Scielo RSS <![CDATA[Revista de la construcción]]> vol. 21 num. 3 lang. es <![CDATA[SciELO Logo]]> <![CDATA[Effect of industrial wastes on self-cleaning properties of concrete containing anatase-TiO<sub>2</sub>]]> Abstract: Concrete decomposing the organic compounds on because of natural or anthropogenic contaminating sources with photocatalysis existing in its structure is called self-cleaning concrete. In this study, the self-cleaning concrete with industrial waste has been searched from the point of mechanical and physical characteristics. Fly ash, blast furnace slag and sepiolite materials has been used as industrial waste in concrete. Titanium dioxide (TiO2) has been used as photocatalysis material. Specimens with the dimensions 15×15×15 cm were produced using 0 %, 10 %, 20 % and 30 % industrial wastes and 0 %, 1 %, 3 %, 5 % TiO2 by weight instead of cement. Compressive strength, unit weight, and ultrasonic pulse velocity tests were performed on the specimens after 28 days standard cure. Rhodamine-B test in Italian UNI 11259 standard and additional Phenantroquinone test have been performed as self-cleaning test. XRF test also has been made on some of the samples for the chemical analysis. The best photocatalysis performance has showed in the concrete including 5 % TiO2. Test results show that 10 % use of industrial wastes in self-cleaning concrete production is recommended from the point of economic and environmental benefits. <![CDATA[Flexural behavior of concrete beams reinforced with glass fiber reinforced polymer and steel bars]]> Abstract: In this study, a comparative experimental analysis is performed between steel-reinforced concrete beams, which are dimensioned based on NBR 6118 (2014), and beams reinforced with glass fiber-reinforced polymer (GFRP) rebar, which are dimensioned based on ACI 440.1R (2015) after being subjected to a four-point bending test. The beams are dimensioned to resist the same force and to satisfy the service limit state (SLS). Results show that the two groups of beams exhibit similar vertical displacement behaviors until the SLS-DEF, whereas the GFRP beams exhibit larger deflections. At the ultimate load, the beams with fiberglass bars indicate a higher resistance by approximately 64% compared with those with metal bars. <![CDATA[Effect of silica fume and basalt fibers on the fracture parameters of magnesium phosphate cement incorporating fly ash]]> Abstract: Magnesium phosphate cements are implemented for several purposes demonstrating significant mechanical properties in limited durations. However, brittle behavior of this material needs utmost concern and tensile performance may be enhanced with the proper application of fibers increasing both ductility and energy absorption capacity. This research studies the effect of basalt fibers (BF) and silica fume (SF) on the fracture parameters of magnesium phosphate cement (MPC). MPC mortar mixtures were prepared with different SF (0, 5, 10%) and BF amounts (0, 0.5, 0.75, 1 % by wt.). Also fly ash was adopted with a constant ratio for all mixes. Compressive strength and splitting tensile strength results indicated that addition of SF into mixtures extensively developed the matrix structure and improvements were noted with the increasing SF content. The inclusion of BF enhanced the flexural behavior although there were significant improvements in the fracture energy as well as the double-K parameters. Improvements in the tensile capacity of specimens with high BF were prone to the amount of SF percentage such that inclusion of 1 % BF performed best with 10 % SF added mixtures. Load-CMOD (crack mouth opening displacement) curves obtained from notched three-point tests were given for all specimen series and parameters were calculated according to the double-K criterion. Addition of BF resulted in higher toughness values however presence of SF was very significant in establishing appreciable development in toughness values. Brittleness index was implemented to establish clear conclusions on the findings and best performance was seen for specimens with 10% SF and 1% BF. <![CDATA[Gravel impact compaction piers as a method of soil improvement]]> Abstract: The purpose of this study was to evaluate the performance of gravel impact compaction piers system (GICPs) in improving a 3.5m thick loose silty sand in a multilayer coastal soil system located in Bushehr, Iran. The liquefiable sandy soil layer was layered on clay layers with moderate to very stiff consistency and below the engineering embankment layer with a thickness of 1.8 m. Implementation of gravel impact compaction piers is a new generation of aggregate piers. Gravel impact compaction piers were used to improve the liquefiable soil layers and to increase the bearing capacity and reduce subgrade settlement to withstand surface infrastructures. The process of making gravel impact compaction piers in a triangular or square-patterned grid was created using three types of special mandrels and feeding and compacting the gravels in the cavity in several stages without removing the soil from the cavities. The experience gained in this case study showed that artificial liquefiable was created immediately after the construction of these piers in a limited area and the soil became unstable. After about 11-14 days, the soil stabilized rapidly. The results of the standard penetration test in the matrix soil around the piers showed that the amount of (N1)60 in compacted soils was in the range of 21-30 and on average 15 times the amount of (1-3) in the initial soil. Also, the relative density of the initial soil was increased from 25% to 75% after soil improvement. Accordingly, by relying merely on the compaction properties of the piers and without relying on other primary soil remediation factors, such as piers drainage and soil texture change, the safety factor of the improved soil is 1.7-1.95 times the minimum required according to the two risk levels in the design. <![CDATA[Experimental and numerical dynamic identification in an RC tower]]> Abstract: In this study, the dynamic behavior of one of the prominent structures in Istanbul, Üsküdar Observation Tower (UOT) has been investigated. The structural system of the tower is formed by a reinforced concrete circular tube having 2.8 meters outside diameter with a 40 centimeter thickness. By referring to the ground level, it starts from -18.2 meter due to five basement stories around the tower and its height is 44 meters. Two reinforced concrete floors were partially hanged over at 36 meter and 40 meter in height. The tower has an independent structural system from the ground level but a non-structural cladding assembly connects it to an adjacent building in the complex. With the mentioned structural features, Ambient Vibration Survey (AVS) was utilized to obtain the dynamic characteristics of UOT by Peak Picking (PP) method. The obtained dynamic properties were discussed with the peculiarities of UOT. While the performed analysis revealed the ineffectiveness of the adjacent building and the underground stories in the dynamic behavior of UOT, the torsion action of the floors has been noted. A numerical model has also been constructed to obtain the dynamic characteristics of UOT by Finite Element Analysis (FEA). The model calibration required to increase the code-based modulus of elasticity of the concrete by 23% for pairing the experimental and numerical dynamic properties. The reasons of the increase and the correlation between AVS and FEA were discussed. <![CDATA[Influence of hemp shiv, cement, and water content on the properties of lightweight hemp composites produced using different sizes of hemp shiv]]> Abstract: This study investigated the production and properties of lightweight hemp composites produced using waste industrial hemp stems cultivated in Turkey. Hemp stems were separated from their fibers and fragmented to obtain hemp shiv aggregates in the laboratory. Twelve mixtures were prepared with varied volumetric ratios of hemp: cement (H:C) and hemp: water (H: W) using different sizes of hemp shiv. The influence of mix proportions on the physical and mechanical properties of hemp composites were investigated. Besides, microstructure of hemp composites was examined. The hemp composites produced were in the apparent density range of 312 to 928 kg/m3 and exhibited 0.20 to 1.24 MPa compressive strength. The water absorptions of samples were in the range of 3.47 and 8.50 kg/m2.h1/2. The apparent density and compressive strength of hemp composites decreased with the increase of H:C ratio, but this situation is the opposite for increase of H: W ratio and hemp shiv size. Besides, increase in H:C ratio or hemp shiv size caused higher water absorptions. <![CDATA[An experimental study on the blast responses of hollow core concrete slabs to contact explosions]]> Abstract: Measures taken against preventing damages in structures against explosive load are a popular matter of investigation among researchers. Generally, numerous studies were conducted on reinforcement materials for outer surfaces, reinforcement design, and utilizing fibers produced from various materials. In this study, a hollow-core slab was manufactured with concrete, which had a regular strength, and a design that discharged the explosive energy upon contact explosion via the hollow cores of the slabs and prevented the redirection of the explosive energy to the area below the slabs was investigated. Because the hollow-core slab in the study did not have any lateral reinforcement, the utilization of the tensile strength of the concrete proved advantageous. For this purpose, in the experimental tests of the study, contact explosions were conducted on hollow-core slabs with hollow diameters of 14 cm for each core. Before the explosion tests, the TNT equivalent of 910gr explosive was determined by performing the TNT equivalent tests. In the explosion tests of prepared hollow core concrete slabs, 125 gr, 250 gr, 375 gr, and 500 gr dynamites were used as the explosive materials. In conclusion, the explosive loads that the slabs could withstand were calculated and various slabs with distinctive hollow-core diameters were determined depending on the amount of the explosives. <![CDATA[Safety monitoring analysis in a construction site using eye-tracking method]]> Abstract: Construction work is one of the most dangerous business lines. As a result of occupational accidents in construction works, there are consequences that will affect human life such as injury and death, as well as serious financial losses. Especially in developing countries, despite the increase in precautions regarding occupational safety, occupational accidents continue to occur. Human behavior is an important factor in construction work accidents. In the sector where generally low-educated level workers work, analyzing the precautions and occupational safety training results are important to reduce construction work accidents. Eye-tracking technique, a technology that is spreading around the world, finds its place in different sectors. Especially with the use of mobile eye trackers instead of fixed eye trackers, this eye-tracking technology has also become usable in site implementations in the construction industry. In the construction sector, some studies are done especially on occupational safety issues using eye-tracking techniques in recent years. In this study, a site study was done with construction workers using a mobile eye-tracking approach by creating a track with different hazard sources in construction where a fatal occupational accident occurred. In this context, the attention levels of construction workers against different sources of danger and the risk of accidents created by these sources were measured with the mobile eye-tracking technique. The results obtained from the study were shared with the occupational safety experts on the site and the results are interpreted. All workers participating in the experimental study were workers that previously got occupational safety training. Therefore, according to the outcomes of this experiment, the effectiveness of the occupational safety training they received is measured and some suggestions are made. <![CDATA[Comprehensive evaluation of transverse joint spacing in jointed plain concrete pavement]]> Abstract: Transverse joint spacing is one of the fundamental input parameters in structural design of jointed plain concrete pavement (JPCP). It has to be determined considering many factors to produce a well-performing and cost-effective JPCP. In this study, a comprehensive evaluation of transverse joint spacing in JPCP was carried out based on the followings: (1) guidelines based on previous studies, the Federal Highway Administration and the American Concrete Pavement Association recommendations were summarized; (2) empirical and mechanistic-empirical (M-E) pavement design methodologies were reviewed; (3) current state highway agency practices in USA were surveyed as part of this study and the survey results were documented; (4) effects of joint spacing on JPCP performance were evaluated based on field observations; and (5) lastly, an economic analysis was performed to evaluate effects of joint spacing on life-cycle costs. This study demonstrated that a joint spacing between 15-18 ft (4.6-5.5 m) seems to be provide a safe zone for both performance and cost effectiveness. <![CDATA[Response surface optimization of geopolymer mix parameters in terms of key engineering properties]]> Abstract: The main aim of the current study is to search the impact of variable matrix phase features on fly ash based lightweight geopolymer mortars (LWGM). Another scope of the study is to obtain performance oriented optimum mixture proportions through response surface method (RSM). In order to have low unit weight for LWGMs, pumice aggregate was utilized as a part of the aggregate. The investigated engineering properties are water absorption, drying shrinkage and thermal conductivity. By performing optimization analysis, it was aimed to obtain the best numerical models representing the experimental results depending on the input variables. The decrease of liquid (alkali activators) to powder (fly ash) ratio, Na2SiO3 solution to NaOH solution ratio and increase of sodium hydroxide molarity led to improvement of compressive strength. Dry thermal conductivity values in dry state were observed to be less than those of saturated ones. Moreover, the higher sodium hydroxide molarity and lower Na2SiO3 solution to NaOH solution ratios, and liquid to powder ratios resulted in further shrinkage reduction. Depending on the goals of maximum compressive strength, minimum water absorption, and drying shrinkage, optimum values for molarity, SS/SH, and l/p factors were determined as 14 M, 1.586, and 0.45, respectively. <![CDATA[Tool for the integration of building performance information within the BIM process]]> Abstract: Decision-making regarding building performance in all construction project phases is a complex task. This article addresses the challenge of managing building performance information throughout construction project phases. It proposes a tool that assists in verifying the building performance requirements for different stakeholders and supports the integration of this information within the BIM process. The developed tool allows the launch, monitoring, and creation of a database with information about the project, the work, and the stakeholders. A practical study was chosen to test this tool. Its result is particularly meaningful to all stakeholders, as it prioritizes the information and underlying activities for the collaborative project development among the participants. In summary, the information integration related to the requirements to guarantee the building performance, co-related to the construction project development phases, is essential for improving internal processes. It is worth mentioning that managing this information is not a simple process and requires contextual knowledge, leadership, and management and communication skills. <![CDATA[Axial compressive behavior of short tie-columns with strapping spiral ties]]> Abstract: Spiral ties with rectangular cross sections have been developed as a new technology in construction, reducing the workforce in the reinforcement production series, because the worker does not have to place the tie reinforcement for the columns on the construction site. In this paper, a new type of tie was evaluated in short tie-columns subjected to axial compression to be applied in confined masonry. A comparison was made in this paper among spiral ties, with circular and rectangular cross sections, and traditional closed ties. The main aim of this research is to prove that these rectangular cross section spiral ties can be used in tie-columns for confined masonry structures. Twenty-one specimens were tested to investigate their structural behavior. As a part of the results, maximum loads, strains, load-displacement curves, and stress-strain relationships, were obtained based on testing standards, for both specimens and component materials. In addition, the fracture energy in compression and the ductility index were assessed. These results demonstrate that spiral ties with rectangular cross section have an efficient structural response compared to traditional and circular spiral ties. <![CDATA[Prediction of strength and shrinkage of ternary blended concrete with fly ash, slag and silica fume]]> Abstract: In the recent years, there has been increased in concern on shrinkage response of concrete systems as abundant cases of premature deterioration were reported. The major factors affecting the deterioration of a concrete system are quality, composition and the surrounding environment. In connection with this, the work concentrates on the study of long-term effects on materials used in the concrete (supplementary cementitious materials SCMs) such as fly ash, slag and silica fume as a blended concrete system. To carry out the experimental work, nine concrete mixes were designed for varying proportions of SCMs and w/b. Evolution of compressive strength, elastic modulus, shrinkage and selected durability parameters were tested under a controlled laboratory condition. Based on the work, it was found that the inclusion of fly ash, slag and silica fume on the concrete systems enhance the compressive strength in long-term, also the shrinkage response of the ternary systems shows a substantial reduction in the measured strain. Durability performance like chloride penetration and sorptivity had a better performance in comparison with the conventional concrete systems. <![CDATA[Mechanical performance of ETC RC beam with U-framed AFRP laminates under a static load condition]]> Abstract: In the presented paper, an attempt has been made to first find the permeability of the Euphorbia tortilis cactus (ETC) concrete by the water permeability method and infiltration method. After that, the flexural strength of the ETC RC beam wrapped with AFRP kelvar 149 is carried out by a 2-point load test. This research aimed to develop a more durable, flexural, and sustainable beam under static load. Based on the state-of-the-art information available in the literature, 3-layer Kelvar 149 AFRP is considered as a laminate to solve the deflections of the ETC beam. In this project, RCC beams were strengthened by ETC and aramid FRP sheets. Novel results are obtained by different layers and patterns of Aramid FRP sheets. Based on the investigation 3-layers Kelvar 149 perform well than a normal concrete beam. As no result based on hydraulic conductivity and drying shrinkage of a beam with AFRP laminates are available in the literature, the obtained results are validated with the finite element method (ABAQUS) under static load conditions. <![CDATA[Relative density influence on the liquefaction potential of sand with fines]]> Abstract: Liquefaction is a loss in soil’s resistance which can lead to disastrous and expensive consequences in terms of human lives and material damages, hence the interest of this laboratory study. The article explores the relative density influence in addition to the main parameter of the fines content on the liquefaction potential of soils. The study is based on a very large number of undrained monotonic triaxial tests undertaken on samples of reconstituted saturated sand and silt mixtures with 6 levels of initial relative density ranging from 15 to 90%. The materials used are levied from different level of deepness in the coastal region of Kharouba in the wilaya of Mostaganem. In this experiment, the sand-silt mixtures were separated to form the study samples. The aim of this work is, on one hand, to confirm and update the results of previous works (Bensoula et al., 2018) and on the other hand the study of the influence of relative density on the liquefaction potential of soils and the introduction of the concept of relative density threshold. The results of the tests confirm that the studied soil is most likely to be liquefied at a fines content between 0 and 30% depending on the equivalent intergranular voids and the equivalent relative density. These parameters are primordial for the characterization of soils sensitivity to liquefaction. In this study, the results showed that the resistance to liquefaction increases in a linear way with the relative density up to a threshold relative density value according to the fines content, which means that increasing the relative density improves the liquefaction resistance but only up to a threshold value of relative density given according to fines content <![CDATA[Effects of mix-design variables on the workability, rheology and stability of self-consolidating concrete]]> Abstract: This study investigates the effects of basic mix design variables such as water/cement ratio (w/c), slump flow, coarse-to-total aggregate ratio (CA/TA), and maximum aggregate size (Dmax) on the main characteristics of self-consolidating concrete. The w/c of the mixtures was either 0.42 or 0.50. The CA/TA ranged between 0.45 and 0.53. Slump flow was adjusted to 550, 650 or 720 ±20 mm by varying the superplasticizer content. Dmax was varied as 10, 15 and 20 mm. V-funnel, L-box, rheometer, sieve segregation tests and a new test method, recently developed by the authors, for dynamic segregation resistance were performed. The effect of each variable on the test results were effectively summarized in a table. Increasing the w/c, CA/TA and Dmax decreased the superplasticizer demand and increased the flowability. When the slump flow, w/c and CA/TA were higher, viscosity was found to be lower. Higher values of CA/TA and Dmax were found to reduce the passing ability. Increasing the slump flow (or superplasticizer content), CA/TA and Dmax disturbed the stability. Generally, the effects of w/c and slump flow on the SCC characteristics were more pronounced when compared to those of CA/TA and Dmax. Good correlations were obtained between several test results. <![CDATA[Ultimate capacity prediction of RC and SFRC beams with low shear span-depth ratio using NLFEA and inverse analysis]]> Abstract: In this study, the capacity and ultimate behavior of Reinforced Concrete (RC) and Steel Fiber Reinforced Concrete (SFRC) beams are evaluated. Nonlinear Finite Element Analysis (NLFEA) and the inverse analysis technique were used to model its structural response using the ATENA finite element software. The smeared crack approach, the crack band model, and advanced constitutive models were used to reproduce concrete fracture. The analyzed beams were subjected to rupture in a four-point bending test setup. The relationship between the shear span and the depth of the beams was 1.5. Four scenarios were analyzed, RC beams with and without stirrups, and SFRC beams without stirrups with volumes of 0.57% and 0.76%. The results obtained in the modeling are discussed in terms of the ability of the models to numerically reproduce the relationships: load versus displacement, load versus strain, crack patterns, and failure modes. The analysis techniques allowed to reproduce the experimental response of the beams with good agreement. They show great potential to solve structural engineering problems. <![CDATA[A study on investigating the effect of lignosulfonate-based compaction aid admixture dosage on the properties of roller compacted concrete]]> Abstract: In this study, roller compacted concrete was produced by using a modified lignosulfonate-based chemical admixture which is suitable for use in wet, semi-dry or zero slump concrete, and the effect of admixture dosage on the physical and mechanical properties of the concrete was investigated. In the production of roller compacted concrete, the cement content was 300 kg/m3 and the chemical admixture dosages have been changed as 0%, 0.3%, 0.6% and 0.9%. Percentage of compactibility, total water absorption, unit weight, ultrasonic pulse velocity, dynamic modulus of elasticity, concrete compressive strength at the ages of 3 and 28 days were determined for the roller compacted concrete specimens. Roller compacted concrete with the lowest percentage of water absorption, the highest percentage of compactibility, ultrasonic pulse velocity, compactness, compressive strength and dynamic modulus of elasticity was the concrete produced with 0.6% admixture dosage. With the concrete design and the chemical admixture in question, it has been observed that the optimum dosage of chemical admixture for the production of the best quality concrete in terms of the concrete properties examined was 0.6%. <![CDATA[Soil-structure interaction analysis of Çelebiağa Mosque, Pertek-Türkiye]]> Abstract: After the construction of the Keban Dam, some settlements with historical, cultural, and natural value were flooded. A scientific committee consisting of academicians and public authorities decided to the relocation of the buildings including the historical Çelebiağa Mosque. In this study, the seismic soil-structure interaction analysis of the historical Çelebiağa Mosque, which was dismantled and reconstructed in a separate region due to the construction of the Keban Dam was carried out. The analysis of the masonry mosque was performed with the SAP2000 finite element analysis software. The Winkler foundation model was used to idealize the soil environment on which the historical mosque was built. The effects of soil-structure interaction on historical masonry mosque were examined in terms of transmitted acceleration, response spectra, and lateral displacement at various heights of the structure. Depending on the results of the analysis, the effects of soil-structure interaction of a reconstructed historical masonry building were investigated. PGA was obtained as 0.51g at the flag level of the minaret under the Kocaeli earthquake and 0.94g under the Sivrice earthquake. Again, the maximum horizontal displacements of the minaret at the flag level were obtained as 11 cm and 8.5 cm under the Kocaeli and Sivrice earthquakes. The behavior of historical masonry structures under earthquake loads has been interpreted by considering the geological conditions. <![CDATA[The effect of iron chip additive on structural behavior of under-reinforced and over-reinforced cantilever beams]]> Abstract: This study focused on whether industrial iron chips waste can be recycled by using them in the production of reinforced concrete cantilever beams. The amount of aggregate in the range of 0-4 mm in the concrete used in the production of cantilever beams was determined. And this amount was reduced by 10%, 20% and 40% and replaced with iron chips. Cantilever beams have been produced in two different ways as under-reinforcement and over-reinforcement by changing the diameters of the tension reinforcement. Thanks to the experimental setup, the cantilever beams were loaded at their end points. In the experimental study, the load-displacement curves of the cantilever beams were obtained. According to the findings obtained in the study, under-reinforced cantilever beams behaved more ductile than over-reinforced cantilever beams. Cantilever beams with 40% iron chip additive reached the highest strength and exhibited the most brittle fracture examples. Cantilever beams containing 10% and 20% iron chip additives increased their ductility values up to 14.54% and decreased their strength up to %17.27 compared to reference cantilever beams.