Search

In this investigation, highly sensing smart cement grouts were developed using 0.8 water-to-cement (w/c) ratio and adding up to 3% sodium silicate. The sensing grout was also used to repair...

The smart cement behavior with 0.3% sodium metasilicate (SMS) at 80°C (176°F) under two different environments was investigated in this study. The smart cement was made using the class H oil well cement and 0.1% conductive filler to make it a bulk chemo-piezoresistive material with highly sensing property. The smart cement was cured in air and also submerged in water-saturated sand at 80°C up to 28 days. The smart cement initial resistivity (ρo) decreased from 0.97 to 0.87 Ω·m with 0.3% SMS, a 10% decrease. Similarly the minimum resistivity (ρmin) decreased from 0.81 to 0.72 Ω·m with 0.3% SMS, an 11% decrease, which is an indication of the chemo-resistivity of the smart cement. The resistivity changes were higher than the unit weight changes in the smart material. The resistivity of the smart material oven cured in saturated sand at 80°C was 55 to 75% less than the resistivity of the material cured at 80°C after curing for one, seven, and 28 days. The material resistivity with 0.3% SMS cured in ...

There is increasing interest in developing relatively quick test procedures to evaluate the effectiveness of composite coatings to reduce the infiltration of water and salt solutions into concrete structures to rapidly rehabilitate and extend the service life of reinforced concrete structures. In this study, concrete was first treated with two different types of silanes and then coated with a latex-based coating to investigate the sensitivity of the test procedure to resist the diffusion of water and 15% NaCl salt solution into concrete at room temperature. The concrete used in this study had a compressive strength of 36.5 MPa, with about 1.6% water absorption capacity in 21 days. The performance of concrete with composite coatings was investigated by using the immersion test, followed by the drying test. On the basis of 21 days of immersion test in water, the weight increase in specimens coated with one type of silane and latex coating was 1.21%, which was half of what was observed with the other silane ...

In this study, the effects of initial temperature, catalyst content, and activator content on the gelling time and maximum curing temperature of two polymeric grouts were investigated. Because the grouts are used in various environmental conditions, the grouts were investigated at three different initial temperatures (4.4, 15.7, and 26.7°C, or 40, 60, and 80°F). The catalyst and activator contents varied from 0.5% to 3% of the total weight of grout mix. Gelling times for the polymer grouts were measured, and the curing temperatures for the mixtures were monitored during and after the gelling process. The gelling time reduced with increased catalyst and activator contents and increased initial temperature for both the polymer grouts. One grout exhibited shorter gelling time and lower temperature rise during the gelling process than the other grout. Both artificial neural network (ANN) and nonlinear relationship (NLR) models were used to predict the observed grout behaviors. For each grout, a total of 48 te...

The electrical resistivity and mechanical properties of carbon fiber-reinforced cement mortar (CFRCM) were investigated. Both cylindrical and prism specimens were used in this investigation to determine the effects of size and shape of specimen on the physical and mechanical properties of the CFRCM systems. Carbon fiber loading was varied up to 6% (w/w), and water-to-cement ratios (w/c) of 0.5 and 1 were used. The specific electrical resistivity of the plain mortar with w/c ratio of 1 (>66,000 Ohm m) was reduced to 3,750 and 0.23 Ohm m upon increasing the carbon fiber content to 1 and 6% (w/w), respectively. The percolation theory was used to represent the variation of the electrical specific resistivity with fiber content in the cement mortar. Increasing the w/c ratio decreased the strength and toughness of the CFRCM composites. Increasing the fiber content increased the peak strain and toughness, but decreased the Young's modulus and electrical resistivity of cement mortar composites. Pulse velocity tests showed that the specimen shape also affected the dynamic Young's modulus, dynamic shear modulus, and the dynamic Poisson's ratio. The compression strength of the CFRCM was influenced by the w/c ratio and the fiber content. A model was used to predict the compressive stress-strain behavior of different CFRCM systems, and relations between static and dynamic properties have been developed. Empirical relations were developed to relate the specific electrical resistivity to unit weight, Young's modulus, and pulse velocity.

Pipe-in-Pipe (PIP) configurations are considered as a practical solution to deepwater oil production to prevent hydrate formation and paraffin deposition during the transportation of crude oil to production facilities. The optimal design of a PIP configuration requires a balance between the structural performance and the thermal insulation of the grout material used to fill the annular space. In this study, the effect of aggregates (4–19.1 mm) , sand (0.4–5 mm) , and microspheres (

Epoxy-based coatings are used in the rehabilitation and protection against acid attack in industrial and wastewater facilities made of concrete and clay bricks. In this study, the performance of two epoxy-based coatings on sewer grade clay bricks was evaluated using a combination of bonding strength and acid resistant tests over a period of three years. The test results showed that the bonding strength of the epoxy coatings depended on the dry and wet surface conditions of the clay brick at the time of coating. The bonding strength varied from 0.2 MPa to 3 MPa. The coating films effectively reduced the liquid uptake of the coated clay bricks and pinholes influenced the weight gain of the coated clay bricks. There was no direct relationship between bonding strength and acid resistant (weight gain) of the tested coatings. A film model was developed to predict the weight change in coated clay bricks. The mass transfer coefficients of the coatings varied from 0.8×10-12 to 7.8×10-12 m2/s and 1.7×10-12 to 6.6×1...

The compressive and tensile properties of polyester polymer and polymer concrete were studied under various curing conditions, temperature, and strain rate. The curing temperature was varied from room temperature to 80°C. The strain rate was varied between 0.01% to 60% strain per minute and the temperature between 22°C and 120°C. The optimum curing condition for polymer and polymer concrete are different. The strength, failure strain, modulus, and stress-strain relationship of polyester polymer and polymer concrete are influenced by the curing method, testing temperature, and strain rate to varying degrees. The influence of test variables on the mechanical properties of polymer and polymer concrete are quantified. Pretreating the aggregates with a silane coupling agent further enhances the compressive and tensile strength of the polymer concrete. The compressive strength of polymer and polymer concrete are related to their compressive modulus and splitting tensile strength. A constitutive model is used to predict the compressive stress-strain behavior of polymer and polymer concrete.

The effect of polymer content and glassfiber content on the compressive behavior of polyester polymer concrete is investigated at room temperature. The polymer content varies between 10% and 18% of...