Sulfate Resistance Of Cements Research Articles

Study of waste-derived high-sulfate artificial aggregates with regenerative capacity

To develop artificial aggregates (AAs) with potential for large-scale applications, this study focused on artificial high-sulfate aggregates (AHAs) with recycling capacity, prepared using various solid wastes, and a sulfate-resistant concrete system was designed. AHAs are prepared using a slurry consisting of ground granulated blast-furnace slag, steel slag powder, and phosphogypsum. Combining AHA and sulfate-resistant cement produces sulfate-resistant concrete. The results show that the produced aggregate is lightweight, and the PA-3 samples exhibit cylindrical compressive strength (10.77 MPa) close to that of natural aggregates. The PA-3 sample contains more C–S–H gels and has a denser structure owing to the formation of protofibrous ettringite at the appropriate Ca/Si ratio. Microanalysis of the mortar–aggregate interface in concrete reveals that S is the key element distinguishing the aggregate from the mortar. Moreover, the results indicate that some of the AHAs have regenerative capacity, and their waste can be reintroduced into aggregate production. This study aims to inspire research and development in the field of sulfate-resistant concrete systems and promote the wider use of AHAs in the concrete market.

Research on the Classification of Concrete Sulfate Erosion Types in Tumushuke Area, Xinjiang

Tumushuke, a significant node of “the China–Pakistan Economic Corridor” and “the Silk Road Economic Belt”, is strategically located in the southern region of Xinjiang. Due to the widespread distribution of its salty soils, concrete construction safety is significantly compromised. The construction of this project used sulfate-resistant cement, which was costly to construct. Six groups with varying sulfate immersion concentrations were set up to perform sulfate erosion tests and sulfate freeze–thaw coupling tests, respectively, based on the survey of the distribution of sulfate concentration in the area. The Tumushuke area’s concrete erosion kinds were classified using a microanalysis of the degraded concrete. The findings indicate that the concrete primarily exhibits gypsum-type erosion when the sulfate concentration is greater than 20,000 mg/kg, ettringite–gypsum-type erosion when the sulfate concentration is between 15,000 and 20,000 mg/kg, and ettringite-gypsum-type erosion when the sulfate concentration is less than 15,000 mg/kg. The erosion product, carbon–sulfur silica-calcite, also occurs under sulfate freeze–thaw coupling. In the Tumushuke area, ettringite-type erosion damage is primarily found in low-sulfate areas in the southwest and a small portion of the northeast. In contrast, higher-sulfate areas in the central northward area are primarily affected by ettringite–gypsum and gypsum-type erosion damage. The results of this study can provide a basis for adopting different anti-sulfate erosion measures for engineering construction in different regions.

Assessment of mechanical, durability and microstructural performance of sulphate-resisting cement concrete over portland cement in the presence of salinity

The current understanding of the sulphate attack mechanism on ordinary Portland cement (OPC) concrete within the construction sector is not yet well understood. The primary objective of this study is to focus on and discuss how to minimize the sulphate attack on concrete. The main purpose of this research is to better understand and improve the mechanical, durability, and microstructural characteristics of concrete under saline and non-saline/normal environments. This investigation involved the use of artificial seawater in the concrete mixing process and ensuring saline conditions for the concrete specimens in the laboratory. In addition, an approach for assessing the influence of using sulphate-resisting cement (SRC) in concrete to differentiate the performance from OPC concrete is also investigated. Silica fume (SF) is used as a partial cementitious material in SRC concrete by 10% and 20%. The concrete performances were examined by several rheological, mechanical, durability, and microstructural tests and compared the corresponding performances with the SRC-artificial seawater (SRCASW) and OPC-freshwater (OPCFW) concrete. Test results show that the strength of concrete decreased linearly from the OPCFW to SRCASW. Among SRC-artificial seawater concrete mixes, the mix with 10% SF shows the best strength outcomes i.e., 28.84, 36.22, and 37.54 MPa at 7, 28, and 56 days respectively, which is an average of 12.5% higher than the mix with 20% SF. A concrete mix of SRC with 10% SF displays the highest durable behavior, achieving chloride penetration and electrical resistivity at a very low range (936 columbus and 290.7 Ω-m, respectively). In addition, microstructural images of the SRC concrete mixes indicate no visible crack due to sulphate inclusion. An analytical approach has provided a conservative estimate with the experimental results and standard code of practice for predicting mechanical properties. Finally, this study revealed that SRC incorporation in concrete increased the long-term serviceability of the structures against salinity.

Behavior of Potential of Half-Cell AISI 1018 and GS in Concrete Buried in Sand in the Presence of MgSO4

This project, in the area of reinforced concrete corrosion, evaluated the potential of half-cell AISI 1018 CS (Carbon Steel) and GS Steel (Steel with galvanized coating); 15 cm long bars were used as reinforcement in specimens of concrete buried in a Type SP Sand (contaminated with 0% and 3% MgSO4). The experimental arrangement of this research represents the case of the elements of the foundations of concrete structures that are planted near marine areas where this type of soil exists with the presence of high contents of depassivating ions such as sulfates. The study specimens were made with two concrete mixtures with a water/cement ratio 0.45 but with different types of cement (Portland Cement and Sulfate Resistant Cement). For monitoring the half-cell potential according to ASTM C 876-15, the specimens were buried in the clean SP soil and in the same soil but contaminated with MgSO4. After more than 270 days of exposure to uncontaminated SP sand contaminated with MgSO4, the behavior of the half-cell potentials or corrosion potentials show that the specimen made with the sulfate-resistant cement and reinforced with GS Steel (Steel with galvanized coating) presents the highest resistance to corrosion by MgSO4 at a concentration of 3%.

Self-Compacting High-Strength Textile-Reinforced Concrete Using Sea Sand and Sea Water.

In this study, a self-compacting high-strength concrete based on ordinary and sulfate-resistant cements was developed for use in textile-reinforced structural elements. The control concrete was made from quartz sand and tap water, and the sea concrete was made from sea water and sea sand for the purpose of applying local building materials to construction sites in the coastal area. The properties of a self-compacting concrete mixture, as well as concrete and textile-reinforced concrete based on it, were determined. It was found that at the age of 28 days, the compressive strength of the sea concrete was 72 MPa, and the flexural strength was 9.2 MPa. The compressive strength of the control concrete was 69.4 MPa at the age of 28 days, and the flexural strength was 11.1 MPa. The drying shrinkage of the sea concrete at 28 days exceeded the drying shrinkage of the control concrete by 18%. The uniaxial tensile test showed the same behavior of the control and marine textile-reinforced concrete; after the formation of five cracks, only the carbon textile reinforcement came into operation. Accordingly, the use of sea water and sea sand in combination with a cement with reduced CO2 emissions and textile reinforcement for load-bearing concrete structures is a promising, sustainable approach.

DEF of high-performance concrete with rapid, non-standard heat-treatment

High-performance concrete is often heat-treated to increase early strength. Standardized temperature conditions for at least 24 h and sulphate-resistant cement thereby preventing delayed ettringite formation (DEF). In contrast, this paper investigates the risk of DEF for rapidly heat-treated HPC with a minimum temperature duration of 1 h to achieve a rapid early strength for stripping. In addition, a binder is used that does not exhibit increased sulphate resistance. For this purpose, standard prisms (L x W x H = 16 × 4× 4 [cm]) are heat-treated at 80 °C between 1 and 6 h without a pre-storage time. Samples with a temperature duration of 24 h serve as reference. First, the pore structure is analyzed using Mercury porosimetry to identify damage to the concrete matrix due to the rapid heat treatment. The investigation of DEF is achieved by two common approaches. The sulphate resistance is determined by means of wet-dry cycles on specimens for 90 days, whereby the changes in mass and strain as well as the cracking pattern on the concrete surface serves as a qualitative evaluation criterion. In addition, the SVA method on specimens directly after heat treatment, which determines the change in mechanical properties and the swelling behaviour of the concrete, leads to a quantitative evaluation of sulfate resistance. The measured pore distribution of the samples shows a significant increase of the capillary pores of up to 109% for decreasing temperature durations. However, the porosity does not affect the sulphate resistance of the concrete. The wet-dry cycles cause no damage due to DEF, since the change in mass and strains decreases with increasing cycles from up to 62.7% to − 2.5%. Furthermore, no visual differences were detected on the concrete surface between specimens with and without sulphate attack. As a result of the SVA test, maximum absolute strains of about 0.1 mm/m occur that are below the limit value of 0.152 mm/m. Also, the mechanical properties do not show a reduction in strength, but even an increase in tensile strength. In conclusion, the high-performance concrete formulation used in combination with rapid heat treatment investigated here did not result in detectable damage due to DEF.

Enhancing the Properties of Sulfate-Resisting Cement

Sulfate-resisting cement is used in construction works when a sulfate attack is probable. This type of cement withstands sulfates due to its low C3A content. On the other hand, the decrease in the quantity of C3A leads to a reduction in the rate of early strength development. To overcome this problem, a hardening accelerator was added to the cement mix. To estimate the effect of the accelerator on some properties of hardened cement, compressive and flexural strength, and drying shrinkage tests were carried out. Four series of cement mortar mixes were made. The hardening accelerator was not added to the control series, while it was added to the others with three different percentages (of cement mass) of 0.5, 1, and 1.5%. The results revealed that the hardening accelerator enhances the compressive strength of all mortar ages while it slightly promotes flexural strength only at early ages. It was also observed that the hardening accelerator strongly inhibits the drying shrinkage strain.

Effect of Polycarboxylate Superplasticizer in Ordinary Portland Cement and Sulfate Resistant Cement

Polycarboxylate superplasticizers (PCE) are the most widely used admixtures in today’s cementitious construction materials. The molecular structure has a decisive influence on the effectiveness of PCE, which also can be tailored to serve in a different cementitious system. The current study investigates the influence of the backbone charge density of PCE on the rheology, hydration kinetics, and adsorption behavior of ordinary Portland cement (OPC) and sulfate-resistant cement (SRC). The results indicate that regardless of the PCE type, OPC requires a higher amount of PCE to be adsorbed to induce changing of rheological parameters and hydration kinetics. Regardless of the cement type, the PCE with a higher charge density exhibits higher adsorption behavior, corresponding to lower viscosity measurement. Compared to OPC, SRC is more sensitive to the introduction of both PCEs and has a lower saturation dosage, indicating that SRC generally provides better workability properties regardless of the PCE.

Effect of Hydrophobic Water Repellent Admixture on the Compressive Strength of Concrete in Highly Aggressive Water (Dead Sea Water as a Case Study)

The compressive strength of concrete may be affected by seepage of salt water. Dead Sea water is a hazardous environment for concrete due to high concentration of salts. The aim of this study was to investigate the effect of Dead Sea water on the compressive strength of concrete containing hydrophobic water-repellent admixture, and to determine the optimum dosage of admixture to be used to reduce this effect. Three types of cement were used (Ordinary Portland Cement, Pozzolanic Cement, and Sulphate-Resisting Cement) with various dose rate of hydrophobic water repellent admixture (0%, 2%, and 4% of cement weight). An experimental approach, in which the specimens were divided based on the type of cement and the specimen’s age, was adopted. Nine control cubic specimens were cured in plain water to ensure that the required compressive strength was reached and (54) specimens were cured in Dead Sea water. The specimens cured in Dead Sea water were tested at 7 and 28 days to investigate the effect of Dead Sea water on the early and long-term strength. The results showed that a reduction in the 28-day compressive strength occurred in all specimens for the three types of cement used, but with the addition of water repellent, this reduction was alleviated, and the optimum percentage of admixture was 2% of cement weight.

Performance of Portland Cement and Sulfate Resisting Cement Concretes against Chloride Attack under different curing Methods

Performance of Portland Cement and Sulfate Resisting Cement Concretes against Chloride Attack under different curing Methods

Surface treatment with silicon-based nanoparticles in Portland cement specimens subjected to physical sulfate attack

The use of simple (SN) or functionalized (FN) silicon nanoparticles in three variants of surface treatments to mitigate the physical sulfate attack was evaluated in mortar specimens made with ordinary portland cement (OPC) or sulfate resistant cement (SR). The treatment variants were: T1 – with a 0.1% suspension of SN, applied by immersion, in the first 72 h of cure; T2 – with a 0.1% suspension of FN, applied by brushing after 28 days of hydration; and T3 – consecutive application of T1 and T2. Subsequently, the specimens were partially immersed in a 5% sodium sulfate solution and subjected to wetting and drying cycles. A physical-chemical characterization was carried out utilizing XRD, XRF, and SEM/EDS and the surface contact angle was determined regularly during the exposure. The results were complemented with a visual analysis of the specimens at the end of the exposure. The results showed that, although the specimens treated with T1, T2 and T3 show a certain degree of deterioration caused by the physical sulfate attack, the treatments have contributed to preventing the entry of the sulfate solution at the beginning of the exposure. Therefore, it is concluded that the treatments are effective in the initial stages of exposure to the physical sulfate attack.

Properties of Rubberized Concrete Prepared from Different Cement Types

At present, global waste tire generation considerably exceeds consumption. Moreover, waste rubber tires (WRTs) are a cause of concern, as huge volumes are being discarded and buried, thus causing serious environmental pollution. Rubberized waste concrete (RWC) is a type of environmentally friendly construction material. The main challenge encountered when manufacturing rubberized concrete is the low adhesive properties between the cement paste and rubber particles. This paper demonstrates the effects, through experiments, of using waste tire rubber instead of recycled coarse aggregate (RCA) on two types of cement, i.e., sulfate-resistant cement (SRC) and ordinary Portland cement (OPC), where SRC is a specially blended cement designed to improve concrete performance and workability in the most aggressive environments. All tested samples contained 10% silica fume (SF) and 0.2% fly ash (FA), and the substitution of recycled aggregate content with waste rubber tier (WRT) at different percentages of 100%, 75%, and 50% was evaluated. The research investigated the synergistic effect on the workability and mechanical properties of various cement types with different amounts of rubber aggregate. It was found that the sulfate-resistant (SRC) type can increase the compressive strength than OPC with a percentage of 25% with the same content of WRT at concrete mix. Moreover, ductility and cracking behavior are improved, and it appears that it is also possible to make lightweight rubber aggregate concrete with this type of mixture.. Using this type of cement, it is possible to restore satisfactory ductility to the waste tires, thus facilitating a reduction in the formation of potential plastic cracks. Moreover, the indicative compressive strength development for SRC with recycled rubber in concrete positively contributes to a reduction in formed cracks. However, SEM microstructural analyses suggest a higher proportion of C–S–H intermixed with sulfate reaction phases of SRC rubberized mortar than those of OPC; thus, given that crystal growth results in a decreased percentage of air voids rather than decreased internal cracking, it is clearly shown that the average crack width increases in OPC mortar compared with SRC. Finally, t-testing was used as an inferential statistical tool to determine whether there is a sizeable distinction between the properties of the two categories of materials, OPC and SRC, by comparing the mean and standard deviation of the values for compressive and tensile strength.

Sulfur concrete made with waste marble and slag powders: 100% recycled and waterless concrete.

In this research, the mechanical properties and durability of sulfur concrete with two different waste aggregates were evaluated. The waste aggregates included ground granulated blast-furnace slag and waste marble powder. The properties of sulfur concrete were also compared with those of the conventional binder concretes (i.e., Portland cement concrete and sulfate-resistant cement concrete). The durability parameters included measuring water absorption capacity and resistance to different harsh chemical environments (5% HCl solution, 5 Molar NaOH solution, and 16% NaCl solution). It was found that sulfur concrete made with slag as aggregate exhibited the maximum strength, i.e., about 2 times higher than that of Portland cement concrete and sulfate-resistant cement concrete. Sulfur concrete made with slag and marble waste powder showed superior mechanical performance compared to that made with river sand. Thus, sulfur binder develops more favorable properties with eco-friendly fillers than it develops with natural sand. In harsh chloride and acidic environment, sulfur concrete with slag powder exhibited about 90-95% lesser mass loss than Portland cement concrete.

Study on the Strength and Hydration Behavior of Sulfate-Resistant Cement in High Geothermal Environment.

The hydration process and compressive strength and flexural strength development of sulphate-resistant Portland cement (SRPC) curing at 20 °C, 40 °C, 50 °C, and 60 °C were studied. In addition, MIP, XRD, SEM, and a thermodynamic simulation (using Gibbs Energy Minimization Software (GEMS)) were used to study the pore structure, the types, contents, and transformations of hydration products, and the changes in the internal micro-morphology. The results indicate that, compared with normal-temperature curing (20 °C), the early compressive strength (1, 3, and 7 d) of SRPC cured at 40~60 °C increased by 10.1~57.4%, and the flexural strength increased by 1.8~21.3%. However, high-temperature curing was unfavorable for the development of compressive strength and flexural strength in the later period (28~90 d), as they were reduced by 1.5~14.6% and 1.1~25.5%, respectively. With the increase in the curing temperature and curing age, the internal pores of the SRPC changed from small pores to large pores, and the number of harmful pores (>50 nm) increased significantly. In addition, the pore structure was further coarsened after curing at 60 °C for 90 d, and the number of multiple harmful pores (>200 nm) increased by 17.9%. High-temperature curing had no effect on the types of hydration products of the SRPC but accelerated the formation rate of hydration products. The production of the hydration products C-S-H increased by 13.5%, 18.6%, and 22.8% after curing at 40, 50, and 60 °C for 3 d, respectively. The stability of ettringite (AFt) reduced under high-temperature curing, and its diffraction peak was not observed in the XRD patterns. When the curing temperature was higher than 50 °C, AFt began to transform into monosulfate, which consumed more tricalcium aluminate hydrate and inhibited the formation of “delayed ettringite”. Under high-temperature curing, the compactness of the internal microstructure of the SRPC decreased, and the distribution of hydration products was not uniform, which affected the growth in its strength during the later period.

Influence of Compaction Energy on Cement Stabilized Soil for Road Construction

Compactness is an important feature to ensure subgrade stability where temperature and water infiltration exist in semi-arid areas. Chemical soil stabilization can improve soil properties. This research studies the impact of compaction energy on stabilized subgrade soil and how to improve its geotechnical characteristics in the experimental tests on both unstabilized and stabilized soil samples by adding ordinary Portland cement and sulfate-resistant cement, in percentages by the soil's weight, in order of identification and classification, to the strength properties tests: compaction at multiple energies, CBR, and UCS. A test protocol was followed to assess the relationship between cement soil treatment, mechanical characteristics, and compaction parameters at different energy levels. Findings show that the higher UCS values were recorded with an increase in compaction energy. The MDD of cement stabilized soil increases as compaction energy increases, whereas the OMC decreases, the UCS improves, and the CBR increases. These improvements have a positive influence on the performance of soil used as a subgrade. The combination of cement stabilization and a high compaction level for subgrades using weak soil can improve strength parameters throughout any phase of earthwork construction design that leads to strengthening subgrades, reducing the thickness, and, as a result, low construction cost. Doi: 10.28991/CEJ-2022-08-03-012 Full Text: PDF

Effect of Polycarboxylic Superplasticizer in Ordinary Portland Cement and Sulphate Resistant Cement

Effect of Polycarboxylic Superplasticizer in Ordinary Portland Cement and Sulphate Resistant Cement

Study of the Mineral and Chemical Variation of the Raw Material Mix Used for Production of the Clinker and the Sulfate Resistant Portland Cement of Al-Hadbaa Plant, Hammam Al-Alil, Iraq

Twenty-four samples (6 samples of raw material mix slurry, 9 samples of cement clinker, 9 samples of sulfate resistant cement) are collected during four months from the production line of Al-Hadbaa Cement Plant, which operates in a wet production method, in Hammam Al-Alil district, south of Mosul city. Some of the studied samples are analyzed for mineral diagnosis by X-ray diffraction device, chemical analysis by X-ray fluorescence device, gravimetric titrimetric chemical methods, and petrographic study for the clinker samples by reflected light microscope and using etching solutions. The research aims to study the variation of the mineral and chemical content in the studied samples. The mineral and petrographical study show that there is no significant difference in the mineral content between the samples of the same type and that the difference is in the percentage of the presence of minerals. The raw materials mix mainly contains calcite and quartz. As for clinker and cement, it contains a lite phase C3S with a stable growth (pure) type with a monoclinic crystal system and a type of unstable growth (impure and containing inclusions) with a trigonal crystal system. In addition to the belite phase C2S of shapes β, α, and ᾱ, the aluminate phase C3A and C12A7 type and the alkaline type containing Na, the ferrite phase C4AF and C2F and the phase of fine crystalline glass. The chemical study indicates that the content of most of the main components SiO2, Al2O3, Fe2O3, CaO, MgO, SO3, Na2O, K2O, TiO2, MnO, P2O5, Cl, and LOI for the raw materials mix, clinker, and cement are close to the samples of the same type of the studied samples. It confirms the proposed specifications by some researchers, except for the deviation in K2O, Fe2O3. It is noticed from comparing the expected clinker content with the actual clinker, as well as calculating some of the qualitative control modules (lime saturation factor, silica, and alumina modulus) to the presence of relative stability in the content of the raw mix and cement produced in the studied cement plant.

Evaluation of Sulphate Resistant Cement and Oil-well Cement Produced in Al-Hadbaa Cement Plant

Twenty-three samples are collected (9 samples of sulfate-resistant cement, 7 samples for each of the oil-well cement, class B and G) during four months from the production line of Al-Hadbaa cement plant, which operates in the wet production method, in Hammam Al-Alil district south of Mosul city. The research aims to evaluate the chemical and physical properties of sulfate-resistant cement and oil-well cement produced in the studied plant according to the approved standard specifications. Some of the samples are analyzed by X-ray diffraction device, and chemically by X-ray fluorescence and gravimetric titrimetric chemical methods. The results of physical tests are obtained (fineness by Blaine method and sieves, water-cement ratio, setting time (initial and final), soundness by autoclave method, and compressive strength) for cement of three types according to the requirements of the Iraqi Standard Specification (no.5, 1984). As well as the results of physical tests (mixing water percent, fineness, slurry density, thickening time, free fluid content, compressive strength, and dry cement density) for oil-well cement are according to the requirements of the American Petroleum Institute specifications for the samples taken from Al-Hadbaa cement plant, which is carried out within the requirements of quality control overproduction. The study concludes that the results of chemical analysis, calculating some of the chemical moduli, percent of mineral phases, and results of physical tests for three types of cement are close in their values, ​​and conforming to the limits of chemical and physical requirements of the Iraqi Standard Specification (no.5, 1984). Except that the aluminate phase C3A content, which is more than the required limit. The results of chemical analysis, calculating the percent of mineral phases, and the results of physical tests for the studied oil-well cement are in conformity to the limits of chemical and physical requirements of the American Petroleum Institute Specifications (API 10A, 2010), for the cement type of moderate resistant for sulfate (class B and G). Except for the values ​​​​of alite phase C3S content, and alkalis (sodium) equivalent Na2OEQ for class G, which are not conforming to specifications.

Mechanical properties of high-ferrite oil-well cement used in shale gas horizontal wells under various loads

As a heterogeneous porous and brittle composite material, oil-well cement cannot withstand the heterogeneous load caused by perforation and fracturing of shale gas horizontal wells, and it is easy to damage the integrity of cement sheath. High-ferrite oil-well cement (HFOC), as a high sulfate-resistant cement, has received extensive attention due to its unique mechanical properties. Based on the service conditions of shale gas horizontal wells, this study discussed the mechanical properties and strengthening and toughening mechanism of HFOC under various loads. The results show that appropriately increasing the content of ferrite in oil well cement can improve the strength and toughness of cement paste. Compared with the Class-G sample, the 28-day compressive strength and tensile strength of the HFOC-3 sample are increased by 19.24% and 51.1%, respectively. The elastic modulus of the HFOC-3 sample is reduced to 6.48 GPa, and the cement paste still has a certain deformation ability under the action of multiple loads. The cement sheath integrity test shows that the HFOC-3 cement sheath can still effectively ensure the cementing quality between the casing and the cement sheath when the cement sheath is damaged. Under impact conditions, the HFOC-3 sample exhibited higher strength and deformation during the energy accumulation stage and the unstable stage. The strengthening and toughening mechanism of ferrite is a synergistic effect of chemistry and physics.

Effects of sulphate resistant cement on marine structural concretes

This examination subject is centered around the capacity of solid method of mortar blend with various concrete sorts which when presented to chloride and sulfate in marine climate influence their solidarity and solidness of the solid. The wellspring of sulfate may either outside or interior. The inside happening sulfate in the climate like ocean water on the sulfate which are the results of mechanical squanders. Interior wellspring of sulfate is the organization of chlorides in addition to sulfates presented in the concrete during fabricate. The solid examples made of various concretes are exposed to the standard test which assesses the solidarity to oppose the chloride and sulfate assaults.