Journal of Materials in Civil Engineering

This paper demonstrates the application of the polygon of voids, or “polyvoids,” as an analytical technique to produce a hot-mix asphalt (HMA) job-formula based only on voids specifications, to Superpave hot-mix asphalt design and analysis. Polyvoids is one of the original analytical tools of RAMCODES (an acronym for rational methodology for compacted geomaterials’ densification and strength analysis). Functions for the definition of voids (i.e., air voids, voids in mineral aggregate, and voids filled with asphalt) as used in this paper are the same as found in the Asphalt Institute’s MS-2: Mix Design Methods and SP-2: Superpave Mix Design manuals. Definition and construction of polyvoids are herein described completely from a logical point of view. The polyvoids centroid is proposed as the job-formula or optimum-binder content for HMA design, based on voids specifications only. Three actual examples of Superpave hot-mix design were used to prove that the asphalt-binder content of the centroid is roughly the same as the one obtained by the sixteen-specimen AASHTO PP28 procedure (AASHTO 2001), but the polyvoids approach needs only six specimens. Also, the polyvoids approach allows the designer avoid a compacted state that is too close to the voids specification limits, allowing the maximum possible variability during production. Obtaining the polyvoids vertices and centroid is easier and more rapid if equations are programmed into spreadsheet software. As it does in the Marshall Mix design method, the polyvoids approach produces important savings in resources and response time in design and research related to Superpave.

The purpose of this study was to investigate the properties of hot-mix asphalt (HMA) prepared with devulcanized crumb rubber–modified asphalt (DCRMA), which was processed by using pre-devulcanized crumb rubber at a lower temperature (165°C). HMA with different DCRMA content in weight were investigated, and it was found that the optimal binder content was 6.1% by weight. The packing grading mixture design method was applied in the design of DCRMA HMA. A series of laboratory tests including the submerged Marshall Stability, wheel tracking test, dynamic modulus test, small beam bending test, and four-point flexural fatigue test, were carried out to characterize the properties of DCRMA HMA. From the experimental results, it could be concluded that the pre-devulcanized crumb rubber can be used as one kind of good modifier for asphalt rubber to improve hot storage stability. DCRMA could also act as a cost-effective, modified binder in dense-graded asphalt mixture, and benefit the low temperature property and prolong the fatigue life cycle.

Steel corrosion owing to chloride ion penetration is one of the most common problems related to the durability of concrete structures. Although previous studies of this phenomenon have produced useful results, they primarily focused on unstressed concrete. To study the effect of stress on the resistance of concrete to chloride ion penetration, tests of stressed specimens exposed to salt solution immersion and salt spray were performed. The chloride contents in uncracked concrete specimens with different water-cement ratios, states and levels of stress, and environmental conditions are analyzed in this article. The results show that the resistance of concrete to chloride ion penetration can be improved by reducing the water-cement ratio. The content of chloride ions is higher in concrete stressed in tension than in unstressed concrete. For concrete stressed in compression, chloride content depends on stress level. Salt solution immersion is more severe than salt spray.

The subject of this paper is the compressive creep behavior of viscoelastic materials, such as high-density polyethylene (HDPE), commonly used to manufacture a multitude of civil engineering products, including polymeric piling, decking, and fender elements. Accelerated methods to predict the tensile creep of polymers are already available. The time-temperature superposition (TTS) model is the basis of several available methods, and one of its derivatives, the stepped isothermal method (SIM), is the basis for an ASTM standard for tensile creep. In this paper, both TTS and SIM have been adapted to study the time- and temperature-dependent compressive creep of HDPE. Experimental test results on virgin HDPE indicate that both TTS and SIM are applicable for predicting compressive creep with some limitations. Preliminary results indicate that the tested virgin HDPE loaded in compression is expected to creep by approximately 2% in 100 years when loaded to an ultimate stress of 2.8 MPa (400 psi) at room temperature (24°C).

A significant problem when dust-suppressing agents are used on gravel roads is that they tend to leach during rainfall. The purpose of this study is to illustrate this problem by using laboratory studies and studies in situ. Both capillary rise and leaching of suppressants were examined by using cylinders filled with wearing course material. Chloride was more prone than lignosulphonate to transport upwards by means of capillary rise, and therefore, it showed a more effective performance over a longer period of time. Optimal percentages of fine material for minimal lignosulphonate and chloride leaching were found to be 15% by weight and 10–15% by weight, respectively. Ions of calcium chloride seemed to flocculate clay particles, which probably prevents them from leaching. To study the in situ longevity of fine material in general, calcium carbonate, mesa, was used as a marker. The fine material in gravel wearing courses must be replenished regularly. Mesa loss was up to 80% after 1 year.

Load-transfer efficiency (LTE) of jointed concrete pavement is typically measured by the ratio of unloaded and loaded slab deflection. However, the maximum tensile stress in a slab is one of the critical mechanical responses that influences the performance of the jointed concrete pavement. Therefore, stress-based load-transfer efficiency, defined as stress reduction in the loaded slab because of the presence of an adjacent unloaded slab, is often considered an appropriate way to quantify LTE. Strain gauge data from full-scale tests collected by the Federal Aviation Administration were analyzed to compute the stress-based LTE of joints under moving loads. The effect of static aircraft gear loads and slab size on the LTE of joints was analyzed by using a two-dimensional finite-element program. FEM-calculated stress-based LTE under static aircraft loading on average was 38% lower than that measured under moving loads. LTE values were similar under various gear positions, gear configurations, and different slab sizes.

Water transport plays a critical role in the freeze-thaw (F-T) response of concrete. This work aims at appreciating various water transport parameters in roller-compacted concrete (RCC) for different pavement applications and correlating these with its F-T performance. The test variables include cement content (100 to $450\mathrm{kg}/{\mathrm{m}}^3$), water-to-cement ratio (w/c) (0.27–1.27), surface finish, and age of concrete. Measurements of concrete mixtures include sorptivity ($S$), desorptivity ($R$), surface inflow velocity ($u_0$), compressive strength, and F-T resistance. Indexes, including inflow velocity, are used to evaluate transport properties of different mixtures. Interaction diagrams are developed to characterize the relationships among sorptivity, desorptivity, w/c, compressive strength, and F-T durability. The results indicate that sorptivity of RCC is comparable to that of conventional concrete and that desorption behavior is linearly related to sorptivity. Surface finish has a definite impact on sorptivity, but its effect on desorptivity is negligible. Curing age refines concrete pore structure, increasing resistance to water ingress. These results provide a better understanding of transport properties of RCC and its influence on F-T resistance.

With the rising recognition of global climate change, the term ${\mathrm{CO}}_2$ emissions is now part of everyday language. The construction industry plays a significant role in economic growth both directly through its activities and indirectly through the provision of buildings and infrastructures for the smooth functioning of businesses. However, this industry is now highly challenged for its detrimental effect on carbon neutral by consuming materials and energy. Research has been conducted to estimate the embodied carbon of construction materials around the world, such as cement, aggregates, aluminum, and steel. These research findings provided fundamental support in estimating the embodied carbon of precast concrete products. This study investigates the production cycle and estimates the embodied carbon of precast concrete columns, which are typically adopted in the Singapore construction industry, where there is a large demand in public housing projects. The results indicate that 609.59 kg of ${\mathrm{CO}}_2$ is emitted in the production cycle of a specific type of precast concrete column. Knowing the embodied carbon of precast concrete columns, regulatory bodies are able to provide further recommendations toward sustainable construction. Research institutes can also benefit from this study to conduct further estimation of embodied carbon of other precast concrete products and finally complete the carbon inventory for the construction industry.

Conventional methods of measuring carbonation and chloride ingress exist, but they are either inaccurate, expensive, or involve destructive testing. In seeking new solutions to this problem, the potential to use novel fiber-optic chemical sensors developed specifically for this application and designed to monitor chemical changes in cementitious materials, in situ and nondestructively, was explored in this study. Three types of fiber-optic sensors were thus constructed, tested, and evaluated, viz a temperature sensor, a pH sensor, and chloride sensors. The temperature sensor was based on the fluorescence decay of temperature-dependent materials, whereas the pH and chloride sensors were based on sol-gel technology, with pH and chloride sensitive indicators impregnated in the sol-gels. All the sensors were tested in situ, and subsequently, the temperature and the pH sensors were embedded in mortar and tested. It was found that both the temperature sensor and the pH sensor could function correctly for over 18 months after placement, but there was an issue with alignment of the sensor each time it was reconnected to the hardware. However, the laboratory tests showed that the chloride sensor was not reversible, and therefore further refinement was considered to be necessary before it could be used in situ in environments where the chloride content was known, from other measurements, to decrease. Research is ongoing to refine the sensor performance and expands the in situ testing program. The sensors themselves are inexpensive to fabricate, but the sensing hardware used in this work is costly because of its high versatility.

Naturally occurring lightweight volcanic pumice aggregate was used for the development of structural lightweight concrete. The primary aim of the investigation was to reduce both the economic costs and the negative environmental effects that are typically associated with production of conventional lightweight concrete containing artificially produced aggregates by taking advantage of New Zealand’s abundant pumice resources. Mixture designs were developed for concrete containing both partially saturated and fully saturated pumice aggregates, achieving compressive strengths up to 40 MPa while maintaining unit weights below $1,850\mathrm{kg}/{\mathrm{m}}^3$. A vacuum saturation system was developed to completely saturate the normally partially saturated aggregates, which was necessary to avoid a loss of workability and to alleviate complications with mix-water calculations that occurred for concrete containing partially saturated pumice aggregates. Experimental investigations into the bond strength and shear strength of pumice concrete were also conducted. The results showed that the mixtures developed outperformed both the bond and shear strength requirements for structural lightweight concrete of the New Zealand Concrete Structures Standard NZS 3101:2006. The research presented demonstrates the effective and innovative use of New Zealand’s abundant resources of naturally occurring pumice aggregates for producing structural lightweight concretes that meet the requirements of New Zealand concrete structures standards.

This study reported an investigation on mechanical behavior of off-white marbles that were selected from a slope and underground cavern. The marble samples with weak structural planes were tested through the multistage loading shear rheological method. The results were used to evaluate the creep behavior of the weak structural planes. It was demonstrated from the obtained creep properties and creep rate characteristics of such structural planes under different normal stress conditions that the green schist weak structural planes showed obvious characteristics of brittle failure, and the shear-creep test curve of the structural plane exhibited three obvious stages. Established on the improved Burger model, a further discussion on the shear-creep mechanism was presented.

Cracks in cementitious materials can substantially increase fluid penetration. Fiber reinforcement can reduce the crack width in cementitious materials, thereby reducing fluid transport. Substantial research has been performed to better understand how fabric reinforcement can be used to improve the mechanical behavior of cement-based composites. As a result, the use of fabric reinforcement is being increasingly used in these applications. Fabric reinforcement is being increasingly selected based on the mechanical properties the fabric provides, but unfortunately, the influence of fabric reinforcement on fluid transport is less frequently considered in the fabric selection process. This paper attempts to provide experimental measurements that indicate the importance of fabric properties on fluid transport. This paper describes a series of experiments in which fluid transport was measured using X-ray radiography in cracked cement paste samples that were reinforced with different commercially available fabrics made with monofilament and multifilament yarns that were both coated and uncoated. Results show that fabrics made of multifilament yarns without coating may be problematic from a durability point of view. However, when multifilament yarns are coated, the fabric behaves as a monofilament system. The transport behavior was observed to be highly dependent on the quality of the coating. This should be considered in addition to mechanical performance in assessing the type of fabrics that should be used for a specific application.

The effects of four of the most common types of surface finish on the appearance of five varieties of ornamental granite, all widely used in building construction and selected for their different colors, were analyzed by means of roughness, color, and gloss measurements. The results demonstrated that different surface finishes produce differences in color, especially in the lightness parameter ($L^{*}$ ), and that the magnitude of these differences depends on the color of the ornamental granite and is greatest in dark colored rocks. However, the variation in the color parameters with the different surface finishes did not depend on roughness, and no general conclusions could be drawn regarding the influence of the roughness on the color of ornamental granite. Gloss values were affected by the color of the ornamental granite, but in a different way for smooth and rough surfaces. Variation in gloss also depended on the mineral composition of the rock. Gloss and roughness were inversely related, but only within the range of low roughness values. In addition, the color gamut of the studied ornamental granites was defined within the CIELAB color space. These results will contribute to providing a standardized, objective method of characterizing the color of granite that will be useful for different workers in the field of building construction.

There exists an effort to develop dosage methodologies for cement improved soils based on a rational criterion, as in concrete technology, in which the water to cement ratio plays an essential role in strength determination. This study aims to assess the strength controlling parameters of two clays with distinct coarse grained materials (silty clay and sandy clay) treated with cement and to show that the porosity/cement ratio plays a fundamental role in target strength assessment of clayey materials. The controlling parameters evaluated were the cement content, porosity, and porosity/cement ratio. A number of unconfined compression tests and suction measurements were performed for the present work. The results show that a linear function better fits the unconfined compressive strength-cement relationship. The strength increased exponentially with the reduction in porosity for the studied soil-cement mixtures. Finally, the porosity/cement ratio is shown to be a key parameter in an evaluation of the unconfined compressive strength of the clayey soils studied.

The paper presents the potential and effect of treated tire chips on the unconfined compressive strength in the reference mix containing fly ash, lime, and gypsum. Dry, sodium hydroxide–, and carbon tetrachloride–treated tire chips were used in the study. The tire chip content varied from 5 to 15%. The specimen prepared was cured for 7, 28, 90, and 180 days with three different curing methods (in a dessicator, burlap, and water-filled container). The results indicated that the unconfined compressive strength of the reference mix with dry tire chips can be increased by treatment with carbon tetrachloride and sodium hydroxide. The increase in unconfined compressive strength was highest with carbon tetrachloride treatment. The results further revealed that the increase in unconfined compressive strength was highest when cured in water-filled container, followed by burlap and dessicator. The unconfined compressive strength increased with curing period, and the increase was significant up to a curing period of 90 days. With the increase in tire chip content (5–5%) in the reference mix, there was a decrease in the unconfined compressive strength. This decrease in the unconfined compressive strength was highest when cured in water-filled container, followed by burlap and dessicator. The reference mix with treated tire chips may be used for road subbase with light traffic.