Tensile Strength Of Cement Research Articles

Prediction Models for Estimating Compressive Strength of Concrete Made of Manufactured Sand Using Gene Expression Programming Model.

The depletion of natural resources of river sand and its availability issues as a construction material compelled the researchers to use manufactured sand. This study investigates the compressive strength of concrete made of manufactured sand as a partial replacement of normal sand. The prediction model, i.e., gene expression programming (GEP), was used to estimate the compressive strength of manufactured sand concrete (MSC). A database comprising 275 experimental results based on 11 input variables and 1 target variable was used to train and validate the developed models. For this purpose, the compressive strength of cement, tensile strength of cement, curing age, Dmax of crushed stone, stone powder content, fineness modulus of the sand, water-to-binder ratio, water-to-cement ratio, water content, sand ratio, and slump were taken as input variables. The investigation of a varying number of genetic characteristics, such as chromosomal number, head size, and gene number, resulted in the creation of 11 alternative models (M1-M11). The M5 model outperformed other created models for the training and testing stages, with values of (4.538, 3.216, 0.919) and (4.953, 3.348, 0.906), respectively, according to the results of the accuracy evaluation parameters root mean square error (RMSE), mean absolute error (MAE), and coefficient of determination (R2). The R2 and error indices values revealed that the experimental and projected findings are in extremely close agreement. The best model has 200 chromosomes, 8 head sizes, and 3 genes. The mathematical expression achieved from the GEP model revealed that six parameters, namely the compressive and tensile strength of cement, curing period, water–binder ratio, water–cement ratio, and stone powder content contributed effectively among the 11 input variables. The sensitivity analysis showed that water–cement ratio (46.22%), curing period (25.43%), and stone powder content (13.55%) were revealed as the most influential variables, in descending order. The sensitivity of the remaining variables was recorded as w/b (11.37%) > fce (2.35%) > fct (1.35%).

Influence of Octacalcium Phosphate addition on physical-mechanical properties of Glass Ionomer Cement

OBJECTIVE: The aim of this study was to evaluate the influence of octacalcium phosphate (OCP) addition to conventional glass ionomer cement (GIC).METHODOLOGY: A commercial glass ionomer cement (Vidrion R – S.S. White Artigos Dentários Ltda – Rio de Janeiro, Brazil) was used in this study. OCP was added to powder in 1.5 and 3 wt%. GIC without OCP addition was used as control. Specimens were produced to evaluate radiopacity, setting time and diametral tensile strength of cements. Radiopacity was assessed by phosphor plate system with alluminium step-wedge for comparison. For setting time determination, Gilmore needle (100 g) was used to determine final setting reaction. Diametral tensile strength was measured in a universal testing machine. Data were analyzed by one-way ANOVA at a significance level of 95%.RESULTS: Results showed no statistically significant difference in tested properties with octacalcium phosphate addition in any concentration.CONCLUSION: OCP addition to GIC did not influence materials properties.

Strontium ions substitution in brushite crystals: the role of strontium chloride.

The incorporation of strontium chloride to brushite cement was successful to introduce strontium ions within the lattice of brushite crystals. The effect of strontium ions on brushite cement properties was concentration dependent; such that, the addition of 5% and 10% (w/w) SrCl2 significantly increased the cement FST and the addition of 10% SrCl2 decreased the cement tensile strength. Further, cement weight loss was shown to be increased by cement modification with SrCl2. The combination of ionic substitution and the degradability of brushite cements would constitute a system for the local delivery of strontium ions in the treatment of osteoporosis.

Incorporation of fibres in geothermal well cements

Fibre-reinforced cements are of potential value in geothermal well cementing jobs due to their ability to withstand higher tensile stresses than conventional cements. Screening tests were performed to evaluate different fibre types with the objective of identifying systems offering the greatest improvement in cement tensile strength. The fibres investigated included steel, stainless steel, carbon, basalt and glass. The baseline cement matrix was standard Class G cement/40% silica flour and variations on this were latex-modification and lightweight formulations incorporating either perlite or microspheres. The fibres that showed the best performance at low volume fraction were 13 mm brass-coated round steel fibres. Steel and carbon microfibres also improved the tensile strength provided the volume fraction was high enough. Thermal and hydraulic properties of cements reinforced with steel fibres were measured and compared with unreinforced mixes. Based on the results, selected fibre types will be used in further property characterization studies and engineering analysis of geothermal wells completed with fibre-reinforced materials.

Bonding of a composite restorative material to etched glass ionomer cement.

AbstractThe tensile bond strengths of a composite restorative material to phosphoric acid etched restorative glass ionomer cement were examined as a function of cement brand, time after mixing at which etching was performed, thickness of film on enamel and dentine and extent of exposure to water during cement maturation.Optimum bond strengths were obtained with mature cements isolated from water during maturation. Bond strengths were similar to or greater than tensile strengths of cements and many currently available dentine bonding agents for composites. Bonding to etched cement occurs by micromechanical interlocking and the zone of bond failure in tension was in the surface layer of the cement.

The effect of temperature on the compressive and tensile strengths of cements

The effect of temperature on the compressive and tensile strengths of cements

Effect of Soaps on the Properties of Portland Cement

Calcium and sodium stearate soap additions in the ordinary portland cement have been studied by mixing 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 per cent respectively by weight of cement. Cement and sand mortar in the ratio of 1:3 with diiferent percentages of additives were tested for workability and water retention properties. It was observed that calcium soap was more effective in increasing the workability and sodium soap in water retention property. Setting time on the neat cement with additives indicated that both the soaps acted as accelerator and both the initial and as well as the final setting time were reduced in each case. The tensile strength of cement was not affected much in the case of calcium soap addition while a little lowering in strength was observed in the case of sodium soap.

Discussion on Retrogression in Tensile Strength of Cement

Discussion on Retrogression in Tensile Strength of Cement

Retrogression in the Tensile Strength of Cement

Retrogression in the Tensile Strength of Cement

Closure to Retrogression in Tensile Strength of Cement

Closure to Retrogression in Tensile Strength of Cement