Preparation and performances of a novel intelligent humidity control composite material

A novel intelligent humidity control composite material with excellent humidity control performances has been prepared, comprising a natural polymer derivative (carboxymethyl cellulose (CMC)), a porous natural mineral (sepiolite), and an acrylic acid (AA)/acrylamide (AM) copolymer. It features high moisture adsorption capacity, fast response to humidity changes, small equilibrium humidity control range and good acid gas absorbability. It is suitable for maintaining a proper micro-environment for places such as museums or galleries. The appearance and structural properties of the resultant material have been investigated by scanning electronic microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The humidity control performances of the material at certain relative humidity (RH) and changed absolute humidity (AH) have been measured. The adsorption capabilities of the material for sulphur dioxide and nitrogen dioxide have also been investigated in this study. The results reveal that the material maintains a relative humidity in the 57–60.5% range at 25 °C, and reaches the equilibrium levels within 3.5 h. It is worth noting that the composite material shows an excellent humidity buffering effect at changed AH and temperatures. The equilibrium moisture adsorption amount is 78.6% of its own weight. The adsorption capacities for nitrogen dioxide and sulphur dioxide are 227 mg g^?1 and 288 mg g^?1, respectively.     

Direct utilization of liquid slag from phosphorus-smelting furnace to prepare cast stone as decorative building material

Discharge of huge amount of liquid slag from phosphorus-smelting electric furnace has posed serious threat to the environment. In this study, a novel approach of directly recycling the liquid slag to prepare cast stone as decorative building material was proposed and experimentally tested. In our lab experiments, 76 wt.% water-quenched slag was re-melted at 1400 °C for 0.5 h (thus simulating liquid slag from phosphorus-smelting electric furnace), and then mixed with 18 wt.% quartz powder and 6 wt.% calcined kaolinitic clay, and subsequently melted together at 1450 °C for 1 h into modified liquid slag which was cast, heat-treated, annealed and transformed into cast stone. The optimal temperature for heat-treating cast stone ranges from 850 to 900 °C. And as-prepared samples present excellent properties of bending strength, acid resistance and alkali resistance. ESEM images show that their microstructures are composed of spherical granules with particle sizes of about 0.2–0.4 μm, which are non-crystalline as indicated by the results of XRD analysis. EDS results show that the contents of major elements in the granule are different from those in its background area. Results of TCLP test show that heavy metals from raw slag have been solidified in the cast stone. The practical feasibility of the new technology was examined further by on-site experiments, in which fresh liquid slag from phosphorus-smelting electric furnace was directly mixed with quartz and kaolinitic clay to produce cast stone. The results were quite stable and consistent with those of lab experiments, proving that the proposed approach of direct utilization of both energy and material of liquid phosphorus slag to produce cast stone as decorative building material is feasible, cost-effective and environment-friendly.     

Design and optimisation of laser scanning for tunnels geometry inspection

The use of terrestrial laser scanning technology in engineering surveys is gaining an increasing interest due to the very high spatial density of the acquired data. Recent improvements regarding the speed, accuracy, software algorithms and the fall in price have introduced a high potential for large scale applications of this technology in highly demanding engineering environments such as tunnels. Railway tunnels, in particular those of a long length, create challenges for surveyors due to their elongation to obtain satisfactory geometry of the scanned data. The purpose of this paper is to give an optimal solution for surveying tunnel geometry using laser scanning technology to reliably inspect railway tunnels and create “as-built” documentation.The proposed methodology provides optimisation of scanning parameters, scans registration, the georeferencing approach and the survey control network design. The maximal size of the scanner shifting along the tunnel alignment is primarily conditioned by factors including the incidence angle of the laser beam and the point density distribution. The authors introduce the so-called arbitrary georeferencing approach in long tunnel scanning that controls the point cloud geometric distortions to the required limits and contributes to time and material resources savings. Optimal design of the survey control network ensures the required positional accuracy and the reliability of the measurements, together with a cost effective approach to tunnels surveying.The proposed methodology is followed by the empirical results of the modelling and profiling of 12 tunnels in a single track railway. The lengths of these tunnels are from 60 m to 1260 m, with a total length of 3.5 km. Due to the specific geometry of the case study tunnels, the maximal favourable laser incidence angle is 78° with a distance of 13 m and consequently the optimal size of the scanner shifting along the tunnel alignment is 26 m. The survey control network is designed with the condition that the optimal reliability factors are within the required limits for engineering networks. A priori estimation of the control network positional uncertainty and a posteriori adjustment results shows that the achieved positional accuracy of the control points is approximately five times better than the requested absolute accuracy of the tunnel model: σ_m = 2 cm. On the largest tunnel example it is shown that the arbitrary georeferencing approach assures that the optimal registration error size is within the requested limits.     

Lime based steam autoclaved fly ash bricks

About 10 million tonnes of fly ash are produced yearly as waste from coal fired thermal power plants in Turkey. Only a small portion of this waste is utilized as a raw material in the production of cement and concrete. In this study, Seyitömer power plant fly ash was investigated in the production of light weight bricks. Fly ash, sand and hydrated lime mixtures were steam autoclaved under different test conditions to produce brick samples. An optimum raw material composition was found to be a mixture of 68% fly ash, 20% sand and 12% hydrated lime. The optimum brick forming pressure was 20 MPa. The optimum autoclaving time and autoclaving pressure were found 6 h and 1.5 MPa, respectively. The compressive strength, unit volume weight, water absorption and thermal conductivity of the fly ash–sand–lime bricks obtained under optimum test conditions are 10.25 MPa, 1.14 g/cm³, 40.5% and 0.34 W  m⁻¹ K⁻¹ respectively. The results of this study suggested that it was possible to produce good quality light weight bricks from the fly ash of Seyitömer power plant.     

CFRP strengthened openings in two-way concrete slabs – An experimental and numerical study

Rehabilitation and strengthening of concrete structures with externally bonded fibre reinforced polymers (FRPs) has been a viable technique for at least a decade. An interesting and useful application is strengthening of slabs or walls where openings are introduced. In these situations, FRP sheets are very suitable; not only because of their strength, but also due to that they are easy to apply in comparison to traditional steel girders or other lintel systems. Even though many benefits have been shown by strengthening openings with FRPs not much research have been presented in the literature.In this paper, laboratory tests on 11 slabs with openings, loaded with a distributed load are presented together with analytical and numerical evaluations. Six slabs with openings have been strengthened with carbon fibre reinforced polymers (CFRPs) sheets. These slabs are compared with traditionally steel reinforced slabs, both with (four slabs) and without openings (one slab). The slabs are quadratic with a side length of 2.6 m and a thickness of 100 mm. Two different sizes of openings are used, 0.85 × 0.85 m and 1.2 × 1.2 m.The results from the tests show that slabs with openings can be strengthened with externally bonded CFRP sheets. The performance is even better than for traditionally steel reinforced slabs. The numerical and analytical evaluations show good agreement with the experimental results.     

Seismic friction base isolation performance using demolished waste in masonry housing

The conversion of large amount of demolished waste into alternate source of building material will contribute not only as a solution to growing waste problem of waste disposal, but also it will conserve the natural resources of other building material and thereby reduce the cost of construction. The present work makes an effort to safe and economic use of recycled mortar as a supplementary material. Conventional and recycled brick prisms were casted with varying percentage of demolished waste added (0%, 10%, 20%, 30%) replacing cement and tested under compression testing machine. As the replacement is increasing, the strength is decreasing. A 1:4 scale single storey brick model was fabricated on shake table for dynamic testing using pure friction isolation system (friction material for coarse dry sand, μ = 0.36). Pure friction isolation technique can be adopted economically in developing countries where low-rise building prevails due to their low cost. The superstructure was separated from the foundation at plinth level, so as to permit sliding of superstructure during severe earthquake. The observed values of acceleration and displacement responses compare fairly with the analytical values of the analytical model except in displacement beyond 2.4 kN. It also concluded that 20% replacement of cement by demolished waste could be safely adopted without endangering the safety of the masonry structures under seismic load.To have an idea that how much energy is dissipated through this isolation, the same model with fixed base was tested and results were compared with the isolated free sliding model and it has been observed that more than 70% energy is dissipated through this pure friction isolation technique. In case of base isolation, no visible cracks were observed up to a table force of 4.25 kN (1300 rpm), whereas for fixed base failure started at 800 rpm and complete bond failure was observed at 1300 rpm.     

Production of non-constructive concrete blocks using contaminated soil

In this research, a heavily contaminated humus-rich peat soil and a lightly contaminated humus-poor sand soil, extracted from a field location in the Netherlands, are immobilized. These two types of soil are very common in the Netherlands. The purpose is to develop financial feasible, good quality immobilisates, which can be produced on large scale.To this end, two binder combinations were examined, namely slag cement with quicklime and slag cement with hemi-hydrate. The mixes with hemi-hydrate proved to be better for the immobilization of humus rich soils, having a good early strength development. The heavily contaminated soil with 19% humus (of dm) could not be immobilized using 398 kg slag cement and 33 kg quicklime per m³ concrete mix (binder = 38.4% dm soil). It is possible to immobilize this soil using 480 kg binder (432 kg slag cement, 48 kg quicklime) per m³ of mix (58.2% dm). An alternative to the addition of extra binder (slag cement with quicklime) is mixing the soil with sand containing particles in the range of 0–2 mm. This not only improved the compressive strength of the immobilisates, but also reduced the capillary absorption. All the mixes with the lightly contaminated soil were cost-effective and suitable for production of immobilisates on a large scale. These mixes had good workability, a good compressive strength and a low capillary absorption. The leaching of all mixes was found to be much lower than allowed by the regulations. Given these results, the final mixes in the main experiment fulfilled all the financial and technical objectives.     

Strength enhancement of Eskisehir tuff ashlars in Turkey

Tuff has always been a type of material used as natural building stone in building sector since early times. The reason for such a common use despite its low strength properties and high porosity is the fact that tuff is lightweight, easy to process and has good isolation properties. Another practical area for tuff in building sector is its use in cement production as pozzolan. Making use of tuffs’ high porosity and of cement production process, what is aimed in this study is enhancement of strength properties of white tuff blocks in the Eskisehir–Derbent Ciftligi region by means of treatment in slaked lime bath. Half of the tuff samples were kept in slaked lime bath for 1 day and the other half were kept for 1 week and then they were subjected to uniaxial compression tests (UCS). The tests were conducted on the sample groups kept for 7 days and 28 days under atmospheric conditions like those of concrete tests. Analysis of variance among the test results showed that it was appropriate to keep tuff blocks in lime-water for a maximum of 1 day and to air-dry them for 7 days. This method proved successful in ensuring a 100% increase in UCS of the white tuffs in the Eskisehir-Derbent Ciftligi region.     

Experimental and finite element analysis on the steel fiber-reinforced concrete (SFRC) beams ultimate behavior

Steel fiber-added reinforced concrete (SFRC) applications have become widespread in areas such as higher upper layers, tunnel shells, concrete sewer pipes, and slabs of large industrial buildings. Usage of SFRC in load-carrying members of buildings having conventional reinforced concrete (RC) frames is also gaining popularity recently because of its positive contribution to both energy absorption capacity and concrete strength.This paper presents experimental and finite element analysis of three SFRC beams. For this purpose, three SFRC beams with 250 × 350 × 2000 mm dimensions are produced using a concrete class of C20 with 30 kg/m³ dosage of steel fibers and steel class S420 with shear stirrups. SFRC beams are subjected to bending by a four-point loading setup in certified beam-loading frame, exactly after having been moist-cured for 28 days. The tests are with control of loads. The beams are loaded until they are broken and the loadings are stopped when the tensile steel bars are broken into two pieces. Applied loads and mid-section deflections are carefully recorded at every 5 kN load increment from the beginning till the ultimate failure.One of the SFRC beams modeled by using nonlinear material properties adopted from experimental study is analyzed till the ultimate failure cracks by ANSYS. Eight-noded solid brick elements are used to model the concrete. Internal reinforcement is modeled by using 3D spar elements. A quarter of the full beam is taken into account in the modeling process.The results obtained from the finite element and experimental analyses are compared to each other. It is seen from the results that the finite element failure behavior indicates a good agreement with the experimental failure behavior.     

Granulated foam glass–ceramic material from zeolitic rocks

The objective of this research work was to investigate the production of granulated foam glass–ceramic material from zeolitic rocks. The investigations have shown that grinding raw materials to particle size less than 0.5 mm and adding 13.8% of alkali content provide production of material with the following properties: particle density – 340 kg/m³, strength – 1.6 MPa and water adsorption – 13% at firing temperature of 850 °C. Expanded zeolite with alkali content is a material of glass–ceramic composition with amorphous part of 38.6% and crystalline part of 61.4% that gives higher strength in comparison with sponge glass.     

Autoclaved brick from low-silicon tailings

The load-bearing brick is made from low-silicon tailings by pressing and autoclaving process, in the presence of alkali-activated slag/fly ash cementing material (AAFSC). Tailings accounts for 83% of the total mass of the brick. The compressive strength of the brick is up to 16.1 MPa, bending strength 3.8 MPa, and with low drying shrinkage and good freeze–thaw resistance. Some factors influencing the mechanical strength of the brick including forming pressure, forming water content and curing regime, are investigated. The hydration products, freeze–thaw durability and anti-carbonation characteristics of the products are discussed.     

Determination of support pressure for tunnels and caverns using block theory

The estimation of support requirements to stabilize underground structures is of prime importance for rational design of these structures. The characterizing parameters of rock mass may vary with depth. Determination of these parameters by drilled cores and Ground-Probing-Radar (GPR) is difficult and expensive due to anisotropy of rock mass. Laboratory testing is also expensive. Also the in situ conditions are difficult to simulate in the laboratory. The designer is thus resorting to empirical methods and analytical methods to determine these parameters. Often, the analytical techniques may mesmerize the designer to feel the problem and its solution on the screen of the computer. In this paper, an attempt has been made to develop algorithm based on Block Theory with geological information & mechanical properties of rock for determining the rock pressure. Limitations of this technique are number of joint sets not less than three and width of the opening up to 25 m. The algorithm determines all the wedges formed at a time by 3, 4, 5, 6, …, n joint planes with excavation plane responsible for manifestation of rock pressure at roof/wall. All the permutations and combinations for wedge formation can be considered in this respect. Rock pressure for design is determined for reinforcement of the underground openings. Spacing of rock bolts is found out as an additional feature. The alignment of the opening for optimal reinforcement can also be determined. Case history of Tehri Power House, India is taken up for analysis. The empirical correlations developed by Goel (1994) are used for comparative study. It was found that no appreciable rock pressure was developed at walls. Roof pressure is determined to be 140 kPa, which is almost same as observed. It is thus established that block theory may be applicable for design criterion up to depth of 500 m.     

Linked multicontinuum and crack tensor approach for modeling of coupled geomechanics, fluid flow and transport in fractured rock

In this paper, we present a linked multicontinuum and crack tensor approach for modeling of coupled geomechanics, fluid flow, and solute transport in fractured rock. We used the crack tensor approach to calculate effective block-scale properties, including anisotropic permeability and elastic tensors, as well as multicontinuum properties relevant to fracture-matrix interactions and matrix diffusion. In the modeling, we considered stress dependent properties, through stress-induced changes in fracture apertures, to update permeability and elastic tensors. We evaluated the effectiveness and accuracy of our multicon-tinuum approach by comparing our modeling results with that of three independent discrete fracture network (DFN) models. In two of the three alternative DFN models, solute transport was simulated by particle tracking, an approach very different from the standard solute transport used in our multicon-tinuum modeling. We compared the results for flow and solute transport through a 20 m × 20 m model domain of fractured rock, including detailed comparison of total flow rate, its distribution, and solute breakthrough curves. In our modeling, we divided the 20 m × 20 m model domain into regular blocks, or continuum elements. We selected a model discretization of 40 × 40 elements (having a side length of 0.5 m) that resulted in a fluid-flow rate equivalent to that of the DFN models. Our simulation results were in reasonably good agreement with the alternative DFN models, for both advective dominated transport (under high hydraulic gradient) and matrix-diffusion retarded transport (under low hydraulic gradient). However, we found pronounced numerical dispersion when using larger grid blocks, a problem that could be remediated by the use of a finer numerical grid resolution, while maintaining a larger grid for evaluation of equivalent properties, i.e. a property grid overlapping the numerical grid. Finally, we encountered some difficulties in using our approach when element sizes were so small that only one or a few fractures intersect an element-this is an area of possible improvement that will be pursued in future research.     

Comparing the conventional soil stabilization methods to the consolid system used as an alternative admixture matter in Isparta Darıdere material

In this study, it was aimed to improve the existing poor local soil without excavating it using mixed stabilization method for soil stabilization. For this purpose, lime and cement which are commonly used as conventional stabilization additives were used along with Consolid444 + Solidry additives which are studied as alternative soil stabilization additives, and the results from the tests were compared. In this study, material from Isparta Dar?dere being used by Isparta Public Waterworks Administration to achieve water and liquid impermeability in dam constructions, filling works, etc. was used as poor soil material for the purpose of improving its bearing capacity. All additives added to Isparta Dar?dere natural soil material which is inappropriate to be used as a bearing in any road construction significantly increased the bearing capacity of this material and enabled it to be used as sub-foundation and foundation material in a road construction.     

Improvement of residual compressive strength and spalling resistance of high-strength RC columns subjected to fire

This paper investigates the spalling properties of high-strength concrete in order to improve the residual compressive strength and spalling resistance in specimens subjected to 3 h of unloading fire conditions. This study consists of three series of experiments with eighteen different specimens varying in fiber type and content, finishing material and simultaneous fiber content and lateral confinement. They were fabricated to a 300 × 300 × 600 mm mock-up size. Results of the fire test showed that the control concrete was explosive, while the specimens that contained more than 0.1 vol% of polypropylene (PP) and polyvinylalcohol (PVA) fibers were prevented from spalling. One specimen, finished by a fire endurance spray, exhibited even more severe spalling than the control concrete. The specimen containing 0.1 vol% of PP fiber and using a confining metal fabric at the same time, showed the most effective spalling resistance; in particular, the residual compressive strength ratio was even higher than that of the control concrete before the fire test. It was demonstrated that adding fibers in concrete prevented the spalling occurrence and confining metal fabric around the main bars of concrete specimens can secure the strength of structures during the conditions of elevated temperature.     

Properties of EPS RHA lightweight concrete bricks under different curing conditions

The depletion of non-renewable resources has become an alarming issue nowadays. Many environmentalists and researchers have been investigating the use of waste materials as a renewable resource for use especially as raw materials in construction. This paper reports on the potential use of waste rice husk ash (RHA) and expanded polystyrene (EPS) beads in producing lightweight concrete bricks. The RHA was used as a cementitious material since it is a lightweight reactive pozzolanic material. RHA was used as partial cement replacement, while the EPS was used as partial aggregate replacement in the mixes. Bricks of 215 mm × 102.5 mm × 65 mm in size were prepared in this study. The engineering properties of the bricks were investigated. Among the properties studied were hardened concrete density, compressive strength and water absorption of the EPS RHA concrete bricks. Scanning electron microscopy (SEM) analysis was also performed on the brick samples. Four types of curing conditions were employed in this study. These include full water curing, air dry curing, 3-day curing and 7-day curing. It was found that the properties of the bricks are mainly influenced by the content of EPS and RHA in the mix and also the curing condition used.     

Assessing of the fresh concrete properties of self-compacting concrete containing sawdust ash

Evaluation of self-compactability of SCC mixes containing SDA as powder material and naphthalene sulphonate (NS) and melamine sulphonate (MS), respectively, shows that optimum workability range for the slump flow test lie between 665 mm and 680 mm, while the V-funnel test is 8.2 s and 8.4 s. These values show that adequate mix stability and self deaeration are achieved. Results of the self-compactability of the SCC mixes using the U- and L-box are within the targets and tolerance values stipulated by EFNAC (2002). These are 28.5 mm/29 mm and 0.85/0.85, respectively, for mix containing NS and MS.     

Parametrical static analysis on group studs with typical push-out tests

Group studs are known as shear connectors in steel and concrete composite structures. By now, many composite bridges have been characterized by long lateral cantilevers. The shear studs are actually under biaxial action consisting of shear force and action in light of lateral bending moment on concrete slab induced by long cantilever and passing by moving loads. Moreover, lateral bending moment may even lead to the initiation of bending-induced concrete cracks. These two situations can both affect mechanical performance of group studs. Thus, a parametrical FEM analysis was carried out, in which damage plasticity was introduced to simulate material nonlinear behavior. In the analysis, lateral bending moments respectively inducing maximum concrete crack widths of 0.1 mm and 0.2 mm, shank diameters of 13 mm, 16 mm, 19 mm and 22 mm and stud heights including 80 mm and 100 mm were parameters. It was found that mechanical behavior of group studs with large shank diameter would be less affected by biaxial action and initial bending-induced concrete cracks seemed unfavorable to stud shear stiffness. On the other hand, typical push-out tests were executed to investigate reductions of shear stiffness and shear capacity of group studs. The reliability of FEM analysis was also verified based on the tests. In addition, stud shear capacity evaluations according to several design specifications were presented. It indicated shear capacity evaluation of Eurocode 4 got a relatively large safety factor. Moreover, the applicability of these specifications for group studs on shear capacity evaluation was also discussed.     

Damage to surface structures due to blast vibration

This paper describes effect of blast produced ground vibration on damage potential to residential structures to determine safe levels of ground vibration for the residential structures and other buildings in mining areas. Impacts of 341 blasts detonated at two mines were monitored at the test structures and 1871 blast vibrations signatures were recorded on or near the test structures. Cosmetic cracks in a native brick-mud-cement house were detected at peak particle velocities (PPV) between 51.6 and 56.3 mm/s. The reinforced concrete and cement mortar (RCC) structure experienced cosmetic cracks at PPVs of 68.6–71.3 mm/s at the first floor, whereas at second floor it was detected at PPV levels of 71.2–72.2 mm/s. Minor damage in brick-mud-cement house was recorded at PPV levels of 81.0–89.7 mm/s. The RCC structure at first and second floors experienced minor damage at PPV levels of 104 and 98.3–118 mm/s, respectively. The brick-mud-cement house experienced major damage at PPV level of 99.6–113.0 mm/s, while major damage was recorded in RCC structure on first floor at PPV of 122 mm/s, the second floor at PPV levels of 128.9–161 mm/s. Recommended threshold limits of vibrations for the different type of structures is based on these measurements and observations.     

Fast automatic registration of range images from 3D imaging systems using sphere targets

The use of 3D imaging systems (e.g., laser scanners) in construction has grown significantly in the past decade. Range images acquired with such systems often require registration. This paper describes an automatic method to rapidly locate spheres and perform a registration based on three pairs of matching points (centers of fitted spheres) in two range images. The proposed method is directly applicable for regularly gridded datasets obtained with instruments that are typically used for construction applications and whose maximum ranges are greater than 50 m. A lab was scanned from two locations at three different scan densities. Four spheres were located in the lab, and the total number of points hitting the four spheres was a small fraction (< 0.01%) of all the points in the dataset. At the highest scan density, the registration of two datasets with 6.4 × 10⁶ and 3.4 × 10⁶ points is obtained in less than 30 s. At the medium scan density, two range images with 1.6 × 10⁶ and 0.8 × 10⁶ points can be registered in less than 2 s.