Journal of Materials in Civil Engineering

The authors applied sonic tests to study the propagation of sonic waves through stone masonry walls. In particular, tests were made to study the effect of the joints and the influence of the characteristics of the stones surface, rough or smooth, on the measurement of the sonic velocities on granite masonry specimens. A series of direct, indirect, and impact echo sonic tests were performed on single stones and on columns of stones with dry and mortar joints to obtain $P$- and $R$-wave velocities. The results allowed a better understanding of the influence of the stones characteristics and the samples geometries, namely the number of joints, to the global response of the masonry to the propagation of sonic waves. This study also allowed verifying the complementarity of the different sonic test configurations and the interest to cross information from more than one technique to obtain more reliable information. Finally, significant results were also achieved concerning the relationship between the parameters obtained for $P$ and $R$ waves.

Drying shrinkage because of moisture diffusion is a critical factor influencing the durability of concrete structures. Numerical simulation of moisture diffusion and drying shrinkage inside concrete, on the basis of the mechanism of drying shrinkage, is significant to better understanding and predicting drying shrinkage-induced cracking. To correctly simulate the drying effect on concrete deformation, diffusion coefficient, surface factor and other factors are essentially required. This paper presents the simulations of shrinkage tests of concrete blended with fly ash and ground granulated blast furnace slag based on the theory of three-dimensional nonlinear moisture diffusion. The related parameters are identified by the inverse finite-element analysis approach using the design optimization module of ANSYS. The environmental humidity effect on shrinkage strain and the relationships between the identified parameters with the fly ash content are discussed.

Seismic refraction using the longitudinal or P wave method of survey was carried out at some highway locations with the object of evaluating the compaction quality of subgrade and subbase at the locations. These highways traverse different geologic terrain. The survey delineated two layers in most of the locations with various values of velocities that generally increase with depth. Soil samples were also obtained for the different subgrades. Compaction and classification tests were carried out on the soil samples. Seismic refraction theory was reviewed and was used to obtain a profile of the layers. The profile pattern of the layers was found to be indicative of the quality of compaction of the subgrade.

In this study, cyclic tension-compression tests on cylindrical specimens are performed in order to investigate fatigue characteristics of bituminous mixtures. Sinusoidal loading is applied at 10 Hz in controlled axial strain mode at 10°C. Axial strain and axial load are measured as well as radial strain, thanks to a specially designed device. The evolution of Poisson’s ratio and volumetric strain is observed during fatigue tests. Fatigue test results are analyzed considering six different fatigue life criteria (using either classical complex modulus drop, nonhomogeneity of the strain field, or dissipated energy evolution, among others). During the first phase of fatigue tests, some skewing phenomena (e.g., thixotropy and heating) are predominant and create reversible effects that must not be interpreted as fatigue. A method to take into account these phenomena is also applied to obtain a corrected damage value at failure. This parameter is shown to be a constant intrinsic value. Based on this result, a new approach is also proposed to predict failure. This method enables stopping tests at 300,000 cycles. The approach has the interest to limit the testing time duration to less than 8.5 h (with 10 Hz frequency).

In view of the importance of the diffusion of oxygen molecules in concrete to the durability assessment and design of reinforced concrete structures located in a marine or deicing salt environment, it is essential to determine its oxygen diffusivity. This paper presents an effective medium approach for evaluating the oxygen diffusivity of concrete. Since the aggregate, bulk cement paste, and interfacial transition zone (ITZ) have different morphological characteristics and contributions to the diffusion of oxygen molecules in concrete, concrete is modeled as an isotropic three-phase composite material. Based on the stereological analysis of aggregate size distributions and the statistical geometry of composites, the ITZ volume fraction is formulated analytically. By introducing a hypothetical homogeneous medium of nonzero oxygen diffusivity and applying the general effective medium approach, an analytical solution is derived for the oxygen diffusivity of concrete. The primary advantage of the approach is that the ITZ percolation effect is taken into account and the oxygen diffusivity bounds are satisfied. Finally, some numerical comparisons are made to show the good consistency between the proposed approach and experimental results obtained from the research literature.

Time-dependent prestress losses in historic unreinforced clay brick masonry (URM) walls strengthened using unbonded posttensioning were investigated, with a particular emphasis on masonry shortening resulting from creep and shrinkage. An experimental program was undertaken that involved continuous monitoring of masonry shortening occurring in prestressed URM wallettes over a period of 180 days. The test wallettes were extracted from a real historic URM building and were subjected to varying magnitudes of prestress, representing axial stresses that would be developed at the wall base when strengthened using unbonded posttensioning. A rheological model is proposed for predicting masonry creep shortening, which can subsequently be used to predict posttensioning losses. It was established that a prestress loss of up to 16.4% for normal threaded steel bars and up to 5.4% for sheathed greased seven wire strands can be expected in posttensioned historic URM walls when the tendons are posttensioned to a stress of ${0.5f}_{\mathrm{pu}}$.

Ethylene-vinyl acetate (EVA) redispersible powder was used to modify mortar. The tensile strength of EVA-modified mortar and the interface bond strength of EVA-modified mortar and porcelain tile, cured under $20\pm 3°\mathrm{C}$ and relative humidity $50\pm 5\%$, were tested. The interface bond mechanism of EVA-modified mortar and porcelain tile was discussed. Results obviously showed that EVA redispersible powder improved the tensile strength of mortar. The interface bond strength between EVA-modified mortar and porcelain tile increased with the increase of EVA content in mortar and did not always increase with the extension of curing age. Microstructure analysis illuminated that polymer film was being formed by EVA latex powder along the hydrated products and the mortar–porcelain tile interface. The EVA improved interface bond strength by penetrating the capillary and pore of porcelain tile accompanied with hydrated products.

Use of a reliable and accurate measuring system to determine lateral pressure exerted on formwork by self-consolidating concrete can lead to economic and safe formwork systems. In this paper, a portable and field-compatible pressure device is developed to enable factors affecting lateral pressure of fresh concrete on formwork system to be explored prior to conducting onsite full-scale tests. The pressure device requires a sample of 16 L of fresh concrete to determine lateral pressure envelope that can be exerted by a concrete column of up to 13 m in height. The pressure device enables the simulation of such concrete head using an overhead pressure exerted onto the fresh concrete. A number of parameters are used to validate the pressure device, including placement rate as well as mix designs of various paste volume, slump flow, ratio of water to cementitious material, maximum size of aggregate, and dosages of chemical admixtures. The test results indicated that the repeatability of the lateral pressure values obtained using the pressure device shows relative error of about 7%. The validation of the pressure device clearly showed that the device adequately reflects the effect the various factors affecting lateral pressure characteristics of fresh concrete.

Road construction and maintenance require large quantities of virgin aggregate (VA). Using waste aggregate as an aggregate replacement reduces the extraction of new aggregate, pressing demand on existing landfill sites, and emissions of wastes into the environment. This study assessed the use of recycled marble aggregates (RMA) as replacement for virgin aggregates in hot mix asphalt (HMA). The aim of this study was to evaluate the possible use of hot mix asphalt containing RMA for roads with medium traffic volume. For this purpose, RMA was replaced by VA at rates of 15, 25, 40, and 60% in HMA. Resilient modulus, indirect tensile fatigue, dynamic creep, and indirect tensile strength ratio tests are performed to evaluate the field performance suitability of HMA. The results show that, for mixtures containing RMA, resilient modulus and fatigue life are slightly lower than those for the control mix, and they decreased when the RMA increased in the mix. In addition, the direct relationship between the percentage of RMA and rutting potential limited the use of RMA in hot weather. Moreover, because of the low percentage of ${\mathrm{SiO}}_2$ in marble, the tensile strength ratio increased with increasing RMA. According to the results obtained in this study, using a certain amount of RMA to replace VA in HMA is acceptable for roads with medium traffic volume.

In the year 2006, the price of asphalt binders in the United States increased by almost 50% over the 2005 prices. The use of higher recycled asphalt pavement (RAP) percentages with locally available binders was adopted as an approach to reduce the demand on specialty more expensive virgin binder and virgin aggregates in Virginia. The purpose of this study was to investigate concerns that the performance of these higher RAP mixtures could be compromised because of excessive mixture stiffening due to the aged RAP binder. The results indicated that measured binder stiffnesses of high-RAP mixtures are not significantly affected by RAP amount, high temperature true grade of high-RAP mixtures averaged only approximately 2.0°C above that of base virgin binder, and that the correlation between binder stiffness and flow number for the selected high-RAP mixtures considered was good. The study concludes that the addition of higher amounts of RAP to asphalt-concrete mixtures currently produced in Virginia has not resulted in excessively stiffened mixtures as previously thought; the stiffnesses of high-RAP mixtures are primarily governed by the virgin binder stiffness.

The problem of graffiti is not entirely restricted to urban areas, but also appears frequently in rural communities and along traffic infrastructure. Besides its aesthetic and societal effects, graffiti cause considerable removal costs and subsequent costs for repairing damages caused by improper graffiti removal. Over the last two decades, strategies have been developed to combat graffiti in the built environment, including the development of protective measures in the form of antigraffiti systems (AGSs). Antigraffiti systems promise to be affordable and easily applicable for a wide range of substrates, and many products have already been on the market for many years. In practice, however, successful application of AGS and removal of graffiti depend on many factors in which the type of coating and condition of the substrate play critical roles. The optimal environmental goal is to use AGS without any cleaning chemicals except for pure water. Available studies on the behavior of the same AGS on various substrates can show completely different results concerning the cleaning efficacy and the durability of the AGS under different climatic conditions. The question of which properties of an AGS are most essential for its efficiency has still not been fully investigated. The goal of this study was to investigate cleaning efficacy in conjunction with hydrophobic and oleophobic properties of the AGS on different substrates. The results showed that hydrophobicity and oleophobicity are important for dense substrates but have a low influence on porous substrates. In this case, cleaning efficiency is majorly determined by the physical properties of the substrates.

This paper reports on an investigation of the use of expanded perlite aggregate as saturated lightweight aggregate (LWA) with respect to the mechanical and dimensional stability properties of engineered cemetitious composites (ECC). Expanded perlite aggregate was soaked in water for 24 h before its use in ECC, and replaced 10, 20, and 30% of the aggregate that was used in ECC production. The mixture proportion of a standard ECC mixture with properties that have been extensively reported in the literature is used as a reference. The properties of the specimens are compared in terms of compressive strength, flexural strength, midspan beam deflection capacity, matrix fracture toughness, drying shrinkage, autogenous shrinkage, and restrained shrinkage. The compressive strength and flexural strength of the specimens were adversely affected with presoaked LWA replacement. Midspan beam deflection capacities were partially improved, whereas matrix fracture toughness values decreased by the presoaked LWA replacement, which is beneficial with respect to the multiple cracking behavior of ECC. Presoaked LWA replacement slightly increased the drying shrinkage with respect to the reference mixture. However, the use of presoaked expanded perlite aggregate in ECC production increased the age of restrained shrinkage cracking and decreased the autogenous shrinkage capacity significantly. Therefore, together with the comparable and enhanced composite mechanical, ductility, and dimensional properties of the standard ECC mixture, the use of presoaked LWA in ECC production should improve the durability and extend the service life of structures under environmental exposure.

Utility wood poles are extensively used to support electrical-transmission and distribution lines in North America. Wood poles are exposed to extreme weather conditions, making them vulnerable to internal deterioration resulting in loss of pole strength, which can compromise the reliability of energy supply to customers. Ultrasonic testing is a nondestructive method that has been used for evaluation of the internal condition of in-service wood poles. However, the current assessment criterion is mostly based only on the first arrival of compression waves. This paper presents experimental and numerical methods for the detection of voids in wood poles using ultrasonic waves; the wood is considered as an orthotropic material. This investigation involves ultrasonic testing of a red-pine pole without and with a void. Changes in both compression wave velocity and wave attenuation are used to identify the presence of a void. An orthotropic finite-element model, calibrated with experimental results, is used to study the propagation of ultrasonic waves in a cross section of red-pine poles. Experimental and numerical results show that for a void–pole diameter ratio of ${ø}_{\text{void}}/{ø}_{\text{pole}}=0.2$ and frequency of 50 kHz ($\lambda =1.7{ø}_{\text{void}}$), the wave velocity across the pole decreases an average of 20%, whereas the wave is attenuated by a factor of 10. Thus, the consideration of wave attenuation in addition to wave velocity is critical to improve the reliability of current methodologies. The compression wavefront shows a triangular shape before reaching the pith of the wood pole, after which it shows a circular shape, as in the case of an isotropic material. In addition, the surface wave shows displacements mostly in the radial direction instead of the typical retrograde ellipse in an isotropic medium.

The use of supplementary cementitious materials as partial replacements of the cement in concrete will play a significant role with respect to the environmental control of greenhouse effects and global temperature reduction. The development of geopolymer concrete (GPC), in which all of the portland cement is replaced with fly ash (in combination with sodium hydroxide and sodium silicate solutions), offers a promising alternative to ordinary portland cement concrete. This paper evaluates the durability characteristics of low-calcium fly ash–based geopolymer concrete that was subjected to a corrosive marine environment. A series of GPC beams, which contained fly ash with 8- and 14-M concentrations of NaOH and ${\mathrm{SiO}}_2/{\mathrm{Na}}_2\mathrm{O}$ solutions, respectively, and were centrally reinforced with a 13-mm rebar, were tested for accelerated corrosion exposure with wet and dry cycling in artificial seawater and an induced current. A sudden rise in the current intensity that is attributable to specimen cracking was indicative of durability. The test results indicated excellent resistance of the geopolymer concrete to chloride attack, with a longer time to corrosion cracking relative to ordinary portland cement concrete.

This paper presents the engineering characteristics of blends of recycled clay masonry (RCM) with recycled concrete aggregate (RCA) from two material producers from South Australia. The proportion by dry mass of RCM was 20% of the total mass. Results are reported of standard engineering classification tests and static and repeated loading triaxial tests (RLTT). Specimens were tested between 60 and 100% of optimum moisture content (OMC) and at a constant dry density ratio. Matric suctions were measured by the filter paper method to study the influence of suction on strength and to establish soil water characteristic curves (SWCC). Triaxial testing indicated that cohesion varied between 9 and 89 kPa and was dependent on molding moisture content, matric suction, and the material source. Resilient modulus and permanent strain were also influenced by suction. Permanent deformation was able to be modeled successfully using a relationship developed between number of load repetitions and initial matric suction. Based on the laboratory testing program, the recycled clay masonry blends appeared to be suitable for application as subbase.

The effect of early-age carbonation curing on the microstructure and properties of lightweight concrete with expanded slag aggregates was examined. Carbonation was performed on concretes either immediately after casting or after 18-h air curing. Their corresponding carbon uptake was 8 and 23%, respectively, based on cement content. A process involving initial air curing, carbonation curing, water compensation, and subsequent hydration was developed to maximize the degree of carbonation and hydration. Reaction products of carbonation-cured concretes at early and late age were characterized by using thermogravimetrical (TG) analysis, X-ray diffraction analysis, and scanning electron microscopy. Although the presence of calcium carbonates was evident, the microstructure was nevertheless typical of amorphous. It was believed that early carbonation of concrete consumed calcium hydroxide, calcium silicate hydrates, and anhydrous calcium silicates while producing calcium carbonates of different polymorphs and amorphous calcium silicate hydrocarbonates.

Asphalt mix compaction is dependent on many factors, particularly gradation, asphalt grade and content, aggregate size, temperature, and compactor manufacturer. The new development in polymer-modified asphalt has a major impact on asphalt pavement compaction in the field. Although it leads to improving overall mechanical characteristics, there are concerns that mixes become drier and more difficult to compact. This paper aims to develop compaction indices using the Superpave gyratory compactor to evaluate the workability and compactability of the mixes during the routine mix design process and prior to laydown operations. Workability is reflected in the ease of blending the mix components using construction equipment. Compactability is reflected in the mixes’ stability and resistance to densification under traffic loading. To identify adequate thresholds for the compactability indices, performance testing is required to validate the long-term behavior of these mixes. This was accomplished in two phases: laboratory performance testing and field performance testing. The former was conducted using Hamburg wheel tracking, rutting, and dynamic modulus tests, whereas the latter phase was accomplished through accelerated pavement testing. Evaluation of the mixes’ internal structure effect on the compaction indices, in terms of aggregate orientation and number of contacts, was also investigated.

According to standards, the durability performance of fiber-cement sheets must be evaluated by comparing the modulus of rupture (MOR) before and after durability tests (freeze-thaw, soak-dry, and warm water) are completed. This paper investigated the MOR of two different fiber-cement sheets samples before and after durability tests as well as its ductility and toughness. Results showed no significant difference between the MOR of control specimens and that of the specimens submitted to durability tests except in the case of the freezing and thawing test where after 100 cycles, a 7–9% decrease was observed. The differences between the MOR of the control specimens and that of the specimens submitted to durability tests were negligible and acceptable in accordance to the requirements of the standard. However, toughness and ductility decreased considerably in specimens of sample 1 by 25, 35, and 15%, respectively, when exposed to soak-dry (25 and 50 cycles) and warm water conditions. In turn, the reduction in toughness and ductility for specimens of sample 2 exposed to soak-dry (50 cycles) and warm water conditions were of 40 and 7%, respectively. The results of this investigation suggest that ductility and toughness should also be considered to assess the durability performance of fiber-cement sheets.