Journal of Materials in Civil Engineering

Palm oil fuel ash (POFA) cement-based aerated concrete is a new type of lightweight concrete produced by integrating POFA, a by product of palm oil mill as a partial cement replacement in aerated concrete. This paper presents the effects of using a different character of mixing constituent such as size of sand, various amounts of gas foaming agent, and a range of superplasticizer content on the compressive strength and density of aerated concrete with and without POFA. POFA passing $300\text{-}\mu \text{m}$ sieve was ground until its fineness is 99% passing $45\text{-}\mu \text{m}$ sieve was incorporated as partial cement replacement. POFA cement-based aerated concrete was prepared by adding 20% of POFA by weight of cementitious materials. It was discovered that POFA cement-based aerated concrete continues to exhibit higher strength compared to ordinary portland cement aerated concrete throughout the experimental program. Thus, this newly found material could be used as environmental friendly construction material since it possess adequate strength fulfilling the requirement in ASTM allowing it to be used as nonload-bearing element yet having lower density below $1,000\text{kg}/{\text{m}}^3$ .

Early age carbonation curing of slag-cement concrete was investigated to assess the feasibility of binding ${\text{CO}}_2$ in slag-cement building products while improving their short-term and long-term performances. Four binder types were compared: an ordinary portland cement; an 85/15 slag cement; a 75/25 slag blend; and a 50/50 slag blend. A 2-h carbonation-curing treatment allowed concretes to bind 8–10% ${\text{CO}}_2$ by mass of binder and attain as much as 82% of the 24-h hydration strength. The subsequent strength development of carbonated concrete was slower in the first 24 h possibly due to the carbonate buildup, but it was comparable to the conventionally hydrated concrete after 28 days. The carbonated concrete was shown to have a fracture toughness comparable to that of the hydrated concrete. The freeze/thaw durability of the concrete in deicing salt solution was vastly improved by the carbonation treatment. The pH of the carbonated concrete was reduced but was still above the threshold level required for the passivation of iron. The use of slag in carbonation curing is beneficial to strength gain, shrinkage reduction, and deicing salt resistance.

Wollastonite is abundantly available in Rajasthan, Tamil Nadu, Uttarakhand, and Andhra Pradesh states of the Indian Union as a low-cost material. In this study, investigations were made on pastes and mortars to evaluate its potential as a new material for admixing with ordinary portland cement with or without microsilica. Its physical and chemical properties were analyzed. Wollastonite consists of 45.6% of CaO and 48% of ${\text{SiO}}_2$ , mostly in amorphous form. It has an average specific surface area of $842.7{\text{m}}^2/\text{kg}$ and retention on 45-micron sieve of 3.20%. When ground to fine powder, it attains an average particle size of 4 microns which is about 4.5 times finer than ordinary portland cement. Scanning electron microscope images show that wollastonite particles were solid, acicular in shape, and have rough surfaces. Several cementitious mix proportions of ordinary portland cement, wollastonite, and microsilica were investigated for normal consistency, initial and final setting time of paste, and compressive strength of mortar. Test results indicate that the mortar, which contains 82.5% cement, 10% wollastonite, and 7.5% microsilica, as cementitious material attains the highest compressive strength. The mortar, which contains 77.5% cement, 15% wollastonite, and 7.5% microsilica, as cementitious material achieves compressive strength higher than the conventional OPC mortar along with rendering maximum cement replacement for better economy of concrete work. It was observed that the compressive strength of mortar varied logarithmically with the days of moist curing and linearly with the proportion of admixing. Suitable predictive models are presented accordingly.

Concrete structures that are damaged due to cracking and spalling, associated with corrosion of reinforcing bars, are often repaired using shallow depth surface patches. Cracking and full or partial delamination of the patch repairs due to shrinkage and continued corrosion is generally unavoidable. The repair typically lasts only for a few years in corrosive environments associated with coastal regions or the use of deicing salts. To provide more durable patch repairs, the use of a fiber-reinforced polymer (FRP) fabric applied as an overlay on top of a traditional polymer concrete patching material was investigated. The FRP overlay can serve as a secondary reinforcement and act as a barrier against the diffusion of moisture and chloride ions, thereby improving the performance of the patch by reducing cracking and slowing down the corrosion process. Two-dimensional finite-element analysis was used to select a suitable FRP material and configuration for the overlay. The effectiveness of the proposed improved repair method was assessed using accelerated corrosion testing of rectangular concrete prism specimens with a polymer concrete patch and an FRP overlay. Reinforcement mass loss and expansive strains in concrete due to corrosion were measured on specimens with and without the FRP overlay. The measurements indicated reductions in concrete strains, crack propagation, and corrosion level when the FRP overlay was used. Three-dimensional finite-element analysis was conducted to understand the influence of using an FRP overlay on the concrete stress distribution and the arrest of cracking.

In this study, rubber-sand particle mixtures are investigated to understand their stress-deformation and elastic modulus characteristics. Specimens are prepared with various size ratios, sr $\left(=D_{\text{rubber}}/D_{\text{sand}}\right)$ , between sand and rubber particles, and different volumetric sand fractions, sf $\left(=V_{\text{sand}}/V_{\text{total}}\right)$ . Small strain shear waves are measured under a $K_o$ -loading condition incorporated with the stress-deformation test by using an oedometer cell with bender elements. The stress-deformation and small strain shear-wave characteristics of rigid-soft particle mixtures show the transition from a rigid particle behavior regime to a soft particle behavior regime under a fixed size ratio. A sudden rise of the $\Lambda$ factor and the maximum value of the $\zeta$ exponent in $G_{\text{max}}=\Lambda {\left({\sigma }_o^{\prime }/\text{kPa}\right)}^{\zeta }$ is observed at $\text{sf}\approx 0.4–0.6$ regardless of the size ratio (sr). The transition mixture shows a high sensitivity to the confining stress. The volume fraction for the minimum porosity may depend on the applied stress level in the rigid-soft particle mixtures because the soft rubber particles easily distort under load. In this experimental study, the size ratio and volumetric sand fraction are the important factors which determine the behavior of rigid and soft particle mixtures.

There is an increasing need to identify the effect of mix composition on the rheological properties of cementitious grouts using minislump, Marsh cone, cohesion plate, washout test, and cubes to determine the fluidity, the cohesion, and other mechanical properties of grouting applications. Mixture proportioning involves the tailoring of several parameters to achieve adequate fluidity, cohesion, washout resistance and compressive strength. This paper proposes a statistical design approach using a composite fractional factorial design which was carried out to model the influence of key parameters on the performance of cement grouts. The responses relate to performance included minislump, flow time using Marsh cone, cohesion measured by Lombardi plate meter, washout mass loss and compressive strength at 3, 7, and 28 days. The statistical models are valid for mixtures with water-to-binder ratio of 0.37–0.53, 0.4–1.8% addition of high-range water reducer (HRWR) by mass of binder, 4–12% additive of silica fume as replacement of cement by mass, and 0.02–0.8% addition of viscosity modifying admixture (VMA) by mass of binder. The models enable the identification of underlying factors and interactions that influence the modeled responses of cement grout. The comparison between the predicted and measured responses indicated good accuracy of the established models to describe the effect of the independent variables on the fluidity, cohesion, washout resistance and the compressive strength. This paper demonstrates the usefulness of the models to better understand trade-offs between parameters. The multiparametric optimization is used to establish isoresponses for a desirability function for cement grout. An increase of HRWR led to an increase of fluidity and washout, a reduction in plate cohesion value, and a reduction in the Marsh cone time. An increase of VMA demonstrated a reduction of fluidity and the washout mass loss, and an increase of Marsh cone time and plate cohesion. Results indicate that the use of silica fume increased the cohesion plate and Marsh cone, and reduced the minislump. Additionally, the silica fume improved the compressive strength and the washout resistance.

Recycling of waste material is one of the effective solutions of its disposal problem. Fly ash produced by coal-based thermal power plants and phosphogypsum (PG) produced by fertilizer plants producing phosphoric acid as constituent of fertilizers, take huge disposal area and creates environmental problems. Stabilization/solidification of fly ash improves the engineering properties and reduces the environmental problem like leaching and dusting. This paper presents the laboratory test results of a Class F pond ash alone and stabilized with varying percentages of lime (4, 6, and 10%) and PG (0.5, and 1.0), to study the suitability of stabilized pond ash for road base and subbase construction. Standard and modified Proctor compaction tests have been conducted to reveal the compaction characteristics of the stabilized pond ash. Bearing ratio tests have been conducted on specimens, compacted at maximum dry density and optimum moisture content obtained from standard Proctor compaction tests, cured for 7, 28, and 45 days. Both unsoaked and soaked bearing ratio tests have been conducted. This paper highlights the influence of lime content, PG content, and curing period on the bearing ratio of stabilized pond ash. The empirical model has been developed to estimate the bearing ratio for the stabilized mixes through multiple regression analysis. Linear empirical relationship has been presented herein to estimate soaked bearing ratio from unsoaked bearing ratio of stabilized pond ash. The experimental results indicate that pond ash-lime-PG mixes have potential for applications as road base and subbase materials.

The objective of this contribution is to experimentally investigate whether self-compacting concrete (SCC), while in its fresh state, behaves differently compared to traditional concrete. To serve this cause several self-compacting and conventional concrete mixes of two strength classes are produced at the laboratory, and properties such as robustness, slump flow loss, and formwork pressure are assessed. All mixtures are designed for vertical casting into walls and tested accordingly. Special laboratory apparatus, such as tilting drum and forced paddle mixer, patterned laboratory pump, and pressure sensors are used for mixture production, material maintenance, and formworks casting to best simulate in situ conditions. Tests are also carried out in hardened concrete to assess mechanical properties as well as concrete durability at the age of 28 days.

This study was performed to define and evaluate specific mechanisms that control deicer scaling (freeze-thaw) resistance in slag cement concrete. Modified ASTM C672 procedures were used to measure the deicer scaling resistance of concrete made with grade 120 slag cement substituted for ordinary portland cement at equal mass replacement levels of 30 and 50%. Two types of coarse aggregate, two Type I portland cement brands, and several curing methods were studied. The effects of carbonation were found to be a main cause of reduced scaling resistance in slag cement concrete, as supported by trends among curing methods and by variations in the chemical composition of portland cement. For concrete cured under ambient and low-carbonation conditions, increased carbonation is correlated with an increase in the concrete’s scaling loss. These experimental results supported a proposed behavioral model linking cement hydration, concrete carbonation, and deicer scaling resistance. Decreased scaling resistance in concrete cured under moist conditions did not correlate with carbonation, but was likely caused by other factors related to continuous moisture present during curing.

Aggregates are the most widely used construction materials in the world in structures built from both asphaltic and portland cement concrete composites. The performance of these composites is affected by aggregate shape characteristics (e.g., angularity, texture, and dimensions). The aggregate imaging system (AIMS) is a computer automated system that was developed to measure aggregate shape characteristics using digital camera images of aggregates. This paper addresses four issues concerning AIMS measurements: (1) enhanced ways of handling and classifying the large data sets typically generated; (2) enhanced automation in processing fine aggregate images that appear to contain touching particles; (3) an improved consideration of measurement variability or repeatability between different operators, different AIMS units, and for aggregate placement and orientation; and (4) comparison of AIMS dimensional measurements with true three-dimensional measurements using X-ray computed tomography on a large coarse aggregate data set. The various aggregate sets used in this study covered a broad range of angularity and texture. The AIMS measurements of the ratios of dimensions were found to have excellent agreement with the more accurate X-ray computed tomography values, but the measurements of the individual dimensions were systematically low by about 10%.

The combined effect of moisture and mechanical loading on asphalt mixtures has been recognized as one of the main causes of premature deterioration of flexible pavements. This paper presents a micromechanical model of moisture-induced damage in asphalt mixtures. The model couples the effect of moisture diffusion and mechanical loading to quantify the level of damage within the mixtures. The mechanical properties of the materials are defined as a function of the amount of moisture content. The cohesive zone modeling technique is used to simulate adhesive damage at the aggregate-mastic interfaces. Damage is evaluated based on the location and time for crack initiation and propagation at the aggregate-mastic interfaces and on the level of strains and stresses within the bulk of the mastic. Results show that micromechanical models provide a better understanding of moisture damage mechanisms in asphalt mixtures and can guide the development of continuum damage models.

This research deals with the mechanical characterization of laminated glass beams (glass-interlayer-glass) subjected to bending, with the main purpose of evaluating the coupling that the interlayer is able to establish between the glass sheets; in fact, the interlayer provides the glass plies with the ability to work more or less jointly. Four-point-bending tests (constant load) were performed on glass beams laminated with different interlayer plastic sheets. Shear tests (constant load) were performed on laminated glass specimens to determine the viscosity properties of the interlayer, when laminated between glass sheets. The parameters of viscosity, determined by the shear tests, make it possible to reproduce the time-dependent behavior of the composite beam, both numerically and by means of a closed-form procedure. The experimental results were compared with those obtained with the theoretical model and with the numerical simulation. The comparison among the different polymer interlayers shows that they are able to influence differently the mechanical behavior of the laminated composite and that their performance degrades at different rates as a function of time.

Increasing the damping level is an important approach toward the rise of earthquake resistance capability of a structure. In this paper, the steel tube is filled with metal foam for increasing its damping level. A parameter identification method is developed for studying the contribution of different metal foams to the damping. Specimens of steel tubes of 1.2- and 2.4-mm wall thickness filled with open cell pure aluminum, close cell pure aluminum and close cell aluminum alloy are fabricated and experimentally studied with the developed parameter identification method. It is found from the experiment that under large excitation, the open cell pure aluminum foam and close cell aluminum alloy can increase the components’ damping level up to five times comparing with the steel tube itself.

This study investigates the effectiveness of metakaolin (MK) on the improvement of durability of concretes to sulfate attack. Experimental parameters of the study were MK replacement levels, water to cementitious materials ratio, initial curing procedure in terms of air curing and water curing, and type of the sulfate exposure regimes such as continuous and drying-immersion cyclic exposures. The degree of sulfate attack was evaluated by the reduction in compressive strength (CS) of concrete. The tests were conducted at specified periods up to 365 days. At the end of initial curing, concrete specimens were divided into three groups such that the first group was transferred into tap water to be used as control in the assessment of CS reduction while the other groups were immersed in 10% ${\text{Na}}_2{\text{SO}}_4$ solution for the period of 365 days under continuous or cyclic exposures. The results indicated that inclusion of MK as modifying agent increased the resistance of concrete against sulfate attack depending mainly on the MK replacement level, w/cm ratio, and initial curing procedure adopted.

Thermal conductivity measurement is a quick and easy test for compacted soils. This study presents the results of thermal conductivity testing on silt compacted under standard and modified Proctor efforts. A comparison of moisture content measurements from both lab oven and field oven is also presented and discussed. Measured thermal conductivity was correlated to the bulk density and water content. It is further correlated to Young’s modulus and Shear modulus of the compacted silt, which were determined through ultrasonic pulse velocity measurements. Several trends were observed which may be used to correlate soil thermal conductivity of the compacted silt to compaction and elastic moduli for quality control/quality assurance of compacted soil.