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The sustainability of the concrete industry is in jeopardy because it is one of the biggest consumers of natural resources. Environmental and monetary issues are the main difficulties the concrete industry is currently dealing with. In this study, the potential substitution of sawdust ash for cement in the production of concrete is explored. In this project, the potential substitution of sawdust ash for cement in concrete production was explored, a typical carpentry waste, and then we utilize several testing techniques to examine how it impacts the mechanical characteristics of concrete. In an experiment, the compressive, tensile, and flexural strengths of concrete samples made with various ratios of sawdust ash and cement were examined. The samples were made following ASTM C-109, ASTM C-496 and ASTM C-78 for compression, tensile and flexural testing. In place of cement, saw dust ash was added to the M-15 (M indicates ‘mix’ and 15 indicates compressive strength of 15MPA) sample in weight percentages of 5%, 10%, 15%, 20%, and 25%. The concrete samples were tested to ascertain their compressive, tensile, and flexural strengths after 14 days. Comparisons between the results and untreated concrete were done. In this study, the behavior of concrete was investigated when sawdust ash was replaced for cement to weight-based extents of 0%, 5%, 10%, 20%, and 25%. This could address the problem of how to dispose of sawdust ash while also enhancing the properties of concrete.

This study explores the efficacy of Recycled Fine Powder (RFP) derived from construction and demolition waste as a sustainable substitute for Ordinary Portland Cement (OPC) as a Calcium (Ca) source in geopolymer mortar. Fresh properties of Geopolymer Mortar (GPM) were evaluated in terms of slump-flow, initial-final setting time, whereas hardened properties were evaluated in terms of Compressive Strength (CS), Water Absorption (WA), porosity, acid attack, and dry shrinkage at both ambient and heat curing. Results indicate that the RFP performs well in all mixes. However, mix C10R10 shows the overall best results, as 17% higher compressive strength was observed as compared to mix C20R0, which further increases to 88% when compared to mix C0R0. Thus, RFP provides sufficient Ca content as an activator in GPM.

Recycled concrete aggregates (RCAs) and supplementary cementitious materials (SCMs) may substitute some cement and natural aggregates (NA) in concrete manufacturing. However, their effects on recycled aggregate concrete (RAC) compressive strength are difficult to model. Reactivity, silica, and alumina modulus were examined for cementitious materials' chemical complexity. Random Forest approaches were developed to predict and analyze RAC compressive strength. Even with RCAs and SCMs, the RF model accurately estimated concrete compressive strength. The Variable Importance (VI) research examined how input factors affected RAC compressive strength. VI indicated that silica fume contributes most to RAC compressive strength, followed by cementitious materials' reactivity modulus, cement content, silica modulus, fine natural aggregate content, and coarse natural aggregate dosage. The water dosage, water/binder ratio, and RCA content lower the RAC compressive strength. As a result, to highlight, the amount of SCM was not significant, but its nature was (i.e., hydraulic, silica pozzolanic, or alumina pozzolanic).

The main problem of our cities is the lack of treatment and final disposal of construction and demolition waste (CDW), which, accompanied by a lack of knowledge, becomes a major problem. Likewise, a city in the north of Peru (Cutervo) is not immune to the problematic reality experienced in the country and worldwide, since the lack of CDW management projects has generated the formation of informal dumps. The main objective of this research is to determine the technical and economic feasibility of using CDW for the production of pedestrian pavers, given that it includes measurements of the physical and mechanical characteristics to be analyzed. It is concluded that the use of CDW in the production of paving stones is feasible, from the economic and technical aspects, incurring a reduction in cost.

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.

At present, social problems have been seen, such as the presence of brick residues in the streets and heavy rains, affecting the population in general, so it has been seen as convenient to use recycled brick as a material for the preparation of a pavement.permeable for parking lots in order to mitigate the impact produced by the rains. The present investigation used the 22factorial design of experiments for the optimization of the designs, for which two variables were manipulated, the recycled brick and fine aggregate. The research sought to improve the compressive strength of the perviouspavement. It was possible to improve the compressive strength of the permeable pavement, obtaining an average compressive strength at 28 days of 217 kg/cm2using proportions of 4% ground recycled brick and 8% fine aggregate, a modulus of rupture of 29.97 was also obtained. kg/cm2and a permeability of 0.241 cm/s. With the results obtained and in accordance with the ACI 522r-10 Standard, it is concluded that brick, due to its high resistance, allows the use of a lower proportion of fine aggregate to avoid reducing permeability and thus a permeable pavement for parking lots can be made.

This paper investigates the feasibility of using recycled plastic composed of polypropylene (PP) and high-density polyethylene (HDPE), as a basis for the fabrication of plastic bricks for non-structural walls starting from the material characterization. The deformation properties of plastic bricks were evaluated under the application of compression, flexural and traction forces; the thermal analysis of the material was carried out by means of the ignition test, differential scanning calorimeter (DSC) and its water ab-sorption capacity was also tested. Satisfactory results were obtained in the tests carried out; It was found that the compressive strength of the material complies with the requirements of standard specifications for conventional bricks (clay - concrete), and the physicochemical properties of the composite meet specifications of material for use in non-structural walls; which makes it an innovative material with enormous potential for use in the construction sector.

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.

Little is known about the applications and use of hydrated lime currently produced in Ecuador. The present research focuses itsstudy on 6 samples of hydrated lime marketed locally. Their performance was deter-mined based on the national standard NTE INEN 488 in masonry mortars. These initial tests made it possible to identify the lime with which the mortar with the highest compressive strength is obtained. We worked on a mortar design that incorporates this lime and reaches the resistance established by the NTE INEN 2518 standard. A mortar of 3.5 MPa at 28 days was cata-loged in the standard as a type O mortar for use in non-load-bearing masonry and plastering. These results are expected to contribute to the knowledge of Ecuadorian lime and facilitate its incorporation in the construction of local buildings.

The cerambycid insect Xylotrechus arvicola is considered a pest that affects the wood of the grapevine (Vitis vinifera) in the major wine areas of the Iberian Peninsula. The larva of this insect perforates the grapevine wood, resulting in structural and biomechanical failure of the vine plants. Vine samples from wood damaged by Xylotrechus arvicola larvae were picked up from different vineyards and grape varieties. Compressive and flexural tests were performed in order to assess the mechanical behaviour of the wood samples. Total length of the cracks in wood samples (TLCWS) that appeared on the surface of the grapevine wood samples after the mechanical tests was measured. Compressive strength (CS) and flexural strength (FS) decreased with the increase of the cross-sectional area (CSA) of both branches and trunks, regardless of damage condition or water content. Moreover, the resistance was lower in damaged wood. In addition, this was verified through the linear regression coefficients of the interaction CS x CSA and FS x CSA. TLCWS in branches and trunks of damaged samples was greater that in undamaged samples. Also, TLCWS within the same damage condition and part of the plant was higher in dry samples than in fresh samples. The damaged wood would show a higher vulnerability to common mechanical stress suffered by the grapevines in the field including heavy winds, fruit overweight or harvesting machines shaking (when mechanically collected). Larvae of this insect altered the mechanical behaviour of the trunk and branches of grapevine wood. The mechanical strength of wood was more negatively affected when the CSA of the branches and trunks increased. Longer TLCWS was found in affected wood.of an emerging grape pest, Xylotrechus arvicola (Coleoptera: Cerambycidae)

In recent past years, plastic waste has been a environmental menace. Utilization of plastic waste as fine aggregate substitution could reduce the demand and negative impacts of sand mining while addressing waste plastic challenges. This study aims at evaluating compressive strengths prediction models for concrete with plastic—mainly recycled plastic—as partial replacement or addition of fine aggregates, by use of artificial neural networks (ANNs), developed in OCTAVE 5.2.0 and datasets from reviews. 44 datasets from 8 different sources were used, that included four input variables namely:- water: binder ratio; control compressive strength (MPa); % plastic replacement or additive by weight and plastic type; and the output variable was the compressive strength of concrete with partial plastic aggregates. Various models were run and the selected model, with 14 nodes in hidden layer and 320,000 iterations, indicated overall root mean square error (RMSE) , absolute factor of variance (R2), mean absolute error (MAE) and mean absolute percentage error (MAPE) values of 1.786 MPa, 0.997, 1.329 MPa and 4.44 %. Both experimental and predicted values showed a generally increasing % reduction of compressive strengths with increasing % plastic fine aggregate. The model showed reasonably low errors, reasonable accuracy and good generalization. ANN model could be used extensively in modeling of green concrete, with partial waste plastic fine aggregate. The study recommend ANNs models application as possible alternative for green concrete trial mix design. Sustainable techniques such as low-cost superplasticizers from recycled material and cost-effective technologies to adequately sizing and shaping plastic for fine aggregate application should be encouraged, so as to enhance strength of concrete with partial plastic aggregates.

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.

Fe-based BMGs are well known for its attractive combination of structural, magnetic and corrosion properties. These alloys are widely used in industry because of low price and good glass forming ability (GFA). In this paper, the effect of partial substitution of Cr with Co on GFA, mechanical and magnetic properties of Fe48Mo14Cr15-xCoxB6P8Si7Y2 bulk metallic glasses was studied. The samples were prepared by copper mold casting technique in rod form. The elaborated alloys were structurally investigated by X-Ray diffraction (XRD) and differential scanning calorimetry (DSC), while the mechanical properties were investigated by compressive and nanoindentation tests. Also, the magnetic properties were investigated. The GFA was estimated by several criterion or parameters (reduced transition temperature Trg, ΔTx, α, β, γ and δ parameters). It was found that the addition of Co instead of Cr leads to a slight increase of the glass forming ability of Fe-Mo-Cr-B-P-Si-Y family. Also, an increase in magnetic properties, hardness, elastic modulus and compressive strength has been noted.

Se informó que la producción mundial de cemento Portland fue de 4650 millones de toneladas en 2016. Dicha producción de cemento exige una cantidad significativa de recursos naturales y energía. Además, la producción de una tonelada de cemento Portland emite alrededor de 0,87 toneladas de dióxido de carbono. Este valor se reduciría significativamente al utilizar cementos ternarios elaborados con residuos industriales como escoria granulada de alto horno molida (GGBFS) y cenizas volantes de carbón (CFA). Además, se promueve la economía circular mediante el uso de residuos industriales (GGBFS y CFA) y se aumenta la durabilidad del hormigón en ambientes agresivos. Por el contrario, inducen un retraso en la ganancia de resistencia a la compresión como resultado de la reacción puzolánica. En este trabajo se ensayaron mezclas ternarias de cemento con proporciones GGBFS y CFA (25% y 40%) sobre morteros estándar. En consecuencia, se realizaron medidas de resistencia a la compresión a los 2, 7 y 28 días. Se discutieron las interacciones estadísticas entre GGBFS y CFA en los resultados de resistencia a la compresión de los morteros de cemento Portland ternarios. Abstract Global production of Portland cement was reported to be 4.65 billion tons in 2016. Such cement production demands a significant amount of natural resources and energy. Furthermore, the production of one tonne of Portland cement emits about 0.87 tons of carbon dioxide. This value would be reduced significantly by using ternary cements made with industrial wastes such as ground granulated blast-furnace slag (GGBFS) and coal fly ash (CFA). In addition, circular economy is promoted by using industrial wastes (GGBFS and CFA) and the concrete durability in aggressive environments is increased. By contrast, they induce a delay in the compressive strength gain as result of the pozzolanic reaction. In this paper, ternary cement mixes with GGBFS and CFA proportions (25% and 40%) were tested on standard mortars. Accordingly, compressive strength measures at 2, 7 and 28 days was performed. Statistical interactions between GGBFS and CFA on the compressive strength results of ternary Portland cement mortars were discussed.

A regulatory framework is required to ensure the correct design of Fibre-Reinforced Polymers (FRPs) increasingly being used as an externally-bonded strengthening system on concrete columns. Several design guidelines on the confinement of FRP concrete have been developed over the past few years worldwide, each proposing a different approach, resulting in different predictions. This study aims to evaluate and compare nine international design guidelines used to predict the compressive strength of confined concrete in FRP-strengthened concrete columns and weigh them against experimental results. The results of this investigation reveal that the predictions from the guidelines on the compressive strengthening of FRP-confined concrete are generally suitable for circular columns, with the ACI-440 and CNR-DT 200 guideline predictions being two of the most accurate. Nevertheless, the guidelines generally tend to overestimate the load-carrying capacity for the compressive strength of FRP-confined concrete in non-circular columns, for which further experimental work using large-scale specimens is required.

In order to better match the multi-level structural characteristics and multi-scale fracture process of cementitious composite, multi-scale hybrid fiber-reinforced strain hardening cementitious composite (MsHySHCC) was designed by adding hooked steel fiber and calcium carbonate (CaCO3) whisker into conventional polyvinyl alcohol (PVA) fiber-reinforced SHCC. Compressive properties of PVA-SHCC and MsHySHCC were evaluated experimentally. The results indicate that the designed MsHySHCC had a better compressive performance than that of PVA-SHCC. Moderately partially substituted PVA fibers by steela fiber and CaCO3 whisker enhanced the compressive parameters, however, further substitution of PVA fibers by increasing the content of CaCO3 whisker didn’t bring a higher promotion. Two kinds of semi-theoretical compression constitutive models were developed from the perspective of damage mechanics theory and geometrical mathematical description, respectively. It was found that both of the proposed models can be applied to predict the uniaxial compressive stress-strain relationships of PVA-SHCC and MsHySHCCs.

Abstract— The aim of this project is to develop and study different kinds of concrete in order to improve its thermal properties to be used in reinforced concrete structures of thermally active building systems (TABS). For this reason different specimens and testing procedures were proposed to study, on the one hand thermal conductivity of concrete made with three different types of cement (CEM I, CEM II and CEM III) and two different kinds of aggregate (limestone and siliceous) at three different levels of humidity (0%, 50% and 100%) was analized. On the other hand, compressive strength of concrete was also studied. Results from thermal tests showed that specimens made of concrete with cement CEM II, siliceous aggregate and humidity of 100% had higher values of conductivity than the other specimens; while mechanical tests showed that concrete with cement CEM I and limestone aggregate had a higher compressive strength. In conclusion, concrete made of cement type CEM II and siliceous aggregate improved the conductivity of concrete for its use on thermal active structures. Thermal conductivity was also improved by high levels of humidity in concrete. Contrary to the expectations, concrete specimens made of cement CEM III didn´t show higher thermal conductivity levels than concrete made of cement CEM I and CEM II. Resumen El objetivo del trabajo es el análisis de la influencia de distintas variables sobre la conductividad térmica del hormigón y su resistencia a compresión, para ser usado en estructuras termoactivas. Se valoró la influencia del tipo de cemento, el tipo de árido y la humedad del hormigón. Se llevó a cabo una campaña experimental de probetas de hormigón H-25, elaboradas con tres tipos de cemento diferentes (CEM I, CEM II y CEM III) combinados con dos tipos de árido (calizo y silíceo) en el que se estudió por una parte la conductividad térmica del hormigón en tres grados de humedad diferentes (0%, 50% y 100% de humedad) y por otra parte la resistencia a compresión del hormigón. Los resultados de los ensayos térmicos mostraron valores de conductividad superiores en las muestras elaboradas con cemento CEM II, árido silíceo y 100% de humedad. Los resultados derivados de los ensayos a compresión indicaron que las muestras con cemento del tipo CEM I y árido calizo ofrecieron valores de resistencia a compresión superiores a las del resto de las muestras. Contrariamente a lo que se esperaba, las muestras de hormigón elaboradas con cemento CEM III no ofrecieron valores de conductividad superiores al resto de muestras. Se puede concluir que el hormigón elaborado con cemento CEM II y árido silíceo es más adecuado para su empleo en los elementos estructurales de hormigón de las estructuras termoactivas, siempre que los requerimientos estructurales no se vean comprometidos.

Research developed in the last decades has allowed significant advances in the concrete technology, achieving remarkable improvements in its performancemainly related to its microstructure. In order to relate the behaviour under compressive stresses of high performance concrete (HPC) and the changes in its microstructure, an experimental campaign was developed with specimens of dimensions 160x40x40 mm3. A control mixture without additions and a series of mix designs with partial substitution of cement by of silica fume and metakaolin in different proportions were produced. A low water-to-binder ratio of 0.20 was used, which forced the use of a superplasticizer additive based on modified polycarboxylates, which improved the workability of the mixtures. Silica sand with 98% of SiO2 content and an average particle size of 0.75 mm was used. The specimens were subjected to compressive strength tests at 2, 7, 28 and 91 days, and complementary tests of electric resistivity, mercury intrusion porosimetry (MIP) and differential thermal-thermogravimetric analysis (DTA-TG) at 28 days. The results of the tests showed that the increase in compressive strength with the use of additions was directly related to the reduction in total porosity and the increase in the proportion of total CSH gel / total portlandite, shown by the MIP and DTA-TG tests, respectively. Mixtures with additions showed reductions of the porosity by up to 31.7% compared with the control mixture, while increasing the proportion of CSH gel/ total portlandite by up to 17.1%. The use of small particles of mineral additions significantly increased the electric resistivity of HPC specimens as evidenced in the present study. This is explained by the reduction in the percentage of large capillary pores and the relative increase of small capillaries, which could enhance the durability of the concrete elements. Resumen La investigación desarrollada en las últimas décadas ha permitido avances significativos en las prestaciones del hormigón, a través de la mejora de su microestructura .En este trabajo se presentan los resultados de una campaña experimental encaminada a mostrar la influencia de la microestructura del hormigón de altas prestaciones (HPC por sus siglas en inglés) en su resistencia a compresión. Se elaboró una mezcla de control sin adiciones y una serie de mezclas con sustituciones parciales del cemento con humo de sílice y metacaolín en diferentes proporciones. Se usó una relación de agua/conglomerante de 0,20, lo que obligó al uso de un aditivo superplastificante basado en policarboxilatos modificados, el cual mejoró la trabajabilidad de las mezclas. Se usó arena de sílice con 98% de contenido de SiO2 y un tamaño de partícula promedio de 0,75 mm. Con ellas se confeccionaron probetas de dimensiones de 160x40x40 mm3.Las muestras se ensayaron a compresión a los 2, 7, 28 y 91 días, y se realizaron ensayos complementarios de resistividad eléctrica, porosimetría de intrusión de mercurio (PIM) y análisis térmico termogravimétrico diferencial (ATD-TG) a los 28 días. Los resultados de las pruebas mostraron que el aumento en la resistencia a la compresión con el uso de adiciones estaba directamente relacionado con la reducción de la porosidad total y el aumento en la proporción de gel C-S-H/portlandita total. Estos aspectos se confirmaron con los ensayos de PIM y ATD-TG. Las mezclas con adiciones mostraron reducciones de la porosidad hasta en un 31,7% en comparación con la mezcla de control, a la vez que incrementaron la relación gel C-S-H/portlandita total hasta en un 17,1%. El uso de pequeñas partículas de adiciones minerales aumentó significativamente la resistividad eléctrica de las muestras de HPC, lo que confirma la reducción del porcentaje de poros capilares grandes conectados y el aumento de capilares pequeños, lo que además de la resistencia a compresión mejora la durabilidad del hormigón.

Carbon fiber jacketing is an efficient technique for increasing the strength and strain capacity of concrete circular and square section columns subjected to axial load, although confinement efficiency decreases for rectangular cross-section members. The research project BIA 2016-80310-P includes an experimental program on intermediate-size plain concrete specimens strengthened with carbon fiber jackets, mostly with square and rectangular cross-sections. The results, alongside others with similar characteristics from two databases published, are compared to predictions of four international guides. The incidence of the key parameters in the experimental results is analyzed, such as the aspect ratio of the section, the effective strain in FRP jacket attained at failure or the rounded corner radius. As a result, two efficiency strain factors are proposed, one for circular and another for rectangular specimens. The predictions contained in certain guides, based on a simple linear design-model, are improved by using the proposed efficiency strain factor for rectangular sections.

Interaction between microbially induced calcium carbonate precipitation (MICP) and compaction procedures to stabilise raw soil materials has been studied with the aim of producing earthen engineering structures. Initial tests to optimise MICP in aqueous medium and in selected soils were performed. MICP and compaction were finally applied to assess medium-size elements. The main result was that sandy soils should be compacted before irrigation treatment to close the existing voids and prevent bacterial sweeping, whereas clayey soils should be compacted after irrigation treatment to avoid the plugging effect. MICP improved small sand soil compressive strength by up to 32% over the value reached by compaction alone. However, MICP had no positive effect on coarse soils and soils with an optimum particle size distribution: MICP treatment was not able to fill large connected voids in the first case and it caused little void generation due to bacteria sporulation in the second.

To encounter the issues of waste materials, low tensile strength of concrete and environmental impacts of cement production, research is needed to develop a sustainable concrete. This study has endeavored to investigate the effects of using recycled coarse aggregates (RCA), various types of wastewater effluents, fly ash, and glass fibers on the mechanical and durability behavior of recycled aggregate concrete (RAC) incorporating with fly ash and glass fibers (FGRAC). Six different kinds of wastewater effluents for the mixing of concrete, 100% replacing the natural coarse aggregates with RCA, and 30% replacement of cement with fly ash were used for the development of concrete. The experimental measurement portrayed that the textile factory effluent presented the highest compressive and tensile strengths of concrete. Fertilizer factory effluent portrayed the highest water absorption, mass loss due to acid attack, and chloride penetration to concrete.

This paper aimed to evaluate the long-term compressive strength development of the sewage sludge ash/metakaolin (SSA/MK)-based geopolymer. SSA/MK-based geopolymeric mortars and pastes were produced at 25ºC with different SSA contents (0 - 30 wt.%). Compressive strength tests were run within the 3-720 curing days range. A physicochemical characterisation (X-ray diffraction and scanning electron microscopy) was performed in geopolymeric pastes. All the geopolymeric mortars presented a compressive strength gain with curing time. The mortars with all the SSA evaluated contents (10, 20, 30 wt.%) developed a compressive strength over 40 MPa after 720 curing days at 25ºC. The maximum compressive strength of the mortars with SSA was approximately 61 MPa (10 wt.% of SSA), similarly to the reference mortar (100% MK-based geopolymer). The microstructure analyses showed that the SSA/MK-based geopolymer presented a dense microstructure with N-A-S-H gel formation.

Due to the increasing use of rapid construction methods and the challenges of maintaining construction schedules, a growing demand exists for procedures that can assure quality of work without sacrificing the pace of construction. The quality control of construction materials specifically, the mechanical properties of concrete are among the most important concerns in today’s construction industry. In the present study, the correlation between fiber-reinforced concrete’s compressive strength and dynamic modulus to its ultrasonic pulse velocity is investigated at early ages up to 7 days after mixing. An experimental program involving 189 FRC specimens were designed containing different types of structural fibers, fiber volume fractions, and water-to-cement ratios. Mathematical equations were developed to predict the early-age compressive strength and dynamic modulus of four different types of fiber-reinforced concrete based on ultrasonic pulse velocity. The predicted compressive strength and dynamic modulus from the proposed equations showed good agreement with the measured ones.

The substitution of the normalized aggregate by residual foundry sand (WFS) was studied on the physical properties of mortars by means of resistance to compression and capillary absorption tests. The aggregate was replaced by WFS in its natural state (WFS), washed residual foundry sand (WFSW) and heat treated residual foundry sand (WFST). The WFS had a percentage of bentonite, which was sought to be thermally activated. It was found that the physical behavior of the mortars containing WFS and WFSW was similar to that of the control sample. The clay recovered from the sand washing was evaluated for its pozzolanic potential, it was found that, with the thermal treatment, the montmorillonite acquires pozzolanic behavior. Mortars with WFST presented a drop in compressive strength. The pozzolanic effect achieved in the clay was not reflected in the compressive strength of the mortars with WFST.

The flexural strength of pavement concrete is generally deduced by testing beams or by applying empirical equations. In this investigation, concrete mixtures were manufactured, incorporating 0, 20, 50 and 100% Reclaimed Asphalt Pavement (RAP), by weight, as a replacement for natural aggregates. The compressive strength was measured using cubic specimens and the flexural strength was measured for three types of specimens; beam, semicircular (SCB) and modified beam. This study proposes logarithmic and power equations that allow the estimation of the flexural strength of a concrete mix that incorporates RAP as a function of its compressive strength. Linear or power models are proposed to predict beam flexural strength from SCB specimens and a logarithmic model for modified beam specimens. Statistical analyses show that the proposed prediction models can be considered sufficiently accurate and their use is justified.

ABSTRACT The objective of this study is to evaluate the effect of sugarcane bagasse ash on the compressive strength and water absorption index of soil-cement bricks. The ash was sieved without chemical and/or physical treatment to reflect the use of this material in real manufacturing processes. The addition of natural ash decreased the quality of the bricks, reducing the compressive strength and increasing the water absorption index.

Walls made of soil present serious failures due to their exposure to rain and groundwater. In addition, due to their hygroscopic characteristics, compressed earth blocks (CEBs) present low resistance to water penetration and high capillary absorption coefficients. Therefore, CEBs combined with a cold asphalt emulsion were experimentally analyzed as an alternative to reduce their capillary absorption coefficient and improve their resistance to water penetration. The emulsion was incorporated in proportions of 25%, 50%, 75% and 100% with respect to the weight of water. The capillary absorption, resistance to compression, and moisture penetration of each sample were studied in order to calculate the optimal proportion of the mixture. Based on the results, CEBs with 50% asphalt emulsion exhibit the best characteristics of protection against humidity, thus guaranteeing the compressive strengthrequired for traditional construction.

The compressive strength parallel to grain of earlywood and latewood from the yellow pine sapwood and heartwood areas was examined in the study. The structure of the basic structural elements of wood - tracheids, which conduct water and/or perform the mechanical function - was also characterized. The compressive strength parallel to grain of latewood in the sapwood area was found to be twice as high as the compressive strength parallel to grain of earlywood. The compressive strength parallel to grain of latewood in the heartwood area, on the other hand, was found to be 2,5 times higher than the compressive strength parallel to grain of earlywood. This was due to the density of particular areas of wood and the dimensions of structural elements - tracheids. In the sapwood area, the density of latewood was ca. twice as high as the density of earlywood. Similar relationships were found for heartwood. The thickness of latewood tracheids was found to be 1,5 times greater than the thickness of earlywood tracheids. These relationships were observed in sapwood and heartwood. The diameter of earlywood tracheids in radial direction was twice as large as the diameter of latewood tracheids. These relationships were observed in yellow pine sapwood and heartwood.

Basalt was used as an ornamental stone in any historic and ancient cities in Jordan. Measuring the uniaxial compressive strength (UCS) and the tangent Young’s modulus (Et) in the laboratory requires premium quality specimens with special core dimensions. This research focuses on correlations both UCS and Et with Leeb Rebound Hardness Test (LRH). In the laboratory, UCS, Et, and LRH were performed on 90 core samples extracted from 30 different rock boulders collected from the neighboring area of Umm al-Jimal, a historic city in northeastern Jordan. A strong power correlation with (R2 = 0.888, RMSE = 5.464) was found between non-destructive LRH value and UCS. On the other hand, a moderately strong linear regression with (R2 = 0.792, RMSE = 4.661) was found between Et and LRH. In conclusion, non-destructive LRHs can be used as indictors for evaluating both UCS and Et during the restoration of the historic city Umm al-Jimal and the rehabilitation of other existing structures.

To ensure the safety of wooden structures, estimation of wood strength is based on the characteristic strength values. The Brazilian standard (NBR, in Portuguese Norma Brasileira Regulamentadora) 7190 proposes equations to estimate the strength properties with a simplified procedure, which allows obtaining the characteristic values through relations that correlate different mechanical properties. Using these equations, the values of tensile (ft0,k) and shear (fv0,k) strength can be calculated in a simplified way from the compressive strength (fc0,k) values. In the present work, 36 tropical hardwood species were evaluated for tensile, shear and compressive strength in the direction parallel to the grain, with a total of 1296 experimental measurements, and the precision of the relations defined by the Brazilian standard was assessed using the analysis of variance (ANOVA) method. Two-parameter regression models, based on linear, exponential, logarithmic and geometric functions, were used as an alternative proposal for the estimation of the strength properties. The statistical analysis validated the proposed relations, with the linear (ft0,k) and geometric (fv0,k) regression models being the models of best fit, with the coefficients of determination (R2) equal to 63,02 % and 70,15 %, respectively. In addition, new simplified equations were suggested. The least squares method was used to determine the optimal coefficient (α) for validation of the Brazilian standard equations. The obtained coefficients validated the tensile strength relationship (ft0,k = fc0,k / 0,77), but failed to validate the shear strength relationship (fv0,k = 0,12∙ fc0,k). In the latter case, the obtained values were significantly higher (up to 91 % higher) when compared to those estimated by the Standard

The objective of this research was to evaluate the physical-mechanical properties of wood-cement boards produced with waste particles of Pinus spp. and sufficient levels of pozzolans to assimilate all Ca(OH)2 produced during the hydration reactions of Portland cement. The pozzolans used were: silica fume, metakaolin, rice husk ash, and calcined ceramic waste. The values of the pozzolans were determined based on the theoretical determination of the Ca(OH)2 content produced by the hydration reactions of Portland cement. The pozzolanic activity index was determined by the modified Chapelle test, according to NBR15895:2010 and NF18-513:2010 standards. The boards were produced through cold compression, and the test specimens were produced and tested for physical and mechanical properties at 28/91 days of curing, according to ASTM-1037:2012, EN-317:1993, NBR-9778:2005 and ASTM-642:2002 standards. The minimum values employed in the Bison® commercial process were used as reference for the physical-mechanical characterization. The boards produced presented good physical-mechanical properties even with high levels of replacement of cement by pozzolans. These properties were similar to the ones presented by the reference boards, despite the significant reduction in the specific mass of the prototype boards, which demonstrates the technological possibility of use of these materials in the production of wood-cement boards.

Granite rock has powerful alterations at several meters of depth. The clayed sand resulting is commonly known as jabre. This “in situ” mixture of cement-stabilized soil requires a laboratory formula. Even when the test section is correctly verified, the mechanical properties of the homogeneous mixture of jabre exhibit high degrees of dispersion. The laboratory work undertaken included particle-size analysis and screening, defini­tion of liquid and plastic limits, compressive strength, dry density and moisture content over stabilized samples, modified Proctor, California Bearing Ratio (CBR) and the determination of the workability of the hydrauli­cally bound mixtures. The stress resistance curve was analyzed by means of a multilinear model of unconfined compressive strength (UCS). Since practical engineering only requires UCS for 7 days, in order to gain greater knowledge of the material, other UCS transformations were used at other curing times such as 7, 14 and 28 days.

This study investigates the effect of adding different size fractions of the same pore forming agent (sawdust) on the material’s compressive strength and heat transfer. The samples were dry pressed and fired at high temperature inside an oven. Phase transformations were evidenced by a combination of differential thermal analysis, thermogravimetry and mass spectrometry (DTA-TGA-MS) and X-ray diffraction (XRD) techniques, in the temperature range of 24-900 ºC. Image analysis (IA) and compression tests were performed to explain the mechanical behaviour of the samples. The thermal conductivity was obtained by using combined photopyroelectric calorimetry (PPE) and lock-in thermography (LIT) techniques. The pressing direction has an impact on the distribution of pores and the heat transfer by conduction.

The aim of the paper is to decouple the physical and chemical effects of limestone filler (LF), when used as a cement replacement. The effects were decoupled using LF and a chemically inert material (brucite Mg(OH)2). Paste, and mortar specimens were steam cured for 16 hours at 55°C. The heat of hydration, thermal analysis, x-ray diffraction, and compressive strength, were evaluated at 16 hours and at 28 days. LF can adversely affect the properties through dilution effect. However, heterogeneous nucleation compensates for the dilution effect at 16 hours while the production of mono-carboaluminate compensates for the dilution effect at 16 hours and 28 days. The study could be broadened by considering a wider temperature range. The originality lies in the method of decoupling the physical and chemical effects. Measurable effects of the physical and chemical contribution of LF are evident on the mechanical and transport material properties.

This study investigated the physical-mechanical effects of cement-lime mortars containing recycled aggregate of construction and demolition waste (CDW). The natural aggregate (NA) was replaced by volume at 25%, 50%, 75% and 100% by mixed recycled aggregate (MRA) obtained from the CDW crushing. Five types of mortars were prepared with a volumetric ratio of 1:1:6 (cement, lime and aggregate) and water/binder ratio based on the fixed consistency of 260 mm. The effects of MRA on fresh and hardened mortars’ properties were analyzed. The results were analyzed using a one-way ANOVA. MRA incorporation improved most of the physical-mechanical properties of mortars tested, except for hardened bulk density, water absorption and porosity. In the long-run, mechanical strengths significantly increased in all compositions, especially those with higher percentages of MRA. The results obtained showed that the use of MRA in masonry mortars is an alternative to reduce the generation of waste and consumption of natural resources.

This paper presents the study of four gypsum mixtures, focusing on the role of both inorganic and organic additives and on the micro-structural features and mechanical properties. Additives have been chosen among those most reported in historical recipes, for example magnesia, lime putty, rabbit glue. The selected mixes refer to gypsum-based materials used in artworks manufacture, such as plasters, mouldings, stuccoworks, pastiglia. Blank reference materials were prepared on purpose according to the specific recipe, in order to verify the final composition and to highlight the hardening mechanisms and the formation of setting compounds. The chemical composition was related to workability properties and final mechanical resistance and the action of additives as retardants was studied with interesting results. For instance, MgO imparts good properties to the mechanical features, especially with regard to the compressive strength characteristics.

This work presents the finite element analysis of partially stiffened cylinders subjected to axial compression at elevated temperatures. The compressive strength is calculated for self-weight conditions and the influence of the temperature on the material response is also investigated. In the oil industry, pressure vessels are commonly used operating at complex design conditions such as high-pressure profiles and/or elevated temperature gradients which affect considerably the structural response of inner components. Among them, risers become sensitive steel elements withstanding heavy compressive loading due to self-weight, as well as, insulation elements added to protect them from the elevated temperature gradient. Most risers structurally fail at the bottom end due to buckling caused by self-weight and temperature effects. To remediate this situation and to guarantee the integrity of the riser, longitudinal stiffeners are welded at the bottom end. Hence, a proper determination of the compressive strength of the cylinder, taking into account the influence of the longitudinal stiffening and the corresponding temperature, is required. Results indicate that the use of longitudinal stiffeners in deformed cylinders increases the strength to buckling in percentages that vary according to the cross-section of the profiles.

Compared to conventional concrete, high-performance concrete production offers such benefits as greater ease of placement, smaller sections, improved finishing and higher strength and durability. For the design of these types of concretes, it is advisable to carry out studies on pastes or mortars in order to evaluate admixture - cementitious material compatibility. This evaluation entails verifying fresh state properties and evolution over time. The aim of this work is to evaluate the behavior of mortars made with different water reducers as well as binary and ternary cements, and their connection to the properties they acquire in hardened state. Fluidity in the fresh state and absorption, density and compressive strength in the hardened state were evaluated. The results show that the impact of superplasticizers is not restricted to the fresh state, as influence on the development of the degree of hydration and compacity can also be noticed.

En los últimos años en Venezuela se ha presentado una crisis en la demanda, comercialización y producción del cemento, material necesario para la construcción, por lo cual se han venido utilizando cementos adicionados sin ningún tipo de regulación. En este trabajo se presenta la caracterización físico-mecánica de tres mezclas de concreto con relación agua/cemento de 0,45 y relación agua/cemento de 0,60 con diferentes tipos de cemento Portland, Tipo I, Tipo CPCA1, y la tercera mezcla corresponde a Tipo CPCA1 retribuyéndole el 15% de adición en su propio peso, desarrollando una mezcla de mejor calidad. Estos concretos se caracterizaron según: asentamiento, tiempo de fraguado, porcentaje de porosidad total, porcentaje de absorción de agua y resistencia mecánica a la compresión. Los resultados demostraron que la mezcla de concreto elaborada con CPCA1 no cumple con los requisitos mínimos establecidos en la norma venezolana para su uso en la elaboración de concreto estructural, ya que entre otros parámetros su resistencia a la compresión está por debajo del valor de diseño. En cuanto al CPCA1 retribuyéndole el 15% de adición en su propio peso cumple con los requisitos establecidos, y puede ser utilizado en la fabricación de elementos estructurales de concreto.

This article presents the results obtained in the mechanical properties of the addition of soot, which is a byproduct of cooking the bricks used in Santander brickworks. The clay used was initially characterized using the manual granulometric method, following the NSR 10 standard. Chemical and mineralogical compositions were analyzed using an X- ray Diffraction technique. The analysis of the mechanical properties of ceramic was developed through compression tests, according to the guidelines of the Colombian NTC: 4017 Technical Standard. The results show that adding less than 60% in mass of soot residues, when clay is added, increases the compressive strength to 265.31 kg / cm2 in average. This increase is significant taking into account that the minimum compression value according to the standard is 140 kgf/cm2.

Adobe has been used in construction since the first civilizations in the world, and to improve its mechanical properties, organic stabilizers were added. We studied the compressive strength of adobe cubic samples made with soil from the Sierra Region of Ecuador and organic stabilizers. Four organic stabilizers were studied: cow manure, nopal sap, straw and bull blood, which were added in specific percentages individually and in combination. Field and laboratory tests were carried out according to “Proyecto de actualización – versión 1 de la Norma Peruana E.080 de Noviembre 2013”. The results showed that the four organic stabilizers improve the compressive strength, having an increase from 0.5 to 13.1%. By using 10% of cow manure with 20% of bull blood the adobe compressive strength increased 13.1% in relation to the basic adobe.

Mount Erciyes is a huge stratovolcano of the Central Anatolian province in Turkey and it has produced calc-alkaline and pyroclastic rocks, which have been widely used as dimension stone in low-storied buildings and especially in historical monuments in the past. In the region there are some 205 quarries extracting volcanic rocks. In this study, the locations of these quarries and information on their annual stone production are evaluated. In order to assess the material properties of the Mount Erciyes volcanic products, petrographic analyses and a number of rock mechanical tests were carried out. Significant correlations were found between the properties of the rock samples. In particular, there is a significant relationship between thermal conductivity and some non-destructive measurement values such as P-wave velocity, Equotip and Schmidt hardness, and it is clear from the regression equations that these tests can be used as indicators for evaluating the Mount Erciyes products.

This study was aimed at determining the optimal glue quantity for bamboo lamination. Bamboo laminated boards were produced using glue applied at three different rates: 150 g/m2, 200 g/m2 and 250 g/m2. The boards produced were evaluated for their physical (density, longitudinal, tangential, radial and volumetric shrinkage) and mechanical (impact bending strength, modulus of elasticity, modulus of rupture and maximum compressive strength parallel to grain properties. It was discovered that the boards were uniform in their investigated physical properties but the glue quantity significantly influenced both the impact bending strength and modulus of rupture of the boards. Based on the results, it was observed that the boards produced with glue applied at the rate of 200 g/m2 met all the technical specifications on the basis of the investigated physical and mechanical properties, hence, concluded to be the optimal glue quantity for bamboo lamination.

Structured and unstructured factors affect concrete product. Structured factors are related to concrete production and unstructured factors are related to the construction process. This study focuses on examining the perceived importance of unstructured factors (i.e., construction-related factors) on concrete compressive strength, concrete costs and production rates on the jobsite and understanding the influence of construction experts’ characteristics, such as profession, on their perceptions. A comprehensive literature review was performed to identify unstructured factors. A survey was then designed and deployed to 297 experts from the construction industry and academia to examine the importance of the identified factors through the relative importance index (RII) method and to further identify additional unstructured factors. Likert aggregation and tests for equality of odds were used to compare and analyze responses of two groups of participants, namely architects and engineers. Curing humidity, crew experience and compaction method are the top three factors perceived to affect concrete compressive strength, whereas crew experience, mixing time and compaction method are the factors perceived to affect concrete costs and production rates the most. Crew experience, compaction method and mixing time dominate the global ranking of perceived affecting factors for concrete compressive strength, costs and production rates. Architects were found to be more likely to perceive high or very high impacts of these factors on concrete. The present study increases our understanding of construction-related factors to facilitate project management and preserve concrete characteristics.

This research aimed to study the effect of finenesses of bagasse ash (BGA) on the alkali-silica reaction of mortar. The BGA sample was ground to have particles retained on a sieve No. 325 of 33±1% and 5±1% by weight. Ground BGA samples were used separately to replace ordinary Portland cement (OPC) at rates of 10, 20, 30 and 40% by weight of binder to cast mortars. The compressive strengths and the alkali-silica reaction (ASR) of mortars were investigated. The results showed that a large particle size of BGA is not suitable for use in lowering ASR because it results in a low compressive strength and high expansion due to ASR. The mortars containing BGA with higher fineness exhibited higher compressive strength and lower expansion due to ASR than the mortars containing BGA with lower fineness. The results also suggested that the ground BGA retained on a sieve No. 325 of less than 5% by weight is suitable to be used as a good pozzolan which provides high compressive strength and reduces the expansion of mortar due to ASR even though it contains high LOI. The obtained results also encourage the utilization of ground BGA effectively which leads to reduce the disposal of bagasse ash.

An effective scheme to formulate high performance and multifunctional cement based mortar composites reinforced with varying lengths of carbon fibers has been devised. The detailed investigations pertaining to the fracture response of composites in cracks initiation and progression phases, their conducting mechanism and volumetric stability were performed with varying loads of 6mm and 12mm long carbon fibers at two different w/c ratios i.e. 0.45 and 0.50. The experiments concluded that an optimum addition of carbon fibers results in substantial improvement of fracture properties alongside significant reduction in electrical resistivity and total plastic shrinkage. The field emission scanning electron microscopy of the cryofractured specimen revealed crack arresting actions of uniformly distributed carbon fibers through successful crack bridging and branching phenomenon.

The temperature at which the alkaline activation process takes place is a significant factor in the evolution of the mechanical properties of coal ash cementitious base material. In this work, the influence of temperature (8 a 38 °C) and curing time (3 and 28 days) on the mechanical properties of the alkaline synthesis of two coal ashes was evaluated through the study of the mineralogical evolution of the cementitious phases by XRD and FTIR. We found that the type of zeolite, a synthesis product, depends on the study factors. For values above 28 °C and at least 7 days, alkalinely activated cements with compressive strength above 20 MPa were achieved. Other parameters, such as SiO2/Al2O3 ratio, percentage of unburned coal and particle-size distribution, should be taken into account in the variation of mechanical performance.

This paper presents an experimental study on the behavior of cement stabilized rammed earth (CSRE) column reinforced with steel under axial loading and its comparison with unreinforced and bamboo reinforced columns. Effects of structural parameters such as tie / stirrup spacing on the failure pattern, lateral and axial deformation of columns are studied. Test results show that the load-capacity of columns increases with increase in lateral / tie reinforcement ratio. Maximum axial and lateral deformations occur in columns with least tie spacing. Behavior of CSRE columns reinforced with close tie spacing is characterized by gradual spalling of cover at the failure zone. Steel reinforced columns perform better than other column types in terms of load-capacity; hence it may be used as structural member adjacent to walls for low-rise rammed earth houses. Proposed reinforcement technique can be adopted in the field for enhancement of greater strength and performance of columns.

The purpose of this study is to determine correlations among content of concrete water, compressive resistance and Ultrasonic Pulse Velocity (UPV). Cylindrical concrete specimens, 200 mm long and 100 mm in diameter made from a mixture of Portland cement type I, and a water/cement ratio (w/c) 0.5, have been studied. The curing of the specimens was performed under standardized conditions and indoor environmental conditions. It determines the water content in each specimen by difference in weight and subjecting them to UPV tests and to compressive resistance test during the first 28 days after the setting. The results show a model of logarithmic type that describes the relationship between the compressive strength with the water content of concrete and the UPV during the curing stages proposed.