Journal of Materials in Civil Engineering

Near-infrared (NIR) spectroscopy was used to predict the longitudinal tensile modulus, the longitudinal tensile strength, and the creosote content of wood from an out-of-service southern pine utility pole. Tensile samples were cut from the pole in the radial direction and near-infrared spectra were obtained before testing. Coefficients of determination $r^2$ , of 0.80–0.86 were obtained between the NIR spectra predicted modulus and measured modulus. Coefficients of determination for strength were lower, 0.58–0.63. After tensile testing, the specimens were ground in a mill and spectra were obtained from the homogeneous ground samples. There was a slight decrease in the coefficients of determination using the ground samples, 0.76–0.82 for the modulus and 0.46–0.57 for the strength. Creosote content was difficult to predict with the NIR spectra of the whole sample, but coefficients of determination $>0.9$ were obtained with the ground samples. There was little difference in the results for spectra collected over the $350\text{–}\mathrm{2,500}\mathrm{nm}$ range and those obtained with just looking at the $950\text{–}\mathrm{1,850}\mathrm{nm}$ range. This suggests that it will be feasible to predict the mechanical properties of treated timber using lightweight, relatively inexpensive, portable instruments rather than larger, more expensive systems that cover the entire NIR range.

Increased ductility of columns made with high-strength concrete (HSC) can be accomplished through proper confinement of the concrete core. To determine the effectiveness of welded wire fabric as transverse reinforcement in HSC columns, an experimental investigation involving testing of ten full-scale columns in axial compression was conducted. The performance of columns laterally reinforced with welded wire fabric (WWF) was compared with that of unconfined concrete. Axial stress-strain diagrams of the concrete core from the experimental tests showed that substantial gains in strength and ductility of columns laterally reinforced with WWF can be achieved if the volumetric ratio of transverse steel was larger than 3.5%. Critical points on the stress-strain curve of confined concrete were determined and a mathematical model that considers the effect of the volumetric ratio of transverse steel on the stress-strain relationship is proposed. Comparison between the proposed model and the experimental results showed good agreement between the two.

When the benefits of self-compacting concrete (SCC) are added to those resulting from the addition of discrete steel fibers to cement based materials, a high performance material, designated as steel fiber-reinforced self-compacting concrete (SFRSCC), is obtained. The present work is part of a research project that was conducted to develop a lightweight precasting SFRSCC panel for building façades. The SFRSCC mix design strategy and the experimental research conducted to characterize the bending and the compression behavior of SFRSCC at ages ranging from $12\mathrm{h}$ to 28 days are presented. A particular effort is made to assess the SFRSCC postcracking behavior, carrying out three point notched beam bending tests. The equivalent and the residual flexural tensile strength parameters, proposed by RILEM TC 162-TDF to characterize the toughness of steel fiber reinforced concrete, are determined for the designed SFRSCC. To evaluate the stress-crack opening diagram of the designed SFRSCC, an inverse analysis is performed, fitting the experimentally obtained force-deflection curves. The influence of the age on the SFRSCC fracture parameters is analyzed. SFRSCC prototype panels were tested to assess their flexural and punching resistance.

Coal-tar emulsion sealers are used to protect hot-mix asphalt pavements from damage due to the spillage of petroleum-based materials. This paper contains the results of a study, which has field tests and laboratory tests, concerning the effect of various amounts of aggregate, temperature variations, a polymer additive, and aging on the material properties of coal-tar emulsion mixtures. The material properties tests included thermal expansion, creep stiffness test, and by measuring tensile strength, the stress-strain relationships. The study results indicate that the thermal expansion of the mixtures increased with increasing amounts of coal-tar emulsion; however, this effect was slightly reduced with the addition of a polymer additive. Creep stiffness values increased with age and increasing amounts of aggregate in the mixture. The results of the stress-strain evaluation were not consistent. Increased amounts of aggregate, lower temperatures, and decreased amounts of polymer generally resulted in greater stress levels being achieved prior to failure.

Cushioning materials are one of the most important auxiliary equipments in pile driving whose equality has great influence on the quality of construction. In this paper, the static and dynamic behaviors, mainly focused on elastic modulus and recovery coefficient, of three commonly used cushioning materials of pine wood, asbestos–rubber board, and disk spring are fully discussed by different experiments. The static loading is used to measure the static elastic modulus and recovery coefficient while the methods of back-calculation according to the natural frequency of a cantilever beam and slope of a dynamic stress-strain curve are individually adopted to determine the dynamic elastic modulus, and the dynamic recovery coefficient is measured by making normal impact of the spherule to the base plate. The tests show that the dynamic elastic modulus and recovery coefficient from the dynamic test are more applicable in modeling the actual behavior of cushioning materials in pile driving than is the static. Among these three materials, the disk spring is considered to be the most optimum material in pile driving for its high, steady recovery coefficient (above 0.9).

A low temperature cure inorganic matrix, known as geopolymer or polysialate, is currently being investigated for use in high temperature applications. It provides an excellent opportunity for achieving the goal of producing low cost high temperature resistant composite. This paper deals with the fatigue performance of composites made using this matrix and carbon fabrics. Thirty five laminates were tested under cyclic flexural loading conditions. Both the strength and stiffness properties of coupons subjected to as many as ten million cycles of loading are reported. Failure surfaces were examined using an optical microscope and three degradation mechanisms were observed. Microcracks developed on the tension face of the sample during the first loading cycle. These transverse cracks did not grow during the following cycles. The fatigue cycles also created longitudinal cracks prior to failure. These longitudinal cracks developed at the end of a stable stage in which there was minimal loss of stiffness. When the density of longitudinal cracks became large, their interaction with the transverse microcracks induced the composite failure.

Blended calcium sulfate (BCS), an industrial by-product from hydrofluoric acid, was successfully stabilized with 120 grade, ground, granulated blast furnace slag (GGBFS) in a laboratory. A full-scale field testing section was then built to evaluate the in situ performance of the stabilization schemes determined in the laboratory and the impact of coarse aggregates (retained on the No. 4 sieve) on stabilization efficiency. An elaborate laboratory and in situ testing program was performed to provide construction quality control and to characterize the mechanical properties of stabilized BCS. The GGBFS-stabilized BCS performed well in terms of strength, stiffness, and water resistance, but fly ash was not effective in stabilizing BCS. The viability of field mixing techniques and field curing conditions was confirmed by the testing results, which provided some experimental basis for BCS stabilization in the future.

There is a growing interest in the use of fabrics as reinforcements for cement composites due to their superior performance in comparison to other cementitious composites. This paper compares the effects of two processing methods, casting and pultrusion, on the tensile properties of fabric-cement composites. Four fabric types were used, including bonded glass mesh, woven polyvinylalcohol, woven polyethylene, and warp knitted weft insertion polypropylene. The evolution of crack spacing and crack width as a function of applied strain as well as stiffness degradation were correlated with tensile responses of various composites. Pullout tests and microstructural analysis were conducted to better understand the tensile behavior. The advantages of using pultrusion are clear. Pultruded fabric-cement composites exhibited improved mechanical performance, especially those that incorporated knitted fabrics made from multifilament yarns with an open junction point. This improved performance is due to the improved bonding by the impregnation of cement paste during pultrusion, which helped fill the spaces between the filaments of the bundled yarns.

This paper presents the study on compaction characteristics of pond ash. Three different types of pond ash have been used in this study. The effects of different compaction controlling parameters, viz. compaction energy, moisture content, layer thickness, mold area, tank size, and specific gravity on dry density of pond ash are highlighted herein. The maximum dry density and optimum moisture content of pond ash vary within the range of $8.40–12.25\mathrm{kN}∕{\mathrm{m}}^3$ and 29–46%, respectively. In the present investigation, the degree of saturation at optimum moisture content of pond ash has been found to vary within the range of 63–89%. An empirical model has been developed to estimate dry density of pond ash, using multiple regression analyses, in terms of compaction energy, moisture content, and specific gravity. Linear empirical models have also been developed to estimate maximum dry density and optimum moisture content in the field at any compaction energy. These empirical models may be helpful for the practicing engineers in the field for planning the field compaction control and for preliminary estimation of maximum dry density and optimum moisture content of pond ash.

There are several questions that are not well understood with respect to the long-term stability characteristics of lime-treated expansive soils in spite of being used as a conventional technique to improve the properties of expansive soils. This paper examines the long-term stability characteristics of FoCa bentonite soil (FoCa represents the first two letters of the two towns between which this type of soil is excavated: Fourgues and Cahaignes) using 4% lime treatment. The long-term stability characteristics referred to as durability in the paper were interpreted taking into account the influence of wetting–drying and freezing-thawing cycles on key engineering properties which include swelling and strength behavior of both untreated and lime-treated FoCa. In addition, leaching tests were carried out to study the ${\mathrm{Ca}}^{2+}$ ions and pH concentration changes of the percolating water from both treated and untreated compacted expansive soil specimens analyze the permanence of the clay treatment. Finally, to highlight the changes induced in the texture of the material, pore size volume and distribution were investigated by mercury intrusion tests.