Properties Of Cement Matrix Research Articles

Utilization of silica fume coated waste PET flakes in concrete

The purpose of this study is to use SF-coated flakes obtained from PET bottles in cementitious materials instead of SF-uncovered PET discarded flakes. The fundamental objective of this experiment is to see how encapsulating waste plastic materials with mineral additives such as silica fume impacts the fresh and stiffen characteristics of concrete. A previous investigation into the usage of several kinds of plastic shapes in the cement pastewas also conducted. The inadequacy of connecting between both the concrete mix and the plastic is the main source of concern, as the strength falls short of the grade's requirements. The goal of this research is to increase the interfacial adhesion of discarded PET flakes with cementitious material by covering them with a chemical additive like silica fume and using epoxy resins as an adhesive. Either of these benefits includes that by using plastic materials leads to lightweight concrete, determined by the amount of discarded plastic contained. The experiment was carried out by combining PET plastic flakes with dimensions of (10 × 15) mm. as bond weight at four different intervals of 0 %, 1.5 %, 3 %, and 4.5 %. The contemporary and solidify properties of cement matrix were examined over the inclusion of SF-coated plastic flakes and conventional PET flakes.

Identifying the influence of redispersed polymers on cement matrix properties

The physical-mechanical influence and chemical effect of calcium formate, vinyl acetate/versatate, and vinyl-acrylate copolymer on the processes of solidification, hardening, and structure formation of the cement matrix were studied during the research reported here. The compositions of mixtures containing additives in the amount of 1, 3, and 5 wt % were investigated. Noteworthy is the water-holding nature of vinyl acetate/versatate and vinyl-acrylate copolymer. With the introduction of appropriate additives, an increase in working time of the mixtures is noted, which was manifested in prolonging the end time of solidification duration. Calcium formate reduced the end time of solidification duration with an increase in the content of the additive. During 28 days of hardening, a decrease in strength gain was observed with an increase in the content of the additive compared to control samples. At 1 wt % of the additive, the decline in strength on day 28 was 8.7 % for calcium formate, 13 % for versatate, and 15.5 % for vinyl-acrylate copolymer. For versatate and vinyl acrylate with the addition of 3 and 5 wt % in the mixture, the loss of strength is 23–25 % and 27–56.7 %, respectively. 5 wt % calcium formate admixture, compared to 3 wt %, on day 7 and day 28 of hardening has a higher strength index. This nature of the effect of additives is explained by the formation of polymer structures throughout the volume of the mixture with the introduction of versatate and copolymer vinyl acrylate, as well as their chemical interaction with the components of the cement binder during hydration in the formed alkaline medium. Calcium formate plays the role of both a filler and a hardening accelerator due to the introduction of an additional amount of calcium ions. The reported results can be used as a basis for continuing to study the effect of redispersed additives on the durability of cement articles, the development of new formulations for building mixtures, and their potential use in the production of concrete.

Mechanical properties and antifreeze performance of cement-based composites with liquid paraffin/diatomite capsule low-temperature phase change

Freezing-thawing cycles is one of the most common and severe factors to concrete in service. The research focuses on breaking through the bottleneck of passive frost resistance of traditional concrete materials. Based on the principle of phase change heat storage and release, liquid paraffin/diatomite microcapsule phase change material was prepared by controllable assembly method. Its physical and chemical properties and thermal properties were explored by modern characterization methods. At the same time, it is introduced into the cement matrix to explore its specific effects on the thermal conductivity, mechanical properties and frost resistance of concrete materials. The results show that liquid paraffin/diatomite capsule phase change materials (CPCMs) cement-based test block has stable chemical properties and excellent thermal properties. The heat resistance limit is 280 ℃. Adding liquid paraffin/diatomite capsule phase change material will weaken the thermal conductivity and mechanical properties of cement matrix, but at the same time, it will significantly improve the frost resistance of cement matrix. The mass loss after freeze–thaw cycles can be reduced by 47%, the compressive strength loss and flexural strength loss are reduced by 186% and 99%, respectively. The negative effect of liquid paraffin/diatomite capsule phase change material on the flexural strength of the cement matrix is greater than the compressive strength.

Synergistic effects of carbon black and steel fibers on electromagnetic wave shielding and mechanical properties of graphite/cement composites

This study is focused to develop a broadband and high-efficiency electromagnetic (EM) shielding cement composites by the application of different scales conductive fillers, such as graphite, carbon black (CB) and steel fiber. The synergistic effect of CB and steel fibers addition on the EM wave shielding/absorbing characteristics and mechanical properties of cement matrix with 10 % graphite by weight to cement was examined. The results reveal that the shielding properties can be visibly enhanced by the addition of CB and steel fibers, and the maximum shielding efficiency (SE) of 73.7 dB and average SE of 59.3 dB of the graphite/cement composite with 1 % CB and 30 % steel fibers (by weight of cement) can be obtained, and the bandwidth for SE > 50 dB reaches 14 GHz (4–18 GHz). In addition, the EM wave absorption capacity is also acceptable, the reflection loss of the graphite/cement composite contains 2 % CB and 10 % steel fibers can be lower than −5 dB in 6–18 GHz. Thus, the developed cement-based composite can better solve the issue of EM pollution due to the excellent shielding and absorption properties, avoiding the secondary pollution caused by completely reflective shielding. Furthermore, the mechanical properties which can meet the requirements of conventional engineering applications was achieved, the maximum flexure and compressive strength exceed 10 MPa and 40 MPa, respectively.

Effect of the MCM-41 mesoporous silica on the microstructure and performance of cement matrix

The paper describes the results of research on the influence of the MCM-41 mesoporous silica on the selected properties of cement matrix. The MCM-41 used in the study was produced from waste solution after production of synthetic ash zeolites, which made the material much cheaper than its commercial counterparts. Mechano-physical properties were evaluated and the microstructure was analyzed by XRF, XRD, SEM-EDS, and nitrogen adsorption/desorption tests. The most beneficial content of the MCM-41 was found to be between 0.5 and 1%. It was noticed that the excess of active silica causes disturbances in the proper hydration process, which was schematically modeled. No studies have been reported in the literature so far which would be devoted to the assessment of the influence of the MCM-41 on the properties of the cement matrix, and the research conducted indicated a very high application potential of this additive.

Cement matrix containing lightweight aggregate based on Non-Metallic Fraction Printed Circuit Boards (NMFPCB'S)

Materials such as river sand, used in construction, have a high demand, and thus generate great environmental impacts while being extracted, such as erosion of the rivers banks and your siltation. With the increasing restriction of river sand extraction which can generate a reduction in the product's offer in the civil construction sector, it is necessary to develop waste recycling technologies for the production of sands with less environmental impact. One of the alternatives for the production of mortar for construction is the replacement of sands extracted from rivers by waste from other industries, such as the electronics industry that presents large and growing production worldwide, due to technological advances. Thus, this work aims to evaluate the influence of partial replacement of quartz sand by lightweight aggregate based non-metallic fraction of printed circuit boards (NMFPCB's) on the properties of cementitious matrix in the fresh and hardened states. For this, the electronic components of the printed circuit boards (PCBs) were removed, they were grinded and then through magnetic and electrostatic separation processes to separate the most valuable and abundant part of metals. The water to cement ratio was 0.48 in all the experiments, the Portland cement to sand ratio was 1:3 (in mass) for the control, and the mortars with NMFPCB's replacement of sand by volume of 25% and 50% were also made. These were characterized mechanically by axial compressive strength test at different ages. The partial results showed that with the increase of sand substitution by NMFPCB's there was a reduction of the mortar consistency index in the fresh state. Results showed that matrix that suffered the substitution of sand by light aggregate, decreased the compressive strength in relation to the reference, but have potential to use in construction industry as blocks or non-structural elements.

Study on surface modification of CaSO4 whisker and mechanism of enhancing mechanical properties of oil-well cement

Based on the mechanism of whisker strengthening cement, this study used ethyl orthosilicate (TEOS) to modify CaSO4 whisker (CSW) to improve the mechanical properties of cement matrix. The designed structure and morphology of modified CaSO4 whisker (MCSW) were characterized by means of FTIR, SEM, XRD, contact angle and XPS. The test results showed that SiO2 was successfully grafted on the MCSW due to the reaction between Si(OH)4 and –OH on surface of MCSW. Subsequently, the improvement effect of MCSW on the mechanical properties of cement matrix was investigated, and the mechanism of MCSW reinforced cement stone was studied by means of SEM, XRD, and 29Si NMR. Results indicated that the compressive, flexural and splitting tensile strength of cement with MCSW were 1.86, 2.31, 1.62 times higher than those of cement with CSW, respectively. The triaxial stress-strain curve of MCSWC showed higher strain capacity. The SEM analyses displayed that MCSW was tightly wrapped by hydration products. The XRD and 29Si NMR analyses revealed that SiO2 covered on MCSW surface participated in hydration reaction and form more C-S-H chains, which enhanced the interfacial adhesion between MCSW and cement matrix and thus improved the mechanical properties of oil well cement.

The single freezing episode of early-age cementitious composites: Threshold properties of cement matrix ensuring the frost resistance

The freezing is recognized as one of the most dangerous phenomena jeopardizing the durability of cement-based materials. In this work, the cementitious material exposed to a single freezing event after 1, 2, 3, 7, 14, 21, and 28 days of hydration was investigated. The change of mechanical parameters, e.g. compressive strength and Young’s modulus, due to individual water crystallization was determined. Water freezing in cement paste proceeds at depressed temperature, which can be calculated using Gibbs-Thomson equation. The change of the in-pore ice content profile in temperature domain along with hydration was calculated using differential scanning calorimetry and was related with the degradation of mechanical properties. The two dominant mechanisms inducing water freezing can be recognized in cement paste: gradual ice penetration and ice nucleation. The change of microstructure along with hydration was monitored using mercury porosimetry. These observations allowed to determine the threshold properties which provide the resistance of cementitious materials to the single freezing at early age. The research was supplemented with isothermal calorimetry and XRD data of the applied binder.

The Use of Palm Oil Mill Effluent as Mixing and Curing Water in Cement-Based Composite

The scarcity of water, especially during the dry season, is the main factor influencing water consideration with unknown characteristics for mixing cement mortar and concrete. This study investigates Palm Oil Mill Effluent (POME) effects as mixing and curing water on the hardened cement matrix properties. The cement pastes were prepared with ordinary Portland cement, which was used as a binder. In contrast, Potable Water (PW) and POME were used separately for mixing cement and a mixture of cement and sand to produce cement paste and cement mortar, respectively. Two different mix ratios of cement: sand of 1:3 and 1:5 with the constant water-to-cement ratio of 0.5 were used to prepare the cement mortar. The PW and POME were also utilized as the liquid curing media for hardened cement mortar until the testing ages of 7, 14, and 28 days. Soundness, normal consistency, and setting times tests were performed to evaluate cement paste’s fresh properties, while unit weight and compressive strength tests to determine the hardened properties of cement mortar at different ages. The results showed that soundness, normal consistency, and setting times of cement paste with POME as mixing water were higher than that of PW. This indicates that POME exhibits the potential of serving as retarding admixture. The unit weights of mortar (1:3 or 1:5 mix proportion) with POME as mixing water were lower than those produced with PW as mixing water after curing in PW or POME for 28 days; but for the mortar with POME as mixing water, the unit weight was slightly higher when cured in POME than water at the same curing age. The mortar specimens with 1:3 mix proportions with PW as mixing and curing water had the maximum 28-day compressive strength values of 26.01 N/mm2, while a decrease of 20% was recorded when cured in POME. Further decrease in 28-day compressive strength values was recorded cement mortar with 1:3 mix proportions and POME as mixing water after being cured in PW and POME. A similar trend was observed for cement mortar with 1:5 mix proportion with POME as mixing water when cured in PW and POME, and PW as mixing water when cured in POME, compared with the cement mortar with PW when cured in PW for 28 days. The maximum strength reduction of 20% specified by the standard for cement composite or concrete at 28 days of curing for water from the questionable source was exceeded with the use of POME as mixing water. It can be concluded that POME is not suitable for mixing cement mortar.

The Synergistic Effect of Secondary Raw Materials and Nano Additive on the Properties of Cement Matrix

The purpose of the research presented in this paper was to analyse the synergistic effect of nano SiO2 (NS), fluidized catalytic cracking catalyst waste (FCCCw) and calcinated at 700°C temperature paper sludge waste (PSw) on the properties the cement matrix. Nano materials are known to reduce voids between cement particles, accelerate cement hydration, and increase the strength of cement matrix. A certain amount of FCCCw and PSw in the cement mix also accelerates cement hydration and increase the compressive strength of the system, but it is important to analyse the synergistic effect of these materials on the properties of cement matrix. The results showed that both waste materials are active pozzolanic additives. The optimal quantities in terms of positive effect on the cement matrix are 10% of FCCCw and 2.5% of PSw. The paper presents the results of XRD analysis, density, ultrasonic pulse velocity and compressive strength tests with hardened cement paste. A 22% increase in compressive strength compared to the control specimen was observed in specimens where 10% of cement was replaced by FCCCw and where NS was additionally added. The replacement of cement by 2.5% of PSw increases the compressive strength about 7%. Moreover, the compressive strength of specimens containing 10% of FCCCw, 2.5% of PSw and NS increases even though the content of cement is reduced. Hardened cement paste specimens containing FCCCw, PSw, and NS have better density and ultrasonic pulse velocity values. XRD analysis showed that a combination of FCCCw, PSw, and NS added to the cement mix increases the amount of calcium hydrosilicates formed, reduces the amount of free portlandite and unreacted cement minerals (allite and belite).

Advanced characterisation of the early age behaviour of bulk hydrophobic mortars

Over the last 15 years, bulk hydrophobic treatment of cementitious materials with silanes and siloxanes is in the scientific focus. They are beneficial in terms of reducing water uptake by capillarity, however, this is often followed by an impact on cement hydration leading to the decrease in structural properties of cement matrix. The aim of this paper is to study the influence of different incorporation modes of a silicone-based hydrophobic agent used for the bulk hydrophobic treatment of mortars, and to evaluate their effect on cement hydration and the early age properties. Two different incorporation modes are compared: an emulsion of silane and silicone resin and microencapsulation of silicone resin. Each of these is incorporated in mortars prepared with CEM I and CEM III/A. Based on the combined measurement of isothermal calorimetry, electrical resistivity, ultrasonic pulse velocity, compressive strength, thermal expansion coefficient and autogenous deformation at early age, it is shown that the emulsion, as a delivery method of hydrophobic agent, affects the early age mechanical behavior of cement-based systems, for both types of cements. The microencapsulation on the other hand, prevents these effects from occurring, and is therefore suitable for bulk hydrophobic treatment.

Flexural response and durability aspects of ECC containing stone slurry powder

Depletion of natural resources and generation of solid wastes has become worldwide problem. The present investigation emphasizes the potential use of stone slurry powder in engineered cementitious composite. In this study, silica sand (SS), locally available fine river sand (FS), was used as fine aggregate and SSP was used as partial replacement of SS and FS by 25% and 50% for each type of sand. The performance of various mixes was evaluated by assessing the flexural, electrical resistivity, air permeability and sorptivity characteristics. To assess the microstructural properties of cement matrix, material characterization was also done. The findings demonstrate that utilization of SSP as SS and FS replacement in ECC increased the flexural strength, mid-span deflection and electrical resistivity and also showed positive results by decreasing air permeability and sorptivity. From this study, it is concluded that the use of SSP as SS and FS subrogation promotes the unique characteristics of ECC and also can be applied in harsh environmental conditions.

Improving Saudi Class G Oil-Well Cement Properties Using the Tire Waste Material.

After oil and gas well drilling, they should be cased and cemented to ensure the stability of the wellbore and to isolate the trouble zones. To achieve these jobs, several additives are incorporated into the cement slurry to improve the cement matrix durability, especially at temperatures above 230 F. The tire waste material is an industrial waste that comes from automobile tires. The purpose of this work is to investigate the prospect of utilizing tire waste in oil-well cement under high-temperature and high-pressure conditions of 292 F and 3000 psi. Three cement samples with different concentrations of the tire waste material were prepared. The effects of tire waste on the cement rheological properties, elastic and failure parameters, and permeability were examined. The results showed that adding 0.3% by weight of cement (BWOC) of the tire waste material considerably improved the cement to the cement slurry and cement matrix properties, and it decreased the cement plastic viscosity by 53.1% and increased its yield point by 142.4% compared to the base cement. The cement samples with 0.3% BWOC of tire waste have Young’s modulus which is 10.8% less than that of the base cement and Poisson’s ratio of 14.3% greater than that of the base cement. By incorporating 0.3% of the tire waste, both compressive and tensile strengths of the cement increased by 48.3 and 11.7%, respectively, compared with those of the base cement. The cement permeability was decreased by 66.0% after adding 0.3% of the tire waste. Besides the improvement in the properties of cement, the use of the tire waste material has other economical and environmental advantages because these are very cheap materials dominant in our life.

The effect of methyl hydroxyethyl cellulose on the cement matrix properties

The effect of a methyl hydroxyethyl cellulose additive on the technical and physical-mechanical properties of the cement matrix has been investigated. The study involved cellulose ether of low (11,000–16,000 MPa∙s), medium (17,000–23,000 MPa∙s), and high (20,000–30,000 MPa) viscosity. The additives were introduced into cement in the amount of 0.25, 0.5, and 0.75 % by weight. It has been established that the introduction of cellulose ether in cement leads to an increase in the normal density of the slurry and extends the duration of the mortar setting. The normal density of cement slurry increases with the introduction of cellulose ethers of low viscosity (LV) and medium viscosity (MV) by 5.4‒16.8 %; when introducing the ether of high viscosity (HV), by 21.3–41.4 %. This confirms the high water-retaining capacity of methyl hydroxyethyl cellulose, which increases with increasing viscosity of the additives. The setting duration of cement slurry increases, depending on the concentration and viscosity of the additives, by 2‒4 times, compared with an additive-free material. There is also a significant reduction in the strength of the cement matrix in the early periods of hardening (1–7 days) depending on the concentration of the additives, by 2.2–4.2 times. The strength of the samples is least affected by the cellulose ether of low viscosity, largest – by that of high viscosity. The reduction of strength is observed at the age of 28 days, although not very much pronounced. Compared to the additive-free cement, the strength amount to: for the ester of low viscosity at concentrations: 0.25 % by weight – 14.3 %, 0.50 % by weight – 23.9 %, 0.75 % by weight – 40.5 %; for the ether of medium viscosity, respectively, 23.8, 26.2, and 33.3 %; for the ether of high viscosity, 28.6; 45.2, and 61.0 %. The corrosion resistance of the cement matrix with methyl hydroxyethyl cellulose additives is increased at a concentration of up to 0.25 % by weight and then gradually decreases. The above results make it possible to recommend using, in the production of dry construction mixtures, the cellulose ethers of low and medium viscosity, which would ensure the required time to maintain the solution mobility and the sufficient strength of the resulting material

Foam concrete production with addition of microsilica

The article deals with the influence of microsilica on technological properties of cement matrix and finished foam concrete. The possibility of replacing a part of the binder with microsilica was evaluated.

Physical properties and microstructure of plastic aggregate mortars made with acrylonitrile-butadiene-styrene (ABS), polycarbonate (PC), polyoxymethylene (POM) and ABS/PC blend waste

This paper investigates cement mortars made with waste plastic aggregates (polycarbonate-PC-, polyoxymethylene -POM-, acrylonitrile-butadiene-styrene -ABS-, an ABS/PC blend -ABSC- and polyethylene terephthalate -PET-) as partial sand replacements at 5–20% by volume.Even at 20% plastic content, the strength surpasses the standard strength requirements for masonry, rendering and plastering mortars, with compressive strengths ranging from c.37–71 MPa and flexural strengths reaching 4–9 MPa. Most plastics, in contents up to 15%, enhance the flexural strength of the standard cement mortar which can improve the resistance to tensile stress caused by loading and expansion by frost, salt or swelling clays.The plastic aggregates increase the cement mortar's ability to deform on stress application, delaying failure and turning the typical brittle failure of cement mortars into a ductile failure, a notable asset for those specifying repair mortars for masonry which typically deforms over time.The fall in the mechanical/hygric properties and density caused by the plastic (>15% content), is mainly due to the proliferation of disrupted interfaces rather than to the physical properties of the plastics themselves. There is not significant direct correlation between the properties of the mortars and those of their plastic aggregates – except for the compressive strength. The relationship can sometimes appear inverse, suggesting that larger differences between plastic and cement matrix properties can enhance incompatibility and lower durability. However, the grading, shape and surface characteristics of the plastic particles impact the properties of the resultant mortars. The results highlight the performance of the ABS (best graded plastic) barely rising the hygric properties, even at 15% replacement, and showing high strengths and sealed interfaces.

Uncertainty quantification of the mechanical properties of lightweight concrete using micromechanical modelling

This paper presents a micromechanical modelling framework for analysing the effects of microstructural uncertainties on the mechanical properties of heterogeneous materials. Specialised to lightweight concrete, the proposed framework addresses numerous microstructural uncertainties including the random size, spatial distribution and volume fraction of lightweight expanded polystyrene (EPS) inclusions, as well as the variation of cement matrix properties. A ”taking-placing” algorithm was used to realistically generate three-dimensional, heterogeneous microstructures of EPS concrete with EPS particles embedded into the cement matrix. The nonlinear behaviour of the cement matrix and EPS particles were taken into account by damage and plasticity material laws. By modelling the size, volume fraction and spatial distribution of EPS particles, as well as the properties of the cement matrix as stochastic parameters, the developed model can quantify the inherent uncertainty of EPS concrete. Extensive Monte Carlo simulations for more than 900 EPS concrete samples were performed for uncertainty quantification using finite element modelling. Enabled by a developed automated workflow, the proposed method can simultaneously perform a large number of computational steps on a single platform. A good agreement between the numerical and experimental results was obtained. The significance of each microstructural uncertainty on the mechanical behaviour of EPS concrete was examined in detail. In addition, the effect of particle size on EPS concrete was investigated. While this study focuses on the uncertainty quantification of EPS concrete, the proposed method can be applicable to a wide range of heterogeneous materials.

Evaluation of coppe slag as aggregate addition on properties of cementitious matrix

This work aims the performance of concretes copper slag-added evaluated in fresh state by slump test and in hardened state by compression strength in 7 and 28 days of cement hydration, durability indexes as water absorption and binder efficiency by cement index. In fresh state, the results showed that the samples with copper slag presented lower slump than the reference sample. In hardened state, with 30% of copper slag addition, the compression strength was reduced only by 9% and 8% in comparison with the control series, for 7 and 28 days, receptively. Also, for 28 and 48 days of cement hydration, the water absorption showed lower values in the series with copper slag, indicating a beneficial performance of this waste in the cementitious matrix. Also, the binder efficiency was verified in the work. As the higher the slag in the mixture, lower was the cement consumption and, consequently, higher was the efficiency of the cement, resulting in a low increased in the cement index. The control series, at 28 days of cement hydration, achieved 11 kg·m-3·MPa-1 while the 30% copper slag-added series achieved 12 kg·m-3·MPa-1, which is only 9% higher than series with no consumption of copper slag, indicating a great performance of the copper slag in this cementitious matrix. Keywords: copper slag; cementitious matrix; replacement; concrete.

The Laboratory Examination of Cement Matrix with Inbuilt Hazardous Waste

This paper deals with laboratory examination of cement matrix with inbuilt hazardous waste of its different contents. The paper examines the influence of waste content on the properties of cement matrix using the verification the physic-mechanical properties. These properties will be examined also at different time periods to examine the durability of designed cement matrices.

Influence of Selected Metal Oxides in Micro and Nanoscale on the Mechanical and Physical Properties of the Cement Mortars

The paper describes the results of the influence of three metal oxides’ particles: microparticles of Fe2O3 (d ≤ 5 μm) and Fe3O4 (d ≤ 5 μm) as well as nanoparticles of NiO (d ≤ 50 nm) on the cement matrix properties. Four different contents of each metal oxides’ particles were applied: 0.5, 1, 2 and 3 wt.%. The studies regarding different physical and chemical parameters of cement matrix specimens such as compressive strength, water absorption, microscopic and structural properties have been carried out and the results of these studies are presented and discussed. It was shown that the micro and nanoparticles in the amounts of 2÷3 wt.% can influence the cement hydration process and thereby enhance the compressive strength of mortar. The higher enhancement was obtained during the first seven days of hardening due to so called filling effect. In the following stage of hydration the strengthening effect diminished. This phenomena was convergent with the XRD analysis, which proved that the micro- and nano-particles did not react with the cement paste components.