Cement-sand Mixture Research Articles

Behavior of Ferro-Cement Slabs Modified by Polymer under Low Velocity Impact

Ferro-cement is a type of thin reinforced concrete made of cement-sand mortar mixture with closely spaced of relatively small diameter wire meshes. The main aim of this work was to study investigate the behavior of Ferro-cement slabs under impact loading. A total of 36 Ferro-cement slabs were constructed and tested under low velocity impact, The main parameter considered in the present investigation was number of wire mesh layers, content of (SBR) polymer and height of falling mass (falling velocity). A special testing rig was used to achieve the impact forces using a falling mass (1300 gm steel ball) dropped from (2.5, 1.2 and 0.83 m) height. (500 ×500×50 mm) slabs were used for each test. The polymer (SBR) was used as a ratio by weight of cement of 3%, 5% and 10%. The number of required blows for caused the first crack and final failure was recorded. The results exhibited that the number of blows which were required to make the first crack and failure, increased with increase of polymer content and number of wire mesh layers.

Continuous stiffness assessment of cement-stabilised soils from early age

Recently, an innovative technique based on continuous modal identification of the first flexural resonant frequency of a simply supported composite beam has been proposed for continuous evaluation of the E modulus of concrete from the instant of casting (termed EMM-ARM: elasticity modulus measurement through ambient response method), and has been successfully compared with other existing techniques. In view of its potential applications for the laboratory and in situ characterisation of cement-stabilised soils, the extension of using EMM-ARM for these materials has been preliminarily tested with promising results, but the extension of the procedure has also resulted in the identification of new challenges. The purpose of this paper is to show the results and conclusions of an experimental programme devised to evaluate a sand–cement mixture from compaction to 28 days later by comparing several testing methodologies: EMM-ARM, unconfined cyclic compression tests, bender-extender elements, and ultrasonic contact probes. Attention is also given to the issue of obtaining in situ samples using the EMM-ARM technique through a specially designed mould.

Prediction of unconfined compressive strength of pulverized fuel ash–cement–sand mixture

Recently, ground improvement has become much more feasible. Chemical stabilization is a quick and affordable approach to enhancing soil characteristics. An important avenue of research is discovering alternative materials for use in soil enhancement. Pulverized fuel ash (PFA), which is a waste byproduct of coal power plants, has been shown to reduce the environmental risks and costs involved in construction. In this study, a series of unconfined compressive tests were performed for various mixtures of cement, PFA, and sand; the tests considered both the curing period and the optimum moisture content (OMC). In addition, multiple variable linear regression was used to analyze laboratory data in order to obtain an empirical relationship that can be used to predict the unconfined compressive strength (UCS) of a PFA–cement–sand mixture. The accuracy of the model was verified using statistical indices. The first objective of this study was to assess the effects of PFA content on the UCS of the mixture. The second was to investigate the impact of the OMC on the UCS. The focal point of this study was its derivation of a relationship that can be used to estimate the UCS on the basis of existing variables. The results indicated that PFA can strengthen sand in terms of the UCS and that excessive PFA in a mixture may adversely affect the UCS of a medium. Therefore, a mixture must have an optimum proportion of compounds. The OMC plays a vital role in enhancing UCS. The UCS of different mixtures can be predicted with an acceptable level of accuracy by using the relationship derived in this study.

Comparative Study of the Geopolymers Synthesized from Various Types of Construction Wastes

Demolition of old houses and construction of new buildings are in peak in urban sectors which generate a huge amount of construction wastes. These wastes are rich source of alumino-silicate. Geopolymerization can transform a wide range of alumino-silicate materials into building materials with excellent physicochemical properties. Thus, geopolymers have been synthesized from construction wastes such as sand-cement-mixture (SCM), concrete mixture (CM), brick dust (BD), etc using alkali and alkali-silicate as activators. Parameters like alkali concentration (for dissolution of alumino-silicate), ratio of alkali-silicate to construction wastes and curing time were varied to improve the quality of geopolymeric products. The maximum compressive strengths of geopolymeric products obtained from BD, SCM and CM were 60.0, 47.0 and 45.5 MPa respectively. Nepal Journal of Science and Technology Vol. 14, No. 1 (2013) 81-86 DOI: http://dx.doi.org/10.3126/njst.v14i1.8926

Key parameters for strength control of rammed sand–cement mixtures: Influence of types of portland cement

The present research aims to quantify the influence of distinct types of Portland cement, amounts of cement, porosity, curing time period and porosity/cement ratio in the assessment of unconfined compressive strength (qu) of rammed sand–cement mixtures. A program of unconfined compression tests considering distinct types of Portland cement (types I, III and IV), porosities (η), cement contents (C) and curing time periods (t) was carried out in the present study. It was found that a ratio between porosity and cement [(η/Civ)−1.5] applies to all equations that control the strength of blends (for the curing periods and cement types studied here). The qu values of the specimens moulded for each cement type and curing period were also normalize (i.e. divided by the qu attained by a specimen with porosity/cement ratio equals to 20). It was found that a single power function adapts well to the normalized values for all the cement type and curing period studied. From a practical viewpoint, this means that carrying out only one (1) compression test with a specimen moulded with a specific cement time and cured for a given time period, allows the equation that controls the strength for distinct porosity and cement content to be determined.

Effect exerted by a radio wave electromagnetic field on the rheological properties of water and portland-cement systems

We have studied the effect of the regimes of high-frequency (radio wave) electromagnetic treatment of gauging water on the process of structurization and on the technological characteristics of portland-cement systems. It has been established that the radio wave electromagnetic activation of water leads to a reduction in its surface tension, dynamic viscosity, and shear stress, as well as intensifies the formation of coagulation structures in a portlandcement slurry and aids in increasing the mobility of cement-sand mixtures.

Moisture content influence on the thermal conductivity and diffusivity of wood–concrete composite

The aim of the work reported in this paper is to determine the influence of moisture content on the thermal proprieties of wood–concrete composite, i.e. thermal conductivity and thermal diffusivity. The wood shavings have been incorporated, without any preliminary treatment, into a sand–cement mixture. Five formulations containing different percentage of shavings have been prepared and have been examined herein. The experimental results show that the lightening of concrete by wood shavings increases the thermal insulation capacity by decreasing the thermal conductivity and diffusivity; however these proprieties are strongly dependent on water content. The thermal conductivity increases rapidly with water content. Its experimental evolution with water content was confirmed by the comparison with three theoretical models. The values of the thermal diffusivity depend on the used counting model. The results stemming from three most used models are compared between them, and they show that in general the thermal diffusivity presents a maximum corresponding to a water content value Wm.

초음파 반사이미지와 고유주파수 변화를 이용한 해상 기초구조물의 세굴도 평가

Abstract Local loss of geomaterials, which reduces the stability of the structures, around foundation of offshore structure occurs due tothe interaction between water and ground. The objective of this study is to evaluate scouring in offshore foundation structures byusing ultrasonic reflection method and natural frequency analyses. Sand-cement mixture is prepared to model the ground, which isencountered the scour depth and the scour shape. Ultrasonic wave and natural frequency are measured according to the scourdepth. Ultrasonic transducers are used to measure the ultrasonic wave, and strain guages are used to measure the natural fre-quency. Ultrasonic transducers are fixed on horizontal movement system and rotational movement system for the change of loca-tion. Strain guages are attached on upper part of model monopile. Ultrasonic reflection image and strain responses are monitoredin laboratory experiment. Maximum scour depth is estimated by natural frequency, and the characteristics of the scour shape areestimated by ultrasonic reflection image. This study suggests that the ultrasonic scanning and natural frequency analyses may beeffectively used to monitor the characteristics of the scour depth and shape. Key words : Monitoring, Monopile, Natural frequency, Ultrasonic imaging, Scour

Production Cycle for Large Scale Fission Mo-99 Separation by the Processing of Irradiated LEU Uranium Silicide Fuel Element Targets

Uranium silicide fuels proved over decades their exceptional qualification for the operation of higher flux material testing reactors with LEU elements. The application of such fuels as target materials, particularly for the large scale fission Mo-99 producers, offers an efficient and economical solution for the related facilities. The realization of such aim demands the introduction of a suitable dissolution process for the applied U3Si2compound. Excellent results are achieved by the oxidizing dissolution of the fuel meat in hydrofluoric acid at room temperature. The resulting solution is directly behind added to an over stoichiometric amount of potassium hydroxide solution. Uranium and the bulk of fission products are precipitated together with the transuranium compounds. The filtrate contains the molybdenum and the soluble fission product species. It is further treated similar to the in-full scale proven process. The generated off gas stream is handled also as experienced before after passing through KOH washing solution. The generated alkaline fluoride containing waste solution is noncorrosive. Nevertheless fluoride can be selectively bonded as in soluble CaF2by addition of a mixture of solid calcium hydroxide calcium carbonate to the sand cement mixture used for waste solidification. The generated elevated amounts of LEU remnants can be recycled and retargeted. The related technology permits the minimization of the generated fuel waste, saving environment, and improving processing economy.

Effect of fiber reinforcement on triaxial shear behavior of cement treated sand

Conventional triaxial compression tests were conducted to determine the effect of cement and polypropylene fiber reinforcement on sand. The cement content was 3% (dry wt.) of the sand and specimens were cured for seven days. Fibers 0.012 m in length and 23 μm thick were added at 0.0%, 0.5% and 1% (dry wt.) of the sand–cement mixture. Samples were prepared at 50% and 70% relative densities and triaxial tests were performed at confining pressures of 100, 300 and 500 kPa. Stress–strain and volume change behavior, and stiffness and energy absorption of the soil were measured and compared with results of previous studies. The addition of fibers increased peak and residual shear strengths of cemented soil and changed its brittle behavior to a more ductile one. Initial stiffness for 0.1% axial strain decreased as fiber content increased. Adding fiber increased the energy absorption by 20–50%. Fibers were more effective on shear strength parameters at 70% relative density.

Failure envelope of artificially cemented sand

The present research aims to quantify the influence of the amount of cement, the porosity and the porosity/cement ratio in the assessment of tensile strength and triaxial strength of an artificially cemented sand, as well as in the development of a failure criterion to represent the non-linear failure envelopes of the studied sand–cement mixtures.

Acoustic-radio wave activation of tempering water for Portland cement systems

The effect of the complex acoustic-radio wave treatment of water on the index of activity of the hydrogen ions, the rheological characteristics of the cement-sand mixtures tempered by this water, and the technological parameters of the obtained plasticized fine-grained concretes was studied. Two methods were used to reach the maximum effect on the index of the activity of the hydrogen ions of the water, the mobility, the storability of the prepared concrete mixes, and the density and compressive strength of the concretes. The first method was a four-minute complex acoustic-radio wave treatment of the water (high frequency (5.28MHz) + ultra sound (44 kHz)) that was followed by the four-minute additional impact of a high-frequency field. The second method used was a four-minute complex treatment of used water (high frequency (5.28 MHz) + ultra sound (1 MHz)) followed by the two-minute extra impact of a high frequency field. The assumptions concerning the mechanism of the acoustic-radio waves activation of the water and the effect of this water on the process of hardening used and the structure of the Portland cement systems are expressed.

Influence of Cement-Voids Ratio on Stress-Dilatancy Behavior of Artificially Cemented Sand

The addition of cement is an interesting remediation technique when the project requires improvement of the local soil for the construction of pavement base layers, in slope protection of earth dams and canal linings, as a support layer for shallow foundations and to prevent sand liquefaction. The present study was carried out to quantify the influence of the amount of cement and the porosity in a cement-voids ratio, defined as the ratio between the volume of cement and the volume of voids of a mixture, on the stress-dilatancy behavior of an artificially cemented sand. A program of triaxial compression tests considering three distinct cement-voids ratios was carried out with two combinations of volumes of voids and volumes of cement at each cement-voids ratio. Results showed that the stress-dilatancy relationship is alike for a given cement-voids ratio and that the stress-strain behavior is also similar. The cement-voids ratio is therefore an appropriate parameter to assess stress-dilatancy of the sand-cement mixture studied.

Parameters Controlling Tensile and Compressive Strength of Artificially Cemented Sand

The enhancement of local soils with cement for the construction of stabilized pavement bases, canal lining, and support layer for shallow foundations shows great economical and environmental advantages, avoiding the use of borrow materials from elsewhere, as well as the need of a spoil area. The present research aims to quantify the influence of the amount of cement, the porosity, and the voids/cement ratio in the assessment of unconfined compressive strength qu and splitting tensile strength qt of an artificially cemented sand, as well as in the evaluation of qt /qu relationship. A program of splitting tensile tests and unconfined compression tests considering three distinct voids ratio and seven cement contents, varying from 1 to 12%, was carried out in the present study. The results show that a power function adapts well qt and qu values with increasing cement content and with reducing porosity of the compacted mixture. The voids/cement ratio is demonstrated to be an appropriate parameter to assess both qt and qu of the sand-cement mixture studied. Finally, the qt /qu relationship is unique for the sand-cement studied, being independent of the voids/cement ratio. DOI: 10.1061/ASCEGT.1943-5606.0000278 CE Database subject headings: Tensile strength; Compressive strength; Soil cement; Compacted soils. Author keywords: Tensile strength; Compressive strength; Soil cement; Compacted soils.

Fundamental Parameters for the Stiffness and Strength Control of Artificially Cemented Sand

The treatment of soils with cement is an attractive technique when the project requires improvement of the local soil for the construction of subgrades for rail tracks, as a support layer for shallow foundations and to prevent sand liquefaction. As reported by Consoli et al. in 2007, a unique dosage methodology has been established based on rational criteria where the voids/cement ratio plays a fundamental role in the assessment of the target unconfined compressive strength. The present study broadened the research carried out by Consoli et al. in 2007 through quantifying quantifies the influence of voids/cement ratio on the initial shear modulus (G0) and Mohr-Coulomb effective strength parameters (c′,ϕ′) of an artificially cemented sand. A number of unconfined compression and triaxial compression tests with bender elements measurements were carried out. It was shown that the void/cement ratio defined as the ratio between the volume of voids of the compacted mixture and the volume of cement is an appropriate parameter to assess both initial stiffness and effective strength of the sand-cement mixture studied.

Fiber reinforcement effects on sand considering a wide cementation range

This paper describes laboratory drained standard triaxial tests conducted on artificially cemented Osorio sand specimens reinforced with randomly oriented discrete extensible polypropylene fibers. Cemented specimens were prepared with cement contents varying from 0% to 10% by weight of dry sand and cured for seven days. Fiber length and diameter were 24 mm and 0.023 mm, respectively, in the contents of 0% and 0.5% by weight of dry sand–cement mixture. Test results indicated that the addition of cement to sand increases stiffness, peak strength and brittleness. Both cement and fiber insertions affect dramatically the stress–dilatancy behavior of the sand. The fiber reinforcement increases peak strength just up to a certain cement content (up to about 5% in the present study), increases ultimate strength, decreases stiffness and changes the cemented sand brittle behavior to a more ductile one. The triaxial peak strength increase due to fiber inclusion is more effective for smaller amounts of cement, while the increase in ultimate strength is more efficacious when fiber is added to sand improved with higher cement contents. Peak strength envelopes indicate that the friction angle is about 46° for fiber-reinforced specimens containing up to 7% cement content, reaching 51.5° for higher cement contents. Cohesion intercept is drastically affected due to fiber addition to all cement contents, increasing for cement contents up to 4% and reducing for higher cement contents. It is important to make clear that the trends observed herein are relevant for the soil, cement and fiber type used in the present research and that further studies are necessary to generalize such findings.

Characterization of the Failure and the Effect of Carbon Fiber Reinforced Composites on the Cracking in Cement Constructions I-Tensile Characteristics

Recently, fiber reinforced plastics have found applications in civil engineering. Owing to their mechanical properties, these materials have replaced steel and steel plates for external crack repairs in deteriorated structures. Fiber reinforced plastic sheets can be fixed to the structural parts in need of repair, using suitable adhesives. In this article, a new clamping system is introduced that simulates the actual cracking effect. Carbon fabric and its reinforced epoxy laminated composite material are used to join together two parts of a sand-cement mixture by an adhesive at three different gage lengths. Upon the effect of cracking, the performance of the adhesive joint is found to act differently with each material. The three-layer laminated composite is found to act better than the fabric. Each gage length shows a different joint strength.

Sound transmission loss of tiled brick walls

Walls made from hollow bricks joined with mortared joints are often found in the construction of buildings. Brick walls are also used as noise barriers. Over time, mortared joints develop gaps and cracks that reduce the noise-reduction capability of a brick wall. Ceramic tiles or a combination of plaster and ceramic tiles can be applied to the surface of a brick wall to improve the noise reduction as well as the visual appearance of the wall. This paper reports the results of measurements of the sound transmission loss of test specimens of brick walls faced with ceramic tiles. Tiles were applied to the surface of the bricks by two methods: (1) with dabs of a sand-cement mixture and (2) by means of a commercial tile adhesive. For some test configurations, a coating of plaster was first applied to the surface of the brick wall. Wall test specimens were constructed using 70-mm-thick or 110-mm-thick hollow bricks. The greatest improvement in sound transmission loss (and in the corresponding sound transmission class [STC] rating) was provided by wall test specimens where both sides were coated with plaster and with tiles applied to one side by dabs of the sand-cement mixture.

Control of Penetration of Macroglobules from Polymer Solution into the Bulk of a Porous Solid

Penetration of poly(butyl methacrylate) macroglobules into solid porous samples of chalk, clay, cement, and cement-river sand mixtures was studied as influenced by the macroglobule size.

Characterisation and treatment of roads covered with zinc ashes, muffle furnace fragments and lead slags from former non-ferrous metal industries in Belgium.

Zinc ashes, muffle furnace fragments and lead slags from non-ferrous industries were applied to pave roads in the North of Belgium. From an inventory it appeared that there are at least 490 km of such roads. In our survey the materials on these roads were characterised. The total metal concentration, the availability and the leaching as a function of time were determined. It appeared that these materials contain high concentrations of heavy metals, some of which are readily available. The high leaching of some metals makes them as such unsuitable as secondary construction material. Methods for the application of these materials for road construction were examined where the materials replaced part of the sand and gravel fraction in lean concrete and in bituminous mixtures, or where they replaced the sand in sand-cement mixtures, all these to be used for road foundations, cycle tracks, etc. When lead slags were applied in lean concrete, a material was obtained complying with the standards for secondary construction materials and with sufficient compressive strength for road foundations. When zinc ashes or muffle fragments were used to replace sand in sand-cement mixtures, again a suitable construction material was obtained. The other combinations tried out were rather unsuccessful, because of high metal leaching and/or poor compressive strength.