Journal of Materials in Civil Engineering

The effects of various amounts of organic montmorillonite (OMt) on the morphology and physical properties of bitumen before and after ultraviolet (UV) aging were investigated. The microstructures of OMt modified bitumens were characterized by X-ray diffraction (XRD) analysis. The morphology of the binders was analyzed by atomic force microscopy. According to the XRD results, OMt modified bitumens form an intercalated nanostructure. As a result of UV aging, OMt modified bitumens show lower viscosity aging index and softening point increments than unmodified bitumens, which are further decreased by increasing the OMt content, indicating the satisfactory UV aging resistance of OMt modified bitumen. However, the softening point increments and viscosity aging index decrease slowly when OMt content increases above 6% by weight. UV aging significantly influences the morphology of bitumen. The contrast between the matrix and dispersed domains is decreased and a single-phase trend occurs in the bitumen during UV aging. However, these changes can be prevented effectively with the addition of OMt. The influence of OMt on the morphology of bitumen before and after UV aging depends on its content. According to the results of physical properties and morphology analysis before and after UV aging, the recommended content of OMt is 6% by weight.

The performance properties of rubberized asphalt binders at high, intermediate, and low temperatures were evaluated as a function of Fischer–Tropsch (FT)–paraffin wax content. The rubberized binders were blended using five different wax content levels (0, 1.5, 2.5, 3.5, and 4.5% by binder weight) to produce warm rubberized binders. They were then artificially aged over the short term and long term through the rolling thin film oven (RTFO) and pressure aging vessel (PAV) procedures. Superpave binder tests were performed with the rotational viscometer, the dynamic shear rheometer (DSR), and the bending beam rheometer (BBR). In general, the results of this study suggested that (1) the viscosity of rubberized binders at 135°C can be reduced by the addition of a wax additive, as expected; (2) the rubberized binders with higher wax content can result in binder performance that meets current Superpave binder requirements, especially for cracking resistance parameters (i.e., ${\mathrm{G}}^{*}\sin \delta$ and stiffness); and (3) the wax content can be increased up to 3.5% for the rubberized binders, resulting in more temperature reduction for mixing and compaction.

The paper is focused on the comparison between uniaxial and biaxial laboratory test results for polyester coated fabric. A short literature review concerning coated woven fabrics with emphasis on biaxial tensile tests is presented. A description of the polyester-coated fabric under biaxial test by means of constitutive models and material parameter values is proposed. To establish the right values of the ultimate tensile strength, flat and curved grips are tested.

This paper describes the findings of the experimental works undertaken to investigate the performance of zinc-rich paint (ZRP) to provide cathodic protection to chloride-contaminated RC structures. The program of experimental works was designed and conducted to assess four principal properties, viz (1) conductivity, (2) adhesion with concrete (short term and long term), (3) durability, and (4) electrochemical polarization. These properties considered together define the ability and effectiveness of the materials to act as an anode for impressed current cathodic protection. The research findings indicated that a specific proprietary ZRP product showed that optimum conductance was obtained with three coats producing a 280–320 μm thickness, with good adhesion to the concrete substrate, in which values obtained ranged between 1.65 and 3.5 MPa with and without applied current. It was capable of withstanding/supporting high levels of current, i.e., more than $300\mathrm{mA}/{\mathrm{m}}^2$, and the service life of the ZRP coating was estimated to be well in excess of 20 years at an applied current density of $10\mathrm{mA}/{\mathrm{m}}^2$.

The primary objective of well cementing is zonal isolation, which needs to be met by an appropriate cementitious material that can withstand high temperature and pressures. In this paper, the thermal stability of class G oil well cement (G-OWC) paste is evaluated in terms of the change in compressive strength, volume, and microstructure after heat treatment. The results show that the thermal exposure up to 200°C did not have a significant effect on the strength and volume of the samples. The cement paste experienced substantial strength loss and shrinkage between 200 and 1,000°C. After heating up to 1,000°C, only 6.3% compressive strength was left for the sample. The drastic thermal damage is attributed primarily to the evaporation of chemical bound water and decomposition of hydration products in the cement paste as the temperature increases to 440°C. The transformation of C-S-H gel to larnite ($\beta \text{-}{\mathrm{C}}_2\mathrm{S}$) after exposure to 650°C and the decarbonation of calcite after exposure to 850°C also induces degradation in the structure of G-OWC paste. This study indicates that the G-OWC may be used in the viscous crude oil cementing with service temperature below 200°C.

Fiber-reinforced concrete (FRC) has become a viable new material used in various constructions such as building pavements, large industrial floors, and runways. In this research, basalt chopped fibers in filament form were used to develop an FRC material called basalt fiber-reinforced concrete (BFRC) to study the possible improvement in the 28-day compressive strength and modulus of rupture, though the latter one is more important for the construction of pavements, industrial floors, and runways. The basalt fiber specimens were cast using basalt filament fibers of three different lengths and three different amounts. Clumping of fibers at high fiber amounts caused mixing and casting problems. These problems become even more severe when long fibers are used at the high fiber dosage amount. The results indicated that 36-mm-long chopped basalt filament fiber and a fiber amount of $8\mathrm{kg}/{\mathrm{m}}^3$ are optimum for achieving high performance in both the compressive strength and modulus of rupture. This paper discusses the test matrix and test results obtained from various BFRC and plain concrete specimens.

The quality of compaction significantly influences the performance of asphalt mixtures. Insufficient compaction often leads to excessive premature permanent deformation, excessive aging, and/or moisture damage. The research reported in this paper was aimed at developing a prediction model for laboratory compaction of asphalt mixtures. The model was developed based on extensive laboratory measurements and it includes parameters that describe aggregate shape characteristics, aggregate gradation, and binder content. The results show that the asphalt mixture type, aggregate properties, and binder content have a significant effect on the slope and intercept values of the laboratory compaction curves. Two models that describe both the slope and intercept of the laboratory compaction curves of asphalt mixtures are presented. These models provide valuable inputs that can be used to quantify the compaction effort needed to compact asphalt mixtures in the laboratory and correlate this effort to field compaction requirements.

The main objective of the research study described herein is to build two analytical models based on artificial neural networks (ANNs) and the statistical mixture design (SMD) method to predict the required performance of ultra-high-performance concrete (UHPC). Two different curing conditions—heat treatment and water storage—were applied to the specimens. To train the neural network, a total set of 53 different mixtures was designed based on the design matrix of SMD. The statistical analysis results showed the adequacy of both models to predict the required performance of UHPC; however, the ANN model could predict the compressive strength (water storage) and slump flow with higher accuracy than the SMD. The optimum combination of the cement, silica fume, and quartz flour was determined to be 24, 9, and 5% by total volume to achieve a flowable mixture with the highest compressive strength. The accuracy of the model was verified with additional experimental tests.

This paper presents a systematic series of tests and analysis on the mechanical properties of membrane structures under static loading. First, the uniaxial and biaxial tests are conducted to study the mechanical properties of coated fabrics under different loading protocols. Then, the model experiments are carried out to evaluate the mechanical behaviors of membrane structures under uniform loading. Finally, the finite-element analysis is conducted to compare with the experiment results. Results show that with proper processed, the strength of double-layer membrane can achieve 1.8 times that of single-layer membrane. The loading history has significant effects on the mechanical properties of coated fabrics. The numerical results using the elastic constants of the material without initial loading are relatively compatible with the experiment data. Besides, slightly differences are still observed between the load-deflection curves of experiment results and numerical calculation. This is because the mechanical behaviors of experiment models contain both the geometric and material nonlinearity, while the material nonlinearity is ignored in the numerical calculation.

In this study, cement was partially replaced with a Class-F fly ash (FA) at a level of 70% to produce high-volume fly ash (HVFA) concrete (F70). The F70 was modified by partially replacing the FA with an equal combination of silica fume (SF) and slag at levels of 10 and 20% by weight. All HVFA concrete types were compared to plain portland cement (PC) concrete. After curing, the specimens were exposed to elevated temperatures ranging from 400 to 1,000°C with an interval of 200°C. Weight and compressive strength before and after firing were thoroughly explored. The various decomposition phases were identified using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicated a higher relative strength of all HVFA concrete types. The F70 exhibiting the highest relative strength. The 10% $\mathrm{SF}+10\%$ slag blend exhibited good fire performance followed by the 5% $\mathrm{SF}+5\%$ slag blend up to 600°C; then severe degradation in residual strength was observed at 800 and 1,000°C.

The research reported in this paper investigates the coefficient of thermal contraction (CTE) and coefficient of thermal expansion (CTE) of asphalt concrete (AC) under different conditions in the laboratory. As a first step, the CTC and the CTE of AC at different temperatures ranging between $-20$ and 55°C were measured using field samples to examine the temperature effect. Then, the difference in the CTC and the CTE values in the vertical and horizontal directions (cross anisotropy) were evaluated using field samples. The influences of air void (AV), aggregate type, and aggregate gradation on the CTC and the CTE values were also investigated using laboratory prepared SuperPave gyratory samples. The deformation measuring devices, LVDTs, were calibrated using a zerodur to eliminate the temperature effect on the LVDTs. Results show that the CTC and the CTE values of AC are nonlinear with temperature and vary with aggregate type. However, gradation of aggregate and AV of sample do not affect the CTC and the CTE values significantly. The findings of this paper are highly expected to be useful in calculating the temperature-induced stress in AC using any design/analysis tool.

Synthetic polymer fluids are becoming a popular replacement for bentonite slurries to support excavations for deep foundation elements. However, the rheological properties of the polymer fluids used in excavation support have not been studied in detail, and there is currently confusion about the choice of mathematical models for this type of fluid. To advance the current state of knowledge, a laboratory study has been performed to investigate the steady-shear viscosity and transient viscoelasticity of a polymer support fluid. It is found that over the shear-rate range measurable with the Fann viscometer, an industry standard instrument, the power-law model can be used to represent the results, whereas the Bingham plastic model will significantly overestimate the viscosity at low shear. When evaluated over a much wider shear-rate range with a cone-and-plate rheometer, the polymer fluids show signs of approaching limiting viscosities at the very low and high shear rates, and for this behavior the Carreau model is more appropriate. From a series of oscillatory tests, the viscoelastic properties of the polymer fluid have been shown to be very different from those reported for their bentonite counterparts. The key engineering implications of the rheological results have been discussed.

The effect of mixture composition and coarse aggregate density on the shear strength and cracking behavior of self-consolidating concrete (SCC) beams are presented in this study. The experimental test parameters included coarse/fine ($\mathrm{C}/\mathrm{F}$) aggregate ratio (ranging from 0.7 to 1.2), coarse aggregate size (10 and 20 mm), coarse aggregate type/density (slag, expanded slate, and crushed stone), and varying compressive strengths (26–72 MPa). The density of the tested mixtures varied from 1,848 to $\mathrm{2,286}{\mathrm{kg}/\mathrm{m}}^3$. The study investigates the fresh properties of all tested mixtures and the shear strength and cracking behavior of 16 full-scale concrete beams. Based on some selected design codes, the ultimate shear strength of the tested beams is also predicted. The results showed that SCC mixtures with a higher $\mathrm{C}/\mathrm{F}$ ratio or bigger normal-weight aggregate had better flowability and less high range water reducer admixtures (HRWRA) demand. Although all tested beams showed comparable normalized shear strength, beams with a high $\mathrm{C}/\mathrm{F}$ ratio or bigger normal-weight aggregate had higher postdiagonal cracking resistance. The results also showed that the expanded slate and slag lightweight aggregates were found to be relatively strong (compared to most common lightweight aggregates) as they did not entirely break along the diagonal crack. Increasing the volume of these lightweight aggregates in SCC mixtures not only reduced the mixture density but also enhanced the postdiagonal cracking resistance.

Open graded friction course (OGFC) is effective in improving the surface function of asphalt pavements. However, it is prone to clogging including deformation-related and particle-related clogging. The aim of the research reported in this paper is to investigate the permeability loss or reduction due to deformation-related clogging and explore the critical size of solid particles attributed to OGFC particle-related clogging. A special falling head permeameter was developed with consideration of both rainwater flowing procedure and the pavement transversal slope. Eight types of OGFC mixtures with different air void contents, gradations, and nominal maximum aggregate sizes were prepared for deformation-related clogging evaluation. Wheel rutting tests were conducted on the OGFC samples with different loading times under two load levels [(1) 700 kPa, and (2) 900 kPa] at 45 and 60°C, and next were permeability tests using the developed permeameter. Permeability loss after different wheel loading times were calculated to explore the effects of the initial air void content, nominal maximum aggregate size, temperature, and loading pressure on deformation-related clogging. Furthermore, seven types of suspension liquids were prepared for particle-related clogging evaluation. For each suspension liquid, the proportions of solids trapped in OGFC air void, passing OGFC sample, and retained on the sample surface were calculated after permeability tests to determine the critical sizes of particle attributed to particle-related clogging. Results show that with the increase in wheel loading times, the permeability of OGFC mixture shows a steady decrease after a sharp initial decline. Permeability loss due to deformation-related clogging can be reduced effectively by using larger nominal maximum aggregate size and larger air voids. Values of 0.15–0.3 and 1.18–2.36 mm are the critical sizes of trapped particles in OGFC mixtures.

Recycled aggregate concrete (RAC) has attracted tremendous attention from engineering practice and academic research throughout the world as an effective way to resolve the problems caused by the construction and demolition waste. It is generally accepted that RAC consists of five phases [(1) natural aggregate, (2) old interfacial transition zone (ITZ), (3) old hydrated cement paste, (4) new interfacial transition zone, and (5) new hydrated cement paste], among which the interfacial transition zones are of great significance to the behavior of RAC, due to their characterizations as the weakest links in the concrete mixture. It has been recognized that the shape of aggregates plays an important role in the mechanical behavior of concrete. However, there is very limited information about the shape effect of aggregates on the behavior of the ITZs in RAC. A mesoscale model of RAC is employed in the research reported in this paper to investigate the mechanical behavior of the ITZs under uniaxial compression with differently shaped aggregates. Large stress concentration factors (SCF) have been found at the morphological transitions of the aggregate. A comparison between the distributions of SCF along the ITZs indicates that the shape of aggregates has a more pronounced influence on the stress distribution along the old ITZ than that along the new ITZ, which may be due to the old hydrated cement paste attenuating the shape effect of aggregates on the new ITZ. A quadratic polynomial equation can be curve-fitted to characterize the relationship between the maximum SCF along the ITZs and the fractal dimensions of aggregates.

Cement-emulsified asphalt mortar (CAM) is a critically important engineering material for a slab ballastless track. Segregation, which results in a density difference between the upper and lower part of the hardened CAM, is the most important factor that affects construction quality in practice. With the aim of decreasing the segregation of CAM, a minute amount of associative thickener, in which the mass ratio of the thickener to emulsified asphalt was 0, 0.2, 0.4, 0.6, 0.8, and 1.0%, respectively, has been incorporated into CAM, and the effects were systematically studied in terms of rheological behavior, segregation, microstructure, and construction quality of CAM. The results showed that the segregation resistance of hardened CAM was dramatically improved by increasing the thickener, whereas the rheological behavior characterized by the workability and fluidity indexes was prone to worsen. Considering the technical and economic aspects, an optimum mass ratio of the associative thickener to emulsified asphalt of 0.4% was recommended. Simultaneously, the microstructure analysis indicated the proper amount of thickener takes an active role in the compacting matrix and in refining the pores of the hardened CAM. Furthermore, in the practical application, the thickener could increase both the surface hardness and homogeneity of CAM.

A state-of-the-art review of simple analytical fracture mechanics models for calculation of the splitting capacity of timber beams loaded perpendicular to the grain direction by connections is presented. It is shown that most of the already available models are closely related and appear naturally as special cases of the most general model available. A new model, which is a semiempirical extension of an existing model based on a beam-on-elastic-foundation theory, is proposed. The so-called van der Put model, which forms the theoretical basis for the splitting equations used in the European and Canadian timber design codes, appears as a special case of the proposed model. The treatment of the splitting problem in some major timber design codes is reviewed and discussed based on the theoretical models and new test results. The approach used in the European timber design code where the maximum shear force on either side of a connection is considered rather than the total load applied on a connection is not in agreement with the test results presented. While the European and Canadian timber design codes apply a constant value for a material property related to the splitting performance irrespective of the material considered, the presented experimental results indicate that the material property for Radiata pine laminated veneer lumber can be close to twice the value for Douglas fir glulam. The presented test results also show that despite the fact that Douglas fir glulam has a significantly higher mean perpendicular-to-grain tensile strength than Radiata pine laminated veneer lumber, the splitting failure load of Radiata pine laminated veneer lumber is nevertheless significantly higher than that of Douglas fir glulam. The latter finding seems to be in disagreement with the German timber design code, according to which the splitting strength is proportional to the perpendicular-to-grain tensile strength.

Based on an extensive testing program, this study presents the mechanical behavior of a lightweight expanded clay aggregate (LWA). This material is currently being used in many civil engineering works and particularly in geotechnical applications due to its low weight, high shear strength, and favorable drainage characteristics. The present investigation is based on a particulate mechanics approach aimed at the quantification of appropriate model parameters in order to describe the material’s mechanical performance. The first part of the study concentrates on the determination of the physical and mechanical properties of the particles themselves. Relevant hydro-mechanical aspects of the particulate material are investigated. The second part focuses on the mechanical behavior of the aggregates. Using the compaction characteristics and stress ranges prescribed by the product manufacturer, a series of laboratory tests was performed on materials with two different grain-size distributions and water content conditions. The results obtained in the first part contributed to the determination of a phenomenological interpretation of the mechanical behavior of the aggregate. Finally, the quantification of nonlinear stiffness, internal friction angle, and its dependency on normal effective stresses and $K_0$ for the design of civil engineering works is presented. This research also offers relevant support for the development of constitutive models.

The performance of porous asphalt concrete (PAC) is dependent on its microscopic void features, which may refer to content and distribution of its constituents. In other words, PAC mixtures with identical air voids may have significantly different performances under given loading and environmental conditions. Air voids and their distributions are determined by aggregate gradation, nominal maximum aggregate size (NMAS), and binder content. Therefore, it is necessary to investigate the correlation among material composition, microscopic void features, and material performance. In this study, X-ray computed tomography (CT) images were obtained and analyzed to study microscopic void features of different PAC mixtures. Experimental tests were performed to study permeability, acoustic absorption coefficients, clogging, shear strengths, wheel tracking, and Cantabro loss of those PAC mixtures. The following findings were observed: (1) microscopic void features were significantly affected by gradation and NMAS; (2) for PAC mixtures with the same air content and NMAS, the coarser graded mixtures had the larger equivalent diameter of air voids; and (3) linear relationships were found between equivalent diameter and material performance, including Cantabro loss, dynamic stability, shear strength, anticlogging property, and noise reduction.

The cement paste attached to natural aggregates has a significant effect on the quality of recycled concrete aggregates (RCAs) because it usually has higher porosity and lower strength than natural aggregates. This work attempted to improve the quality of RCAs through carbonation of the attached cement paste. During carbonation reactions, ${\mathrm{CO}}_2$ reacted with $\mathrm{Ca}{(\mathrm{OH})}_2$ and calcium silicate hydrate ($\mathrm{C}─\mathrm{S}─\mathrm{H}$) to form ${\mathrm{CaCO}}_3$ and silica gel, which filled the pores in the attached cement paste. Thus, carbonation increased the density, and decreased the water absorption and crushing values of the RCAs. It, thus, increased the flowability and compressive strength and decreased drying shrinkage of the recycled aggregate mortars.

This paper evaluates the replacement of natural aggregate coarse fraction for recycled concrete aggregate (RCA) in hot mix asphalt (HMA) concrete production, an area in which studies are recent and scarce. Crushed stone coarse aggregates (CSCA) were replaced by RCA with a 30 MPa compressive strength in the following percentages: 0, 25, 50, 75, and 100%, and mixed with asphalt cement (AC) 50-70. Volumetric and mechanical properties resulting from the Marshall mix design method, along with permanent deformation and durability by the moisture-induced damage test (Lottman), were analyzed. The results indicate that, although RCA shows higher absorption, higher Los Angeles abrasion, and lower density than the crushed stone aggregates, the mixtures showed satisfactory results for use as an asphalt concrete surface layer on low-volume roads. Wheel tracking tests presented permanent deformations ranging between 4.4 and 9.3%. It was also perceived as an adhesiveness improvement in the RCA mixture. The results reinforce the need to seek alternatives to reduce the binder consumption when coarse RCA is used in HMA production.

This paper discusses the improvement expected in the service life of reinforced concrete (RC) structural elements subjected to chloride-rich environments through the use of blended cement. Comparisons are made between concretes with ordinary portland cement (OPC) and fly ash-based portland pozzolana cement (PPC) at three water-to-cement ratios ($w/c=0.57$, 0.47, and 0.37). Through a comprehensive experimental program, the apparent chloride diffusion coefficient ($D_c$) and corrosion current density ($i_{\text{corr}}$) were evaluated for these concretes. The study reveals that (1) although service life depends on both initiation and propagation periods, the propagation period is less significant when the severity of the environment is high; and (2) the service life of an RC structure can double if PPC is used instead of OPC when chloride-induced corrosion is critical.

Gravel deposits are materials that contain large particles. The mechanical behavior of such materials is conventionally examined using large-scale tests such as large-scale triaxial and in situ shear tests. However, the large-scale tests may not fully represent the gravel deposits in the field or cannot obtain the deformation parameters. This study estimated the elastic and shear-strength properties of gravel deposits using nonconventional methods. Field investigations at various locations were performed to obtain the material factors, including the gravel content, the diameter in the grain size distribution curve that corresponded to 50% finer ($D_{50}$), the unconfined compressive strength of the gravel, and the penetration strength of the matrix. Seismic-wave testing was conducted to obtain the elastic parameters at each location. Around each location, the critical slope profiles with greatest gradients or heights were back-calculated to obtain c-phi curves, of which the envelope represents the shear strength of the gravel deposit. The mechanical properties of the gravel deposits were correlated with the four material factors and P-wave velocity using regression analysis. The Young’s modulus was correlated with the P-wave velocity, the unconfined compressive strength of the gravel, and the penetration strength of the matrix. The cohesion of a gravel deposit was correlated with the penetration strength of the matrix. The Poisson’s ratio and the friction angle were correlated with the four material factors. The results were successfully tested using data on two gravel deposits at other locations. For the gravel deposits in central Taiwan, the unconfined compressive strength of the gravel and the penetration strength of the matrix significantly affect the elastic properties, and the penetration strength of the matrix controls the shear-strength properties. Although the proposed regression models serve as a preliminary evaluation of the elastic and shear-strength properties of the gravel deposits in central Taiwan, these nonconventional concepts are applicable to gravel deposits elsewhere.

This research focused on the stiffening effect of the filler on the asphalt mastic of microsurfacing. One challenge that researchers are faced with in the field of bituminous materials is the interaction between the filler and binder. In this study, a new conceptual model for filler stiffening of the mastic was developed that allows the asphalt mix designer to establish the minimum and maximum filler concentration to incorporate in the asphalt mixture. The proposed model has only one parameter that can be determined using the filler and asphalt emulsion selective properties, such as D10 and pH of the filler and the asphaltene content of the emulsion. A new mechanism for the stiffening effect of filler on mastic was developed based on the physicochemical interaction between filler and bitumen. Based on the model, the increase in mastic stiffness ($G^{*}$) as a function of the increase in filler concentration can be divided into three regions: diluted region, optimum concentration region, and concentrated region. A new property of filler, named zeta potential, was introduced to determine the stiffening effect of filler on mastic. The effectiveness of the proposed model to capture the true behavior of mastic was also investigated through the correlation between the complex modulus results of mastic and asphalt mix cohesion. Finally, the capability of the model to predict the complex modulus of a new set of filler-binder systems with different properties than those used to develop the model was evaluated. Using the proposed model, there is no need to test the mastic or asphalt mixture at different filler concentrations in order to select the optimum filler amount.

This study was carried out to compare the moisture resistance of two types of mixtures [i.e., hot mix asphalt (HMA) and stone matrix asphalt (SMA)]. To achieve this purpose, three dense and three gap-graded aggregates were selected and tested according to a modified Lottman test procedure. The results were analyzed using a statistical methodology called response surface methodology (RSM). A mathematical model correlating stripping potential of mix with bitumen content and grading was developed based on statistical concepts that can be utilized for prediction purposes. The statistical analysis showed that except for the quadratic term of bitumen content in the case of indirect tensile strength (ITS) in saturated gap-graded mixtures, the linear, quadratic, and interactive terms of these factors were statistically significant in ITS of dry and saturated samples and the tensile strength ratio (TSR). Second-order polynomial models were also successfully fitted to the experimental data. The results indicated that SMA mixtures exhibit better moisture resistance than HMA mixtures.

Controlled low-strength material (CLSM) is a self-consolidating cementitious material used as backfill in narrow trenches. The high content of aggregates and water in CLSM leads to a special behavior that is closer to soil than concrete. Consequently, mixture proportioning methodologies for conventional concrete do not apply to CLSM. The objective of this paper is to propose a new methodology to achieve the optimal composition that fulfills the flowability and compressive strength requirements of the material. Instead of computing the aggregate or the cement separately, all solid particles in the mixture are considered concurrently to estimate the water content in terms of water-to-solid ratio (W/S). In this way, the compressive strength can be modified without compromising the desired flowability. An example application is presented and an experimental program is conducted to validate this philosophy. The results confirm that the methodology proposed provides compositions that satisfy the main requirements of CLSM, thus representing a contribution to the use of more economical and adequate materials.