibre-reinforced gypsum specimens with increasing proportions of polypropylene fibres and monitored by means of digital image correlation (DIC). The results show that fracture under Mode II conditions is relatively easy to induce with both tests, but once fracture begins, it is extremely difficult to induce a fracture process under Mode II. In general, Mode II has an important role at the onset on fracture, but Mode I predominates afterwards.

This paper investigates the use of Na2CO3 as an alkaline activator on the durability of the alkali-activated slag (AAS) mortar toward sulfates and acids. The behavior of this binder in these aggressive environments is compared to those of slags activated with Na2SiO3 and NaOH. In addition, the setting times, workabilities, mechanical properties and drying shrinkage were evaluated. The AAS had superior workabilities, faster setting times and higher shrinkage rates than the Portland cement (PC). Increases in the activator dosages had positive effects on the mechanical strengths of the materials. Na2SiO3 was the best activator in terms of strength development, but it led to much higher shrinkage. The AAS showed less expansion and lower weight losses than the PC when exposed to sulfate and acids, respectively. The Na2CO3-AAS exhibited less shrinkage and higher resistance to sulfuric acid than the other activators, but the mechanical strength seen at early ages was low.

The design of render-mortars from construction and demolition waste (CDW) was evaluated. Fine aggregates from red-clay-brick waste, mortar and concrete waste were used, together with recycled expanded-polystyrene (EPS) as lightweight filler. Mixes composed of 70%-recycled aggregates, and 30% consisting of a matrix of Portland cement were produced. Characterization tests were conducted on the physical, mechanical, thermal, and acoustic properties. The render-mortar A4, A7 and A9 can be classified according to compressive strength results as CSI-W0 for interior use under standard UNE-EN-998-1. The A7 mortar, with the best physical and mechanical results, contained 21% EPS, 17.5% brick waste and 17.5% mortar waste. Mix A4 obtained the lowest thermal conductivity, 0.12 W/m·K - a reduction of 79% compared to the commercial-mortar AC1. The acoustic absorption properties were also enhanced by the incorporation of EPS, such that the A4, A7, and A9 mixes were identified as Absorbent for the frequencies of 2000 Hz and 4000 Hz.

In this study, the clogging mechanism of pervious concrete was evaluated using three different cloggers such as, Sand (S), Clay (C), and combination of sand and clay (S &C). The clogging mechanism was performed through falling head permeability apparatus, using clogger sediment load at the rate of 50, 150, and 200 grams in repetitive clogging cycles. It was observed from the results that combined (S & C) clogger shows overall critical results of clogging as 80% of the clogging was seen in 3 to 4 cycles. Moreover, it was observed from the results that pervious concrete mix made with R- type of aggregate gradation shows optimum compressive strength of the order of 8.6, 15.9, and 17 MPa at 7, 28 and 56 days of curing. Furthermore, the visual inspection test shows that clogging by clay clogger shows an even distribution of sediment on the whole length of the sample.

Efforts are made to alleviate thermal problems in buildings. The use of thermal mortars for coating with vermiculite as aggregate is used for this purpose, but the use with mineral additions is still scarce, especially the rheology through squeeze-flow. Thus, it was aimed to evaluate the behavior in fresh, hardened state and in the thermal conductivity of these mortars. Mortars containing Portland cement, lime, vermiculite, sand, and additions of metakaolin or ceramic brick waste, in the proportion of 1:1:6 (Cement: Lime: Sand), were evaluated. The sand was replaced by vermiculite in 40%, and the additions added in the proportion of 20% to the cement mass, and the water content determined with the spread obtained on the consistency table. Mixtures containing 20% mineral addition and 40% vermiculite proved to be feasible, reaching minimum values according to the respective standards.

Bond deterioration in reinforced concrete (RC) structures is frequently caused by aging, environmental factors, overloading, or poor design. This deterioration may cause the structure to lose its aesthetic, and eventually collapse. The behavior of structures that exhibit bond deterioration is poorly understood and inadequately maintained. The response of RC structures exhibiting bond loss under tension load is presented in this paper. In order to comprehend the impact of bond loss in RC composite, the RC system was first built for a pullout. It was then expanded to the nib corner of RC dapped end beams. Additionally, the system was analytically examined using 3-dimensional FEmodel. The bond loss created a weak zone with internal cracks parallel to the bar’s axis. The nib section separated from the full depth of the dapped end, while the hanger reinforcement resisted the diagonal tension cracks. The dapped section must therefore be given more consideration during monitoring and maintenance.

The traceability of granite blocks consists in identifying each block with a finite number of colour bands that represent a numerical code. This code has to be read several times throughout the manufacturing process, but its accuracy is subject to human errors, leading to cause faults in the traceability system. A computer vision system is presented to address this problem through colour detection and the decryption of the associated code. The system developed makes use of colour space transformations and various thresholds for the isolation of the colours. Computer vision methods are implemented, along with contour detection procedures for colour identification. Lastly, the analysis of geometrical features is used to decrypt the colour code captured. The proposed algorithm is trained on a set of 109 pictures taken in different environmental conditions and validated on a set of 21 images. The outcome shows promising results with an accuracy rate of 75.00% in the validation process. Therefore, the application presented can help employees reduce the number of mistakes in product tracking.

In this study, a novel technique for producing synthetic aggregates using industrial by-products was experimentally investigated. Taguchi method is used to identify the optimum mix design proportion to develop durable synthetic aggregates. For this, different combinations of quaternary binders including ordinary Portland cement, ground granulated blast furnace slag, metakaolin, and lime powder was used. The obtained results revealed that the synthetic aggregates prepared with optimized mortar mix enhanced the compressive strength by 5.9%. Then the performance of synthetic aggregates was evaluated based on their mechanical and durability properties. Microstructural properties of the produced aggregates were examined. The results showed that optimum mix is highly effective than control mix. The manufactured synthetic aggregates are in accordance with the ASTM C 330 standard requirements. Therefore, our study contributes to the advancement in the sustainability by developing a method for producing synthetic aggregates from industrial byproducts.

The use of high percentages of substitution of Portland cement by pozzolans can provoke the total consumption of portlandite. The present research proposes the study of ternary systems of Portland cement (PC), fly ash (FA), and hydrated lime (CH). After 180 days of curing, the mortar with 50% substitution of PC by FA obtained 65.9 MPa versus the mortars with an addition of 20% of CH and control mortar (100 PC) that obtained 69.9 MPa and 76.7 MPa respectively: this behavior is very positive value considering that tested FA containing mortars had a 50% of Portland cement. Regarding the effect of the amount of extra hydrated lime on durability issues, the evolution against carbonation of PC-FA and PC-CH-FA mortars was studied: the reduction of carbonation velocity was around a 37% for the mortar with CH respect the PC-FA mortar.

This work aims to obtain parameters of thermal performance of various types of plaster blocks for vertical sealing. The methodology consisted of making test elements with 8 types of plaster blocks, in addition to plasterboard of different densities. Thermal resistance, transmittance, capacity, and delay were calculated, according to the Brazilian standard NBR 15220. Thermal behavior tests were carried out with controlled heating through a heat source, digital thermometer, infrared thermography, and an instrumented thermal chamber developed for this work. The experimental results corroborated with the trend indicated by the calculated parameters. The massive and hollow blocks of 100 mm had the best results followed by the 76 mm hollow blocks. The 50- and 70-mm massive blocks were among those with the worst thermal behavior. The study through the thermal chamber and real test elements associated with the normative methods allowed the practical verification regarding the thermal behavior of the components.

The paper shows a comparative study of the influence of whitening additives (kaolin, TiO2 and СаСО3) on the production of decorative alkali-activated slag cement and mortars with a degree of whiteness of at least 70%; as well as their influence on the structure formation and evolution of physico-mechanical properties. According to results obtained, kaolin provides chemical bonding of Na+ into insoluble zeolite-like compounds; and CaCO3 densifies the structure and reduces shrinkage deformations. At the early stages of hardening (up to 7 days), the additions of kaolin and calcite, due to their significant amount (15 and 24%), reduces the compressive strength of the cement paste; nevertheless, at later ages (until 90 days) the difference in strength almost disappears. The high colourfastness and weather resistance of pigmented cements under the influence of ultraviolet radiation and freeze/thaw cycles has been established. A comparative assessment of the economic efficiency has shown that СаСО3 is the best cost-effective additive.

Nowadays, it is imperative to reduce the energy bill in order to contribute to a more sustainable planet. In this sense, the use of materials that contribute to the energy efficiency of buildings is a very important contribution to achieve this goal. Mortars incorporating phase change materials (PCM) can make an important contribution to this end, due to its thermal storage capacity, increasing the energy efficiency of buildings. In this work several mortars with different PCM contents were developed, using different binders (cement, aerial lime, hydraulic lime and gypsum). The aim of this study was to apply data mining techniques such as artificial neural networks (ANN), support vector machines (SVM) and multiple linear regressions (MLR) to forecast the compressive and flexural strengths of these mortars at different exposure temperatures. It was concluded that ANN models have the best predictive capacity both for compressive strength and flexural strength. However, the SVM models have a flexural strength forecasting capacity very close to ANN models.

This paper examines the effect on mechanical properties such as compressive strength, flexural strength, and dynamic modulus of elasticity (DYE) of different proportions of wollastonite (β-CaSiO3) and colloidal nano-silica (n-SiO2) partially replacing cement. Durability indicators (water absorption, sorptivity and sulphate treatment test) were also examined to ascertain the quality of hardened paste mixes with respect to the control mix. The regression models were found for mechanical properties using different parameters from the results obtained, and statistical relations were established and validated. Regression analysis shows the significance of every parameter considered and model for the prediction of mechanical strengths. Finally, the results were substantiated by the microstructural characterization by FESEM. β-CaSiO3 and colloidal n-SiO2 replaced cement by 15%, and 1.5%-6% with an offset of 1.5%, respectively at low (0.25), medium (0.40) and high (0.55) water/binder (w/b) ratio. FESEM micrographs showed dense Calcium-silicate-hydrate (CSH) gel and stratlingite (CASH) was formed by blended cement paste mixes containing β-CaSiO3 and n-SiO2. n-SiO2 at 3% and CaSiO3 at 15% replacements of cement (NS3 mix) was the optimum replacement level for the cement paste mix. Analysed regression model suggests that the models and parameters were found significant and can also be used for prediction (based on R2 values and p-value).

Magnesium oxalate cement, a novel alternative to portland cement, can be made at room temperature by reacting dead-burned magnesia and salts of oxalic acid. Since oxalic acid can be made using captured carbon dioxide, oxalate cements may even be carbon negative. However, emissions related with the decarbonation of magnesite at high temperatures make this hard to achieve. This study investigates the effect of replacing magnesia with granulated blast furnace slag on some physical and mechanical properties, as well as the mineralogy and microstructure of oxalate cements. Whewellite and Weddellite are identified when slag is used, in addition to Glushinskite which forms from magnesia. Slag-only mortars undergo faster but less complete reactions and show lower resistance to water than their magnesium oxalate counterparts. An equal-part combination of dead-burned magnesia and slag gives the highest 28-d strength (> 35 MPa), pH~7, and high water resistance.

In this study, a low-ammonium enzyme-induced carbonate precipitation (LA-EICP) technique is proposed that utilizes the cation exchange capability of zeolite to remove ammonium, an environmentally harmful by-product of urea hydrolysis. The LA-EICP process is a modified enzyme-induced carbonate precipitation (EICP) suitable for soil stabilization, by mixing zeolite and resulting solution of urea hydrolysis. The amounts of calcium carbonate precipitated and ammonium ions removed by the synthetic calcium-modified zeolite were analyzed through tube precipitation tests. In addition, the unconfined compressive strengths of the soil specimens were measured and compared to investigate the reinforcing effect of LA-EICP. The precipitation of calcium carbonate within the soil specimen was also confirmed by scanning electron microscope and energy dispersive spectrometry analyses. The results showed LA-EICP can precipitate the same amount of calcium carbonate as conventional EICP, while removing almost all ammonium ions. In addition, the LA-EICP-treated specimen showed a higher strength improvement than the conventional EICP-treated specimen, due to the combined effect of the calcium carbonate and the zeolite.

Ladle furnace slag (LFS) shows excellent potential for valorization. Despite this, landfills are typically its final destination, mainly because of technological barriers in its valorization process. This work examines the potential use of LFS as a partial cement/fine aggregate replacement, focusing on the effects of LFS composition and particle size distribution on concrete physico-mechanical properties. Chemical/mineralogical characterization of raw/hydrated samples, fresh-/hardened-state concrete properties, and volumetric instability tests were evaluated. Our results show reduced mechanical performance with LFS replacement, reaching compressive strength values of 32-42 MPa after 28 days. LFS mineralogical characterization reveals the absence of free CaO and the presence of periclase with its hydration/carbonation products. Therefore, the weathering/maturity process mainly affects free CaO. Furthermore, the observed volumetric instability issues were within the Code on Structural Concrete (Spanish abbreviation: EHE) established limits (0.04%), suggesting that the remaining periclase could be responsible for this expansive behavior.

Sandstones have been widely used in construction for their abundance, aesthetics, and ease of extraction. To determine sandstones’ quality, it is essential to analyse their petrographic and petrophysical properties and sensitivity (durability and conservation) to environmental agents. This paper evaluates the physical-mechanical changes undergone by Sierra de la Demanda (Burgos, Spain) sandstone under combined and induced water and salt aggression and assesses ESTEL 1100’s effectiveness and suitability as a treatment. This sandstone is porous, permeable, dense and quartz-rich with high hardness and strength. The treatment improved its petrophysical properties by modifying its pore geometry and connectivity, reducing absorbency, permeability and anisotropy, and further increasing its hardness and resistance. Salts did not substantially modify its properties as its porosity type absorbed the crystallisation pressure. Ultimately, its pore system and predominantly quartz composition make it a high-quality, weather-resistant material compatible with the treatment applied.

Alkali-activated slag (AAS) materials activated by NaOH or waterglass has been long-term criticized for the developed substantial shrinkage. To this regard, this paper explored MgO as both an activator and an expansive agent to prepare shrinkage-free AAS. The setting time, mechanical strength, pore structure, autogenous shrinkage, drying shrinkage, and hydration products of MgO-activated AAS were studied. Experimental results confirmed that MgO can effectively mitigate the autogenous shrinkage and drying shrinkage of AAS via the expansive deformation caused by Mg(OH)2. Generally, AAS with a higher dosage of MgO developed less shrinkages and refiner pore structures with more gel pores. An optimal dosage of 9% MgO is recommended to prepare AAS with near zero shrinkage and the highest flexural strength.

Manganese enters the clinker from alternative fuel and alternative raw materials. It is present in the iron ores utilized in the cement burning and is found in the slags employed as supplementary cement materials. The jouravskite, as a member of the ettringite family, may form in limestone cement when exposed to sulfate media. To understand its effect on the hydration process, the expansion of small cylindrical clinker pastes doped with synthesized jouravskite and ettringite in magnesium sulfate solutions was measured with a micrometer; and the compressive strength of representative cubes was monitored. The phases formed were characterized by means of X-ray diffraction, infrared spectroscopy and scanning electron microscopy. The jouravskite is found to be a strong retarder for clinker hydration probably due to its adsorption on the cement hydrates.

This study aims to investigate the effect of two periods burning conditions on the chemical properties of rice husk ash (RHA). Gray correlation theory analysis combined with a scanning electron microscope was used to precisely analyze the impact of RHA particle sizes on the mechanical properties and microstructure of mortar. The experimental results reveal that prolonging residence time at 600 ºC could significantly reduce the carbon content and boost the silica content in RHA. The potassium content of RHA could be reduced by burning at a low and then high temperature. Additionally, gray correlation analysis indicated that the particle sizes of 5 -10 μm in RHA could positively accelerate the gaining strength of mortar, followed by 10-15 μm and < 5 μm. At the micro-scale, incorporating RHA with a mean particle of 5.9 μm could accelerate the formation of calcium silicate hydrates having a low Ca/Si by secondary hydration reaction, subsequently leading to the increment of mortar strength.

Recycled concrete aggregates (RCAs) have been demonstrated as an alternative source to exhaustible natural aggregates. In this paper, we focus on the enhancement treatments for coarse and fine RCAs and the effect of these treatments on the durability of recycled concrete (RC) made from treated RCAs by the weakening and strengthening of the cement paste adhered to their surface. We conducted comparative analyses on the improvement of durability and mechanical properties. The results showed that the reduction of water absorption in RCAs increases the compressive strength of RC and that there is a strong linear trend of improvement in the carbonation depth, chloride ion penetration, and compressive strength of RC. For fine and coarse RCAs, the treatment mechanism and particle size are determinants in efficiently improving RC durability.

This study investigated the fresh, physical, and mechanical properties of self-compacting geopolymer mortars (SCGs) with synthetic wollastonite microfiber (SWM). SCGs were designed with Class F fly ash (FA) as a binder by activating it with Na2SiO3 and NaOH solutions. First, SWM was produced in the laboratory. Alkali ratios were determined as 1.5, 2.0, and 2.5, whereas SWM percentages were utilized as 0%, 4%, 8%, and 12% by weight of the binder. After geopolymer mortars were cured at 80 oC and 100 oC for 24 hours, respectively, they were kept at room temperature until testing age. The compressive strength, flexural strength, ultrasonic pulse velocity, dynamic modulus of elasticity, water sorptivity coefficient values, and physical characteristics of SCGs were tested at the end of the 28th day. The highest compressive strength value was obtained as 28.9 MPa for SCG-1.5-8 cured at 100 oC, while 6.5 MPa was measured as the highest flexural strength for SCG-2-12 cured at 80 oC.

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Warm mix asphalt (WMA) and crumb rubber modified asphalt in the field of asphalt paving have been demonstrated to be green technologies for producing environmentally friendly pavement. However, limited research has assessed the behaviours of mixtures including both technologies. This study performed research aligned with environmental considerations and sustainability to examine the design and manufacturing of dense asphalt mixtures incorporating a crumb-rubber modifier through a wet or dry process and a specific vegetable additive for WMA technologies. The results indicated that, when rubber is added through a wet process, and a WMA vegetable additive is incorporated, the mixture can be manufactured and compacted at temperatures approximately 25 °C below that of the control mixture, while keeping the mechanical properties within the specifications.

An adequate moisture resistance is a key element to guarantee the durability of asphalt materials. This paper identifies the influence of filler typology and bitumen content on the mechanical response of asphalt mortars before and after water action. Two fillers were evaluated: Portland cement and Calcium carbonate, along with different contents of a penetration bitumen (B35/50). Stiffness, ductility, and fatigue were evaluated through a new protocol for asphalt mortar samples using a 3-point-bending test on DMA (Dynamic Mechanical Analyzer). The use of Portland cement presents higher stiffness, lower ductility, and improved fatigue and water resistance compared to Calcium carbonate. It is also possible to optimize bitumen content based on fatigue results. Content beyond the optimal reduce variations after water action but compromise fatigue resistance. Lower content leads to a poorer performance in both terms. This methodology enables asphalt mortar characterisation as a tool to optimise the design of asphalt materials.

In microbial induced calcium carbonate precipitation (MICP) system, yeast extract (YE) is needed for spores germination. The aim of this research is to evaluate the minimum amount of YE in mortar that allows spores of Bacillus sphaericus to germinate with limited negative effect on mortar properties. Two YE concentrations of 2 and 5 g/l were tested and compared to a reference without YE. To protect the bacteria in the mortar matrix, spores or cells were encapsulated into porous expanded clay. The ureolytic activity of bacteria with YE variation, the mechanical properties and the healing ability of mortar were assessed. The results show that a YE concentration of 2 g/l provided acceptable mortar properties, while it was sufficient for spores to germinate and provide a satisfactory healing ability to resulting mortar. When vegetative cells are used as a healing agent, it is best to omit yeast extract from the mortar mixture.

After 15 years of exploitation, numerous instances of damage to the concrete pavement motorway located in northern Germany were observed. Detailed macro and microscopic analysis and determination of mechanical properties were performed on the collected cores. It was found that cracks in the coarse and fine aggregate resulted from advanced alkali-silica reaction. No impact of de-icing agents on the destruction of the concrete pavement was found, while attention was paid to the potential intensification of concrete degradation resulting from the increase in traffic on motorways. The results obtained are a detailed supplement to the German research, as this region (Rostock) has not been analysed before.

Fast-growing climate changes are known to have diverse impacts worldwide, even in large cities. Pervious concrete can be a successful safety solution for increasingly frequent heavy rains and floods. This study focuses on achieving an optimized pervious concrete within the scope of international standards by analyzing concretes made with different W/C ratios and vibration times. The results of the study show the strong influence of parameters such as porosity, permeability, and mechanical strengths. Concrete with 0.35 W/C ratio and 40 seconds vibration time was selected for its adequate physical and mechanical properties.

The article presents the results of research on the physical and radiological properties of building ceramics made of mining waste. One method of using mining waste is to use it as aggregate in road construction. However, this alone is not enough to dispose of the entire amount of waste generated. Another promising method of using mining waste is the production of building ceramics (bricks). However, some properties (e.g. the content of natural radionuclides) of the waste may limit the possibility of such use. In the scope of this work, the properties of bricks made from mining waste - shale collected from dumps, were examined. It has been shown that the properties of bricks prepared in this way meet the criteria set out in various standards and legal acts and can be used in construction.

This study examined the preparation of fly ash-based foam geopolymer recipes with the experimental design method and data analysis with the SPSS program. A total of 54 prescriptions were used in the studies, which investigated six different variables. Strength, density, and thermal conductivity analyses were performed. Values were in the range of 0.57-2.75 MPa for strength, 344-592 kg/m3 for density, and 0.089-0.132 for thermal conductivity. Three variables were identified with each having the most significant effect on strength and density values. H2O2, curing temperature, and expanded perlite had the most effect on strength, while H2O2, curing temperature, and alkali concentration had the most significant effect on density. Most influential parameters are plotted on ternary graphs to ensure that the foam concrete (CLC) masonry units used in all types of masonry walls, whether load-bearing or not, can operate under the specified performance conditions.

A novel binder system for cement-based composites depending upon the strength and durability characteristics is introduced in this study. The possibility of calcined red mud cement pastes with and without colloidal nano-silica (CNS) over Ordinary Portland Cement paste (OPC) at three W/B ratios (0.3, 0.4, 0.5) is evaluated. The optimum percentage of cement replacement by red mud (15%) was selected from compressive strength values of different cement replacements (5%, 10%, 15%, and 20%). Colloidal nano-silica (CNS) was added at 0.5%, 1%, 1.5%, and 2 % to the selected red mud cement paste. Water absorption, sorptivity, resistance to sulfate attack, and resistance to acid attack tests were conducted for optimum red mud cement paste with and without CNS. The experimental results are explained based on tortuosity with empirical formulas and mathematical models of pore network distribution. The tortuosity is directly proportional to the inter-connectivity of the pores. The mixes with 15% calcined red mud and 1.5% CNS replacement performed better strength and durability at all W/B ratios. The mix (R15NS1.5) with minimum tortuosity value results in the higher overall performance of the paste. The mixes with a 0.3 W/B ratio give high-performance cement paste compared to higher W/B ratios.

This work is a study about new acoustic panels made of cork granulates coming from stopper by-products to be used as acoustic ceilings tiles, providing a sustainable and environmentally friendly alternative to traditional building materials. Cork granulates were bonded with water-based epoxy and acrylic resins. The obtained panels were acoustically and mechanically tested. The results showed values of sound absorption coefficient close to 0.50 and acceptable flexural strength for their use as suspended ceiling tiles. Therefore, these bio-based panels could be used as an alternative product to the traditional materials used for noise control applications inside commercial spaces like closed entertainment areas.