Water Cement Research Articles

Comparative study of fly ash and rice husk ash as cement replacement in pervious concrete: mechanical characteristics and sustainability analysis

ABSTRACT Pervious concrete is a special type of concrete consisting of cement, coarse aggregate and water. Cement is a widely used raw material for construction including pervious concrete and had led to the release of huge amounts of CO2 to the environment. Therefore, there is lot of research interest in finding supplementary cementitious materials. The present study examined and compared the feasibility of using industrial waste fly ash (FA) and agricultural waste rice husk ash (RHA) for sustainable pervious concrete production. An experimental program was performed with substitution of FA and RHA contents of 5%, 10%, 15% and 20% as cement replacement and water to binder ratio of 0.3, 0.35, 0.4 and 0.45. The characteristics of pervious concrete and sustainability analysis were compared for both FA and RHA replacement with control concrete mortar. The results showed that both FA and RHA have a negative effect on permeability. The compressive strength was optimum for FA content lies between 10% and 15% replacement level and RHA content of 5% replacement level. Furthermore, the utilisation of FA and RHA decreased production cost, the total embodied energy and carbon emission, resulting in cost-effective and eco-friendly pervious concrete.

Thermal Activation of Coal Gangue with Low Al/Si Ratio as Supplementary Cementitious Materials

To effectively utilize coal gangue (CG) with low Al/Si ratio, the thermal activation method was used. The activated CG, as supplementary cementitious materials (SCMs), was added into ordinary Portland cement (OPC) to study its physical properties. The XRD results show that CG undergoes a phase transition from kaolinite to metakaolinite during activation. The NMR tests reveal that the low polymerization state Q3 is continuously broadened, and the Al coordination gradually changes from Al VI to Al V and Al IV. The CG particles are scale-like and glassy with a loose structure. By mixing the activated CG (under 800 °C) with cement (mass ratio = 3:7), the water demand of normal consistency increases by 7.2% and the initial and final setting times extend by 67 min and 81 min, respectively. The rough surface and loose structure of activated CG are the main factors contributing to the higher water demand of normal consistency. The micro-aggregate effect of the activated CG reduces the contact rate between the cement particles and water, and the interparticles, thus slowing down the process of hydration reaction, and leading to longer setting times.

Use of Ground Calcium Carbonate for Self-compacting Concrete Development based on Various Water Content and Binder Compositions

Objective: The development of a Self-Compacting Concrete (SCC) mixture requires a different composition compared to normal vibrated concrete. This experimental study was designed to propose a modification of the concrete mix design formula to produce an SCC mix that meets the specified requirements for both fresh and hardened concrete using Ground Calcium Carbonate (GCC) as local fine powder material. Methods: The research was carried out with a targeted compressive strength between 30 and 60 MPa. The materials that were used in this research were fine natural aggregate, crushed stone as a coarse aggregate with a maximum size of 19 mm, Portland pozzolan cement (PPC), GCC, freshwater, and high-range water reducer. The properties of fresh concrete were tested using the slump-flow test method, while the compressive strength test was carried out on 50 standard cylinders after 28 days of curing with water immersion. Results: Test results indicated that the compressive strength and fresh properties of SCC significantly depend on the water content, the water/cement ratio, the volume ratio between water to the total binder, and the weight ratio between the GCC and Portland cement. Conclusion: Furthermore, using the experimental data based on varied water content and binder compositions produces equations with a good fit for SCC mix design in the compressive strength range between 30 MPa to 60 MPa.

Relationship between internal humidity and drying shrinkage of recycled aggregate thermal insulation concrete considering recycled aggregate content

The unique internal structure and basic properties of recycled coarse aggregate (RCA) and glazed hollow bead (GHB) complicate the shrinkage deformation of aggregate thermal insulation concrete (RATIC). To reveal the time-dependent law and mechanism of the drying shrinkage of RATIC, we experiment on the internal humidity evolution and drying shrinkage of RATIC with various contents of RCA. Moreover, we establish a model for predicting the time-dependent drying shrinkage of RATIC considering the replacement ratio of RCA and the development of the internal humidity of concrete using regression analysis. The results show that adding recycled coarse aggregate promotes cement hydration and water diffusion but aggravates the reduction of internal humidity and the development of the drying shrinkage of the RATIC. This paper proposes a model describing the drying shrinkage of RATIC at various contents of RCA and relates it to the changes in internal humidity so as to provide possible explanations for the drying shrinkage of RATIC influenced by the internal humidity. Finally, the drying shrinkage mechanism of RATIC is well explained using the capillary theory and the internal curing effect.

Effect of the Cement-to-Water Ratio and Fractal Granular Model on the Prediction of Concretes Compressive Strength

The main objective of this work was to highlight the contribution of cement-to-water mathrm{C}/mathrm{W} ratio and the fractal dimension mathrm{FD} model to the prediction of the compressive strength of concrete. In particular, the fractal dimension mathrm{FD} concept relative to the size distribution of the granular mixtures provided an insight into the fineness and compactness of the granular mixtures. The unconventional fractal granular model {mathrm{FGM}}_{mathrm{g}} also effectively contributed to highlight the correlation between cement-to-water ratio and compressive strength {mathrm{R}}_{mathrm{C}28} of concretes. Initially, 99 granular mixtures of concretes composition available in literature were investigated and for which the granular distributions by means of the fractal dimension mathrm{FD} model and the granular range mathrm{D}/mathrm{d} were we determined. Then, 36 concrete mixtures endowed with different granular mixtures were elaborated and analysed. These enabled to validate and evaluate the reliability of the basic granular fractal model {mathrm{FGM}}_{mathrm{g}} and the influence of cement–water mathrm{C}/mathrm{W} ratio of concretes mixtures when predicting the concretes compressive strength {mathrm{R}}_{mathrm{C}28}. The analytical model provided a close correlation with the experimental values of the compressive strength {mathrm{R}}_{mathrm{C}28} of all the concretes. The correlation highlighted the relevance of including fractal granular model {mathrm{FGM}}_{mathrm{g}} that denoted the skeleton of the concretes and the cement–water mathrm{C}/mathrm{W} ratio that referred to the binders into concretes mixtures when predicting {mathrm{R}}_{mathrm{C}28}. The theoretical approach whose effectiveness was highlighted using a "limited" number of real case studies may pave the way for further studies, when selecting the two key-factors for the prediction of concretes compressive strength {mathrm{R}}_{mathrm{C}28}.

Decision Support System for Building Material Supplier Selection using Simple Additive Weighting (SAW) Method

<p><em>XYZ Store is a retail store that sells goods in the form of building materials located in Bandung Regency. This shop sells types of cement products, water pumps and PVC pipes where this shop gets its products by ordering from suppliers. This shop is having difficulty choosing a supplier because it takes time to determine a supplier. Suppliers are contacted by telephone to ask about the availability and price of the building materials needed. If the supplier has the goods, he will buy them immediately and not ask other suppliers. The criteria used in determining suppliers are based on price and availability of goods. The criteria required by this shop are price, product availability, expiry date and delivery speed in accordance with the shop's condition when the goods are needed. The aim of this research is to create a decision support system that can provide supplier recommendations so as to help in selecting suppliers that match the criteria using the Simple Additive Weighting (SAW) method. Supplier selection decision support systems can provide the best alternative suppliers by ranking suppliers with the best performance. This web-based SPK was developed using the programming language PHP, Javascript and using an SQL database.<strong></strong></em></p>

Studying Tensile Strength of the Recycled Coarse Aggregate Concrete Using Double-Punch Test

Using the recycled materials can be considered as a suitable solution for resolving environmental issues. The recycled coarse aggregates (RCA) can be utilized effectively in manufacturing structural concretes. Due to hardness and errors of direct tensile and splitting tensile tests, double -punch test (DPT) can be regarded as a reliable test method for evaluation of tensile strength.In this study, application of DPT was investigated as a less known method for RCA concretes considering effective factors, such as water–to-cement ratio (0.4, 0.5, and 0.6), maximum nominal size of RCA (10 and 19 mm), curing conditions (wet and dry), and replacement level of RCA (0, 50, and 100%) and the results were validated by direct tensile and splitting tensile test results. A statistical analysis was performed to indicate significance of each variable in DPT results of RCA concretes. Also, compressive strength and modulus of elasticity were assessed and their relationships with tensile strength of the specimens were studied.The maximum RCA size, replacement level of RCA, and mechanical properties were diminished in mixtures by increasing water-to-cement ratio. Generally, DPT results showed remarkable proximity to direct tensile test results with a slight increase. In wet curing condition, mean values of splitting tensile, DPT, and direct tensile tests in the specimens containing 19mm of RCA were 11.61, 10.06, and 9.44% higher than those containing 10mm of RCA, respectively. Moreover, results of statistical analysis showed that the studied factors had significant effects on the results and they must be regarded in evaluation of DPT.

Design of concrete mix ratio and the influence of high water absorption resin and water reducer on strength and working performance

The performance of concrete and water cement ratio, water ratio and unit water consumption has a close relationship, concrete mix ratio design is actually to determine the proportion between the three, correctly determine the proportion relationship, can make concrete meet the design requirements. This paper systematically studies the working performance of concrete with different strength grades, and then compares the experimental results with the four concrete strength grades designed. High water absorption resin process increases the tightness of the slurry, to improve the working characteristics of cement, and then improve the durability of cement function. The influence of the high absorption resin curing agent and water reducing agent on different concrete strength and working performance is studied. The test data between high water absorption resin and absorbent are used to form the change curve of various strength grades, the interaction mechanism between high water absorbent resin and absorbent is analyzed, and puts forward an important scientific basis for the study of cement mix ratio.

Experimental Test of Compressive Strength of Concrete by Using Wastewater Tofu

Tofu waste is one type of waste produced by many people in Indonesia because the type of tofu food is the easiest to get. This study used tofu wastewater as a substitute for water and as a concrete treatment with certain changes in cement water components. Tofu water waste is waste that comes from wasted soybean treatment residues that cannot be consumed and the result of this tofu water waste is usually only disposed of. The purpose in this study is to determine the compressive strength value of concrete using tofu waste water and treatment using tofu wastewater. In the implementation using laboratory experimental methods. From the results of the compressive strength test showing the lower compressive strength value of concrete using wastewater tofu obtained a higher compressive strength value compared to using normal water PDAM. The compressive strength value using tofu water is 71.80 kg / cm² at the age of 7 days, 92.30 kg / cm² at the age of 7 days, 119.10 kg / cm² at the age of 7 days 28 days and the compressive strength value of concrete using normal water PDAM Baubau City is 46.30 kg/cm² at the age of 3 days, 59.20 kg/cm² at the age of 7 days and 88.00 kg/cm² at the age of 28 days.

Stabilization nature and unified strength characterization for cement-based stabilized soils

Although extensive studies have been conducted on cement-based stabilized soils (CBS), there is limited research focusing on the effect of water content, sand/silt fraction and particle size distribution of the original clays on the unconfined compression strength (UCS) of CBS. In this study, experimental results were combined with the available data collected from the literatures to clarify the effect of the water content, sand/silt fraction and size distribution on the CBS strength and to develop a generalized predictive strength equation for clays with various gradations, water contents and cement contents. The findings suggest that at a constant cement mass, original dry clay and water, the addition of sand (<80% in this case) has no influence on the UCS. However, at the same cement mass, water, and total soil (e.g., original clay with incorporated sands), the UCS decreases because of less absorbed water and more available water with sand substitution. It can be concluded by the scanning electron microscopy (SEM), that sand acts as hard inclusions within the CBS matrix. Based on the nature of the sand function within the CBS, a modified binder/water ratio (new indicator) was proposed to characterize the UCS by combining the traditional binder/water ratio and the mass ratio of the clay fraction to water. Using the modified binder/water ratio, the strength predictive equation was developed, which is useful as a tool for mix design to attain a target strength. The powerfulness of the equation is confirmed by the prediction results of the available CBS data collected from the literatures. The slope of the equation is found to be dependent on the cement hydration and pozzolanic reaction with clay minerals.

A Resistivity Plate Loading Device for Assessing the Factors Affecting the Stiffness of a Cement-Stabilized Subgrade.

The extent of mixing in the stabilization process and the control of the cement content (C) and water content (w) in the mixture are key to the outcome of the engineering performance of a cement-stabilized subgrade. Intelligent Compaction (IC) quality control has improved quality control and management practices during construction. Intelligent Compaction Measurement Values (ICMVs) selected to evaluate the stiffness properties of cement-stabilized soils do not directly relate to the stiffness properties of the cement-stabilized subgrade and do not consider w and C. Additional tests need to be conducted for calibration of ICMVs. In this study, our solution is the development of a resistivity plate loading test. The resistivity plate loading test features the flexibility in determining the soil stiffness, w, C, and other important factors, such as the time of test effect (hydration) (T) and dry density (ρd). To verify the accuracy of the testing method, laboratory experimental studies were conducted on cemented soils considering ρd, w, C, and T at different factor levels. Multiple response studies based on grey rational analysis (GRA) were conducted. Analysis of the input factors was performed, and their effects on the measured responses were quantified. According to the study, the ρ measured by the device was a powerful indicator of stiffness, ρd, w, C, and T, which showed that the device can be useful equipment for quality control and an advancement in the in situ testing technologies and test equipment. A statistical regression model based on the linear and linear plus interaction terms among the factors is proposed to predict the average responses.

Development and characterization of a controlled low-strength material produced using a ternary mixture of Portland cement, fly ash, and waste water treatment sludge

Controlled low-strength material (CLSM), a widely used replacement for conventional compacted filling material, is self-leveling and self-compacting, currently used in many structural applications. The properties of a CLSM mixture made from cement, fly ash, and waste water treatment sludge (WTS) were examined in this study. The CLSM mixtures were prepared using several water-to-binder (w/b) ratios (0.5, 0.65, and 0.8) and WTS weight ratios (0, 20, 40, and 80%). A solution of 5M NaOH was employed as a mixture accelerator. The influences of WTS addition on the characteristics of both fresh and hardened CLSM were examined. Toxicity characteristic leaching procedure (TCLP) and the change in minerals and microstructures of the CLSM samples were also investigated. The experimental results demonstrated that incorporating WTS into CLSM results in significant changes in fresh unit weight and mixture workability. The CLSM properties were found to be strongly affected by both the w/b ratio and accelerator dosage. Moreover, the TCLP test confirmed that WTS can be used as a safe by-product because the leached levels of heavy metals from raw WTS and resulting CLSM were significantly less than the permitted thresholds. Finally, the CLSM designed using a w/b ratio of 0.65, accelerator of 5%, and 40% WTS achieved the highest performance that meets current relevant Taipei City design regulations for excavatable backfilling.

MATERIALS REQUIREMENT FOR CEMENTING THE SEVEN-INCH CASING LINER IN THE WELL X-13 AT Y FIELD

Cementing is a process of mixing cement powder, water and additives (cement slurry) which will be pumped into the wellbore through casing into the annulus along the wellbore. Liner is a casing hung onto the casing which has been set before. Before the calculation of cementing materials needed, it is needed to collect X-13 well data, in the form of well profile which is consist of casing and tubing dimension. Furthermore, laboratory data for cement and additives is also used. Based on the calculation, the total volume of cement slurry needed for open end interval cementing is 199.7 bbl, with the amount of cement sack needed is 595.2 sacks. The total solid additives needed is 21426.1 lbs and total liquid additives needed is 1294.542 gallons. The total volume of fluid needed to push the cement slurry into the cementing zone is 251.05 bbl.

Towards a Complete Exploitation of Brewers’ Spent Grain from a Circular Economy Perspective

In the present work, brewers’ spent grain (BSG), which represents the major by-product of the brewing industry, was recovered from a regional brewery and fractionated in order to obtain a complete valorization. In particular, the whole process was divided in two main parts. A first pretreatment with hot water in an autoclave allowed the separation of a solution containing the soluble proteins and sugars, which accounted for 25% of the total starting biomass. This first step allowed the preparation of a medium that was successfully employed as a valuable growing medium for different microbial fermentations, leading to valuable fungal biomass as well as triglycerides with a high content of linear or branched fatty acids, depending on the microorganism used. The solid water-insoluble residue was then submitted to a lignocellulose deep eutectic solvent-mediated fractionation, which allowed the recovery of two important main fractions: BSG cellulose and BSG lignin. The latter product was tested as potential precursor for the development of cement water reducers with encouraging results. This combination of treatments of the waste biomass appeared to be a promising sustainable strategy for the development of the full exploitation of BSG from a circular economy perspective.

Experimental Study on Lead-Smelting Slag as Paste Filling Cementing Material

Under the current pressure of mineral product price and market competition, as well as the tightening of ecological and environmental protection policies, energy saving, emission reduction and cost reduction, and efficiency increase have become inevitable trends. Lead-smelting slag of smelter, as an industrial byproduct, is harmful solid waste to be eliminated. In this research, a series of experiments on substitute for cement were done for filling cost reduction under premise of guaranteeing the filling strength, using PC32.5 cement as reference cementing material. Meanwhile, with Portland cement clinker, water quenching slag of BF ironmaking, and lead-smelting slag of smelter in different ratios, four cementing materials were made and named as cementing material I, cementing material II, cementing material III, and cementing material IV. Then, the above five cementing materials including PC32.5 cement were mixed, respectively, with tailing and water to prepare paste backfill slurry with different binder-tailing ratio and concentration. Backfill block was made and cured at 20°C; their uniaxial compressive strengths in different curing ages were measured. The result shows the strength of backfill test block using cementing material I (cement clinker and water quenching slag) without lead-smelting slag is far higher than that of test block using PC32.5 cement as cementing material. The strength of block with 16% lead-smelting slag increased dramatically, which was higher than the strength of block using PC32.5 as cementing material. However, the strength of test block decreased when the content of lead-smelting slag reached 32% and 40%. The more lead-smelting slag was added, the worse influence on strength of backfill would be. Because of large specific gravity of lead-smelting slag and low content of CaO, the hydration activity of lead-smelting slag is far lower than that of water quenching slag. Therefore, using moderate lead-smelting slag as substitute for cement will lead to increase of backfill strength and decrease filling cost.

Predicting the strength of concrete made with stone dust and nylon fiber using artificial neural network

Excessive demand of concrete is causing depletion of natural sand resources. Especially, the extraction of river sand negatively affects its surrounding environment. A sustainable solution to this problem can be the proper utilization of waste materials and by-products like stone dust (SD) as fine aggregate replacement in concrete. The recycling of stone dust as a construction material lessens the use of natural resources and helps to solve landfill scarcity as well as environmental problems. Addition of nylon fiber (NF) as fiber reinforcement can also attribute to enhance the properties of concrete. This research aims at utilizing SD as fine aggregate along with NF, and assessing the compressive strength and splitting tensile strength of concrete. Although the individual effects of incorporating stone dust and nylon fiber in concrete have been investigated in previous researches, their combined effects, as well as effects of water cement (WC) ratio on concrete strength, have not been studied yet. In this study, volumetric percentages of stone dust (20%–50%) and nylon fiber (0.25%–0.75%) and three different water cement ratio (0.45, 0.50 and 0.55) have been considered as three independent variables to develop probabilistic models for compressive strength and splitting tensile strength of concrete using artificial neural network (ANN). The values of coefficient of determination (R2) and other statistical parameters of the developed probabilistic models indicate the accuracy of the models to predict the concrete strength. In terms of compressive strength at early age, the optimal percentages of SD and NF have been found as 20% and 0.25%, respectively. However, the strength gradually drops as water cement ratio elevates from 0.45 to 0.55. The reduction of the splitting tensile strength has been observed for increasing SD from 20% to 50%, whereas, strength increases for rising NF and WC up to mid-level.

Caesium and iodine release from spent mixed oxide fuels under repository relevant conditions: Initial leaching results

Autoclave leaching experiments are conducted on three well-characterised, irradiated, and cladded mixed oxide fuel-rod segments with burnups ranging from 29 GWd/tHM to 52 GWd/tHM to investigate the instant release fraction of fission gases and long-lived fission products and to assess the long-term fuel matrix corrosion. The segments are exposed to bicarbonate solutions as reference groundwater at neutral pH and a synthetic young cementitious water at pH 13.5 under reducing atmosphere (4 vol% H2 in Ar at 40 bar pressure), since 2018. The initial leaching results for the fission products caesium and iodine as representative elements of the instant release fraction were found to depend on the leachate composition as well as on the fuel burnup.Graphical abstract

Static dissolution experiments under hyperalkaline conditions with dispersed and confined SM539 glass

In the context of the geological disposal of vitrified radioactive waste, cracks are expected at the full scale of the glass blocks. To simulate glass alteration in cracks, static dissolution experiments were conducted with confined SM539 glass powder, at 30 °C in a synthetic young cementitious water. Short and long-term glass dissolution rates were determined and compared with those measured in similar experiments with dispersed glass powder. A long-term rate ~ 10 times lower was found, which might be due to a limited access of the solution to the glass surface area, resulting in a much higher local SA/V and faster increase of local concentrations of leached glass constituents, with possibly a lower local pH. In both types of experiments, the altered glass powder was characterised by XRD and SEM-EDX. Some glass particles showed the presence of an amorphous multi-layer and of fibrous and spherical secondary phases.Graphical abstract

Water absorption behavior of hydrophobized concrete using silane emulsion as admixture

Influences of silane emulsion as hydrophobic agent on pore structure of hardened cement paste (hcp), compressive strength and water absorption behavior of concrete were studied through pore structure analysis, water contact angle test and water/isopropanol absorption measurement. Results indicate that silane slightly inhibits early cement hydration and slightly reduces the 28-d compressive strength of concretes. The incorporation of silane significantly decreases the water sorptivity of concretes ascribed to the hydrophobization of capillary walls in hcps, whereas isopropanol absorption is not visibly affected by the addition of silane. The absolute water sorptivity decreases along with increasing water absorption amount for each group of concrete, which is believed to originate from swelling of C-S-H gel upon water absorption. However, the relative water sorptivity of the silane-modified concretes to the plain concrete remains constant during water absorption. A predicting method for long-term water absorption behavior of the silane-modified concrete is proposed.

DEFORMATİON DURABİLİTY - ADJUSTABLE BUFFERİNG BARRİER OF THE BOTTOM HOLE AREA

DEFORMATİON DURABİLİTY - ADJUSTABLE BUFFERİNG BARRİER OF THE BOTTOM HOLE AREA