Portland Limestone Cement Concrete Research Articles

Impacts of advanced metals recovery on municipal solid waste incineration bottom ash: aggregate characteristics and performance in portland limestone cement concrete

The optimization of alternative materials in concrete production continues to garner considerable attention in order to meet sustainability goals and supplement natural materials. Portland limestone cement (PLC) and municipal solid waste incineration (MSWI) bottom ash (BA) have been proposed separately as green cement and coarse aggregate supplement in low-strength concrete production, creating sustainable products and alternative disposal scenario for a waste material. This study discusses the impact of advanced ash processing techniques on aggregates and presents the performance of concrete incorporating both of these products with PLC for the first time. Two sources of MSWI BA were investigated, one as-produced (TMR) and one processed with novel advanced metals recovery (AMR). The AMR process reduced total Al content in ash compared to TMR (20,500 vs 17,000 mg/kg), though not aluminum oxide content, as the AMR process targets metallic aluminum. A composition study on both aggregates supports a reduction in ferrous and non-ferrous metals following the AMR process. All control and test mixes met 28-day compressive strength requirements (17 Mpa). Both AMR and TMR MSWI BA-amended concretes yielded compressive strengths below control specimens (no ash) ranging from 17 to 23 MPa, with little to no difference observed dependent on MSWI BA processing. The life-cycle discussion supports benefits deriving from supplementing naturally mined materials and recovering ferrous and nonferrous metals with the AMR process.

Investigation of Compressive Strength of Slag-based Geopolymer Concrete Incorporated with Palm Oil Fuel Ash

The paper investigated the compressive strength of ground granulated blast furnace slag-based geopolymer concrete incorporated with palm oil fuel ash compared to portland limestone cement concrete. An appropriate geopolymer mix design was first determined. This mix entailed fine aggregates: coarse aggregates: cementitious material: liquid ratio of 2: 2.5: 1: 0.5, respectively, with 100% replacement of portland cement with ground granulated blast furnace slag (GGBS) incorporated with palm oil fuel ash (POFA). An alkaline solution was used in place of water containing sodium hydroxide and sodium silicate. Following this design, five geopolymer mixes were prepared, each of varying POFA-GGBS ratios of 0:100, 25:75, 50:50, 75:25, and 100:0, and a 14M alkaline solution was used. In addition, a control mix was determined, comprising 100% portland limestone cement (PLC) as the cementitious material and 100% water. Three cubic samples were casted for each geopolymer mix with the control mix, and then the geopolymer mixes were thermally cured for 24 hours. The compressive strength test was conducted on the test samples after ambient curing of 7 days and 28 days, and values for compressive strength (MPa) and failure load (KN) were recorded. Through comparative analysis, it was determined that the most efficient geopolymer mix was mix 2 of GGBS: POFA ratio of 75:25 with 14M alkaline solution. Mix 2 achieved the highest compressive strength of 65.41MPa, approximately 21.99% higher than the strength attained by portland cement concrete samples, measured to be 53.62MPa. Thus, geopolymer concrete can achieve greater strength than portland cement concrete. Keywords: Alkaline solution, Geopolymer concrete, cementitious material, ground granulated blast furnace slag, compressive strength, palm oil fuel ash

Early-stage assessment of drying shrinkage in Portland limestone cement concrete using nonlinear ultrasound

Second harmonic generation (SHG), a nonlinear ultrasonic technique, holds great promise for reliable structural health management owing to its nondestructive detection of early-stage damage evolution in cement-based materials. Utilizing the SHG technique, this study focuses on elucidating the contribution of limestone to dimensional stability under drying shrinkage in cement-based materials. Specifically, the acoustic nonlinearity parameter β obtained from the SHG is used, together with uniaxial strain and mass reduction, to characterize the microstructural condition near the surface (∼50 mm) of Portland limestone cement (PLC, Type IL) concrete, which is compared to ordinary Portland cement (OPC, Type I/II) concrete. In both PLC and OPC specimens, β increases remarkably compared with other measured parameters (i.e., change in mass, strain). This demonstrates the sensitivity of this approach to the microstructural modification caused by drying shrinkage, allowing for the discrimination in performance of PLC and OPC.

Cement-based concrete modified with Vitellaria Paradoxa ash: A lifecycle assessment

Building sustainable concrete requires an increasing demand for technology, innovation, and alternative binders to cement. The building sector is technologically driven toward sustainable construction materials and their relationship with the environment. Thus, this study designed three grades of cement-based concrete strengths (C 25, C 30, and C 40) modified with an alternative binder, shea nutshell ash (Vitellaria Paradoxa Ash, VPA). The binder (VPA) was varied at 0–20 wt% of Portland limestone cement (PLC) cured at 28 days, examining the compressive strength cost attained sustainability. Moreover, the embodied energy (EE), global warming potential (GWP) and global temperature potential (GTP) of the concrete compositions were evaluated using the inventory of carbon and energy (ICE) method within the confine of cradle-to-site. Also, the sustainability index (Si) and economic index (Ei) of the concrete mixes were assessed. The results revealed that VPA-cement-based concrete yielded a lesser EE, GWP, GTP, Si, and Eci than the control concrete (Portland limestone cement concrete, PLCC), indicating VPA-cement-based concrete is more sustainable than PLCC. Notwithstanding, an optimum replacement of 15 wt% PLC with VPA is recommended to satisfy all assessments earlier stated for all concrete strength grades. Therefore, these findings can be beneficial in attaining a cleaner built environment and sustainable production. Finally, VPA has proved to be a sustainable building material.

Capillary rise height of sulfate in Portland-limestone cement concrete under physical attack: Experimental and modelling investigation

Capillary rise is a dominate mechanism for the subsequent salt crystallization damage on concrete structures partially exposed to sulfate bearing environments. The aim of this study is to assess the capillary rise height of sulfate (h) in Portland cement (PC) and Portland-limestone cement (PLC) concretes under physical attack. The impacts of limestone contents (0 wt%, 10 wt% and 30 wt%) and water-to-binder ratios (w/b of 0.4 and 0.6) on the pore structures and sorptive property of concrete specimens were investigated. Results show that the effects of limestone content on the capillary rise heights, pore structures and sorptivity of PLC-based concrete specimens differed from different w/b ratios, as a consequence from the competition mechanism between filler effect and dilution effect due to the incorporation of limestone. The heights of efflorescence zone in PLC-based concrete specimens were found to be closely related to their volumes of capillary pores, while those of subflorescence zone only exhibited slight fluctuation at varying compositions. The time-dependent evolution of h can be divided into two stages and almost 35.7%–46.5% of the final height were reached in the first month (the fast increase stage). The capillary rise height h predicted by the modified model demonstrated good agreements with those obtained from experiments, when compared to other prediction models.

Effects of Minimum Cementitious Paste Volume and Blended Aggregates on Compressive Strength and Surface Resistivity of Portland Limestone Cement Concrete

AbstractPortland limestone cement (PLC) has been used in all classes of concrete in Florida since 2017. In order to comprehensively use PLC, this study investigates the effects of cementitious past...

Mechanical and Durability Properties of Portland Limestone Cement (PLC) Incorporated with Nano Calcium Carbonate (CaCO3).

Despite lower environmental impacts, the use of Portland Limestone Cement (PLC) concrete has been limited due to its reduced later age strength and compromised durability properties. This research evaluates the effects of nano calcium carbonate (CaCO3) on the performance of PLC concrete. The study follows a series of experiments on the fresh, hardened, and durability properties of PLC concrete with different replacement rates of nano CaCO3. Incorporation of 1% nano CaCO3 into PLC concrete provided the optimal performance, where the 56 days compressive strength was increased by approximately 7%, and the permeability was reduced by approximately 13% as compared to Ordinary Portland Cement (OPC) concrete. Further, improvements were observed in other durability aspects such as Alkali-Silica Reaction (ASR) and scaling resistance. Additionally, nano CaCO3 has the potential to be produced within the cement plant while utilizing the CO2 emissions from the cement industries. The integration of nanotechnology in PLC concrete thus will help produce a more environment-friendly concrete with enhanced performance. More in-depth study on commercial production of nano CaCO3 thus has the potential to offer a new generation cement—sustainable, economical, and durable cement—leading towards green infrastructure and global environmental sustainability.

The effects of reduced paste volume in Portland limestone cement concrete

In Portland cement concrete, a high content of cementitious materials can cause early cracking. This study investigated the effects of minimised paste volume in structural concrete made with Portland limestone cement and blended aggregates (BA). The effects of using different types of cement and paste volumes were compared. It was found that concrete made using type IL cement (containing 14% limestone powder) showed comparable performance to concrete made with type I/II cement. Based on the results of laboratory testing and numerical modelling, the performance of concretes with different paste volumes was evaluated. The results showed that the paste volume could be reduced by around 27% without affecting the properties of the concrete. Using the BS technique, the paste volume could be further reduced by 24%. Concrete mixes prepared using the BA technique were found to have better potential performance than the reference concrete. It was concluded that the use of type IL cement and BA can effectively reduce the initial cost and carbon dioxide emissions of structural concrete without loss of performance.

Alumina-rich pozzolan modification on Portland-limestone cement concrete: Hydration kinetics, formation of hydrates and long-term performance evolution

In order to further understand the modification mechanisms of Portland-limestone cement (PLC) concrete by alumina-rich pozzolan (ARP), and therefore achieve the proper use of ARP in PLC, the present work investigates the hydration kinetics, hydration products and long-term performance of concrete based on ARP and PLC. X-ray diffraction and thermogravimetry were employed to identify the hydration products, and the heat evolution was detected by a calorimeter. The pore structure, chloride resistance, accelerated/natural carbonation and free shrinkage were monitored. Besides, the chemical interactions between ARP and calcite induced modification on solid volume of hydrates were also evaluated. The results show that ARP can accelerate the hydration of PLC blends, favors monocarboaluminate (Mc) formation at low replacement level and hemicarboaluminate (Hc) at high incorporation levels. Carboaluminate formation significantly increases the solid volume of hydrates due to the lower densities compared to calcium silicate hydrate (CSH) gels, portlandite and calcite. This effect is amplified when Hc is favored due to its even lower density. These positive effects are beneficial to the improvement of pore structure, volume stability and chloride resistance. During long-term curing, PLC concrete with ARP tends to experience a pore structure degradation induced by the transformation of Hc to Mc, which results in nearly 8% reduction of solid volume. These findings help to achieve a better understanding on the modification mechanisms of ARP on PLC concrete, and benefit the design of concrete based on PLC and ARP in practical.

Long-term thaumasite sulfate attack on Portland-limestone cement concrete: A multi-technique analytical approach for assessing phase assemblage

Multiple techniques were applied to the investigation of the phase composition of the deteriorated surface of Portland-limestone cement concrete specimens exposed for 10 years to conditions promoting thaumasite sulfate attack. The results were interpreted in terms of the limestone content of cement and the incorporation of supplementary cementitious materials (SCMs) (natural pozzolana, blastfurnace slag, metakaolin). Thaumasite, detected in high amounts in concrete specimens made without SCMs, was associated with Al to some extent. Considerable degradation of calcium silicate hydrate occurred in all specimens, resulting in the formation of Al-associated cross-linked silicate chains, magnesium silicate hydrate and silica gel, a process most effectively prevented by metakaolin. For the highest limestone content in cement or use of natural pozzolana, thaumasite underwent extensive decomposition. Al incorporation into cross-linked silicate chains increased with increasing limestone content in cement. Longer aluminosilicate chains with larger Al fractions were observed in concrete specimens incorporating SCMs.

Reducing variations in the test results of self-consolidating lightweight concrete by incorporating pozzolanic materials

Portland limestone cement (PLC) has been considered as a suitable alternative for portland cement in self-consolidating lightweight concrete (SCLWC) mixtures. However, certain inconsistencies were reported in terms of strength development and durability properties of the PLC concrete. In addition, fresh SCLWC mixtures are more likely to encounter test results variation than ordinary concrete mixtures. This paper experimentally investigates the fresh and hardened performance of SCLWC incorporating ternary blended cements containing PLC and silica fume (SF), fly ash (FA), natural zeolite (ZE) or metakaolin (MK). The fresh tests were repeated once for each 100-L concrete batch and coefficient of variation as a measure of dispersion of a frequency distribution used to determine the variation of fresh test results of the mixtures. The results show that the pozzolanic materials mixtures have greater but less variable results of flowability compared to the PLC mixture. The coefficient of variation in results of slump flow test is varied 0.8–2.9%. It was also observed that there is a reduction in variation of the V-funnel results as the mean value increased. The obtained coefficient of variation was as low as 7% for zeolite ternary mixtures and the highest variation belonged to the binary mixture by 19.2%. The result of rapid chloride migration test (RCMT) and electrical resistance test indicated that there is a strong correlation between these two variables. Comparing the results to other studies, we recognized that the correlation seems to be unique for each case study.

The role of ambient temperature variation on drying shrinkage development of self-compacting Portland-limestone cement concrete

The ambient temperature records in Iraq show a large variation between day and night reaching 20 C, depending on the season, whether it is summer or winter. For this reason, the aim of this research is to study the effect of these conditions on the drying shrinkage of self-compacting concrete produced by using Portland-Limestone cement (ASTM C595 - Type IL). SCC mixes were designed to attain compressive strengths of 40 and 60MPa at 28days with and without silica fume respectively. Same mixes were reproduced with ordinary Portland cement (ASTM C150 - Type I) for comparisons. Two maximum sizes of aggregate 10 and 20 mm were incorporated in this work. The drying shrinkage was measured for 180 days after 7 days of water curing. The range of ambient (outdoor) temperature variation was from - 4 to + 39°C and the relative humidity ranged from 15 to 60 %. The results of this exposure were compared to that of specimens kept in the shrinkage chamber, with a temperature of 21°C and relative humidity 35%. The current results showed that due to the irreversible nature of shrinkage strain, the drop of ambient temperature and the rise of atmosphere moisture or relative humidity would not reverse the shrinkage strain. It is important to figure the final total accumulated strain when dealing with ambient temperature variation. The drying shrinkage characteristics for concrete made with Type IL cement, are found similar to that for concrete produced with Type I cement.

Chloride ingress in concrete: limestone addition effects

This paper presents analysis and evaluation of experimental results of chloride ingress and chloride-induced corrosion resistance of concrete made with Portland limestone cement (PLC). The results were mined from 169 globally published studies from 32 countries since 1989, yielding a matrix of 20 500 data points. This study showed that chloride ingress in concrete increases with increasing limestone (LS) content, within the range permitted in BS EN 197-1:2011. However, this effect is less for PLC concrete mixes designed for strength equal to corresponding Portland cement (PC) concrete mixes than those designed on an equal water/cement (w/c) basis. The results also showed that Eurocode 2 specifications for chloride exposure, in terms of characteristic cube strength of concrete or w/c ratio, may need to be reviewed for the use of LS with PC. This study also investigated other influencing factors such as cement content, LS fineness, the method of producing PLC, aggregate volume content and particle size, combined chloride and sulfate environment, curing and exposure temperature. A comparison was made for the performance of PLC concrete in terms of pore structure and related properties, strength, carbonation and chloride ingress. Procedures to improve the resistance of PLC to chloride ingress in concrete are proposed.

Modeling of Hydration, Compressive Strength, and Carbonation of Portland-Limestone Cement (PLC) Concrete.

Limestone is widely used in the construction industry to produce Portland limestone cement (PLC) concrete. Systematic evaluations of hydration kinetics, compressive strength development, and carbonation resistance are crucial for the rational use of limestone. This study presents a hydration-based model for evaluating the influences of limestone on the strength and carbonation of concrete. First, the hydration model analyzes the dilution effect and the nucleation effect of limestone during the hydration of cement. The degree of cement hydration is calculated by considering concrete mixing proportions, binder properties, and curing conditions. Second, by using the gel–space ratio, the compressive strength of PLC concrete is evaluated. The interactions among water-to-binder ratio, limestone replacement ratio, and strength development are highlighted. Third, the carbonate material contents and porosity are calculated from the hydration model and are used as input parameters for the carbonation model. By considering concrete microstructures and environmental conditions, the carbon dioxide diffusivity and carbonation depth of PLC concrete are evaluated. The proposed model has been determined to be valid for concrete with various water-to-binder ratios, limestone contents, and curing periods.

Effects of the fineness of limestone powder and cement on the hydration and strength development of PLC concrete

Portland limestone cement (PLC) have been widely used in the world because of its environmental impact, which is less carbon dioxide emissions by using less amount of cement clinkers. Moreover, formation of monocarboaluminates as fillers in cement can improve dense concrete microstructures by reacting with C3A. Also, larger nucleation sites from limestone powder can enhance strengths due to the active cement hydration. Thus, in this study, the effects of the fineness and replacement of limestone powder on the hydration and strength properties of concrete were investigated by X-ray diffraction (XRD), setting times, isothermal calorimetry, compressive strength and mercury intrusion porosimetry techniques. The obtained results showed that the addition of limestone powder accelerated cement hydration by providing nucleation sites for the hydration products, and as a result, the fineness of cement and limestone powder strongly influenced on the hydration reaction and the strength development.

Carbonation resistance of concrete: limestone addition effect

Systematic analysis and evaluation of experimental results on carbonation and carbonation-induced corrosion resistance of concrete made with Portland limestone cement (PLC) are presented; these results have been extracted from 143 globally published studies in the literature since 1986, by 274 researchers from 131 institutions and 34 countries, and yielding a 19 000 data matrix are presented. It is shown that the carbonation of concrete increases with increasing limestone content, within the range permitted by standard BS EN 197-1:2011. This effect, however, is less marked for concrete designed on an equal strength basis to the corresponding Portland cement (PC) concrete than concrete designed on an equal water/cement (w/c) basis. Eurocode 2 standard specifications for XC3 carbonation exposure for characteristic cube strength of concrete (or its w/c ratio) may need to be reviewed for the addition of limestone. Other influencing factors: curing, limestone fineness, total cement content, were also studied. A comparison has been conducted for the carbonation performance of concrete made with PLC and cement containing fly ash and ground granulated blast-furnace slag. Procedures to reduce the carbonation of PLC concrete are proposed. Response to accelerated carbonation, at 3–5% carbon dioxide concentration, of PLC concrete is similar to natural indoor exposure. A conversion factor of 1 week accelerated carbonation equal to 0·75 year natural indoor exposure was determined.

Impact of organic carbon on hardened properties and durability of limestone cement concrete

In this paper, the effect of organic carbon in ground limestone on the properties and behavior of Portland limestone cement (PLC) concrete in normal and aggressive medium was studied. Three different sources of limestone with total organic carbon of 0.94, 0.48 and 0.18% were considered, the cement replacement ratios were 0, 10, 15, 20 and 25% by weight and water to binder ratio was 0.55.Mechanical properties, XRD and TGA experiments were conducted to evaluate the effect of the previous variables on hardened properties of concrete and hydration process of cement paste. Corrosion rate and polarization resistance of reinforcing PLC concrete specimens immersed in 5.0% sodium chloride solution for 12months were measured using potentiodynamic polarization resistance technique. The sulfate resistance of PLC concrete specimens was also investigated. Concrete specimens exposed to wetting and drying cycles in 5% magnesium sulfate solution for 18months were tested. SEMs of limestone cement paste after magnesium sulfate exposure were performed. The results emphasize the essential role of organic carbon on the properties and behavior of PLC concrete for both normal and aggressive medium especially at high ratios of cement replacement with limestone.

Corrosion behaviour of reinforced steel in concrete with ground limestone partial cement replacement

Corrosion of steel bars embedded in concrete made of Portland cement replaced partially with ground limestone is studied. Three variables are considered: replacement ratios with ground limestone (0, 10, 15, 20 and 25% of cement by weight), level of cement content (300, 350 and 400 kg/m3) and fineness of ground limestone (345, 530 and 720 m2/kg). Reinforced concrete specimens are immersed in a 5% sodium chloride solution by weight up to 9 months. The corrosion rate is measured by potentiodynamic polarisation technique. To explain the corrosion behaviour of steel bar embedded in Portland limestone cement concrete, samples are prepared from the same concrete mixes and tested mechanically and physically. X-ray diffraction and thermogravimetric analyses of limestone cement pastes with similar replacement levels are also conducted. The corrosion rate of steel bars embedded in concrete containing ground limestone (530 m2/kg or more) is found to decrease with increase of cement replacement ratio up to 25% by weight. The corrosion behaviour of steel bars and the resistivity characteristics of Portland limestone cement concrete are also found essentially to depend on the cement content of the concrete. The corrosion behaviour of steel bars in Portland limestone cement concrete, as well as the compressive strength of the concrete, is found to be strongly associated with the fineness of limestone relative to the fineness of cement.

Long Term Behaviour of Portland Limestone Cement Concrete Exposed to Combined Chloride and Sulfate Environment. The Effect of Limestone Content and Mineral Admixtures

The long term behaviour of limestone cement concrete, stored in combined chloride and sulfate environment, was studied, taking into consideration the effect of both the limestone content of the cement used and the mineral admixtures addition. Concrete specimens of seven different compositions were prepared. Three of them were made from ordinary Portland cement and from two Portland limestone cements (limestone content: 15% and 35% w/w). The rest four compositions were prepared by substituting a certain amount of the limestone cement (15% w/w limestone content) with natural pozzolana, fly ash, blastfurnace slag or metakaolin. The specimens were immersed in four solutions of various sulfate and chloride contents and stored at 5oC. Visual assessment of the specimens and mass measurements took place up to 55 months. XRD analytical technique was used to identify thaumasite in the deteriorated parts of the specimens. Higher contents of limestone in cement and of sulfates in the storage solutions resulted in more intensive concrete damage. The use of mineral admixtures improved the behaviour of limestone cement concrete. After 24 months of exposure, chlorides delay the deterioration of limestone cement concretes caused by sulfates. After 55 months, the presence of chlorides led to a greater mass loss for them. The specimens containing mineral admixtures showed more intensive deterioration at 24 months when chlorides were present along with sulfates. Their mass seems to not be affected by chlorides. Fly ash was proved as the most efficient material to improve limestone cement concrete's performance, while concrete containing metakaolin suffered from significant damage after 55 months. XRD analysis showed that the damage observed was due to the formation of thaumasite.

Durability performance potential and strength of blended Portland limestone cement concrete

This paper describes a study on the durability potential and strength of composite Portland-limestone cement (PLC) concrete mixtures blended with ground granulated blast furnace slag (GGBS) and/or fly ash (FA). Their performance was compared against ordinary Portland cement, plain PLC and Portland-slag cement concrete mixtures. Using the South African Durability Index approach, results indicate reductions in the penetrability of the composite PLC blends compared to the other mixtures. The durability indicators are chloride conductivity, gas (oxygen) permeability and water sorptivity. Compressive strength of the composite PLC mixtures containing both GGBS and FA showed competitive performance with the comparative mixtures, but FA blended PLC mixtures had diminished compressive strength values. The paper also presents considerations on the practical implications of using blended PLC concrete mixtures.