Mini-slump Spread Research Articles

AI-guided auto-discovery of low-carbon cost-effective ultra-high performance concrete (UHPC)

This paper presents an AI-guided approach to automatically discover low-carbon cost-effective ultra-high performance concrete (UHPC). The presented approach automates data augmentation, machine learning model generation, and mixture selection by integrating advanced techniques of generative modeling, automated machine learning, and many-objective optimization. New data are synthesized by generative modeling and semi-supervised learning to enlarge datasets for training machine learning models that are automatically generated to predict the compressive strength, flexural strength, mini-slump spread, and porosity of UHPC. The proposed approach was used to explore new UHPC mixtures in two design scenarios with different objectives. The first scenario maximizes the compressive and flexural strengths and minimizes porosity while retaining self-consolidation. The second scenario minimizes the life-cycle carbon footprint, embodied energy, and material cost, besides the objectives of the first scenario. The life-cycle carbon footprint, embodied energy, and material cost of the UHPC in the second scenario are respectively reduced by 73%, 71%, and 80%, compared with the UHPC in the first scenario. This research advances the capability of developing cementitious composites using AI-guided approaches.

Modelling the minislump spread of superplasticized PPC paste using Random forest, Decision tree and Multiple linear regression

Workability is one of the key property of concrete which is governed by water cement ratio. In order to improve the workability of concrete without any variations in water cement ratio Superplasticizers(SPs) are added. Cement paste helps us to analyze the property of fresh concrete where the dispersion of cement particle is taken into account. SP’s Cement dispersive properties are governed by dosage and the family. Various dosages and families of SP are considered for estimating workability feature of cement paste which is picked for investigating on rheological properties through Mini slump spread diameter. The prime motive of this analysis includes measuring the workability of different superplasticizers by conducting a minislump test and hence modelling the flow rate of the superplasticized Portland Pozzolona Cement (PPC)paste using the application of random forest(RF), decision tree(DT) and multiple regression algorithms. Testing and training data for a model were 287 unique mixture compositions at a water by cement ratio was 0.37. This mixture was tested experimentally in a laboratory using four types of locally available PPC’s and of SP which can be broadly categorised in to four families. Amount of seven types of SP brands, water content, cement weight were the input parameters for the model and flow rate was the output parameter. The model’s predicted and experimentally measured values of flow speed were compared and the amount of deviation was recorded.

Performance Evaluation of Eco-Friendly Ultra-High-Performance Concrete Incorporated with Waste Glass-A Review

The ultra-high-performance glass concrete (UHPGC) is an advanced UHPC innovative pioneer in sustainable concrete technology. UHPGC technology can provide environmental benefits through the use of post-consumer glass. Economic benefits through the decrease in the amount of landfilled materials are undesirable as they are neither biodegradable nor environmentally friendly and could reduce the costs for UHPC. Compressive strength greater than 150 MPa and mini-slump spread diameter bigger than 250 mm can be achieved, depending on the UHPGC composition and curing temperature. The glass powder (GP) milled to the micro-scale is subjected to low pozzolanic reaction and works as a catalyst speeding clinker dissolution forming calcium silicate hydrate (C-S-H). These reactions have a good positive influence on both UHPC’s mechanical and microstructural properties. This paper overviews previous studies carried out as partial or full replacement of sand or quartz sand (QS), quartz powder (QP), and silica fume (SF) by the use of milled waste glass (WG) in UHPC mixture. Nowadays, the sustainability of the construction sector must be a priority for the scientific community. So, the development of the used materials and methods to extend the lifetime of concrete structures is mandatory.

Effect of porcelain tile polishing residue on eco-efficient geopolymer: Rheological performance of pastes and mortars

Brazil produces 900 mi m2 of ceramic tiles annually, which generates about 60,000 tons of porcelain tile polishing residue (PPR). In previous work, the authors confirmed the feasibility of using PPR in the production of geopolymer pastes regarding mechanical and microstructural properties. This work investigated the rheological and ecological performance of geopolymer pastes and mortars produced with metakaolin replacement by PPR in 0–100%, activated with Na2SiO3/NaOH solution. Rotational rheometry and mini slump test were conducted in pastes, in addition to flow table test for mortars. Furthermore, the CO2 emission related to 1 m³ of mortar was estimated for each composition. Results showed that geopolymer pastes behaved as a Bingham fluid (R2 of 0.999–1.000). The increase in PPR level linearly decreased the yield stress of the pastes from 10.5 to 0.2 Pa, and the viscosity from 4.2 to 1.5 Pa.s. Furthermore, PPR incorporation progressively increased the spread of the pastes (mini slump) and mortars (flow table) by up to 20% and 17%, respectively. The yield stress and mini slump spread of the pastes showed a linear correlation with R2 of 0.992, indicating that this test is efficient to assess the yield stress of geopolymer pastes, as widespread for Portland cement pastes. Finally, PPR incorporation progressively reduced the CO2 emission per m³ of mortar from 636 (0% PPR) to 532 kg CO2-eq/m³ (100% PPR). Replacing 15% metakaolin with PPR reduced the CO2 intensity of the material (i.e. kg CO2-eq/m³.MPa) by 11% and 7% respectively at 7 and 28 days. Overall, PPR incorporation improved the fresh and hardened performance of metakaolin-based geopolymer composites while reducing its CO2 emission, reinforcing the good technical and environmental performance of the residue as binding material.

Self-compacting geopolymer mixture: Dosing based on statistical mixture design and simultaneous optimization

The high flowability of self-compacting geopolymer mixtures (SCGMs), combined with the characteristics of high mechanical performance, durability, and low CO2 emission, has attracted considerable scientific interest. Because it is embryonic, SCGM technology demands efficient dosing methods and the consolidation of mixing rules. This study uses statistical mixture design combined with simultaneous optimization to formulate SCGMs. Thirteen established formulations using screening design methodology form the basis for the elaboration of regression models that relate the mini-slump spread, the V-funnel flow time, the apparent porosity, and the mechanical properties (axial compressive strength and bending strength) of the mixtures with the weight content of the components. The mixtures were prepared using metakaolin, a solution of NaOH, alternative laboratory-prepared sodium silicate (SiO2/Na2O = 3.81), quartz sand, and superplasticizer. The optimal self-compacting formulation, i.e., the one with the highest performance-to-cost ratio, presented NaOH molarity of 9.02 M, Na2O/Al2O3 ratio of 1.42, volumetric concentration of solids equal to 0.52, spreading diameter of 258 mm, flow time of 7 s, compressive strength of 25.16 MPa, and tensile strength of 8.56 MPa. The Scheffé linear polynomials were suitable for predicting the properties of SCGM. The statistical mixture design, combined with multi-objective optimization, was found to be an innovative and reliable alternative for dosing SCGM.

Cement-based composite with humidity adsorption and formaldehyde removal functions as an indoor wall material

Indoor air environment is of great significance for the comfort and health of residents while humidity adjustment and air purification are essential to provide favorable air environment. This paper aims to prepare multifunctional cement-based composite with both humidity adsorption and formaldehyde removal properties for indoor walls. Bamboo charcoal loading silver doped titanium dioxide (Ag/TiO2-BC) was synthesized and used in cement-based paste. Properties of the prepared paste including flowability, bonding strength, humidity adsorption and formaldehyde removal ratio, were investigated. Results show that Ag/TiO2-BC increases superplasticizer demand to keep the mini slump spread at a desirable level due to the higher specific surface area and porous structure of Ag/TiO2-BC. Besides, sample with higher content of Ag/TiO2-BC has lower bonding strength whereas the limit value of 0.5 MPa can be met if cement content is not lower than 30%. Humidity adsorption result indicates that Ag/TiO2-BC significantly improves the humidity content of mixture, which shows an approximately linear trend with Ag/TiO2-BC content. Cement paste with Ag/TiO2-BC has 226.5% higher humidity adsorption capacity compared to that with diatomite, which is the result of combined effects of specific surface area and effective pore volume. Formaldehyde removal result shows that formaldehyde removal ratio increases as Ag/TiO2-BC content rises and equilibrium removal ratio can be reached at 24 h. The removal of formaldehyde by cement with diatomite is due to the adsorption of diatomite while cement with Ag/TiO2-BC has both adsorption and photocatalytic decomposition effects. These findings demonstrate that cement-based composite with favorable humidity adsorption and formaldehyde removal performance as well as traditional properties can be prepared by incorporating Ag/TiO2-BC, showing a high potential to be used as wall materials to enhance indoor air environment.

Development and mechanical behaviour of ultra-high-performance seawater sea-sand concrete

Ultra-high-performance concrete is typically defined as an advanced cementitious material that has a compressive strength of over 150 MPa and superior durability. This article presents the development of a new type of ultra-high-performance concrete, namely, ultra-high-performance seawater sea-sand concrete. The development of ultra-high-performance seawater sea-sand concrete addresses the challenges associated with the shortage of freshwater, river-sand and coarse aggregate in producing concrete for a marine construction project. When used together with corrosion-resistant fibre-reinforced polymer composites, the durability of the resulting structures (i.e. hybrid fibre-reinforced polymer–ultra-high-performance seawater sea-sand concrete structures) in a harsh environment can be expected to be outstanding. The ultra-high strength of ultra-high-performance seawater sea-sand concrete and the unique characteristics of fibre-reinforced polymer composites also offer tremendous opportunities for optimization towards new forms of high-performance structures. An experimental study is presented in this article to demonstrate the concept and feasibility of ultra-high-performance seawater sea-sand concrete: ultra-high-performance seawater sea-sand concrete samples with a 28-day cube compressive strength of over 180 MPa were successfully produced; the samples were made of seawater and sea-sand, but without steel fibres, and were cured at room temperature. The experimental programme also examined the effects of a number of relevant variables, including the types of sand, mixing water and curing water, among other parameters. The mini-slump spread, compressive strength and stress–strain curve of the specimens were measured to clarify the effects of experimental variables. The test results show that the use of seawater and sea-sand leads to a slight decrease in workability, density and modulus of elasticity; it is also likely to slightly increase the early strength but to slightly decrease the strengths at 7 days and above. Compared with freshwater curing, the seawater curing method results in a slight decrease in elastic modulus and compressive strength.

Effect of mixing method on the mini-slump spread of Portland cement pastes

Abstract The current compressive strength test for cement classification is performed under a fixed water to cement ratio according to the Brazilian and European standards, regardless the consistency obtained. However, under practical conditions the amount of water required is related to the rheological need to obtain and maintain a desired workability. Intrinsic cement characteristics influence the water demand such as the cement particle’s granulometry, specific surface area, density, the presence or not of water reducing admixtures, chemical and mineralogical nature of raw materials, etc., influence particles agglomeration state. Because water demand influences the mechanical properties of cement based products, the compressive strength class under a fixed water to solids ratio specified by the standards may not be representative for the user. The present work investigates the influence of mixing conditions on mini-slump spread results, a test that has been used for many years but never standardized. Cement paste samples were produced with varied mixing conditions (time and rotation speed) using a conventional stirrer and subjected to mini-slump spread test immediately after mixing and at fixed hydration times. Results show that mixing and hydration time do influence on mini-slump spread. At lower rotation speeds, results variability increases. Under fixed time after first contact with water, increasing rotation speed leads in a reduction of results variability and increase the test’s repeatability on cement pastes.

Maximum paste coating thickness without voids clogging of pervious concrete and its relationship to the rheological properties of cement paste

All mixture design methods for pervious concrete have been proposed under the hypothesis that cement paste uniformly coats on the surface of aggregate and does not drain off from the aggregate surface to clog the interconnected voids between aggregate particles. To evaluate the maximum paste coating thickness on aggregate (MPCT) that will not result in clogging of voids, understanding of the relationship between the MPCT and the rheological properties of cement paste was reviewed and theoretically analyzed in the present study. A paste drainage test was developed on a flow table to determine the MPCT, with specification of test variables (in terms of the number of flow table drops, the sieve mesh size, and the aggregate size) to ensure good repeatability and precision. Based on testing data of 39 cement pastes, uniform relationships between yield stress, viscosity, mini-slump spread and MPCT were established. The resulting empirical functions were validated by comparing the predicted and measured MPCTs for additional tests. The results will give a better understanding of a critical criterion for mixture design and clogging prediction of pervious concrete.

Modelling the minislump spread of superplasticized PPC paste using RLS with the application of Random Kitchen sink

Super plasticizers(SPs) are added to the concrete to improve its workability with out changing the water cement ratio. Property of fresh concrete is mainly governed by the cement paste which depends on the dispersion of cement particle. Cement dispersive properties of the SP depends up on its dosage and the family. Mini slump spread diameter with different dosages and families of SP is taken as the measure of workability characteristic of cement paste chosen for measuring the rheological properties of cement paste. The main purpose of this study includes measure the dispersive ability of different families of SP by conducting minislump test and model the minislump spread diameter of the super plasticized Portland Pozzolona Cement (PPC)paste using regularized least square (RLS) approach along with the application of Random kitchen sink (RKS) algorithm. For preparing test and training data for the model 287 different mixes were prepared in the laboratory at a water cement ratio of 0.37 using four locally available brand of Portland Pozzolona cement (PPC) and SP belonging to four different families. Water content, cement weight and amount of SP (by considering it as seven separate input based on their family and brand) were the input parameters and mini slump spread diameter was the output parameter for the model. The variation of predicted and measured values of spread diameters were compared and validated. From this study it was observed that, the model could effectively predict the minislump spread of cement paste

Synthesis of a Series of PEG-Based ABA Triblock Copolymers and Their Influence on Rheology of Cement Slurries

A series of water-soluble ABA triblock copolymers consisting of a polyethylene glycol central block joined to two blocks of six different homopolymers have been synthesized via simple solvent-free and ecofriendly routes and characterized by FTIR and 1HNMR spectroscopy. Dispersing and slump-retaining abilities of the copolymers in cement slurries were evaluated by mini-slump spread method. Rheological measurements of samples with the best performance were carried out using a rate-controlled coaxial cylinder viscometer. The test results indicate that the dispersing power of the copolymers in cement pastes is strongly affected by the structure and degree of polymerization of the monomers.

Particle image velocimetry (PIV) to evaluate fresh and hardened state properties of self compacting fiber-reinforced cementitious composites (SC-FRCCs)

This paper presents the results of a comparative study of conventional techniques with an image based non-contact method, both to evaluate fresh and hardened state properties of self-compacting fiber-reinforced cementitious composites (SC-FRCCs). Experimental studies include measurement of mini-slump flow and mold flow test for fresh state and flexural strength, strain localizations and crack propagations for hardened state using both traditional measurement methods and a full field method called particle image velocimetry (PIV), which measures surface displacements and strains using digital image analysis. For mini-slump spread diameter measurements, camera recordings of the spread diameter of fresh mortar at regular intervals were taken and analyzed. The hardened state tests were carried out with un-notched specimens under four-point bending. Beams with 4 varying (beam depth/fiber thickness), “t/fL” ratios and 2 different fiber lengths were tested. During experiments, load–deflection, load–crack opening width curves and propagation of cracks were determined. The progressive opening of the cracks is studied using PIV, and continuous strain fields during cracking are provided. In addition, PIV technique was used to monitor the cross-sectional flexural strain distributions at midspan. Consequently, the results obtained by conventional methods were compared with the results obtained from PIV analyses. The main aim of the current study is to show the potential of PIV to evaluate some of the fresh and hardened state properties of SC-FRCC’s, in comparison with the traditional measurement techniques.

Experimental study of the flow behaviour of superplasticized cement paste

The properties of high performance concrete, mainly in the fresh state are governed by the flow behaviour of the paste phase, which is controlled by the dispersion of cement particles by the superplasticizer. In this paper, experimental procedures for evaluating the flow behaviour of cement paste with different types and dosages of superplasticizers are studied. The rheological nature of the paste is represented through the Bingham and Herschel-Bulkley models. It is observed that the Marsh cone flow time, mini-slump spread and the rheological parameters show the same trend with change in dosage of superplasticizer. Also, the rheological parameters increase with time and rate of increase is more significant at dosages less than the saturation dosage, as determined from the Marsh cone test. It is confirmed that the Marsh cone flow time can be predicted using an appropriate model.

폴리카복실레이트 분자 구조에 따른 시멘트페이스트의 분산 및 흡착 특성 연구

Graft copolymerized polycarboxylate(PC)-type superplasticizers which have carboxylic acid with bond among the molecular structure and polyethyleneglycol methyl ether methacrylate(PMEM) were synthesized by free radical reaction. To investigate their chemical structures and molecular weights, PCs were analyzed by FT-IR(fourier transform spectrometer), C-NMR(nuclear magnetic resonance spectrometer) and GPC(gel permeation chromatograpy). When types of carboxylic acids(methacrylic acid, acrylic acid, maleic anhydride, and itaconic acid) and molar ratios of carboxylic acid/PMEM) were varied, adsorptive and fluid characteristics in cement paste were discussed. As the molar ratio of carboxylic acid/PMEM) was higher, amount adsorbed on the cement particles and the fluidity of cement paste by mini-slump spread testing method were increased. When main chain of PC was methacrylic acid, a larger amount was adsorbed on the cement particles. PCs with acrylic acid as main chain showed higher dispersing power. However, it was confirmed that PCs with dicarboxylic acids(maleic anhydride, itaconic acid) didn`t have good adsorption and dispersibility.

Effects of the synthetic conditions of poly{carboxylate-g-(ethylene glycol) methyl ether} on the dispersibility in cement paste

The objective of this study was to find the relationship between the poly{carboxylate-g-(ethylene glycol) methyl ether} [P(C-g-E)] synthetic conditions and the dispersibility in cement paste. The P(C-g-E)s, which have superior dispersion ability and stability in cement concrete, were synthesized by changing the reaction temperature (R.T.), the reaction time (R.H.) and the initiator concentration (I.C.). The molecular weights and the yields of P(C-g-E)s were analyzed by GPC. Also, the dispersion ability and dispersion stability of P(C-g-E)s in cement paste were tested by the mini slump spread testing method. The dispersibilities of P(C-g-E) in cement paste are strongly affected by the reaction temperature and the reaction time, but weakly affected by the APS dosage in the polymer synthesis. In addition, the dispersibilities of P(C-g-E) in cement paste are more affected by the heavier molecules than the lighter ones in the polymer.

Simple Field Tests to Characterize Fluidity and Washout Resistance of Structural Cement Grout

Abstract The ability to assess rheological properties of neat cement grout, such as those used in structural repair and for filling post-tension ducts, is of special interest for the evaluation of the ease of pumping, spreading into place, and filling of narrow spaces. There is an increasing need to identify dependable and simple test methods that can characterize the consistency of specialty cement grouts and reflect variations in rheological properties during handling and placement. Several tests can be used to evaluate the rheological characteristics of a cement grout suspension, including precise methods for the determination of rheological parameters and simple procedures to assess fluidity. Rheological properties can be accurately determined by using a coaxial cylinder viscometer. However, the use of such a viscometer is mainly limited to the laboratory, and simple methods including the mini-slump spread and the modified Marsh cone tests are usually employed in the field to verify the consistency for quality control. This paper attempts to establish relationships between rheological parameters and fluidity values obtained using simple test methods. Relationships are also determined between the wash-out resistance of structural cement grout and various fluidity and rheological parameters. The derived relationships are based on a wide variety of cement grouts covering up to 210 data points. The various grouts were prepared with W/C ranging between 0.30 and 0.50, Type I and III portland cements, as well as various silica fume replacement values (up to 8% by mass), blast-furnace slag contents of 20 to 60%, fly ash substitutions of 10 to 30%, and limestone filler replacements of up to 30%. The investigated grouts incorporated melamine- and naphthalene-based high-range water reducer, welan gum and cellulose-based viscosity-modifying admixtures, as well as set-retarding admixture. Test results highlight the difficulties of relying on a single empirical test to evaluate the fluidity of a given grout. Correlations between various simple measurements of fluidity and wash-out mass loss and apparent viscosities determined at different shear rates indicate that the mini-slump and wash-out mass loss measurements correspond well to viscosities determined at low-shear rates (5.1 s-1). In contrast, the modified Marsh cone measurement corresponds well to viscosity determined at high-shear rates ranging between 340 and 510 s-1. Because of the pseudo-plastic behavior of structural cement grouts, field quality control tests should include fluidity assessment at low and high shear rates to adequately evaluate the rheological behavior of the grouts.