Lime Content Research Articles

Preparation of Cement Clinker from Geopolymer-Based Wastes.

In order to avoid potential environmental pollution from geopolymer-based material wastes, this work investigated the feasibility of using these materials as alternative raw materials in the preparation of cement clinker. The geopolymer binders and mortars were used as substitutes for natural mineral clays since they are rich in silica and alumina. Simulated geopolymer wastes were prepared by the activation of metakaolin or fly ash by an alkaline silicate solution. The cement-clinkers fired at 1450 °C for 1h were characterized by XRD, XRF, SEM-EDS, and a free lime (CaOf) content test. The anhydrous clinker mineral phases C3S (Ca3SiO5), C2S (Ca2SiO4), C3A (Ca3Al2O6), and C4AF (Ca4Al2Fe2O10) were well-crystallized in all investigated formulations. The free lime was lower than 1.3 wt% in all elaborated clinkers, which indicates a high degree of clinkerization. The results demonstrate that geopolymer binder and mortar materials are suitable substitutes for natural mineral clay incement clinker preparation.

Mechanical and Environmental Performance of Eggshell Lime for Expansive Soils Improvement

Efficient and environmentally friendly alternative binders for expansive soils improvement are needed to practice sustainable geotechnics. This study evaluates the viability of a lime produced from eggshell waste as a green stabilization binder for expansive soils. Three contributions to the literature were achieved: (i) a comparison of the swelling, strength, stiffness, plasticity, and morphology of expansive soils stabilized with hydrated eggshell lime and hydrated industrial lime (i.e. commercially available lime), (ii) a statistical analysis of lime stabilization for swelling control and (iii) a life cycle assessment of eggshell lime versus industrial lime. Free-swell, unconfined compression, stiffness and Atterberg limits tests, and environmental assessment were performed to analyze the bentonite-kaolin-lime blends. Different proportions of bentonite-kaolin, dry density, lime content, and curing time were evaluated. Swelling data was correlated with the porosity/lime index. Results indicate that the alternative binder is a suitable option to improve the mechanical and swelling behavior of expansive soils, presenting higher strength and a reduction in expansion for all analyzed conditions, when compared to the industrial lime. Statistical analyses showed that bentonite content, lime content and dry unit weight factors should be focused for swelling reduction. For both studied limes, the adjusted porosity/lime index was an appropriate parameter to evaluate the swelling of stabilized soils. Life cycle assessment revealed that the alternative binder is a sustainable option as it avoids limestone mineral extraction and improvement.

Effect of lime-stabilised copper slag cushion on swelling behaviour of highly plastic clay

Clay soil is prone to seasonal volume change due to variation in water content. The use of waste materials in civil engineering, especially in road construction, has been in vogue all over the world due to the development of road infrastructure. Copper slag is one such waste material available abundantly from the copper industry in India. This paper discusses the heave and swelling of copper slag–cushioned clayey subgrade prepared in a model test tank. The results revealed that the methodology adopted is effective in reducing the swelling of clay. The thickness ratios of the stabilised copper slag cushion and clayey subgrade bed adopted are 0.25, 0.5, 0.75 and 1.0. The copper slag cushion is stabilised with lime content varying from 2 to 10%. A reduction in heave of clayey soil subgrade bed is observed with an increase in the percentage of lime and the thickness of the copper slag cushion. For a cushion–clay soil subgrade thickness ratio h c/h s = 1, the reduction in the heave of a clayey subgrade bed is 84.4%. The swell potential observed from the present study follows well the trend obtained from the rectangular hyperbolic model.

Carbonation of High-Ca Fly Ashes under Flue Gas Conditions: Implications for Their Valorization in the Construction Industry

The utilization of high-calcium fly ashes (HCFA) from coal-fired power plants in the construction industry is problematic, since their high free lime contents can lead to durability problems. In this research, the carbonation of a high-CaO fly ash has been carried out using simulated flue gas and concentrated CO2, with the aim to assess the valorization potential of such materials in the construction industry. The results show that, at 7 bars total pressure, an up to 36% carbonation efficiency can be achieved in just 30 min when pure CO2 is used; a comparable result with flue gas requires about 4 h of reaction. On the other hand, experiments carried out at atmospheric pressure show significantly different carbonation efficiencies depending on the CO2 concentration of the gas used. All experiments resulted in a substantial reduction in the original free lime content, and after reaction times of 4 h (at atmospheric pressure) and pressures of 7 bars (for any reaction time >30 min), the final free lime values were low enough to comply with the requirements of European Standards for their utilization as additions in cement.

Restoration success in afforestation sites established at different times in arid lands of Central Anatolia

Restoration of degraded lands is among the major challenges in Arid and semi-arid ecosystems. Therefore, in many regions where arid and semi-arid climates prevail, afforestation studies are carried out for restoration purposes. This study evaluated long-term afforestation practices in terms of ecosystem restoration in the arid lands of Central Anatolia, Turkey. For the study, sample afforestation sites of different ages were chosen in the Tuz Gölü-Konya basin. Species in the sites included black pine (Pinus nigra), Russian olive (Elaeagnus angustifolia), sweet almond (Prunus dulcis), black locust (Robinia pseudoacacia), narrow-leaved ash (Fraxinus angustifolia), and mahaleb cherry (Prunus mahalep). For each sampling area, the survival rates, height, and diameter values of species were recorded. Litter on the forest floor was sampled and then representative soil pits were dug at each site to sample soil from different layers (30, 60, 90, and 120-cm deep) of the profile. Bulk density, texture, lime content, pH, salinity, cation exchange capacity (CEC), and carbon (C) and nitrogen (N) concentration were determined for each soil sample. Approximately 2/3 of the black pine seedlings had died in the first 8–10 years of afforestation. The mortality rate in almond and mahaleb seedlings was approximately 20%. After 25–27 years of afforestation, 1/3 and 2/3 of the initial almond and Russian olive seedlings were lost, respectively. The mortality rate for other species was about 80% for the same period. Black pine had reached over 6.5 m, increasing its height by about 11-fold over the last 10–25 years. In the same period, the increase in the height of black locust was 2.8-fold, almond 2.6-fold, and ash 2.5-fold. The least height growth (1.7-fold) for this period was recorded for mahaleb. The amount of litter had increased 3- and 5-fold, at 15–17 years and 25–27 years of plantation age, respectively, compared to its increase in the open control site. After 15 years from planting, soil nitrogen (N) concentration at the first 30-cm depth had increased by about 1/3 compared to the open area. At the same depth, the soil pH value had decreased by 0.15 units after 25–27 years compared to the rest of the profile. These data implied that soil restoration had been initiated at all sites.

Use of building demolition waste as lime treated base course in bituminous road

Building Demolished aggregate are the waste generated when the building is demolished due to disaster like earthquake, flood, tsunami etc. So the generated wastes are piled up to the dumping site or laid over the subgrade soil without treating it which only pollute the environment. In this paper it is studied that the waste aggregate generated after the building is demolished can be used as a base course layer for bituminous pavement. When the quick lime is mixed with the demolished building aggregate it regains its strength as natural aggregate. The CBR values, Resilient Modulus and Compression test result shows the balance mixed of lime, water and aggregate with filler gives the adequate result. So the demolished building aggregate can be use as Lime Treated Base Course (LTBC) for bituminous pavement by treating it with lime. As per IRC SP 89 mentioned compressive strength for cement treated base course should be 2.1 to 5.5 MPa in 7 days whereas the same result should be obtained by lime or fly-ash in 28 days. It is studied that when the excess amount of lime is used that is more than 8% in this study then it may increase the strength but also due to excess lime content shrinkage may occur which leads to crack or fatigue. Similarly resilient modulus calculated from the CBR values gives the satisfactory result. As per IRC 37 for base course resilient modulus can be taken as 300 MPa and 350 MPa.

Reactive, Sparingly Soluble Calcined Magnesia, Tailor-Made as the Reactive Material for Heavy Metal Removal from Contaminated Groundwater Using Permeable Reactive Barrier

A laboratory method was designed and verified that allows for the testing of alkaline, magnesite-based reactive materials for permeable reactive barriers (PRBs) to remove heavy metals from contaminated groundwater. It was found that caustic calcined magnesia (CCM) with high reactivity and low solubility to remove Cu2+, Zn2+, Ni2+, and Mn2+ cations from mixed aqueous solutions can be prepared by calcination at a suitable temperature and residence time. Regarding the solubility of both the reactive material itself and the precipitates formed, the CCM should contain just a limited content of lime. One way is the calcination of a ferroan magnesite at temperatures above 1000 °C. However, the decrease in pH is accompanied by lower efficiency, attributed to the solid-phase reactions of free lime. A different way is the calcination of magnesite under the conditions when CaCO3 is not thermally decomposed. The virtually complete removal of the heavy metals from the model solution was achieved using the CCM characterised by the fraction of carbonates decomposed of approximately 80% and with the highest specific surface area. CCM calcined at higher temperatures could also be used, but this would be associated with higher consumption of crude magnesite. Under the conditions considered in the present work, the product obtained by the calcination at 750 °C for 3 h appeared to be optimal. The full heavy metal removal was observed in this case using less magnesite, and, moreover, at a lower temperature (resulting, therefore, in a lower consumption of energy for the calcination and material handling).

Nutritional status of Eucalyptus plantation and chemical attributes of a Ferralsol amended with lime and copper plus zinc

Brazil is a global reference in forest management for wood production (e.g., pulp and solid wood products), and large areas are planted mainly in acidic and poorly fertile soils, with a predominance of Eucalyptus species. Liming is widely adopted in acidic soils in humid tropical regions planted with Eucalyptus to increase the availability of some nutrients and supply Ca and Mg. However, liming decreases the availability of some micronutrients, such as Cu and Zn, depending on the lime content. Copper and Zn fertilization for Eucalyptus is usually intended to replace the amount of micronutrients extracted after wood harvesting. However, few studies have been carried out to investigate the combined effects of lime and Cu plus Zn application on forest plantations in tropical soils. Here, the effects of these factors on soil chemical-attributes, as well as nutrition, and growth performance of Eucalyptus grandis plantations were evaluated on a medium-textured Ferralsol. The stem volume yield improved after liming, regardless of the rate of application, and after Cu plus Zn fertilization. Liming increased soil pH and Ca and Mg availability and reduced Cu and Zn availability. Overall, liming reduced soil Cu and Zn contents in the residual-fraction, while increasing the fraction bound to organic-matter. High contents of Cu and Zn were linked to the organic-matter fraction in the soil under the Eucalyptus plantation. Eucalyptus trees grown in soils amended with lime had higher values for leaf area index and leaf Ca and Mg concentrations but showed reduced Cu and Zn concentrations. The combined application of lime and Cu plus Zn improved Eucalyptus growth, with the higher contribution of lime compared to Cu and Zn. In conclusion, the combined application of lime and Cu plus Zn is a useful strategy to provide balanced nutrition and optimize stem volume yields.

Effect of Sand and Sand-Lime Piles on the Behavior of Expansive Clay Soil

Expansive clay soil causes serious problems to many structures due to its swelling and shrinkage during wet and dry seasons. With the existence of expansive soil in Ahkmim new city, Sohag governorate, Egypt, some light buildings, road pavements, and buried pipelines have shown some damage. To avoid such damage, prior to construction, expansive clay soils should be stabilized. Different methods are available to improve the engineering properties of these soils such as densification, chemical stabilization, reinforcement, and techniques of pore water pressure reduction. The chemical stabilization of clay using lime is one of the widespread methods that can be used to improve the behavior of expansive clay soil. This study aims to investigate the effect of both sand and sand-lime piles on the behavior of expansive clay soil. A series of laboratory tests were carried out using the conventional Oedometer apparatus. Sand piles with different replacement area ratios (RARs) (4.68%, 10.16%, 24.6%, 35.84%, and 56.9%) were used. Also, sand piles stabilized with different percentages of lime (3%, 6%, 9%, 12%, 15%, and 20%) and with a replacement area ratio of 35.84% were used. The experimental results showed there is a significant improvement in reducing the swelling potential of expansive clay soil reinforced with sand or sand-lime piles. This improvement increases with the increase of both replacement area ratio and lime content.

Effects of fibre type and content on unconfined compressive strength of fibre-reinforced lime or cement-stabilised soils

ABSTRACT Soil reinforcement and stabilisation using a combination of natural or synthetic fibres, lime, cement and fly ash is very useful when construction had been done on weak soil. This study is evaluated the utilisation of fibres, cement and lime as a stabiliser for soil improvement. The unconfined compressive strength (UCS) tests carried out on the specimens containing various contents of cement, lime and fibre after curing times of 7 and 28 days to estimate the optimum mixture design. In preparing specimens, the clay soil was mixed with the desired amount of cement or lime and fibre then compacted at the optimum water content and maximum dry density. The results show that the UCS increases about 7.5 times in a cement content change from 5% to 25% at a curing time of 28 days. However, this value is about 11.5 for lime–stabilised specimens. The UCS of cement or lime-stabilised specimens with or without fibre reinforcement increases as curing time increases from 7 to 28 days. However, it is concluded that the optimum fibre content corresponding to maximum UCS is directly dependent on the type of fibre. Mostly the optimal fibre content varies from 6% to 10% depending on cement type.

Lightweight masonry block without Portland cement

ABSTRACT Huge amounts of fly ash - a substance that does not conform to the ASTM C618 classification due to its chemical properties - have been abandoned in landfills around the world, despite their self-cementing property. It has not been used in concrete making applications due to its large amounts of free lime and sulfate contents. The fly ash in these plants is dumped in landfills, causing serious environmental hazards. Fly ash is disposed to the landfills by belt conveyors after being humidified with water. Therefore, the fly ashes humidified in the landfill areas are hydrated in nature. This hydration is further intensified in landfills by rain and snow. Thus, the free lime content of fly ash decreases due to its long hydration process. In this work, the lightweight masonry blocks were produced by mixing normal and hydrated fly ashes or normal, hydrated fly ash and lime without Portland cement. The compressive strength, water absorption, sorptivity, density, porosity, and thermal conductivity values of the samples produced were determined. The results obtained from these tests showed that lightweight masonry blocks could be produced by using these waste materials in building applications.

Valorization of phosphogypsum as a road material: Stabilizing effect of fly ash and lime additives on strength and durability

Phosphogypsum is a by-product from the phosphoric acid industry following the wet process. Known for its low cost, this process generates large amounts of phosphogypsum, the management of which has so far remained problematic due to the impurities it contains including heavy metals, radionuclides and acidic residuals. It is above all, its acidic nature that hinders its use as a road material since it increases its solubility which in turn makes it sensitive to water variations. This paper presents an investigation on the stabilization of Moroccan phosphogypsum, through neutralizing acidity, while considering both techno-economic and environmental constraints. To this end, mixtures of phosphogypsum and fly ash were prepared then activated with varying quicklime additions (beyond Initial Consumption of Lime) to develop different combinations of phosphogypsum (40–80%), fly ash (20–60%) and lime (4–20%). These have been tested for their mechanical and mineralogical properties at different curing periods (7, 28, 90, 180 days) besides durability against Wetting/Drying cycles, in order to evaluate the stabilizing effect of fly ash and lime. Results from Unconfined Compressive Strength (UCS) tests showed a strength increase with fly ash and lime addition with increasing the curing time. The UCS at 180 days varied between 1 and 3 MPa for formulations containing 4% lime (ICL) while those with 12–20% lime reached 4–7 MPa (12 times higher than UCS at 7days). As for durability, these showed weight losses of up to 10% upon W/D cycles, a strength loss of up to 56% and high porosity compared to formulations with higher lime content which rather gained up to 264% in strength. The influence of curing time and mixture composition on the mineralogy of the prepared composites was assessed through XRD and TGA analyzes highlighting the formation of ettringite as main hydration product responsible for strength development.

Effect of Deep Remediation and Improvement on Bearing Capacity and Settlement of Piled Raft Foundation Subjected to Static and Cyclic Vertical Loading

ABSTRACT The effect of lime piles on the behavior of piled-raft foundation constructed on such soil and subjected to static and cyclic vertical loading was also investigated. The soil samples were contaminated artificially by light fuel oil (LFO) mixed with water and kerosene to simulate the contaminants that are usually disposed directly to the soil from the electricity power plant as a byproduct. The lime columns are holes of 20 mm diameter and 500 mm deep were drilled in the soil and filled with lime mixture. The lime mixture was prepared by mixing a dry soil with 15% of lime and natural water content and then poured into the holes and mixed thoroughly. The lime mixture was left for four weeks to allow the completion of most chemical reactions necessary for improvement and remediation of oil contaminated soil. Aluminum piles of 20 mm in diameter and 300 mm long were installed in soil models and subjected to static and cyclic vertical loading. Load-settlement curves showed that the contaminated soils have more settlement values compared with the intact soil, but improvement and remediation of soil samples showless settlement than that of contaminated samples. Lime piles are considered an efficient technique for decreasing the settlement of piled-raft foundations.

Eco-Geographical, Morphological and Molecular Characterization of a Collection of the Perennial Endemic Species Medicago tunetana (Murb.) A.W. Hill (Fabaceae) from Tunisia.

In order to characterize and conserve the endemic pastoral species Medicago tunetana, many prospecting missions were carried out in mountainous regions of the Tunisian ridge. Twenty-seven eco-geographical and morphological traits were studied for six M. tunetana accessions and followed by molecular analysis using seven Simple Sequence Repeat (SSR). Only five markers were polymorphic and reproductible in the six M. tunetana populations. A total of 54 alleles were observed with an average of 10.8 bands/primer/genotype. Mean Polymorphism Information Content (PIC), Nei gene diversity (h) Shannon’s information index (I) indicated the high level of polymorphism. The generated dendrogram with hierarchical UPGMA cluster analysis grouped accessions into two main groups with various degree of subclustring. All the studied accessions shared 57% of genetic similarity. Analysis of variance showed high significant difference between morphological traits among M. tunetana populations where MT3 from Kesra showed different morphological patterns regarding leaf, pod and seeds traits. Canonical correspondence analysis (CCA) showed two principal groups of M. tunetana populations based on potassium, total and active lime contents in soil. Our results suggest that SSR markers developed in M. truncatula could be a valuable tool to detect polymorphism in M. tunetana. Furthermore, the studied morphological markers showed a large genetic diversity among M. tunetana populations. This approach may be applicable for the analysis of intra specific variability in M. tunetana accessions. Our study could help in the implementation of an effective and integrated conservation programs of perennial endemic Medicago.

Archaeological and Chemical Investigation on the High Imperial Mosaic Floor Mortars of the Domus Integrated in the Museum of Archaeology D. Diogo de Sousa, Braga, Portugal

This paper intends to characterize the floor mortar layers (nucleus, rudus and statumen) of the high imperial mosaics of the domus integrated in the Museum of Archeology D. Diogo de Sousa, the oldest roman housing testimonies known in Braga, Portugal. It offers an important archaeological and historical contextualization and first chemical characterization attempt on the mortars. The study of 13 mortar samples was carried out at a chemical level through X-ray fluorescence spectroscopy (XRF). All samples presented low lime content when compared to similar studies. A high chemical similarity between nucleus mortars (opus signinum) and chemical composition differences between rudus and statumen mortars was determined, confirmed by statistical analyses. Their composition was distinctly related to the stratigraphic position of each floor mortar layer, following Vitruvius’ model, and to the external conditions and treatments (e.g., capillary rise with soluble salts and application of chemical treatments), to which they were submitted.

The Effects of Geocell Height and Lime Stabilization on Unpaved Road Settlements at Different Water Contents

In this study, lime stabilization and geocell reinforcement methods were investigated for a clayey subgrade of unpaved road at different water contents. This study is especially important in terms of determining the soil improvement method for road construction on wet lands. The effects of the geocell height (50, 100, 150, and 200 mm) and lime content (3, 6, and 12%) on the settlement of the subgrade soil at different water contents (25, 28, 30, 32, and 35%) were analyzed. Accordingly, a large scale plate loading test was designed, and it is utilized to achieve loading-settlement curves. The bearing capacity and modulus of subgrade (k) of soil were determined. It was detected that the geocell height and lime content have different effects at different water contents, and the modulus of subgrade reaction became stable beyond a constant height of the geocell. It was understood that none of these two improvements did not meet the Highways Technical Specifications. It is detected that at least these two improvement techniques are needed to be applied together to meet the specifications for the soil examined in this study.

Lime activated flyash-phosphogypsum blend as a low-cost alternative binder

This study investigates the potential of a blended binder formulated from two industrial solid wastes viz. phosphogypsum and fly ash in combination with lime. Three mix proportions of phosphogypsum and fly ash were investigated, and the minimum lime contents required for activation were determined using the Eades and Grim pH test. The lime–fly ash–phosphogypsum blends were then cast into cubes, both in their paste form as well as mortar form, mixed with sand in the ratio of 1:3. They were cured for a period of seven days, and afterwards, their compressive strength was determined. Ordinary Portland cement and lime mortar blocks were also cast as control specimens for comparative evaluation of the strength. The optimal lime–fly ash–phosphogypsum blend was identified and used to construct a masonry prism, and the strengths of the masonry prisms were also evaluated. The optimal lime–fly ash–phosphogypsum blend mortar was also subjected to an X-ray diffraction analysis to determine the reaction products formed during hydration. The study revealed that 5% lime mixed with fly ash:phosphogypsum in the ratio of 3:1 was the optimal proportion which gave the maximum strength to the cubes. The optimal lime–fly ash–phosphogypsum blend mortar developed strength that was higher than conventional Portland cement and lime mortar. The optimal lime–fly ash–phosphogypsum blend mortar masonry prisms developed strength that was comparable to that of Portland cement mortar masonry. The X-ray diffraction analysis revealed the formation of calcium silicate hydrate minerals as well as ettringite and portlandite which were responsible for strength gain.

Cholesky Factorization Based Online Sequential Multiple Kernel Extreme Learning Machine Algorithm for a Cement Clinker Free Lime Content Prediction Model

Aiming at the difficulty in real-time measuring and the long offline measurement cycle for the content of cement clinker free lime (fCaO), it is very important to build an online prediction model for fCaO content. In this work, on the basis of Cholesky factorization, the online sequential multiple kernel extreme learning machine algorithm (COS-MKELM) is proposed. The LDLT form Cholesky factorization of the matrix is introduced to avoid the large operation amount of inverse matrix calculation. In addition, the stored initial information is utilized to realize online model identification. Then, three regression datasets are used to test the performance of the COS-MKELM algorithm. Finally, an online prediction model for fCaO content is built based on COS-MKELM. Experimental results demonstrate that the fCaO content model improves the performance in terms of learning efficiency, regression accuracy, and generalization ability. In addition, the online prediction model can be corrected in real-time when the production conditions of cement clinker change.

Characterization of Mellowing Process to Control Expansion in High-Sulfate-Bearing Soil

Calcium-based stabilizing materials (CBSMs) such as lime and fly ash are extensively used in subgrade primarily to enhance mechanical strength and improve resistance to chemical attack, resulting in more durable roadway. The soluble sulfate phase contained in some soils, however, can react with CBSMs and form ettringite minerals. If the soil is compacted before the end of this reaction, large, unstable, and volumetric swelling can occur. Among several methods to control sulfate-induced swelling, a “mellowing” approach is typically used because of its efficient, economical, and practical benefits when dealing with calcium-based stabilization of soils with significant soluble sulfate contents. Although the mellowing method is one of the frequently used methods, little data is available on the characterization of the specified mellowing process in the high-sulfate-bearing soil during the mellowing period. A research program investigated key factors influencing the mellowing process during the mellowing period, explaining how stabilizer type and content, remixing interval, mellowing period, and temperature play a role in reducing soluble sulfate content. Moreover, for selected mixtures, the 3-dimensional volumetric expansion and retained strength were measured after the mellowing process. Laboratory test results have revealed that a single mellowing process with higher lime content and daily remixing at high temperature leads to the rapid reduction of sulfate content in the soil. Moreover, after the mellowing process, additional soil treatment with fly ash or a combination of lime and fly ash leads to lower expansion and higher retained unconfined compressive strength of the soil mixture.

Synthesis and characterization of belite clinker by sustainable utilization of alumina sludge and natural fluorite (CaF2)

Certain reservations regarding the high energy costs needed for Portland cement production and eco-friendliness of the cement synthesis process are pointed out. Belite clinker synthesis offers an effective alternative approach capable of addressing these reservations by producing cements at reduced temperatures/CO2 emission. The present study suggests a new method to synthesize belite clinkers at even lower temperatures by incorporating the natural fluorite (CaF2) into a mixture of limestone and alumina sludge originated from the water purification plants. The obtained clinkers and their respective cements are characterized by free lime contents, X-ray fluorescence, X-ray diffraction, scanning electron microscopy, refusal, Blaine fineness and mechanical resistance analyses. The obtained results reveal that the synthesized belite cement possesses mechanical strength similar to that of ordinary belite cement. In addition, the introduction of CaF2 into the clinkers not only lowers their preparation temperatures but also facilitates the formation of crystalline phases which eventually leads to inproved hydraulic properties of the cement.