Journal of Materials in Civil Engineering

The present study is focused on evaluating the effect of hydrated lime content on the moisture susceptibility of polymerized stone matrix asphalt (SMA) mixtures by using moist aggregates and three different warm-mix asphalt (WMA) additives. Indirect tensile strength (ITS), tensile strength ratio (TSR), deformation, and toughness were tested to determine the moisture sensitivity of these mixtures. The experimental design included aggregate moisture content ($\sim 0.5\%$ by weight of dry mass of the aggregate), two aggregate sources (B and C), two hydrated lime contents (1% and 2% by weight of aggregate), three WMA additives (Asphamin, Sasobit, and Evotherm) along with control mixture, and four different types of binders [i.e., PG 64-22 + 10% crumb rubber (CR) (minus #40 mesh), PG 64-22 + 15% CR, PG 64-22 + 20% CR, and PG 76-22 + fibers] were used in this study. A total of 256 samples were utilized for the ITS testing. In general, except for the mixture with 10% CR using Evotherm, all other mixtures containing WMA additives met the minimum wet ITS requirement of 448 kPa as per South Carolina DOT (SCDOT) specifications. Test results indicated that 24 mixtures failed to meet the minimum TSR requirement of 85%. Test results showed that by increasing the lime content to 2%, a majority of the mixtures containing WMA showed improvement in the TSR values.

This paper discusses the results of an experimental study conducted on ASTM Grade 420(60) mild steel reinforcement at varying temperatures and strain rates to aid in the design of structures that experience seasonal freezing. The test data for this study were collected by performing monotonic testing of standard reinforcement samples at 20°C (68°F), 5°C (41°F), $-1°\mathrm{C}$ (30.2°F), $-20°\mathrm{C}$ ($-4°\mathrm{F}$), and $-40°\mathrm{C}$ ($-40°\mathrm{F}$) in an environmental chamber that maintained the desired temperature throughout testing. In addition, the response of samples subjected to different strain rates were examined at $-1°\mathrm{C}$ (30.2°F) and $-20°\mathrm{C}$ ($-4°\mathrm{F}$). The effect of cold temperature and/or strain rate on the following key parameters, used to define the stress-strain behavior of the reinforcing steel, was examined: yield strength, elastic modulus, onset of strain hardening, ultimate tensile strength, and ultimate tensile strain. The study revealed that the yield and ultimate tensile strengths increase moderately as the temperature decreases and the strain rate increases. The strength increases associated with low temperature occurred even before reaching 0°C (32°F), confirming that the change in behavior of reinforcing steel is gradual. The elastic modulus and ultimate strain, however, were largely unaffected by both cold temperature and strain rate.

Durability is one of the most important considerations regarding the design of new concrete structures in aggressive environments. Thaumasite sulfate attack (TSA) is one durability consideration. This paper reviews the features of TSA, factors affecting TSA, thaumasite formation mechanisms, and prevention measures. Finally, some needs for future studies are also suggested. TSA can completely destroy the cementitious binding ability of concrete by transforming it into a mush. Many factors affect thaumasite formation and TSA. The four primary factors affecting TSA on portland cement-based materials are low temperatures (below 15°C) and the presence of sulfates, carbonates, and moisture. Apparently, the dissolution–precipitation mechanism can be used to explain most phenomena during TSA. A procedure for field studies is also proposed. Both material compositions and surrounding environments should be considered for the prevention of TSA in concrete structures.

In rigid-framed railway bridges, because of excessive amounts of rebar in beams and columns, overcongestion at the beam-column joints of rigid-framed railway bridges was investigated in this paper. The experiments were conducted on eight one-sixth scaled specimens that include four T-joint and four knee-joint specimens. In the control specimens, the amount of steel rebars and their arrangements and detailings resembled the as-built configuration of the rigid-framed railway bridge in Japan. In the other specimens, the amount of steel rebars was reduced and steel fibers were varied as 0, 1.0, and 1.5% by volume. The experimental results of the specimens were compared in terms of crack patterns, load-displacement relationships, ductility, energy dissipation capacity, and stiffness degradation and found that the performance of the control specimens and specimens with 1.5% of steel fibers and reduced steel rebars was comparable.

This paper presents studies on the properties of fresh and hardened semilightweight self-consolidating concrete (SLWSCC) mixtures, produced with two types of manufactured coarse lightweight aggregates (LWA) and normal weight sand. The first type, a sintered pulverized fuel ash, was made from an industrial by-product, fly ash, whereas the second one, an expanded clay, was produced from a naturally sourced clay. For all mixtures, normal weight sand was used as a fine fraction of aggregates, and the portland cement was partially replaced with a limestone powder. The SLWSCC was produced with different water presaturation regimes of the LWAs. The desired initial slump-flow spread was set between 700 and 800 mm. The effect of three superplasticizers was evaluated by testing properties of SLWSCC, normal weight SCC, and paste mixtures. Three SCC fresh properties were measured: the slump-flow, the V-funnel flow time, and the J-ring blocking step. Moreover, the slump-flow loss was evaluated. The degree of segregation was assessed in both fresh and hardened states. Additionally, the hardened density and the compressive strengths were tested. All SLWSCC mixtures were produced with a desired range of slump-flow spread and with satisfactory passing ability assessed with the J-ring test. SLWSCCs prepared with the expanded clay LWA were less sensitive to the variation of water presaturation levels and showed lower viscosity than those made with the sintered pulverized fuel ash LWA. Only mixtures containing SP-3 superplasticizer showed acceptable workability loss resistance. The saturated surface-dry density of all of the mixtures varied in a range of $2,025\text{–}2,125\mathrm{kg}/{\mathrm{m}}^3$. Mixtures containing 29% of coarse LWAs and 71% of sand (by mass) had 24-h and 28-day compressive strengths above 20 and 40 MPa, respectively, but the mixtures made with the expanded clay were slightly weaker.

Considerable advantages could be achieved if the cold bituminous emulsion mixtures (CBEMs) show comparable engineering properties to hot-mix asphalt (HMA), particularly because CBEMs require no heat within the manufacture and laying process. As a result, such pavement produces less environmental impact, is more cost effective, and requires less energy consumption. This paper focuses on upgrading the CBEMs to a stage whereby their mechanical properties are comparable to traditional HMA. Waste or by-product materials were used within the CBEMs to improve the mechanical properties, namely indirect tensile stiffness modulus and creep stiffness. Five percentages from 0 to 5.5% of aggregate mass in the mixture of the LJMU-FA1 that is waste or by-product material was incorporated in the CBEMs. The results have illustrated a comparative enhancement in the mechanical properties of the new cold mixtures attributable to the use of the specific waste materials. Thus, new CBEMs having superior mechanical properties compared with the traditional HMA were developed.

This paper presents results of experimental and numerical modeling of ductile fracture and failure of elements made of S235JR steel subjected to static tension. The prediction of failure was generally based on the stress modified critical strain (SMCS) model. The numerical simulations were performed using the Gurson-Tvergaard-Needleman (GTN) model, which takes into consideration the material structure. The approach applied in this study was based on the computational cells with microstructurally based length scales. The cell size and initial porosity were determined through microstructural examinations of S235JR steel. The parameters of the GTN model for S235JR steel were established on the basis of the microstructural analysis and the numerical modeling of tensile strength tests. As a result, it was possible to determine the SMCS failure criterion to predict ductile fracture for S235JR steel.

Concrete design codes include equations to estimate the modulus of rupture (MOR), modulus of elasticity (MOE), and splitting tensile strength (STS) of concrete based on the compressive strength. These equations have been developed based on data from normal strength conventional concrete (CC). Precast/prestressed concrete plants require that the concrete used to fabricate their structural members attain high early strength (HES). Plant conditions lend themselves to the use of self-consolidating concrete (SCC) and HES SCC could be an economical option for use under these conditions. However, limited work has been documented to determine if SCC can achieve high early strengths and limited work has been reported to determine if standard design equations are applicable for HES SCC. SCC is proportioned to achieve good flow while maintaining a homogeneous structure. To achieve this, SCC typically has to have higher paste and lower coarse aggregate volumes than CC. These conditions and the addition of newer chemical admixtures and supplementary cementitious materials (SCMs) could result in the mechanical properties of the SCC being different from those of CC. This research investigated the correlations between the compressive strength and the MOE, MOR, and STS. Results indicate that existing equations in the American Concrete Institute (ACI) and the AASHTO load and resistance factor design specifications can be used to estimate the MOE and STS of HES SCC. However, the applicability of AASHTO lower and upper bound MOR expressions depends on the influence of the compressive strength on measured to predicted MOR values. AASHTO lower and upper bound MOR expressions are considered appropriate design equations for SCC mixtures with measured compressive strengths ranging from 55 to 76 MPa (8 to 11 ksi). Equations developed in this research can be used for similar HES SCC mixtures with compressive strengths ranging from approximately 34 to 110 MPa (5 to 16 ksi).

The displacements produced by imposed deformations in buildings are usually compensated for with expansion joints. A field study was conducted in an underground parking facility with large jointless modules to measure the effects of shrinkage and temperature. The advantage of on-site measurements is the possibility to capture the combined effects of different imposed deformations that are usually studied individually in laboratory experiments. This article describes the instrumentation and monitoring procedures, displays and analyzes the registered data, and discusses the obtained results. Ambient and structural temperatures as well as displacements were recorded. Measuring commenced during the initial construction phase and was maintained throughout a period of five years. The measured longitudinal displacements were exclusively caused by shrinkage and temperature, and these displacements were not hindered by structural monolithicity.

The interaction parameter K.Ziegel-B was used as an evaluation index to characterize asphalt-aggregate filler interactions. In this study of asphalt-aggregate filler interactions, the rheological properties of asphalt mastics using two kinds of asphalts and four kinds of aggregate powder under different filler concentrations were measured by a dynamic shear rheometer, the internal influence factors of asphalt-aggregate filler interactions were analyzed, and the significance of influence factors were sorted by using the variance analysis method. The research shows that filler concentration, asphalt components, silica content, and particle size of aggregate powder all have a certain regularity effect on asphalt-aggregate filler interactions. The variance analysis method reveals the contribution order of various influence factors on interactions, the contribution order from high to low are colloid and asphaltene, particle size of aggregate, silica content and filler concentration.

New eco-friendly materials for soil improvement have been developed recently for construction purposes in civil engineering. An organic acid material encourages microbe proliferation over time and accelerates consolidation by biochemical penetration; soil particles are compacted by microbes and pore water is dissipated quickly. However, the effectiveness of organic acid has not yet been established. To investigate the strength characteristics of soil mixed with an organic acid, unconfined compressive strength tests were performed after aging soil samples with and without the organic acid. After 96 days of aging, the strength was generally 1.5–2.5 times greater than that without the organic acid. The pore structure of the soils was observed to change in a scanning electron microscopy analysis, and the change of total bacterial counts revealed the activity of microbes that reflects the strength characteristics. Moreover, this material is likely to be environmentally friendly according to the pH test.