Quick-setting Cement Research Articles

Separation of fluorine and aluminum from secondary aluminum dross by calcium-cured alkali roasting−water leaching

A combined strategy of calcium-cured alkali roasting and water leaching was devised to treat secondary aluminum dross. The effects of calcium oxide dosage, sodium hydroxide dosage, roasting temperature, and time on aluminum extraction behavior and fluorine curing behavior were studied. Under optimal experimental conditions: roasting temperature of 1000 °C, Al꞉NaOH mole ratio of 1꞉0.6, F꞉CaO mole ratio of 1꞉2.5, and roasting time of 2.0 h, fluorine and aluminum were separated, with 99.98% of the fluoride solidified and 52.97% of the aluminum extracted. The sodium aluminate products obtained by evaporation and crystallization from leaching solution met the industrial standards of China. The aqueous residue can be used as a raw material for quick-setting cement. Overall, this study provides an effective and environmentally friendly strategy for the treatment of secondary aluminum dross.

Binder Jetting 3D Printing of Binary Cement-Siliceous Sand Mixture.

Three-dimensional printing allows accurate geometries to be obtained across a wide range of applications and it is now also moving into the architecture and construction industry. In the present work, a unique binary mix composed of ordinary Portland cement (OPC) and quick-setting cement (QSC) was combined with silica sand aggregate in different proportions for a customized binder jetting 3D printing (BJ3DP) process. Specimens were printed using the blended dry powders and deionized water to determine the impact of the processing variables on the properties of the realized specimens. The results show that the properties are influenced by the binary mix proportions and the layer thickness. The investigation found significant improvement in mechanical performance on increasing the proportion of OPC and optimal conditions were identified with proportions of 35 wt% OPC and 5 wt% QSC. Notable enhancements were also observed as the layer thickness was reduced.

Optimization of Mix Ratio of Epoxy Mortar with Super-Early Strength Based on Orthogonal Test

Through adding accelerator to common epoxy mortar and optimizing its mix ratio by orthogonal test, the influences of the contents of filler, diluent, curing agent and accelerator on the early strength of epoxy mortar were studied respectively. Results showed that the filler content has the most significant influence on the compressive strength and splitting strength of epoxy mortar, and the optimum combination of these four contents is A2B2C3D2, on which condition compressive strength of epoxy mortar can reach 71.4 MPa and splitting strength 6.72 MPa at super-early stage (4h, at nursing temperature 25 C). Pull-out test on the anchor bolts with optimum-mix-ratio epoxy mortar as anchorage agent was carried out, and compared to tests with quick setting cement as anchorage agent, proving that the pull-out strength with epoxy mortar as anchorage agent was much higher than that of quick-setting cement. The ultimate pull-out strength of the anchor increased with anchorage depth at pull-out bonding failure, which indicates that the optimized epoxy mortar with super-early strength can meet the needs of emergency repair and other special projects, and can be applied in the fields of structural reinforcement and rapid repair of traffic engineering.

Emergency repair of severely damaged reinforced concrete column elements under axial compression: An experimental study

Reinforced concrete (RC) columns in a framed construction can be severely damaged under earthquake, blast, fatigue and other loads. It is essential to quickly restore the strength and stiffness of columns after its damage for maintaining the serviceability of the building. The objective of this study is to assess the efficiency of different strengthening techniques on emergency repair of the severely damaged RC columns under axial compression. Six short RC columns elements were cast and tested under axial compression until 20% drop in the peak strength. Thereafter, these severely damaged columns were repaired using strengthening schemes, namely (i) repairing the damaged portions using quick setting cement mortar, (ii) Near Surface Mounting (NSM) of CFRP (Carbon Fiber Reinforced Polymer) laminates and (iii) Hybrid strengthening technique. The hybrid strengthening technique uses the combination of CFRP NSM laminates as additional longitudinal reinforcement and external bonding with CFRP fabric for confinement. The hybrid strengthening scheme was found to be the most efficient in restoring the lost strength and initial stiffness when compared to the only NSM strengthening or repair with quick setting cement mortar.

Assessment of Uncertainties in Calibration of Langavant Calorimeters

The semi-adiabatic method, commonly referred to as the Langavant method, is widely applied for routine measurements of the hydration heat of cements. This standardized method is applicable to all cements and hydraulic binders, whatever their chemical composition, with the exception of quick-setting cements. The calorimeters used to perform these hydration heat measurements must be previously calibrated by electrical substitution, in order to determine their coefficient of total heat loss \(\alpha \) and their heat capacity \(\mu \). LNE developed a facility enabling performance of the calibration of these Langavant calorimeters, in order to insure the traceability of the hydration heat measurements to basic quantities such as temperature, time, mass, and electrical quantities. Calibration results of a typical Langavant calorimeter are presented here. The measurement uncertainties of the parameters \(\alpha \) and \(\mu \) have been assessed according to the ISO/BIPM “Guide to the Expression of Uncertainty in Measurement.” The relative expanded uncertainties (\(k = 2\)) of the coefficient of total heat loss \(\alpha \) and the heat capacity \(\mu \) are estimated, respectively, to be about 0.7 % and 15 %.

Reconstruction of Cranial Bone Defects Using a Quick-Setting Hydroxyapatite Cement and Absorbable Plates

Reconstruction of Cranial Bone Defects Using a Quick-Setting Hydroxyapatite Cement and Absorbable Plates

Development of a Plane Isothermal Calorimeter: Relating Apparent Activation Energy of Concrete and the Corresponding Mortar

Abstract This article describes the development and application of a new plane isothermal calorimeter with reduced and adjustable thickness. This innovative calorimeter allows the study of highly reactive materials such as cement grouts or concrete containing quick-setting cements and to perform tests at high temperatures. The development of the new calorimeter consists first of optimizing the dimensions and the geometry of the device. To achieve this, a numerical model is used and tested through a series of experiments. The device is validated through calibration as well as repeatability and reproducibility tests. A potential application of the new calorimeter is then presented focusing primarily on comparing at different scales, i.e., on concrete and on Concrete Equivalent Mortar, the hydration kinetics and the apparent activation energy.

Mechanical characteristics of Asphalt-Cement Concrete foundations (ACC).

Asphalt Cement Concrete (ACC) is a new material. On the basis of Kuhn’s paradigm, conventional methods which are proper for similar road pavement materials were applied for studying the ACC. ACC is obtained from cold mixing technology such ingredients as cement-sand mortar or cement-mineral aggregate mortar, or cement-sand-mineral aggregate mortar with recycled Asphalt Concrete (AC) mixture or with recycled Mastic Asphalt (MA) mixture. Quick setting cement (CEM I 52,5 NA) is used in all mentioned cases. Novelty of the presented material is due to existence of two internal bounds - flexibility and rigidity. Such ACC parameters as stiffness, deformability and strength in general depend on type and characteristics of cementitions grout which coats applied recycled asphalt materials and fills mixture’s air voids. ACC layer stability may be predicted using viscoelastic model parameters of constitutive relations, including Burgers model, under steady and slow loadings, finally expressed by exponential formulae. This is the research study. Its basic part consists of laboratory and field testing and obtained tests results analysis. Further, road pavements were designed with subbase of ACC with improved performance comparing to typical materials.

Gas blowout from shallow boreholes at Fiumicino (Rome): Induced hazard and evidence of deep CO 2 degassing on the Tyrrhenian margin of Central Italy

A borehole drilled at Fiumicino (Rome) down to only 27 m depth in a zone where no gas emission at the surface was known, caused a gas blowout from a pressurized gas pocket confined beneath a clay cover. Gas slowly diffused from the borehole within superficial permeable sand. Seven persons living in three ground floor flats of a near building had to be hospitalized due to CO 2 exposure. All the houses in the proximity were evacuated. At the request of the Fire Brigade two additional boreholes were drilled nearby, hoping that this could rapidly exhaust the gas stored underground. To the contrary the soil gas flux near houses increased and indoor CO 2 air concentration rapidly rose to lethal values (15 to 30 vol.%). As a remediation we suggested to restore the continuity of the impervious gas cover by squeezing quick-setting cement into the formation through new boreholes to be drilled near the existing ones. Although the first cement squeeze reduced drastically the CO 2 soil flux and indoor concentration, six additional squeezes had to be carried out in order to lower the gas emission below the gas hazard threshold. The gas was mostly made of CO 2 (98 vol.%) with minor N 2 and CH 4. Its chemical and isotopic composition ( δ 13C CO2 = − 1.55; 3He/ 4He = 0.314 Ra) is similar to that of the gas manifestations of Mts. Sabatini and Alban Hills volcanic areas. Though being somewhat contaminated by crustal and shallow organic volatiles, these gases likely have a component originated in the mantle, that beneath the volcanic Roman Comagmatic Province is probably deeply contaminated with crustal material. The Fiumicino gas blowout indicates that the area of Central Italy characterized by strong CO 2 degassing extends westerly to include the Tyrrhenian coast.

Time saving during acrylic bone cement setting in femoral stem implantation of hip arthroplasty: A prospective, double-blind, randomised study.

In order to reduce the final stages of cementing time and intra-operative time, we analysed the behaviour pattern of a quick-setting cement. Quick-setting cement permits easy and adequate manipulation, which reduces surgical time and also the technical problems caused by waiting for setting to be completed. In order to verify the efficacy of faster cement, a double-blind randomised study was carried out comparing a type of traditional cement with quick-setting cement. Two groups of 20 patients were compared. The results show that the fast cement reduces setting time by an average of one minute and 55 seconds (p < 0.01) and presents similar manipulation characteristics to those of conventional cement. (Hip International 2005; 15: 143-8).

Time saving during acrylic bone cement setting in femoral stem implantation of hip arthroplasty: A prospective, double-blind, randomised study

In order to reduce the final stages of cementing time and intra-operative time, we analysed the behaviour pattern of a quick-setting cement. Quick-setting cement permits easy and adequate manipulation, which reduces surgical time and also the technical problems caused by waiting for setting to be completed. In order to verify the efficacy of faster cement, a double-blind randomised study was carried out comparing a type of traditional cement with quick-setting cement. Two groups of 20 patients were compared. The results show that the fast cement reduces setting time by an average of one minute and 55 seconds (p < 0.01) and presents similar manipulation characteristics to those of conventional cement. (Hip International 2005; 15: 143-8).

Wide-range viscoelastic measurement using resonating sensors

We have developed a specially designed sensor with its associated instrumentation using a so called acoustical near-field technique based on small resonating horns. Contrary to the conventional measuring devices used in the rheology industry, this sensor enables wide-range and continuous viscosity measurements, including liquid to solid material transition. The sensor is composed of a small piezoelectric element which enables the horn to resonate. Shear waves are generated by means of the thinner part of the sensor (dipped into the material) confining the acoustic field to the tip to ensure local measurements. The frequency is scanned across the resonating frequencies in order to perform these measurements with the maximum of speed and efficiency. The shear moduli G ′ and G ′′ of the material is deduced from the electrical impedance measurement at the resonance frequencies. In case of rapidly changing materials, such as quick setting cements or polyesters, we have developed a specific fast instrumentation based on the impulse response of the sensor, which realizes very fast measurements, typically 30 measurements per second. Modelization and experiments are reported.

A quick-setting refractory cement and the concrete based on it

A refractory cement has been developed for use in concretes. The rapid setting and hardening times predetermine the use of the concrete for rapid repairs of furnace linings with a service temperature of up to 1300°C.

The determination of setting time of portland cement by the vicat test

In quick-setting cements, setting may occur, wholly or partly, within the four minutes of the specified mixing time. The resulting structure, however, is broken by the mixing operation and the cements exhibit a normal, or near normal, setting. Hence, the use of the Vicat test (BS 4550: Part 3) for determining setting times of quick setting cements is not always adequate and may give misleading results.

Strengthening machine foundations

whole foundation or its spalled-off part along the perimeter. As the result of concrete shrinkage, an inward squeezing of the damaged parts of the foundations occurs along the yoke perimeter during the hardening process. The effectiveness of the stressed yokes is determined, not only by virtue of the simple increase in section and the transfer of loadings from the existing to the new part of the foundation but also primarily through joining the cracked parts into a single whole and putting them back into service. The inward squeezing also provides a reliable joining of the existing foundation concrete and the new, strengthening concrete, into a unity performing as a single whole, and it is therefore essential during the design phase to provide for an increased hardening shrinkage of the concrete and to take measures against the formation of shrinkage cracks; and, in carrying out the work, to ensure the necessary inward squeezing. An increase In the hardening shrinkage of concrete can be secured either by keeping the water/cement ratio constant but increasing the plasticity of the mix, i.e., the cement content compared with the design value; or, without changing the cement content, to raise the water/cement ratio to the maximum. However, in this case concrete strength is reduced and this requires the use of a high standard of cement. In order to increase the hardening shrinkage of concrete it is necessary to use rapid-hardening (quick-setting) cements and possuolanic (trass) cement, and also to include hydraulic additives and hardening accelerators in the mix, in quAntities recommended for their principal designation. This is also promoted by limestone and dense sandstone aggregates: During their slow absorption of water in the hardening process of the concrete, a practical reduction of the water/cement ratio, i.e., an increase in concrete strength, occurs.

Concrete for tunnel liners — evaluation of fiber reinforced quick setting cement concrete. 39F, 23T, 15R : Halvorsen, GT Dept. Civ. Engng. Univ. Illinois, Urbana-Champaign, Aug. 1974, 92p

Concrete for tunnel liners — evaluation of fiber reinforced quick setting cement concrete. 39F, 23T, 15R : Halvorsen, GT Dept. Civ. Engng. Univ. Illinois, Urbana-Champaign, Aug. 1974, 92p

Total Hip Replacement

This is an historic account of the development of total hip replacement as it took place in the author's laboratories and surgical clinics from about 1954 to the present time. The study covers five phases: basic research into the lubrication of normal animal joints; the trial of polytef as a low-friction plastic for the hip socket; bonding of implants to living bone by quick-setting acrylic cement; introduction of high-density polyethylene as a successful plastics material for the hip socket; and the attempt to identify a cause of late failure, when the probable alternatives were chemical rejection or bacterial infection, by eliminating airborne infection. ( JAMA 230:1025-1028, 1974)

Some Factors Controlling the Pumping Time of Oil-well Cements

High subsurface temperatures and pressures are making cementing operationsmore difficult as deeper producing horizons are being sought. Recordedbottom-hole temperatures above 200?F and pressures in excess of 12,000 lb. persq. in., obtained by combining hydrostatic and pump pressures, are notuncommon. Insufficient time is available for proper placement of standardPortland cement, because of the shortened setting time produced by theseexcessive temperatures and pressures, therefore special types of cements havebeen developed to overcome these difficulties. From the standpoint ofplacement, the ideal slurry would be one that would remain fluid long enough tobe placed, then harden rapidly, so that there would be a limited amount ofcontamination and the well could be placed on production in a minimum of time.It is highly desirable, therefore, that some method be devised to measureaccurately the time that any slurry will remain in a fluid state while beingpumped into the well. To study the effect of elevated temperature and pressure on fluidity, theauthors have developed the pressure-type consistometer (Figs. 1 and 2)described below, and are presenting data obtained with it, using slurries ofboth quick-setting and slow-setting cements. Studies were made over atemperature range from 110? to 270?F., and a pressure range from atmospheric to3000 lb. per sq. inch. Apparatus The fluidity of cement slurries at atmospheric pressure is usuallydetermined with the Halliburton consistometer or the Thickening Time Tester.These instruments are similar, in many respects, to an ordinary ice-creamfreezer. The slurry to be tested is placed in a container that is rotated at aconstant speed with an electric motor. Constant temperature is maintained bysurrounding the container with a thermostatically controlled bath. The torqueon the paddles, which is proportional to the force needed to shear the slurry, is indicated on a scale. The Halliburton instrument is calibrated from 0 to 100poises against fluids of known viscosity. T.P. 1399