Cylinder Compressive Strength Research Articles

Suitability of BS EN 197-1 CEM II and CEM V cement for production of low carbon concrete

The environmental destruction of global warming as a result of excessive releasing carbon dioxide (CO2) in the atmosphere through burning of fossil fuels is of significant interest to scientific community as well as decision makers and general public worldwide. Electricity generation, transportation, industrial activities and land use changes have been identified as the main contributors. On the other hand, it is widely reported that the concrete industry contributes around 7% to total global CO2 emissions and Portland cement (PC) accounts for 90% of this. A number of researches have been undertaken to address this issue and over the past few years‘ industry have successfully implemented a series of innovative techniques for minimising its environmental impact quite successfully. The concrete construction industry is continued to put a greater emphasis on adopting more sustainable practices. In keeping with this, reported work was carried out to assess the environmental impact of BS EN 197-1 binary and ternary cement concretes and thus their suitability for use in low carbon concrete construction.Results of this research show that the use of binary and ternary cements has a potential to reduce overall embodied CO2 (ECO2) emissions and cost in equal design strength concrete. Studies investigating engineering (compressive cube and cylinder compressive strength, flexural strength, drying shrinkage) and durability properties (initial surface absorption, carbonation) were found to provide comparable and improved results comparing to conventional PC concrete mixes design for equal strength.

Geopolymer Stabilisation of Unfired Earth Masonry Units

Contemporary domestic structures typically use masonry units that are approximately 100mm thick. There is interest in using commercial methods of manufacture to produce earthen bricks that have a similar form factor to conventional masonry The large scale adoption of thin walled unfired earth masonry is dependent on its suitability for use in a load bearing application. High moisture content leading to full saturation, for example as a result of flooding, is a concern for unstablised earth construction, especially as wall thickness reduces. The greatest barrier for earth masonry adoption is the durability of the material when affected by high moisture content. Accidental and intentional wetting of a 100mm thick load bearing unfired earth wall could lead to disproportionate collapse. The paper presents initial findings from an investigation into the use of geopolymer mechanism as a method of stabilisation. The use of geopolymer mechanism was chosen as a possible method of improving the water resilience. Soil that is used for commercial extruded fired brick production was chosen. The soil was selected as the precursor (source of the required silica and alumina) and this was mixed with various sodium hydroxide and sodium silicate activators. Specimens were tested both in their dry sate as well as following 24 hours of submersion in water. Compressive strength of cylinders after saturation, was used as an indicator of effective stabilisation. The maximum dry compressive strength achieved was 10.4N/mm2with the addition of 5% sodium hydroxide and 20% sodium silicate after curing at 105°C. The most significant contributor to the strength gain was the addition of sodium silicate. Although some of the cylinders were able to be tested under fully saturated conditions the strengths achieved were negligible and insufficient for structural application. The potential for geopolymers as a method of stabilising unfired earth bricks is discussed with respect to the compressive strengths achieved.

EXPERIMENTAL AND PREDICTIVE MECHANICAL STRENGTH OF FIBER REINFORCED CEMENTITIOUS MATRIX (FRCM)

Fiber Reinforced Cementitious Matrix (FRCM) are sustainable building materials as it uses lesser quantities of natural resources as raw materials for production, when compared to conventional concrete. This study is an attempt to explore the possibility of using crimped mild steel (MS) fibers (12.5 mm length) as reinforcement in cementitious matrix, with sand-cement and water-cement ratio in line with the ACI Codes. From the experimental results, it was found that when the percentage of MS fibers is increased in cement-based mortar from 0.5% to 2.5% of volume of specimens (with 0.5% interval), there is a corresponding increase in the cylinder compressive strength and splitting-tensile strength at 7 and 28 days, and flexural strength at 28 days. There was an increase in compressive strength of 74%, splitting-tensile strength of 38% and flexural strength of 35% at 28 days, when MS fibers of 2.5% was used, when compared to control mortar specimens (with no fibers). Also, the predictive strength models were developed from the experimental data using statistical regression analysis. It was observed that the experimental results of FRCM highly correlate with the predicted values, with minimum prediction error.

Compressive behaviors of cylindrical concrete specimens made of demolished concrete blocks and fresh concrete

Adopting demolished concrete blocks (DCBs) rather than recycled aggregates in structural members may reduce the cost of reuse of waste concrete. Here DCBs have distinctly larger size than the conventional recycled aggregates. To investigate the effect of DCBs’ size on axial behaviors of the specimens made of DCBs and fresh concrete (FC), and to check whether the interface zones between DCBs and FC are weaker regions in the specimens, two series of tests were conducted in this paper. In the first series of tests, twenty-four cylindrical specimens made of DCBs and FC with a replacement ratio of 30% and twelve cylindrical specimens made of FC alone were fabricated and tested under uniaxial compressive loadings. The height-to-diameter ratio of all the specimens was the same as 2.0, and the diameters of the specimens ranged from 150mm to 400mm. The influences of both the cylinder dimensions and the characteristic size of DCBs on the specimens’ compressive strength, the modulus of elasticity, and the strain at peak stress have been experimentally investigated. Based on the test results, a formula is presented to describe the relationship between the characteristic ratio (i.e., a ratio of the characteristic size of DCBs to the cylinder diameter) and the compressive strength, and a model is established to determine the compressive strength of concrete cylinders with various diameters and different characteristic ratios. In the second series of tests, three 200mm×200mm×50mm specimens cut from two 400mm×400mm×200mm samples made of DCBs and FC were axially loaded, and the initiation and propagation of the specimens’ surface cracks were recorded using the two-dimensional digital image correlation technique. It is found that: (a) the effect of cylinder size on the strength of the specimens made of DCBs and FC is similar to the effect of cylinder size on the strength of the specimens made of FC alone, but the size effect on the relative strength for the former specimens is a little more distinct than the size effect on the relative strength for the latter specimens; (b) in the case that the cylinder dimensions keep constant, the strength of the specimens made of DCBs and FC decreases gradually with the increasing of the characteristic ratio; (c) for both the cylindrical specimens made of FC alone and those made of DCBs and FC, the cylinder dimensions and the characteristic size of DCBs have no clear effects on the modulus of elasticity and strain at peak stress; (d) both the presented formula and the established model mentioned above are in good agreement with the test results; and (e) microcracks do not concentrate in the interface zones between DCBs and FC, and these zones are not obviously weaker regions in structural members.

Effect of Anthracite on Preparation of Ceramsite Using Red Mud

Based on analyzing of chemical composition, mineral composition and thermal stability of red mud, preparation of ceramisite, using anthracite added as foaming agent, was investigated. Internal structure was observed by scanning electron microscopy (SEM). The results showed the bulk density of ceramisite was obviously reduced by anthracite added. The ceramisite with bulk density of 1.30g/cm3, water absorption rate£ ̈WAR£©of 2.98% and cylinder compressive strength £ ̈CCS£©of 9.48 MPa was obtained when weight ratio of red mud/waste glass/bentonites/anthracite was at 73:15:11:1. Majority of porosity in ceramisite was closed based on SEM. The porosity of ceramisite was much higher when anthracite was added as foaming agent than only calcite in red mud was used as foaming agent. The bulk density of the former was lower than that of the latter.

Deformation properties and direct shear of medium strength concrete prepared with 100% recycled coarse aggregates

The lack of a thorough understanding of the structural behavior of recycled aggregate concrete has become increasingly obvious in recent years. This paper presents the deformation properties and direct shear of medium strength structure concrete prepared with 100% recycled aggregate and Class-F fly ash (RAC) as compared to those of the corresponding natural aggregate concrete (NAC). During this study, five water–binder ratios of 0.50, 0.44, 0.40, 0.36 and 0.32 were used to prepare the concrete with target cube compressive strength ranging from 45 to 70MPa using natural or recycled coarse aggregates. Fly ash was added of 25% by cement weight in all concrete mixtures. The results show that the 28-day cube and cylinder compressive strength, flexural and the direct shear strength of RAC were on the average of 85% of those NAC with the same mix proportions. Moreover the modulus of elasticity of RAC was on the average of 14% lower than that of NAC. Furthermore, the drying shrinkage and chloride ion penetration of RAC was on the average of 24% and 14% higher than that of NAC. The results showed that the medium strength structural concrete can be produced by using 100% recycled aggregate and Class-F fly ash.

Ageing and durability of concrete in lab and in field conditions: investigation of chloride penetration

Long-term studies under various natural exposure conditions are still needed in order to understand and quantify ageing and durability of concrete structures, in particular in the case of mixtures which incorporate supplementary cementitious materials (e.g. fly ash). With this purpose, a large-scale and long-term experimental program was initiated a lot of years ago by the LPC network within the framework of the French national project “BHP 2000.” From then, further researches have been carried out in order to complement the program. The present paper focuses on chloride penetration in concrete samples in lab conditions and in reinforced concrete (RC) structural elements exposed for 10 years to two different natural environments (tidal zone in marine environment, as well as road and cold environment). Numerous mixtures (28 day cylinder compressive strengths ranging from 20 to 130 MPa) were studied in these various conditions, e.g. high-performance materials with or without silica fume (SF), as well as normal-strength fly-ash (FA) concretes. Carbonation and chloride penetration depths, along with total chloride concentration and degree of saturation profiles, have been measured on the RC structural elements and analyzed as a function of the exposure conditions and of the mix-parameters. In addition, the chloride data have been compared to lab results. Apparent chloride diffusion coefficients, as well as chloride binding isotherms and capacities, have also been assessed on these structural elements and compared to lab results. Good consistence between results in field and in lab conditions has been highlighted, except when carbonation has affected the field results. In addition, the good performance of SF-HPCs and mature FA concretes has been pointed out in the tested outdoor conditions, as well as that of the mature ground granulated blast furnace slag concretes tested in lab.

Influence of Sintering Temperature on Performance of Red Mud Lightweight Ceramsite

The red mud lightweight ceramsite was made by using red mud, fly ash and bentonite, mixed with a certain amount of pore-forming agent and cosolvent, through the roasting process. Influence of sintering temperature to red mud ceramsite was studied. The microscopic morphology of red mud lightweight ceramsite damage fracture was analyzed by using scanning electron microscope and the roasting mechanism was investigated preliminarily. The results show that for the best sample, its apparent density is 724kg/m3, its bulk density is 574kg/m3; its cylinder compressive strength is 5.5Mpa, the water absorption is 8.6%.

Chloride diffusion coefficient and service life prediction of concrete subjected to repeated loadings

The chloride diffusion coefficient and the service life of concrete with different water to cement (W/C) ratios and under repeated loadings were examined. The W/C ratios were 0·30, 0·35, 0·40 and 0·45 by mass of cement. Loading, repeated five times, was applied to concrete specimens using a WHY series fully automatic testing machine; the maximum loading was 40% and 80% of the axial cylinder compressive strength ( [Formula: see text]). The diffusion coefficients were calculated from the steady state in a chloride migration test by using the Nernst–Planck equation. The service life was predicted using a Life-365 model. The results show that an increase in W/C ratio largely increases the chloride diffusion coefficient of concrete at 28 d. Five times 40% [Formula: see text] and 80% [Formula: see text] Loading increases the chloride diffusion coefficient and decreases the service life for all mixes. The service life of 10 mm concrete cover with a 0·40 W/C ratio is 4·0 years, and decreases by 10·0% and 35·0% when the repeated loadings are 40% [Formula: see text] and 80% [Formula: see text], respectively.

The Preparation of Red Mud Lightweight Ceramsite

The red mud lightweight ceramsite was made by using red mud, fly ash and bentonite, mixed with a certain amount of pore-forming agent and foam stabilizer, through the roasting process. Influence of pore-forming agent on red mud ceramsite was studied. The microscopic morphology of red mud lightweight ceramsite damage fracture was analyzed by using scanning electron microscope. The results show that with 6% pore-forming agent, the apparent density is 731kg/m3, the bulk density is 547kg/m3; the cylinder compressive strength is 3.3Mpa, the water absorption is 9.7%.

Experimental Research of the Rapid Set Cement Concrete for Rapid Repair of Concrete Pavements

The efficient rapid repair for the distressed concrete pavement requires a rapid setting material that can be placed, cured, and opened to the traffic in short period. Normally, the time of the traffic open is determined by the concrete strength gain in the early hours. Meanwhile, the strength development and thermal and shrinkage properties of the concrete affect the structural and bonding performance of the repaired pavement. Type Ⅲ cement and Calcium Sulfoaluminate (CSA) cement are categorized as the rapid set cement (RSC) and are the most widely used as the cementitious material for the concrete structure rapid repair. The compressive strength of the RSC concrete cylinders with different mix proportions had been tested to obtain a strength gain guide for the rapid repair construction. Coefficient of the thermal expansion and shrinkage of the concrete were experimented. The results show that the RSC cement concretes are steady and can meet the requirement of the concrete pavement repair.

Experimental Investigation of Ultra-high Performance Fiber Reinforced Concrete Slabs Subjected to Deformable Projectile Impact

Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) is currently one of the biggest challenging issues in modern concrete technology. The UHPFRC represents a concrete with improved durability and strength, which is significantly higher than in conventional normal strength concrete. This may result in reduced cross-sections and as a consequence smaller dead-load of the structure. The uniaxial compressive cylinder strength of UHPFRC used in this study exceeded 150MPa and the uniaxial direct tensile strength exceeded 10MPa. Several UHPFRC mixtures with different content of fibers were subjected to deformable projectile impact. The ogive-nose projectile weighed 8.04 grams and its average velocity was determined to be 710 m/s. It was shown that plain UHPC specimen failed in the brittle manner which caused that the slab split into several pieces. Further, it was demonstrated that addition of steel micro fibers enhanced the resistance to deformable projectile impact and it was specified that specimens containing 2% of fibers by volume have optimal resistance against impact loading. In addition, response of slabs made of conventional fiber reinforced concrete (FRC) and normal strength concrete (NSC) was studied for comparison. The magnitude of the damage was assessed based on the penetration depth, crater diameter and mass loss. Experimental results clearly showed that implementation of high strength steel micro fibers significantly increased the resistance to projectile impact. It was stated, that UHPFRC has much better resistance to projectile impact in comparison to conventional FRC.

Prediction of Splitting Tensile Strength from Cylinder Compressive Strength of Concrete by Support Vector Machine

Compressive strength and splitting tensile strength are both important parameters that are utilized for characterization concrete mechanical properties. This paper aims to show a possible applicability of support vector machine (SVM) to predict the splitting tensile strength of concrete from compressive strength of concrete, a SVM model was built, trained, and tested using the available experimental data gathered from the literature. All of the results predicted by the SVM model are compared with results obtained from experimental data, and we found that the predicted splitting tensile strength of concrete is in good agreement with the experimental data. The splitting tensile strength results predicted by SVM are also compared to those obtained by using empirical results of the building codes and various models. These comparisons show that SVM has strong potential as a feasible tool for predicting splitting tensile strength from compressive strength.

Studies in ultrasonic pulse velocity of concrete containing GGBFS

This paper presents the results of experimental investigations into the time-dependent ultrasonic pulse velocity (UPV) of concrete containing GGBFS. The UPV was determined at the age of 3, 7, 28, 56, 90, 150 and 180days for twelve concrete mixes using the prism specimens of plain and GGBFS concrete. The amount of cement replaced by GGBFS was varied from 20% to 60%. The UPV of concrete containing GGBFS has been found to be lower than that of plain concrete for all percentage replacements of cement at all ages and for all the mixes. Relationship between cube and cylinder compressive strength and UPV for GGBFS based concrete has been presented. A new model for time-dependent dynamic modulus of elasticity of concrete containing GGBFS has been proposed.

Application of artificial neural networks to predict the bond strength of FRP-to-concrete joints

A Back-Propagation Neural Network (BPNN) model for predicting the bond strength of FRP-to-concrete joints is proposed. Published single-lap shear test specimens were used to predict the bond strength of externally bonded FRP systems adhered to concrete prisms. A database of one hundred and fifty experimental data points from several sources was used for training and testing the BPNN. The data used in the BPNN are arranged in a format of six input parameters including: width of concrete prism; concrete cylinder compressive strength; FRP thickness; bond length; bond width (i.e. FRP width); and FRP modulus of elasticity. The one corresponding output parameter is the bond strength. A parametric study was carried out using BPNN to study the influence of each parameter on the bond strength and to compare results with common existing analytical models. The results of this study indicate that the BPNN provides an efficient alternative method for predicting the bond strength of FRP-to-concrete joints when compared to experimental results and those from existing analytical models.

The Preparation of Composite Zeolite Filter

Using natural-zeolite as main raw material, prepare spherical composite zeolite filter material by adding adhesive, pore-forming agent, etc. By measuring cylinder compressive strength apparent porosity and adsorption capacity of ammonia and doing orthogonal experiment, the optimal process combination is C3A1B3, namely ω zeolite powder : ω adhesive : ω pore-forming agent =55%：35%：10%, activation temperature is 150°C, activation time is 3h.The end product’s packing density is 674Kg/m3, cylinder compressive strength is 4.32MPa, and apparent porosity is 59.02%.

The Performance Test of Composite Zeolite Filter

Use natural zeolite to prepare spherical composite zeolite filter material. With range analysis, the composite zeolite filter material’s packing density is 674Kg/m3, cylinder compressive strength is 4.32MPa, and apparent porosity is 59.02%. Compared with ceramsite, composite zeolite filter whose surface roughness has larger specific surface area and higher porosity. At the start of biofilm formation and stability of the operational phase, composite zeolite filter Biological Aerated Filter (BAF)’s ammonia removal is better than ceramsite BAF, and its Biofilm biomass is higher, thus more proper to be the carrier of BAF.

Effect of silica fume addition and repeated loading on chloride diffusion coefficient of concrete

In this paper, the effect of silica fume (SF) on the chloride diffusion coefficient of concrete subjected to repeated loading was examined. Portland cement was replaced by 5 and 10 % SF. Five cycles repeated loadings were applied to concrete specimens, the maximum loadings were 40 and 80 % of the axial cylinder compressive strength (\( f_{\text{c}}^{\prime } \)), respectively. The diffusion coefficients were calculated from the steady state in the chloride migration test using the Nernst-Planck equation. The service life of concrete in chloride environment was predicted by Life-365 model. The results indicate that the diffusion coefficients of concrete containing 5 and 10 % SF replacements are lower than that of the control concrete at the age of 28 days. This trend increases with the increase of SF replacement. Five cycles repeated loading at 40 % \( f_{\text{c}}^{\prime } \) or 80 % \( f_{\text{c}}^{\prime } \) increase the diffusion coefficients (D28) for all mixes investigated in this study. However, the effect of 80 % \( f_{\text{c}}^{\prime } \) on D28 of concrete with 10 % SF is significantly lower than that of the control concrete without SF. Compared with the control concrete without SF, 10 % SF replacements increase the service life of concrete by more than 10 times.

Experimental Study on the Influence of Ceramist Properties Compressive Strength of Shale Ceramist Concrete

There are 6 group of experimental research to explore the relationship between shale ceramist concrete compressive strength and ceramic cylinder compressive strength, particle size, absorption time. The result shows that the strength of shale ceramist concrete is not only relevant with the ceramic cylinder compressive strength, but also relevant with the aggregate size, absorption time. For single graded particle size concrete, the strength of concrete decreased with grain size increasing. The longer time of ceramic absorption, the more sufficient the ceramist concrete strength development.

Effect of ground granulated blast-furnace slag (GGBFS) and silica fume (SF) on chloride migration through concrete subjected to repeated loading

The effect of ground granulated blast-furnace slag (GGBFS) and silica fume (SF) on the chloride migration through concrete subjected to repeated loading was examined. Portland cement was replaced by 20%, 30%, 40% GGBFS and 5%, 10% SF, respectively. Five times repeated loadings were applied to specimens, the maximum loadings were 40% and 80% of the axial cylinder compressive strength (f′c), respectively. Chloride migration through concretes was evaluated using the rapid chloride migration test and the chloride concentration in the anode chamber was measured. The results indicate that the transport number of chloride through concrete containing 20% and 30% GGBFS replacements and 5% and 10% SF replacements is lower than that of the control concrete, but 40% GGBFS replacement increases the transport number of chloride. Five loadings at 40% f′c or 80% f′c increase the transport number of chloride for all mixes investigated in this study. 5% SF replacement has a very close effect on the chloride permeability of concrete with 20% GGBFS when concrete is subjected to 40% f′c or 80% f′c.