Synthetic Gypsum Research Articles

Structurally controlled synthesis of synthetic gypsum derived from industrial wastes: sustainable approach

AbstractBACKGROUNDThe article demonstrates the possibility of processing spent sulfuric acid and limestone waste into high‐quality synthetic calcium sulfate dihydrate.RESULTSA comprehensive technological scheme for the production of synthetic gypsum from industrial waste was proposed. Mathematical models of the main technological stages were obtained. In the process of acid processing, at the stage of separating gypsum from the mother liquor, a filtrate was formed containing ions such as Na+, K+, Mg2+ and SO42−, which are some of the main ions necessary for plant growth. A positive effect was found when using the filtrate as fertilizer.CONCLUSIONSOptimal values of synthesis parameters that allow one to obtain crystals of the maximum size were determined. A positive effect when using the filtrate as fertilizer was found. These results mean that it is possible to obtain a technology for gypsum with a closed production cycle (waste‐free technology) derived from waste limestone and spent sulfuric acid. © 2021 Society of Chemical Industry (SCI).

High-quality gypsum binders based on synthetic calcium sulfate dihydrate produced from industrial waste

Synthetic calcium sulfate dihydrate, obtained from sulfuric acid waste of chemical plants and waste of the fine fraction of limestone, is a potential source of gypsum-containing raw materials. We investigated the processing of synthetic calcium sulfate dihydrate from sulfuric acid waste to gypsum, high-strength gypsum binder, and anhydrite. The effects of technological parameters on the strength indicators of binders were studied. It was found that the obtained samples of binders (based on synthetic gypsum) meet all standards and even exceed the performance of binders obtained from natural gypsum stone. Our studies show that synthetic gypsum is a promising gypsum-containing raw material for the production of gypsum binders and can be a promising alternative to natural gypsum stone.

The Physico-Chemical and Mineralogical Characterization of Mg-Rich Synthetic Gypsum Produced in a Rare Earth Refining Plant

The physical, chemical and mineralogical characterization of the constituents of magnesium-rich synthetic gypsum produced in a rare earth-refining plant located in Gebeng, Pahang, Malaysia was conducted through elemental chemical analysis, scanning electron microscopy with Energy Dispersive X-ray (EDX)-analyzer, thermal analysis, X-ray fluorescence and X-ray diffraction. The crystalline nature of the by-product was studied using FTIR spectroscopy. Elemental analysis confirmed the presence of Ca and Mg, which are essential macronutrients required by plants and this Ca alongside the high pH (9.17) of MRSG may confer on the material a high acid neutralization capacity. From the result, it was observed that the studied by-product is a heterogeneous crystalline material comprising of gypsum (CaSO4.2H2O) and other major components such as calcium (magnesium) compounds (hydroxide, oxide, silicates, and carbonate) and sulfur. These aggregates may contribute to give an acid neutralization capacity to MRSG. The XRD study of MRSG indicated a high content of gypsum (45.4%), shown by the d-spacing of 7.609 Å (2-theta 11.63) in the diffractogram. The infrared absorption spectra of MRSG indicate close similarities to mined gypsum. The results of the characterization indicated that MRSG has valuable properties that can promote its use in amending soil fertility constraints on nutrient-deficient tropical acid soils.

Influence of the Calcination Temperature of Synthetic Gypsum on the Particle Size Distribution and Setting Time of Modified Building Materials

The paper assesses the influence of the calcination temperature of synthetic gypsum binder on the binding properties of innovative gypsum pastes, as well as on masonry and plastering mortars. The calcination process of gypsum binder was carried out at four different temperatures ranging from 170 to 190 °C. The specimens for testing were prepared on the basis of the obtained raw material with a constant water to gypsum ratio of w/g = 0.75. It was noted that the calcination temperature influenced the setting time of the gypsum. Based on synthetic gypsum, mixtures of masonry and plastering mortars modified with tartaric acid and Plast Retard were designed. During the experiment, the particle diameter distribution of aqueous suspensions of building and synthetic gypsum particles (before and after calcination) was determined using the Fraunhofer laser method. The dimensions of the obtained artificial gypsum grains did not differ from the diameters of the gypsum grains in the reference sample. On the basis of the conducted research, it was found that the waste synthetic gypsum obtained in the flue gas desulphurization process met the standard conditions related to its setting time. Therefore, it may be a very good construction substitute for natural gypsum, and consequently, it may contribute to environmental protection and the saving and respecting of energy.

Slag-Based Gypsum as a Source of Sulphur, Calcium and Silicon and Its Effect on Soil Fertility and Yield and Quality of Groundnut in Southern India

Slag-based gypsum (SBG) is a unique synthetic gypsum which is alkaline in nature, besides calcium (Ca) and sulphur (S); it contains appreciable amounts of iron (Fe), silicon (Si), phosphorus (P) and zinc (Zn). In this study, we evaluated the efficacy of SBG as a source of S, Ca and Si for groundnut in comparison with natural gypsum (NG). The effect of different levels and time of application of SBG on soil fertility and yield and quality of groundnut were also studied. Field experiments were conducted with five treatments which includes two levels of SBG (500 and 625 kg ha−1) applied as basal and basal + split and one level of NG (500 kg ha−1) applied as basal. Basal and basal + split applications of SBG significantly increased the pod and haulm yield of groundnut, pH, electrical conductivity and plant-available nutrients in post-harvest soil. However, N:S ratio, kernel and protein yield and oil content did not vary with SBG application. Applied S, Ca and Si as SBG and their uptake were positively correlated with plant-available S, Ca and Si and pod, oil and protein yield of groundnut, respectively. Basal and basal + split applications of SBG resulted in a similar effect on soil fertility and yield and quality of groundnut. Findings from this study show that SBG can be a potential alternative for NG as a source of S, Ca and Si for groundnut production. Among the treatments, basal and basal + split applications of 625 kg SBG ha−1 substantially improved the fertility of soils and yield and quality of groundnut.

Effect of biopolymers and humic substances on gypsum scaling and membrane wetting during membrane distillation

Membrane distillation (MD) has a great potential in desalination and wastewater treatment, but the application of MD is significantly restricted by membrane scaling. Membrane scaling may be affected by biopolymers and humic substances, which are ubiquitous in aqueous environment. However, the impact of natural organics, in particular biopolymers, on gypsum scaling in MD is seldom investigated. In this work, the impact of such organic compounds on gypsum scaling were evaluated with synthetic gypsum solutions as well as a real desalination brine. Model biopolymers (i.e. bovine serum albumin (BSA) and sodium alginate (SA)) and model humic substances (humic acids (HA)), were used to investigate the effect of organics, and two types of organics occurrence were considered, i.e., forming a layer on the MD membrane and dissolved in the feedwater. Results show that the organic fouling layer exhibited a very limited impact on gypsum scaling during MD. The dissolved organics in the feedwater generally postponed rather than accelerated gypsum scaling and membrane wetting, particularly for BSA and HA. SA was less efficient in restricting gypsum scaling due to its higher carboxyl content and the stronger interaction with Ca2+. The morphological characterization showed that the biopolymers in the feedwater were able to induce crystal deformation and agglomeration, forming irregular cluster-like crystals. Regarding the real desalination brine, the presence of BSA at 50 mg L–1 apparently delayed the occurrence of gypsum scaling from a concentration factor of 2.7–3.2. As a conclusion, the impact of natural organics on gypsum scaling should be considered in designing and operating MD for wastewater treatment.

Utilization of magnesium-rich synthetic gypsum as magnesium fertilizer for oil palm grown on acidic soil.

A study was conducted to determine the impact of applying different sources of Mg, namely kieserite, ground magnesium limestone (GML) and Mg-rich synthetic gypsum (MRSG) on an acid tropical soil, oil palm growth and production. Besides high amount of Mg and Ca, MRSG contains S. Exchangeable Ca in the untreated soil of the plantation was 0.64 cmolc kg-1, but its critical level to sustain oil palm growth was 0.9 cmolc kg-1. MRSG was applied in the plantation as Mg-fertilizer; however, since Ca is also a limiting nutrient, oil palm growth was correlated (r = 0.69) with Ca supplied by the MRSG. Mg needed to sustain oil palm production is normally supplied by kieserite. Its requirement can be met at a lower cost compared to that of the kieserite by using MRSG. Due to MRSG treatment, exchangeable Ca in the soil increased steadily to satisfy the requirement of oil palm for fruit bunches production. From the glasshouse and field study, it was observed that MRSG applied at 1.5 times the recommended rate gave results comparable to that of the kieserite. MRSG treatment resulted in the increase of soil pH to >5 that precipitated Al3+ as inert Al-hydroxides, which eventually enhanced oil palm seedlings growth. Thus, MRSG can also replace GML to increase soil pH and satisfy the Ca and Mg requirement of oil palm. It can be concluded that MRSG has the potential to be used as a source of Mg as well as Ca for oil palm grown on acidic soil.

Structurally controlled synthesis of calcium sulphate dihydrate from industrial wastes of spent sulphuric acid and limestone

Abstract All types of gypsum binders are obtained mainly from the natural gypsum and man-made products. As a sustainable analogue of these materials, synthetic gypsum as a product of spent dilute sulphuric acid and calcium carbonate was proposed. We investigated the effect of various technological parameters on the production of calcium sulphate dihydrate particles with a given morphology. The sizes of calcium sulphate dihydrate crystals with optimal values of technological parameters and exposure time up to 4.5 h increased from 18 to 28 μ m and combined into agglomerates with sizes that mostly lie in the range from 200 to 600 μ m. Synthesized calcium sulphate crystals acquiring a prismatic shape instead of a needle shape which simplified and accelerated the industrial filtration process. Our study shows that a promising sustainable and cheap source of gypsum-containing raw materials is synthetic gypsum, obtained by reacting a suspension of calcium carbonate and spent sulphuric acid.

Paraffin Permeability of Synthetic Gypsum Binders Modified by Individual Polymers

Abstract The paper presents an experimental study of five different gypsum composites taking into account paraffin permeability. The composites consist of synthetic gypsum, paraffin and polymers. The samples were produced from gypsum slurry of mixing ingredients, all in the liquid state. After 7 days of maturing, the condition of the samples was assessed as well as drying time was determined. In the second part, the paraffin tightness of different samples was analysed. The results showed that after three weeks of tests the tightness sample was A4. Other polymers were characterised by lower tightness. The content of polymer had also the effect on the final results, but the direct relation between polymer content and paraffin tightness was not observed.

Novel approach to thermal degradation kinetics of gypsum: application of peak deconvolution and Model-Free isoconversional method

In this work, we have reinvestigated the thermal degradation kinetics of synthetic gypsum (CaSO4·2H2O) using a novel approach based on peak deconvolution followed by the application of Model-Free isoconversional method. Gypsum was prepared using wet chemical route and characterized by conventional X-ray diffraction, in situ high-temperature X-ray diffraction (HT-XRD), infrared spectroscopy (IRTF-ATR), simultaneous thermal gravimetry, and differential thermal technique (TG/DTA). The physicochemical analysis showed that gypsum thermally degrades into calcium sulfate anhydrite (γ-CaSO4; anhydrite III) via an intermediate phase formed by calcium hemihydrate (CaSO4·0.5H2O; bassanite). HT-XRD analyses revealed the difference between the bassanite and anhydrite III phases, although they have a similar structure. The thermal kinetics of gypsum indicated a complex behavior of overall process mechanism consisting of overlapping contributions, which were separated into two individual ones using a mathematical deconvolution of Fraser Suzuki function. The separate thermal processes were analyzed using Model-Free isoconversional and Malek’s methodology. The kinetic results showed that both processes may be represented by Johnson–Mehl–Avrami [JMA(n)] equation which corresponds to nucleation and growth mechanisms, with n > 1. The first process corresponding to the partial dehydration of gypsum into bassanite was carried out by a two-dimensional JMA mechanism, while the second process, attributed to the complete dehydration of gypsum, was performed according to a three-dimensional JMA. Calculations of thermodynamic parameters have shown that the dehydration process of gypsum is accompanied by endothermic effects and requires heat, in agreement with the thermal analysis data.

Recovery of Ca(OH)2, CaCO3, and Na2SO4 from Moroccan phosphogypsum waste

The phosphate industry is commonly associated with a large amount of waste phosphogypsum in its solid form. The vast majority of phosphogypsum is usually discharged into the environment without any treatment and reuse. In this work, we investigate the valorization of the Moroccan phosphogypsum for manufacturing valuable products such as Ca(OH)2, CaCO3, and Na2SO4. These compounds are widely used for industrial applications. The reaction for the chemical conversion process of phosphogypsum (PG) is made in the aqueous solution of sodium hydroxide. The experiments were conducted at room temperature with an exact stoichiometric proportion of PG and NaOH. The efficiency of CO2 capture using phosphogypsum dissolution and portlandite carbonation was established at various concentrations of Ca(OH)2. Parallel experiments using synthetic gypsum samples were carried out to compare the solid phases precipitated from the by-product phosphogypsum. The pH and electrical conductivity measurements were used to monitor the time evolution of the reaction. In addition, an X-ray diffraction analysis was performed to characterize the starting material, synthetic gypsum, and Moroccan phosphogypsum, and to investigate the carbonation efficiency and purity of the solid products.

Feasibility of incorporating phosphogypsum in ettringite-based binder from ladle slag

Abstract Aiming to utilize phosphogypsum (PG) as a construction material, this study investigated the potential use of PG as a calcium sulfate source for the production of an ettringite-based binder (LSG). Six compositions with different percentages and PG's of different origin were hydrated with ladle slag (LS) to form LSG. The hydration, mineralogy and compressive strength of all mixtures were investigated and compared with a reference LSG made of pure synthetic gypsum. The minor impurities in PG, the different particle size distribution as well as the mineralogy induced distinguishable effects on the heat of hydration, phase assemblage and morphology. The results showed that the use of side-stream PG instead of pure gypsum results in superior properties with a 60% increase in compressive strength. This investigation shows high potential to produce a completely by-product-based LSG by combining different sources of industrial side-streams with minimal chemical and energy use.

Quantifying Ca exchange in gypsum using a 45Ca tracer: Implications for interpreting Ca isotopic effects in experimental and natural systems

Abstract Mineral-solution exchange rates of Ca were determined using a 45Ca tracer technique for three types of gypsum: natural cm-long gypsum needles, natural microcrystalline gypsum, and synthetic microcrystalline gypsum. Batch reactors containing the gypsum crystals were equilibrated with a saturated 45Ca spiked solution (Ωgypsum ≈ 1) for 30 days and were sequentially sacrificed to estimate exchange rates. The percentage of gypsum that exchanged was determined using a time-dependent box model, which simulated mineral dissolution and reprecipitation over time with variable extents of back reaction. Large natural needles exhibited no detectable exchange over 30 days, whereas a significant percentage of the Ca in the synthetic and natural micro-crystals exchanged. According to our model-based calculations, 45% of the synthetic gypsum and 20% of the natural gypsum exchanged; because of our experimental design, these extents are not affected by the model framework. The surface area normalized exchange rates were faster over the first five days (1.04 · 10−5 ± 5.84 · 10−6 mol/m2/d in the synthetic micro-crystals and 8.97 · 10−5 ± 7.45 · 10−5 mol/m2/d in the natural micro-crystals) than during the remainder of the experiment (2.37 · 10−6 ± 6.03 · 10−7 mol/m2/d in the synthetic micro-crystals and 2.69 · 10−5 ± 1.23 · 10−5 mol/m2/d in the natural micro-crystals). As the Ca concentration in solution remained constant over the experiment, the observed exchange is thought to be a result of dissolution/reprecipitation at the mineral-solution interface rather than due to net dissolution or net precipitation. The gypsum exchange rates that we constrain are consistent with those of other sulfate minerals, irrespective of their hydration state, but are considerably faster than carbonates over similar time scales. It is not clear if this is a result of the interpretive model framework, which can strongly influence both the derived rate and the extent of reaction, or whether it is a real phenomenon. Because the influence of the model framework is so important, we detail the importance of the solid to fluid mass ratio and the role of a back-reaction flux to the accurate quantification of recrystallization rates and extents. Finally, we apply our numerical model to the reinterpretation of past work and constrain the Ca isotopic fractionation factor associated with extremely slow rates of gypsum precipitation/exchange to be between 0 and −0.1‰.

Comparative study of K2SO4 production by wet conversion from phosphogypsum and synthetic gypsum

This paper proposes a very attractive process for K2SO4 production via the wet conversion of phosphogypsum (PG) and K2CO3. A parallel study of the conversion of two synthetic types of gypsum by K2SO4 was performed in order to compare their reactivity with that of PG.We remark that PG is more reactive and yields the desired results while commercial types of gypsum react slowly and generate unwanted secondary products. The factors affecting the PG conversion processes such as the initial concentration of reagents, the reaction time and the reaction temperature was studied to optimize the reaction conditions. X-ray diffraction (XRD) was used to characterize the PG conversion at different conditions while the other techniques (Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF), scanning electron microscopy (SEM), flame photometer (FP), inductively coupled plasma mass spectrometry (ICP-MS) and thermogravimetric analysis (TGA)) were applied to prove the quality of the final products.Based on the obtained results, the reaction is carried out with stoichiometric proportions between PG and K2CO3. The maximal conversion of PG is attained at 80°C; this temperature corresponds to the higher solubility of K2SO4, which is 1.2mol/l.

PEAT SOIL STABILIZATION IN RAWA PENING SALATIGA CENTRAL JAVA USING SYNTHETIC GYPSUM AND SALT

Peat is known as a problematic soil due to its low bearing capacity as well as its high and long settlement process. Necessary treatment is needed to improve peat soil capability. One of the methods to improve peat soil characteristics is by adding mixed materials. In this study the added materials are synthetic gypsum (CaSO4.2H20) and salt (NaCl). The research was conducted in a Soil Mechanics Laboratory using a consolidation test and direct shear tests. This research aims to find out the effect of CaSO4.2H20 and NaCl on consolidation and shear strength parameters. The soil samples taken for consolidation and direct shear tests were original and treated peat soil. The gypsum synthesis doses varied between 10%, 15%, and 20%, whereas the salt varied between 2%, 4%, and 6%, calculated from the dry weight of peat soil. The mixing of soil and the added materials was carried out under optimum water conditions of Standard Proctor compaction results. After the consolidation and direct shear tests were completed, the Scanning Electron Microscope (SEM) test was performed on the soil samples to determine the components of the peat soil on micron size. The addition of synthetic gypsum and salt resulted in the smallest Cc value of 0.0302 at 4% salt + 20% gypsum and the highest Cv value of 0.130 cm2/s at 6% salt + 20% gypsum. The addition of synthetic gypsum and salt mixture resulted in the highest cohesion, c value of 61,55 kPa at 6% salt + 15% gypsum and the greatest friction angle, ϕ value of 52.24° at 4% salt + 20% gypsum. NaCl gave better results than Gypsum in improving shear strength. A composition of 4%-6% of NaCl and 15%-20% of Gypsum is recommended, if NaCl and gypsum were to be applied simultaneously to improve shear strength.

Optimization of electrocoagulation process for fluoride removal: a blending approach using gypsum plaster rich wastewater

A novel blending approach has been introduced for fluoride removal by means of electrocoagulation. A blend was prepared by mixing synthetic phosphoric acid plant wastewater and gypsum plaster (GP) rich wastewater. This study explores defluoridation of wastewater using the simultaneous effect of chemical precipitation and electrocoagulation. Fourier transform infrared spectroscopy analysis of sludge confirms the presence Ca-F bond, which proves that enhancement in fluoride removal with blending of GP rich wastewater is due to simultaneous action of chemical precipitation and electrocoagulation. Optimization and statistical modeling were done with the help of MINITAB 17 software. Response surface methodology was performed using Box-Behnken Design to predict the fluoride removal efficiency and energy consumption. R2 values of 0.9485 and 0.9998 shows a good agreement between experimental and predicted values of responses. Kinetic study was done to determine the rate constant and it is found out that fluoride removal follows second order kinetic model. Blending approach confirmed the assistive role of GP rich wastewater in the enhancement of fluoride removal efficiency.

Gypsum amendment effects on micromorphology and aggregation in no-till Mollisols and Alfisols from western Ohio, USA

Synthetic gypsum, a by-product of electricity generation, is used as a soil amendment to overcome water ponding, improve soil and water quality, improve field conditions to support farm equipment, and reduce the variability of crop yield in no-till fields by improving hydrology. Gypsum is a source of soluble calcium (Ca) that improves physical properties of the soil by promoting clay aggregation, thereby increasing water infiltration rates and movement through the soil profile. Undisturbed soil samples from Brookston and Celina soils in Ohio, USA were collected to a depth of 75 cm in agricultural fields treated with gypsum for 0, 4, and 12 years to determine changes in chemical and physical properties. Gypsum applications increased exchangeable Ca and Ca: Mg ratios, and promoted clay flocculation and improved soil structure. Mean weight diameter of aggregates increased with gypsum treatment at most depths in both soils. Micromorphological analysis showed variations in porosity (ɸ), pore size distribution, pore shape and aggregate size related to gypsum treatment, soil, and soil depth. There were no consistent responses to years of gypsum application. Gypsum treated soils had higher porosity than untreated soils in all depths <75 cm and a higher percentage of micropores and mesopores compared to the control. Also, gypsum treated soils had larger aggregates than the control for all soil depths examined. Aggregates <100 μm predominated in the Brookston control soils, and < 200 μm aggregates dominated the Celina control soils. However, there was no prevailing aggregate size for gypsum treated soils. In conclusion, our study found positive effects of gypsum on most properties measured; although, not consistently related to years of gypsum applications to both soils.

Impact of Mg rich synthetic gypsum application on the environment and palm oil quality

A study was conducted in an oil palm plantation in Peninsular Malaysia to elucidate the effects of applying Magnesium Rich Synthetic Gypsum (MRSG), a by-product of chemical plant, on the chemical properties of soil, the uptake of heavy metals by the palm trees, the oil quality and its impact on the surrounding environment. The results showed that MRSG application onto soil cropped to oil palm could bring positive impact in terms of soil chemical properties and oil palm production. The quality of the oil was not significantly affected by the continuous MRSG application as shown by the low heavy metals and trace elements of concern content (Cu: 0.062 mg/kg; Fe: 2.10 mg/kg; Mn: 1.93 mg/kg; Pb: 0.006 mg/kg; Zn: 0.103 mg/kg; Cr: 0.354 mg/kg; Ni: 0.037 mg/kg). From the I-geochem index, the soil was found to have values ranging from −3.81 to −1.03 which is considered as uncontaminated. Further, its application did not result in negative impact on the surrounding environment; hence, the quality of the soil and surface water in the plantation and/or the surrounding area remained intact. Phytotoxic elements in the oil palm tissue (As: 0.12 mg/kg; Se: 0.05 mg/kg; Zn: 1.48 mg/kg; Ce: 0.47 mg/kg; La: 0.26 mg/kg; Sr: 3.03 mg/kg) and cytotoxic elements in the oil were below the acceptable limit. Based on the results of the Environmental Monitoring out during the period of the study, it was concluded that application of the by-product of the chemical plant as a source of Mg to enhance soil fertility in the oil palm plantation was considered safe and sustainable. The effects of applying MRSG and Chinese kieserite was almost similar. So, MRSG can be used as a possible source of Mg to replace Chinese kieserite for oil palm production on the Ultisols in Peninsular Malaysia.

Characterization of the role of phosphogypsum foam in the transport of metals and radionuclides in the Southern Mediterranean Sea.

The Gabes Gulf had received huge quantities of phosphogypsum discharged from fertilizer plants. Dumping phosphogypsum in coastal waters leads to the formation of foam layers which can float on the surface and be passively transported to distant areas. This is the first attempt at geochemical and mineralogical characterization of these industrial foams in order to understand their role in the dynamic and behavior of contaminants in marine environment. Chemically, phosphogypsum foams (PGFs) are heavily loaded with radiochemical contaminants. Their mineralogical composition showed a prevalence of synthetic gypsum followed by other secondary minerals including halite, quartz, dolomite, sphalerite-Cd and fluorapatite. PGFs are rich in organic matter (OM), precursor of their formation. Once released in gypseous water, the OM in solution undergoes agglomeration, cementing and flotation steps leading to the formation of floating foams. The foams' OM was found to control the mobility of industrial contaminants contributing then to the marine environment pollution. Consequently, PGFs are the main accumulating, transporting and dispersion agent of phosphogypsum radiochemical contaminants. Thus, PGFs removal has the potential to reduce enormously the dynamics of contaminants transferred from the fertilizer plants to the aquatic environment, reducing thus their impacts on the marine environment and health status in Gabes.

Effects of expansive additive on cement composite properties

Shrinkage is a due to chemical and physical processes in concrete. The results of these are volume changes that may cause cracking, deformation, decrease in strength and especially durability of a construction. The amount of water in concrete, the fine particles content, the dimension of construction, the method of curing of the fresh concrete and environmental conditions (temperature, humidity) are some factors influencing the shrinkage of concrete. This article deals with reduction the shrinkage of cement composites by addition of expansive cement Denka CSA and synthetic gypsum. The additives were used at a dosage of 10% of the original weight of cement. The obtained results showed different impact of these additives to the volume changes and the compressive strength of cement composites. The Denka CSA additive had a positive effect to monitored properties of cement mortars. It caused the lowest shrinkage; slight increasing of long-term compressive strength and decreasing of bulk densities after 2, 28 and 90 days of hardening.