ASTM C1202 Research Articles

BASIC BEHAVIOUR OF NATURAL BANANA STEM FIBER REINFORCED CONCRETE UNDER UNIAXIAL AND BIAXIAL TENSILE STRESS

In order to study the basic behavior of natural banana stem fiber reinforced concrete, three typeof tensile strength test namely split tensile strength, flexural strength and biaxial fatigue flexure strength wereconducted. Comparison of these three type of tensile strength, their crack pattern and the way they fails werebe analyzed and discussed. Results showed that the flexural strength value of the two type of biaxial tests arehigher than the uniaxial test result( ASTM C-1550 have 47.046 % higher than ASTM C-78 and 37.871 %higher than ASTM C-496). The value of tensile strength as measured by ASTM C-1550-02 is slightly higherthan the value of the flexural tensile strength as measured by the biaxial flexure test (21.062%). The lines ofthe crack pattern do not show clear macro fracture cracks before reaching the peak load. As observed, there aretwo peak load values found were the one occurred at the first cracked, after that the load stress curve decreasefor a while and after a few seconds the load increase again to a value smaller than the first peak load value.Thisis because at the time of the first cracking in three axes symmetry, the load that can be maintained by theconcrete specimen had reached its maximum but after that the load increase again because the stress has beentransferred to the fiber, so the stress rises again until the fiber break off. This indicates that the fiber plays animportant role in holding and redistributed the tensile load.

Cymbopogon citratusand NaNO2Behaviours in 3.5% NaCl-Immersed Steel-Reinforced Concrete: Implications for Eco-Friendly Corrosion Inhibitor Applications for Steel in Concrete

This paper studies behaviours ofCymbopogon citratusleaf-extract and NaNO2, used as equal-mass admixture models, in 3.5% NaCl-immersed steel-reinforced concrete by nondestructive electrochemical methods and by compressive-strength improvement/reduction effects. Corrosion-rate, corrosion-current, and corrosion-potential constitute electrochemical test-techniques while compressive-strength effect investigations followed ASTM C29 and ASTM C33, in experiments using positive-controls for the electrochemical and compressive-strength studies. Analyses of the different electrochemical test-results mostly portrayed agreements on reinforcing-steel anticorrosion effects by the concentrations of natural plant and of chemical admixtures in the saline/marine simulating-environment and in the distilled H2O (electrochemical positive control) of steel-reinforced concrete immersions. These indicated that little amount (0.0833% cement for concrete-mixing) ofCymbopogon citratusleaf-extract was required for optimal inhibition efficiency,η= 99.35%, on reinforcing-steel corrosion, in the study. Results of compressive-strength change factor also indicated that the 0.0833%Cymbopogon citratusconcentration outperformed NaNO2admixture concentrations also in compressive-strength improvement effects on the NaCl-immersed steel-reinforced concrete. These established implications, from the study, on the suitability of the eco-friendlyCymbopogon citratusleaf-extract for replacing the also highly effective NaNO2inhibitor of steel-in-concrete corrosion in concrete designed for the saline/marine service-environment.

Mechanical behaviour of micro-fine steel fibre reinforced sulphoaluminate cement composite

In this study, a new cement-based composite with high early strength and toughness was developed by the addition of micro-fine steel fibre (MSF) in sulphoaluminate cement (SAC). The new composite is termed as MSF reinforced SAC composite (MSFRSC). The mechanical behaviour of MSFRSC was experimentally investigated, the flexural toughness and ductility of MSFRSC was evaluated. It was found that the compressive strength, flexural strength, shear strength, flexural toughness and ductility of MSFRSC were significantly influenced by the curing time and volume fraction of MSF. The compressive strength, flexural strength and shear strength of MSFRSC increased with the increase of curing time, especially during the first three days. The flexural strength and shear strength of MSFRSC improved significantly with the increase of the volume fraction of MSF. The flexural toughness of MSFRSC significantly improved and the ductility slightly improved with the increase of the volume fraction of MSF from 0.0% to 2.0%. The flexural toughness slightly increased and the ductility slightly decreased with the increase of the curing time from 1 day to 28 days. Also, the recommendations of different codes for the evaluation of the flexural toughness and ductility of MSFRSC were compared. The recommendations in ASTM C1609 fully reflected the flexural toughness and ductility of MSFRSC. The recommendations in JG/T 472-2015 distinguished the influence of MSF on the pre-peak and post-peak flexural load-deflection behaviours of MSFRSC. A simplified approach based on JG/T 472-2015 was proposed to evaluate the flexural ductility of MSFRSC.

Determination of the Pozzolanicity of Cocoa Pod Ash at Different Temperatures

Pozzolans are siliceous or aluminous materials which possess little or no cementing property but chemically react with calcium hydroxide at ordinary temperature to form compounds possessing cementitious properties. There is paucity of information on the pozzolanicity of Cocoa Pod Ash (CPA). Hence, this study investigated the pozzolanicity of CPA. Cocoa pods were obtained from selected farms in Egba Odeda, Ogun State Nigeria. The Cocoa pods were washed, sundried and calcinated to ashes in a furnace between 600° C to 1000° C at Science Laboratory Technology Department, Federal Polytechnic Ilaro, Ogun State. Chemical analyses and X-ray Crystallography were carried out on the CPA to determine the types of oxides present and their varying percentages. The oxides were Silica (SiO,), Ferric (Fe,O,), combined percentages of Ferric and Aluminum oxides (Fe,O, and Al,O,), Calcium (CaO), Magnesium (MgO) and Sulphur (SO,). The moisture content and the Loss of Ignition (LOD) of the CPA samples were also determined.The oxides of Silicon, Ferric, Aluminium, Calcium and Magnesium oxide ranged between 6.39-8.00; 0.78 – 0.89; 1.74- 2,29; 7.15-8.42 and 4.38-5.16% respectively. Sulphur trioxide and LOI ranged 3.51- 3.78 and 27.2- 32.0%, respectively. The Xray crystallography showed that the total percentage composition of SiO, Al,O, and Fe,O, in CPA varied from 14.87-24.21%. The study showed that CPA did not satisfy the minimum 70% requirements stipulated by ASTM C618 (2005) for a pozzolan after the analysis of the oxides but it satisfied all the requirements for LOI, hence CPA is a weak pozzolan

Using RCPT determine the migration coefficient to assess the durability of concrete

Portland cement concrete and fly ash concrete were subjected to the ASTM C1202 rapid chloride permeability test (RCPT). When the RCPT was complete, the chloride profiles of the specimens were determined by collecting concrete powder samples at controlling depths. Based on Faraday's laws of electrolysis, the mass of electrolysis deposition is directly proportional to the quantity of electricity (coulombs). This study showed a same phenomenon that a linear relationship was found between the charge passed during the RCPT and the total amount of chloride obtained from the chloride profile. The total amount of chloride in the specimen can be determined by measuring the 6 h charge passed from RCPT. The chloride profile can be obtained based on the measurement of charge passed and the surface chloride content. After the completion of the RCPT, additional step taken during the modified RCPT procedure entails measuring the surface chloride content. Based on the chloride penetration depth obtained from the chloride profile, a modified RCPT method was used to compute the chloride migration coefficient and assess the chloride permeability of concrete.

Fly ash particle characterization for predicting concrete compressive strength

A new classification approach is presented that uses individual fly ash particle measurements to provide improved and more in-depth information about the properties of the concrete. The technique uses machine guided X-ray microanalysis to measure the compositions of 2000 randomly selected particles from 20 different fly ashes. This paper details the methods used to acquire the particle composition data and the derivation of the representative groups of the fly ash particles or classification groups. This method is named the Particle Model. To investigate the utility of these groups, 12 fly ashes were used at a 20% mass replacement of the cement in a series of concrete mixtures, which were tested for compressive strength at various times over 180 d of curing. Seven of the nine particle compositions identified were found to influence the compressive strength of the concrete with a linear model R-squared value of 0.99. The Particle Model showed a statistically significant improvement over the Class C or F classification from ASTM C618 and EN450. This work aims to establish the Particle Model and show that the classification shows promise to be used as a method to predict the physical properties of concretes that contain fly ash.

Evaluation of Specimen Size-Effect in Sedimentary Rocks and Grain Size Effect in Concrete Specimens on Uniaxial Compressive Strength

Summary In rock engineering, the effect of scale on the strength and deformation properties of the rock mass is one of the most important issues. Prediction of uniaxial compressive strength in different diameters using the specimen size-effect models is valuable. To specify the application scope of the specimen size-effect models in the rock and concrete specimens, a few significant study have so far been carried out. This paper proposes a model of appropriate size-effect in sedimentary rocks and concrete specimens. Another object of this paper is discussion on the effect of specimen size and grain size on uniaxial compressive strength of rock and concrete specimens using statistical and experimental methods. The results of this study can be used for engineering designs in or on rocks and are more useful for determining of the elastic constants and compressive strength of rock. Introduction Dependence of compressive strength on the specimen size has a fundamental role in the designing of rock structures. In the rock mechanics, many experimental and analytical methods have been used to determine the specimen size-effect on the mechanical behavior of intact rock. In the area of rock mechanics and solid mechanics, the most notable proposed analytical models to predict the specimen size-effect on the uniaxial compressive strength are including the Weibull statistical theory (1951), the Hoek and Brown empirical theory (1980), the specimen size-effect model using fracture energy theory (Bazant, 1983 and 1984), the multi-fractal scaling model (Carpinteri et al., 1995), the fractal fracture size-effect model (Bazant, 1997) and the unified size-effect model for intact rock (Masoumi et al., 2015). To specify the application scope of these models in the rock and concrete specimens, few significant study have so far been carried out. Methodology and Approaches Statistical analysis of this study, were conducted in each size-effect model by means of a non-linear least-squares fitting algorithm and Levenberg-Marquardt method using SPSS software. In the experimental study, three concrete blocks of approximately 500mm×500mm×500mm in size with three different grain sizes (0-12, 0-20 and 0-25) were manufactured. After the curing time, using a laboratory drilling machine, cylindrical specimens were obtained from blocks with diameters of 56, 68, 72 and 94 mm and with a length-to-diameter ratio of 2.0 (L/D=2.0) according to the recommendation of International Society of Rock Mechanics (ISRM, 2007). ACI-211 standard and ASTM C33 standard were utilized for mixture design of samples and required grain sizes respectively. Results and Conclusions In the sedimentary rocks and concrete specimens, respectively, there was a good agreement between outputs of laboratory tests with the specimen size-effect model using fracture energy and the multifractal scaling model. In experimental study, results of uniaxial compressive strength tests for grain sizes 0-20 and 0-25 mm indicated that increase of the specimens' diameter resulted in first increase and then decrease of uniaxial compressive strength. The results of this study confirmed grain size effect on the predictions of specimen size-effect models (i.e. increase of the grain size, leads to reduction of the value of correlation coefficient for different models. These results can be used for engineering designs in rocks and concrete mixtures.

Effect of alkali silica reaction on the mechanical properties of aging mortar bars: Experiments and numerical modeling

Alkali silica reaction and its effect on concrete and mortar have been studied for many years. Several tests and procedures have been formulated to evaluate this reaction, particularly in terms of aggregate reactivity. However, the data given in the literature concerning the mechanical properties of concrete and mortar are scattered and very little information is available for some properties such as fracture energy. In this study, the mechanical behavior of mortar was evaluated and monitored, under normal and accelerated environmental conditions. Fracture energy, compressive strength and tensile strength were measured for mortar specimens, casted with highly reactive Spratt crushed aggregate, at two different storage temperatures (23℃ and 80℃) and at two different alkali concentrations (immersed in water and in 1 N NaOH solution). Moreover, free expansion tests (according to ASTM C1260) and petrographic observations were performed, in order to relate them to the evolution of the mechanical properties of mortar. Results show a decrease of the mechanical properties associated with specimens at 80℃ in alkali solution and that the deterioration due to alkali silica reaction is counter-balanced by the strengthening of mortar resulting from the hydration process. A multi-physics computational framework, based on the Lattice Discrete Particle Model is then proposed. Numerical simulations based on a complete calibration and validation with the obtained experimental data capture the behavior of mortar subjected to the complex coupled effect of strength build-up and alkali silica reaction at different temperatures and alkali contents.

The role of ambient temperature variation on drying shrinkage development of self-compacting Portland-limestone cement concrete

The ambient temperature records in Iraq show a large variation between day and night reaching 20 C, depending on the season, whether it is summer or winter. For this reason, the aim of this research is to study the effect of these conditions on the drying shrinkage of self-compacting concrete produced by using Portland-Limestone cement (ASTM C595 - Type IL). SCC mixes were designed to attain compressive strengths of 40 and 60MPa at 28days with and without silica fume respectively. Same mixes were reproduced with ordinary Portland cement (ASTM C150 - Type I) for comparisons. Two maximum sizes of aggregate 10 and 20 mm were incorporated in this work. The drying shrinkage was measured for 180 days after 7 days of water curing. The range of ambient (outdoor) temperature variation was from - 4 to + 39°C and the relative humidity ranged from 15 to 60 %. The results of this exposure were compared to that of specimens kept in the shrinkage chamber, with a temperature of 21°C and relative humidity 35%. The current results showed that due to the irreversible nature of shrinkage strain, the drop of ambient temperature and the rise of atmosphere moisture or relative humidity would not reverse the shrinkage strain. It is important to figure the final total accumulated strain when dealing with ambient temperature variation. The drying shrinkage characteristics for concrete made with Type IL cement, are found similar to that for concrete produced with Type I cement.

Field Evaluation of Concrete using Hawaiian Aggregates for Alkali Silica Reaction

Alkali Silica Reaction (ASR) occurs in concrete when the alkali hydroxides (Na+, K+ and OH-) from the cement react with unstable silica, SiO2, in some types of aggregate. The resulting gel will expand when it absorbs water, potentially leading to cracking and overall expansion of the concrete. Concrete aggregates available in Hawaii have not demonstrated a history of ASR, however, results of accelerated laboratory tests using ASTM C1260 indicated a potential for ASR with some aggregates. In order to assess the accuracy of the laboratory test results, a long-term field study of the potential for ASR in concretes made with Hawaiian aggregates was initiated in 2011. Forty concrete specimens were constructed of various concrete mixtures using aggregates from all Hawaiian aggregate sources, and some US mainland aggregates known to exhibit ASR expansion. The specimens are located in an open field site in Manoa valley on the Hawaiian Island of Oahu, exposed to relatively high humidity and frequent rainfall. A weather station at the site records the ambient conditions on a continual basis. This paper describes the field evaluation program and presents the results after six years of monitoring. Comparisons are made between the field observations and accelerated laboratory tests.

Characteristics of meta-kaolin geopolymer Bender-Element (BE) test

Bender element (BE) test is a non-destructive test and is commonly used as an ultrasonic shear wave (S-wave) technique for determining the stiffness of materials. In this research, the ultrasonic shear wave was measured by using the piezoceramic BE in order to monitor the setting and the hardening process of meta-kaolin based geopolymer (MKG). The S-wave was generated and received by piezoelectric ceramic sensors which were placed at opposite ends of the test samples. The effects of the thermal treatment on kaolinite, the mixing proportions between solid and liquid activator and the influence of sodium hydroxide to sodium silicate ratio (NaOH/Na2SiO3) were investigated. Liquid activators were prepared by using chemical portions between 10 M NaOH and Na2SiO3 of 1:1, 1:1.2, 1:1.5, 1:2, 1.2:1, 1.5:1 and 2:1. Subsequently, meta-kaolin (MK) powders were mixed with liquid activators by using solid to liquid rations (S/L) of 0.8:1, 1:1, 1.2:1 and 1.5.1. The physical and mechanical properties included this setting time and the shear modulus of fresh and hardened MKG specimens were measured by BE test. Experimental results showed that the S-wave velocity was closely related to the setting time by measuring penetration resistance (ASTM C403), which indicated that the S-wave velocity can be used to monitor the setting of fresh geopolymer and the long term evaluation of hardened geopolymer.

Freezing and thawing resistance of internally cured high performance concrete

The behavior of internally cured high performance concrete, HPC, exposed to freezing and thawing cycles, was investigated. Two saturated curing agents, Limestone dust and powder of Porcelanite rock, were used to facilitate internal curing for concrete. These agents were used as partial replacements of fine aggregate in two volumetric percentages, 20 and 30 percent. The cast concrete specimens were separated in two groups according to curing method: water-cured and sealed (only internally-cured) specimens. The concrete specimens were subjected to three exposure systems, F0: without freezing and thawing, and F1 and F2: with 50 and 100 cycles of freezing and thawing, respectively. The freezing and thawing test was done as stipulated by the ASTM C666. The conducted tests for each exposure were: compressive and flexural strengths. The results revealed that internal curing does not enhance the concrete resistance to freezing and thawing cycles. Using saturated agents has increased the moisture content of concrete and makes it more vulnerable to frost action deterioration. Sealed specimens for all investigated mixes showed lower reductions in strength than water-cured ones. The lesser water content of these mixes may be the reason for that behavior.

Mechanical Properties of Steel Fiber-Reinforced Magnesium Phosphate Cement Mortar

A new cement-based mortar with high early strength and toughness was developed by adding micro steel fibers (MSF) in magnesium phosphate cement (MPC) mortar. The compressive and flexural tests were carried out to investigate the effect of curing time, MSF volume fraction, sand-cement mass ratio, and water-cement mass ratio on the strength and flexural toughness of MSF-reinforced MPC mortar (MSFRMM). Also, the flexural toughness and ductility of MSFRMM were evaluated according to ASTM C1609. The results of this study showed that the addition of MSF from 0% to 1.6% by volume significantly improved the compressive strength of MSFRMM. The MSFRMM showed high early strength, especially during the first 3 days. The addition of MSFs changed the flexural failure mode of MPC-based mortar from brittleness to ductility, and the flexural toughness of MSFRMM remarkably increased with the increase of MSF volume fraction from 0% to 1.6%. The toughness and ductility of MSFRMM slightly increased with the increase of the dosage of cement. The toughness and ductility of MSFRMM increased with the decrease of the water-cement mass ratio due to the improved density of the mortar caused by the reduction of water.

Preliminary Study of the Use of a Secondary Lead Smelting Slag as an Addition to Portland Cement

In this work, the preliminary study about the use of secondary lead smelting slag (SLSS) as an addition to Portland cement is presented. SLSS is a waste from a Colombian secondary lead smelter. The chemical, physical and mineralogical characteristics of the raw materials were evaluated by X-ray fluorescence, particle size and X-ray diffraction. To assess the SLSS pozzolanic activity, the ASTM C618 standards were used. Additionally, cement pastes added with SLSS as Portland cement replacement in proportions of 0, 5, 10, 20 and 30% were prepared, to study the hydration process at 7, 14 and 28 of curing times. To determine the hydration products the technique of X-ray diffraction was used. Furthermore, the environmental test TCLP (Toxicity Characteristic Leaching Procedure) was performed in pastes with 28 days of curing time. Results showed that SLSS reported an index of pozzolanic activity of 87%, this value meets the standard (greater than 75%). The hydration process showed that since early curing time the waste presented a good reactivity. TCLP results satisfied the environmental standards. The outcomes showed that this waste could be used as a partial replacement of Portland cement.

Performance and Microstructural Analysis of Lightweight Concrete Blended with Nanosilica under Sulfate Attack

The influence of two lightweight aggregates (LWA) on concrete and the effects of cement substitution for nanosilica (NS) on the interfacial transition zone (ITZ) and cementitious matrix of concrete in resistance to attacks by magnesium sulfate (MgSO4) are researched in this work. The aggregates evaluated were perlite, which is a lightweight aggregate of open porous structure, and expanded clay (aliven) with closed porous structure. The variables included in the study were replacement percentage of coarse aggregates by lightweight coarse aggregates (0 and 100% by volume) and replacement percentage of cement by nanosilica (0 and 10% by weight). In the dosage of the mixtures, water/cementitious‐material ratio constant of 0.35 was used. The LWA were characterized by XRD, XRF, and SEM techniques. Compressive strength, water absorption, and volume change in magnesium sulfate solution (according to ASTM C1012 for a period of 15 weeks) of lightweight concretes were evaluated. It was found that the nanosilica had effect on refinement in the pore system; however, the main incidence on the compressive strength and durability of lightweight concrete (LWC) was defined by the characteristics of lightweight aggregate used in its preparation.

Mortars and Concrete Incorporating Palm Oil Fuel Ash and Fly Ash

Number of researchers reported that Palm Oil Fuel Ash (POFA) and Fly Ash (FA) can be used as supplementary cementing material (SCM) in concrete. Both materials have their own significant effects on the properties of concrete and have been accepted by using them for the improvement of workability and strength of concrete. However, studies showed that FA has better pozzolanic properties than POFA. Hence, properties of mortars blended with POFA (untreated and treated) as binary blend (CUP and CTP) and ternary blend that combined with FA (CUPF and CTPF) as cement replacement were investigated. Unground POFA has been used in this study. CUPF and CTPF resulted in significant improvement in the pozzolanic activity compared to CUP and CTP of mortar mix. Pozzolanic activity of ternary blend mortar achieved the specified pozzolanic activity index of 75% based on ASTM C618. Compressive strength of the C80P15F5 concrete with 15% of treated POFA + 5% of FA by weight of binder showed a slightly higher result compared to the control mix. It is suggested that the combination of POFA and FA as pozzolanic material will improves the mechanical properties of mortars and concrete.

Effect of pore structures on gas permeability and chloride diffusivity of concrete

10 concrete specimens with different water-binder ratios and admixtures were manufactured to analyze the relationship between permeability and microstructure of the test concrete. The gas permeability coefficient and effective chloride diffusion coefficient of concrete were measured by Cembureau method and ASTM C1202 test respectively. In addition, the pore structure of concrete was determined by mercury intrusion porosimetry (MIP) and nuclear magnetic resonance (NMR) respectively. Results show that water-binder ratio and admixture have negligible effect on the distribution of pore size below 10 nm. Besides, the addition of admixtures can decrease the porosity of concrete effectively, except basalt fiber. Moreover, there is an obvious correlation between gas permeability (chloride diffusivity) and porosity of the test concrete. A higher proportion of pore within range of 1–100 nm can be obtained by NMR than that by MIP. The results are opposite when the pore size is >100 nm. There is a good correlation between gas permeability coefficients and contributive porosity with pore diameter of 10–1000 nm, meanwhile, chloride diffusivity is well dependent on contributive porosity with pore diameter of 100–1000 nm. The addition of admixtures will change the relationships between two global permeability coefficients and microstructure parameters of concrete.

Five-Hour Autoclave Test for Determining Potential Alkali-Silica Reactivity of Concrete Aggregates: A Multi-Laboratory Study

Abstract Alkali-silica reaction (ASR) is a deleterious chemical reaction that can lead to expansion and cracking of concrete structures. The reaction occurs between alkali hydroxides in the pore solution and reactive forms of silica present in some aggregates. To successfully mitigate ASR in new structures, the potential alkali reactivity of the aggregates must be known. Standardized test methods for this purpose are sometimes too time-consuming for rapid military construction operations. To assess the viability of a five-hour autoclaved mortar bar test method for ultra-rapid identification of aggregate reactivity, researchers in five laboratories participated in a multi-laboratory study led by the U.S. Army Engineer Research and Development Center (ERDC). The test method uses fine aggregate in mortar bars like those used in ASTM C1260, Standard Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method), but the equivalent alkali content of the mortar is boosted to 3.5 % by mass of cement. Mortar bars are cured for 48 hours prior to autoclaving at 130°C for five hours at peak temperature. This paper details the test procedure, expansions, comparisons with the accelerated mortar bar test and the concrete prism test, within- and multi-laboratory precisions, and investigation into the amount of alkali leaching during the test. For 85 % of the 20 aggregates tested, there was agreement between the autoclave test and ASTM C1260 in determining whether or not an aggregate was reactive to some degree. The agreement between the autoclave test and ASTM C1293, Standard Test Method for Determination of Length Change of Concrete Due to Alkali-Silica Reaction, was 100 % for ten of the aggregates for which ASTM C1293 data were available. The average within- and multi-laboratory coefficients of variation were 5.9 and 20.0 %, respectively. Results showed alkali leaching to be between 6 and 9 % per mortar bar. This study demonstrated the viability of the five-hour autoclave test for rapidly assessing aggregate reactivity in military construction operations.

Influence of Fineness of Recycled Glass Waste and Slag on Compressive Strength of Sulphate Resisting Cement Mortars

Background: Cement and concrete industry is responsible for 5% of the worldwide man-made CO2 emission to environment. Therefore, the demands of producing low carbon concrete is increasing every day for climate change mitigation and adaptations. Objective: To minimize the amount of clinker production and associated CO2 emission, the potential use of recycled ground glass waste (GGW) and electric arc furnace slag (EAFS) as a substitute of cement was evaluated through compressive strength tests on mortars and by calculating their strength activity index (SAI) values. Method: At first, two optimized fineness levels were attained for both cement substituting materials used in this study (GGW as glass fine ˂ 38µm (GF), glass superfine ˂ 25µm (GSF) and EAFS as slag fine ˂ 75µm (SF), slag superfine ˂ 32µm (SSF)). In addition to control mortar (CM), four types of binary mortar mixtures were cast by substituting cement 5-20% with GGW (GF and GSF) and 10-30% with EAFS (SF and SSF). ASTM C109 and C311 were employed to perform compressive strength tests and to calculate the SAI values, respectively. Results: The results demonstrated that the strength of mortar increased with increasing fineness of both the cement substitute materials. More specifically, the compressive strength of mortar containing GSF matched with those of CM at 5% substitution and comparable for its other substitutions (10, 15, and 20%) at age of one-year. Similar results were noticed for SSF at its 10% substitution where it produced the best comparable results to CM. However, the strength of mortars containing SF or 30% SSF was significantly reduced as compared to CM. Conclusion: Almost all the mortars containing GGW or EAFS have satisfied the strength activity criteria of ASTM C989 Grade 80 of blast furnace slag, except those containing 20 and 30% of SF. Moreover, the mortars containing GSF and SSF matched BFS of Grade 100 corresponding to their 5 and 10% substitutions, respectively.

The influence of variation in cement characteristics on workability and strength of SCC with fly ash and slag additions

The effects of fly ash and slag on fresh and hardened properties of self-compacting concrete (SCC) were investigated using four CEM I 52.5 N cements produced at different factories according to ASTM C150, two polycarboxylate-acid based superplasticisers, two class F fly ashes and one slag. The differences in the cement characteristics were enough to affect the SCC flow properties. The compatibility of cement and admixtures depended mostly on the concentration of C3A, C2S/C3S ratio, the specific surface area of the cement and the type of superplasticiser used. A protocol to assess the sensitivity of a SCC mix design to a type of cement is proposed.