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The circumstances in which calcium sulfoaluminate (CSA) cements used are multivariate. Considering the curing temperature greatly influence the formation of hydrates, the hydration of CSA cement containing increasing amount of anhydrite which cured at different temperature was analyzed by calorimetry, XRD and DTA-TGA. And the setting time and mechanical strength are measured to explore the correlation between the microstructure revolution and macroscopic performance. Results illustrate that the hydration of prepared CSA cement is highly dependent on the curing regimes and anhydrite dosage. The addition of anhydrite prolongs the setting of CSA cement at 5 °C, while it accelerates the setting at 20 °C and 40 °C. The usage of anhydrite is detrimental to strength development of CSA cement mortars which cured at 5 °C and 20 °C, but it's the opposite at 40 °C. Additionally, elevated curing temperature favors the formation of ettringite, alumina gel and monosulfate within 1 d. CSA cement prepared with higher amount of anhydrite is beneficially used in the hot environment. [ABSTRACT FROM AUTHOR]

Abstract: The objectives of this study were to assess the feasibility of application of dry composite electroplating sludge (CEPS) into preparation of cement-based decorative mortar as green pigment, and to find a new disposal and resource approach for it. Color, water absorption, strength, hydration and leachability of cement-based decorative mortar are investigated. The results show that CEPS can adjust the mortar color well. Although CEPS leads to the increase of mortar water absorption, the water absorption of mortar prepared with 5% CEPS still meets the requirement stated in the Chinese Building Material Industry Standard JC/T 1024-2007. The mortars with CEPS are provided with nearly same compressive, flexural and tensile bond strengths as these of the control. Cement hydration products such as C–S–H gel, Ca(OH)2 and the entringite all can be observed in different specimens. The denser microstructures than that of the control are formed in the mortars with CEPS. It is found from almost similar intensity in Ca(OH)2 peak at 18.007° that CEPS has not notably influence on the cement hydration. It is also evident that heavy metal concentrations in leachates of the mortars with CEPS are far lower than recommended in the Chinese National Standard GB5085.3-2007. It is safe to people's health and environment that CEPS is recycled as green pigment to produce cement-based decorative mortar. [Copyright &y& Elsevier]

• Compressive strength of mortar with VAEC cured at 60 °C is significantly increased. • High curing temperature facilitates the formation of carboxyl-containing substances. • High curing temperature reduces the thickness of polymer film. • The pore structure relates to the content of VAEC and curing temperature. In this work, the roles of curing temperature on the mechanical performance and microstructure of cement paste/mortar modified by VAEC dispersible powder are reported. The experimental results show that as compared with mortars cured at standard condition, the strengths of mortars cured at 60 °C are enhanced, whereas the 100 °C curing temperature makes a side effect. The formation of carboxyl-containing substances is facilitated at elevated temperatures and meanwhile the pores are refined and the thickness of polymer film is reduced together with the pores in the polymer film are increased. These alterations are responsible for the changes of mechanical performances. [ABSTRACT FROM AUTHOR]

• TEA and C-S-Hs-PCE further decrease the setting behavior. • 0.02% TEA and 0.5%–2% C-S-Hs-PCE definitely enhance the compressive strength. • TEA and C-S-Hs-PCE also alter the hydration process. • TEA and C-S-Hs-PCE influence the pore characteristic and CH content. This paper aimed at investigating the action of the combined presence of calcium silicate hydrate seeds - polycarboxylate (C-S-Hs-PCE) and triethanolamine (TEA) on the performances of cement paste/mortar. Simultaneously, the mechanisms behind this action were explored. The results demonstrate that the composite addition of C-S-Hs-PCE and TEA further promotes the setting behaviour of cement pastes, but this promotion depends mainly on the TEA content. The composite use of 0.02% TEA and 0.5–2% C-S-Hs-PCE increases the mortar compressive strengths at 1, 3, 7 and even 28 days. This increase is related to the promotion of tricalcium silicate (C 3 S) hydration at 1 and 3 days, the increment of the calcium hydroxide (CH) content over 1–28 days, and the decrement of the number of gel pores and the volumes of the pores with sizes of less than 100 nm in the pastes with 0.02% TEA and 0.5%–2% C-S-Hs-PCE. However, the composite addition of 0.5%–1% TEA and 0.5%–2C-S-Hs-PCE reduces the compressive strengths at 1 and 28 days: 0.5%–1% TEA and 0.5%–2% C-S-Hs-PCE enhance the monosulfate (AFm) content at 1 day, promote the reaction from ettringite (AFt) to AFm, decrease the CH content, retard the C 3 S hydration at 1 day and 3 days and increase the gel pore quantity and the volume of the pores that are distributed from several nm to 100 nm. As a result, the mortars with 0.5%–1% TEA and 0.5%–2% C-S-Hs-PCE exhibit lower compressive strengths at 1 day and 28 days. These findings provide theoretical guidance for the composite use of TEA and C-S-Hs-PCE in cement-based materials. [ABSTRACT FROM AUTHOR]

• The application of C-S-Hs-PCE and SS significantly shortens the setting time. • The hydration process of cement paste is accelerated by C-S-Hs-PCE and SS. • C-S-Hs-PCE and SS improve the pore structures and affect the chemical shrinkage. • The controls of hydration and properties development via C-S-Hs-PCE and SS are realized. This study reports the effects of combined application of calcium silicate hydrate seed-Polycarboxylate (C-S-Hs-PCE) and sodium sulfate (SS) on the hydration kinetics and mechanical properties of cement paste. The setting time, compressive and flexural strengths, and chemical shrinkage were evaluated. The mechanism of synergistic utilization of C-S-Hs-PCE and SS was explored on basis of the hydration heat releases, pore structures and crystalline phases. The results show that the setting time is shortened and the strengths of cement pastes are improved dramatically with the addition of C-S-Hs-PCE and SS. The incorporation of C-S-Hs-PCE increases the chemical shrinkage, while the co-doped C-S-Hs-PCE and SS can mitigate it. Overall, it accelerates the hydration process especially at early age, the pore structures are refined and the volume of gel micro pores increases due to more formation of gel. In the hardened pastes, the content of calcium hydroxide (CH) increases with the C-S-Hs-PCE and SS dosages, attributed to the further hydration of dicalcium silicate (C 2 S) and tricalcium silicate (C 3 S). This study could be viewed as a reference for the application of C-S-Hs-PCE and SS in cement paste, which is of great significance for its enhancement of early strengths. [ABSTRACT FROM AUTHOR]

• 0.5% β-hemihydrate and dihydrate significantly prolong the setting. • Mortar with 1–4% β-hemihydrate have higher compressive strength at 1 and 3d. • Even 1% β-hemihydrate makes all CAH 10 disappear. • Dihydrate can more significantly facilitate AH 3 and C 3 AH 6 formation. It is still uncertain whether β-hemihydrate and dihydrate gypsum influence the properties, especially the phase conversion, of white calcium aluminate cement (CAC). Therefore, in this study, we prepared CAC pastes/mortars containing β-hemihydrate and dihydrate and comparatively assessed their setting times and compressive strengths. Simultaneously, the influence of β-hemihydrate and dihydrate on their chemical shrinkage, hydration-heat, pore size distributions, crystalline, and thermogravimetric characteristics was investigated. It is interesting that 0.5% β-hemihydrate and dihydrate significantly postponed the setting, whereas more than 0.5% β-hemihydrate and dihydrate slightly prolonged the initial setting and significantly shortened the final setting. Both β-hemihydrate and dihydrate decreased the compressive strength of CAC pastes hardened for 1 and 3 days to different extents; however, CAC pastes with a β-hemihydrate or dihydrate content less than 1% exhibited a high compressive strength at 28 days. Beyond this dosage, the compressive strength of the specimens was found to reduce. In addition, CAC pastes containing more than 0.5% β-hemihydrate or dihydrate exhibited high chemical shrinkage over 3–12 h. Furthermore, β-hemihydrate and dihydrate enhanced the gel micro and meso pores. They accelerated or decreased CAC hydration in the fast reaction and first deceleration periods, prolonged or shortened the induction period, enhanced or reduced the hydration heat before or after 12 h. These cases are closely associated to their contents. Their inclusion restricted CAH 10 formation while promoting the generation of C 2 AH 8 , AFm, and AH 3 and conversion of CAH 10 to C 3 AH 6 after 3 days. Besides, there are some significant differences in their influence on the properties and phase conversion of CAC pastes. For these differences, CAC pastes/mortars with β-hemihydrate and dihydrate presented different setting times and compressive strengths. [ABSTRACT FROM AUTHOR]

• C-S-Hs-PCE promotes the formation of Friedel's salt. • It increases further shortens the setting times of paste with calcium chloride. • It promotes hydration of paste with calcium chloride at different levels. • 2% C-S-Hs-PCE significantly increases the strength of mortar with 2% CaCl 2. Friedel's salt usually forms in cement paste with CaCl 2 , however, it is still uncertain whether calcium silicate hydrate seed - polycarboxylate (C-S-Hs-PCE) promotes the formation of Friedel's salt, especially improves the performances of cement paste/mortar with CaCl 2. Therefore, in this study, X-ray diffraction (XRD) and differential thermal analysis (DTA) were used to quantify the Friedel's salt content in pastes with different contents of C-S-Hs-PCE and CaCl 2. Simultaneously, their setting times and compressive strengths at 1, 3 and 28 days were comparatively analyzed and the pore size distributions, hydration and chemical shrinkages of all pastes were also carried out to investigate the relative mechanism. The results reveal that C-S-Hs-PCE promotes the formation of Friedel's salt in paste with CaCl 2 , but this promotion is related to the contents of C-S-Hs-PCE and CaCl 2. C-S-Hs-PCE hardly influences the compressive strengths at 1, 3 and 28 days of mortars with less than 2% CaCl 2 , however, 2% C-S-Hs-PCE significantly improves the compressive strength of mortar with 2% CaCl 2. It is worth noting that it increases the specific surface area of pore in paste with CaCl 2 , but it decreases the volume and average diameter of pore in it. More importantly, it still enhances the heat flow in the initial fast reaction, first deceleration and induction periods of paste with CaCl 2. It also advances the merged main exothermic peak and enhances the heat flow at this merged peak. It does not increase the hydration heat during 72 h, but 1–2% C-S-Hs-PCE promotes the hydration of paste with CaCl 2 during 72–168 h. It leads to the further decrement in the setting times of paste with CaCl 2 for the hydration promotion in the initial fast reaction, first deceleration and induction periods. [ABSTRACT FROM AUTHOR]

• C-S-Hs-PCE cuts down the setting behavior of paste with EVA-DP. • It increases the strengths at 3d of mortars with EVA-DP. • It promotes hydration of paste with EVA-DP at different levels. • It enhances the apparent density of mortar with EVA-DP. This work aimed to improve the setting behavior and strengths of cement paste/mortar with ethylene and vinyl acetate copolymer redispersible powder (EVA-DP) using C-S-H seeds and polycarboxylate superplasticizer (C-S-Hs-PCE) and meanwhile explore the reasons for these two improvements by means of the heat flow, water requirement, air content, apparent density and pore size distribution. The experimental results show that C-S-Hs-PCE used in this work notably cuts down the setting behavior and increases the strengths at 3d of mortars with EVA-DP; however, less than 2% C-S-Hs-PCE hardly increases their strengths at 28d. C-S-Hs-PCE promotes the hydration of paste with EVA-DP in several manners; it enhances heat flow in the first deceleration period, the initial several hours in the acceleration period and at the main exothermic peaks/merged peak, or advances the onset of the acceleration period, or shifts the maximum of the hydration rate to earlier time. This promotion in the hydration at different levels is the reason for the shortened setting behavior of paste with EVA-DP in the presence of C-S-Hs-PCE. Except for the promoted hydration, the increased apparent density resulted from lowered water requirement, as well as the less pores, especially the middle and large capillary pores, are the other main contributors to the increment in the strengths of mortar with EVA-DP and C-S-Hs-PCE, especially the strengths at 28d of the mortars with 6% and 10% EVA-DP and 2% C-S-Hs-PCE. [ABSTRACT FROM AUTHOR]

• It improves the resistance to the cracking in the plastic period. • It decreases water evaporation loss and bleeding percentage. • Intermolecular hydrogen bonds form in the solution with cement. • It especially promotes the cement hydration at initial reaction. It is still uncertain whether polyacrylamide polymer powder can restrain the cracking of cement mortar in the plastic period and the mechanisms, which are responsible for this role, still need to be systematically clarified. Thus the different contents of the polyacrylamide polymer powder were mixed and various pastes with polyacrylamide were prepared. The cracking behaviors and water evaporation losses of mortars were evaluated. The bleeding percentages, chemical shrinkages, ions concentrations, ultraviolet visible spectra and the characteristics of hydration heat liberations of cement pastes with polyacrylamide polymer powder were investigated to carry out the insight into the role of polyacrylamide polymer powder on the cracking of cement paste in the plastic period. The experimental results indicate that the polyacrylamide polymer powder improves the mortar resistance to the cracking in the plastic period. It decreases the water evaporation loss and bleeding percentage. But it enhances the chemical shrinkage and the increased chemical shrinkage is mainly attributed to the role of polyacrylamide polymer powder on the promotion of cement hydration in the tested ages, especially in the initial fast reaction and the first deceleration periods. The existence of the intermolecular hydrogen bonds is the main reason for lowering the water evaporation loss and bleeding percentages. Acting forces from the intermolecular hydrogen bonds may be additional contributor to the improved resistance to the cracking of cement mortar in the plastic period. The results from this work will provide a reference for the alleviation of the plastic cracking of cement based paste. [ABSTRACT FROM AUTHOR]

• The use of GBFS powder and white CAC increases the chloride binding capacity of hardened gypsum. • The XRD, SEM, and EDS investigations confirm that Friedel's salt forms in the gypsum system. • The possible mechanism is also developed to explain the formation of Friedel's salt. Calcium chloride (CaCl 2) as a common concomitant in flue-gas desulfurization gypsum has a great negative impact on gypsum-based construction materials. Chloride binding in the form of Friedel's salt in the gypsum-dominating system is of great significance, but the feasibility of this approach has not yet been systematically clarified. In this paper, granulated blast-furnace slag (GBFS) powder and white calcium aluminate cement (CAC) were used as the components to explore their roles on the properties and chloride binding capacity of β-hemihydrate. Experimental results prove that CAC significantly improves compressive strength, water resistance, and chloride binding capacity of hardened paste. The XRD, DTG, SEM-EDS and thermodynamic modeling confirm that Friedel's salt forms in this system even at an early hydration time of 30 min. Mercury intrusion porosimetry and SEM results verify that the use of CAC decreases the volume of the pores in the 0.1–100 μm range. Thermodynamic modeling outcomes are consistent with the experimental data helping to explain the hydration and evolutions of β-hemihydrates in the presence of CaCl 2 , GBFS, and CAC at early hydration ages. [ABSTRACT FROM AUTHOR]

• It significantly increases the strengths and anti-penetration capacity. • It reduces the water capillary absorption and drying shrinkage. • It slightly affects chemical shrinkage and significantly reduces pores volumes. • It promotes the early hydration of waterproof paste. Aimed to enhance the performance of the cement and powder silane water repellent based waterproof mortar, different contents of nucleation C-S-H seed were thus introduced into various mortars and pastes, their performances such as strengths, water capillary absorptions, anti-penetration capacities, drying shrinkages and chemical shrinkages were evaluated. The pore size distributions of hardened mortars, heat liberations and crystalline phases of pastes cured for different ages were also measured to explore the mechanisms which are responsible for the enhanced performances. The results indicate that the nucleation C-S-H seed significantly increases the strengths and anti-penetration capacity, reduces the water capillary absorption and drying shrinkage of the waterproof mortar. It slightly affects the chemical shrinkage, but significantly reduces the volumes of the pores, especially the gel and large capillary pores. Overall, it promotes the early hydration of the cement and powder silane paste. It accelerates the conversion of ettringite (AFt) to monosulfoaluminate (AFm) and increases calcium hydroxide (CH) content in the hardened paste cured for 3d. It cuts down the entering time of acceleration period and the contents of un-hydrated clinker phases such as tricalcium silicate (C 3 S) and dicalcium silicate (C 2 S). These results will provide a theoretical reference for the preparation of cement and powder silane based waterproof mortar with better performances. [ABSTRACT FROM AUTHOR]

• Less than 0.2% TEA·HCl cuts down the initial setting time more significantly. • Less than 0.1% and 0.2% TEA·HCl enhances the compressive strength at 3 and 7d. • Cement paste with TEA displays the greater chemical shrinkage than with TEA·HCl. • TEA and TEA·HCl pose a different role on the cement hydrated product morphology. It is still uncertain whether there are some differences between their influences of TEA and TEA·HCl on the properties of cement paste. Thus, this work aimed to evaluate the differences between their influences of TEA and TEA·HCl on the properties of cement paste. Then the cement pastes or mortars with 0%, 0.01%, 0.015%, 0.02%, 0.06%, 0.10%, 0.20%, 0.50% and 1.00% TEA and TEA·HCl respectively were prepared and their setting times and compressive strengths were investigated. Meanwhile, the chemical shrinkage, pore size distributions, hydration heat releases, thermogravimetric (TG) characteristics and microstructures of vaious pastes were studied to explore the mechanisms that are responsible for these differences. The results show that less than 0.2% TEA·HCl reduces the initial setting time more significantly, whereas 0.02%, 0.06% and 0.1% TEA·HCl are inclined to shorten the finial setting time as comparing with the same content of TEA. Less than 0.1%, 0.02% and moderate TEA·HCl more significantly enhance the compressive strengths at 3 d, 7 d and 28 d respectively in comparison to the same content of TEA. These pastes with less than 0.2% TEA·HCl have the greater chemical shrinkage at 24 and 72 h, the cement pastes with less than 0.02% TEA·HCl provide the greater rate of hydration liberation in the initial fast reaction period, these pastes with 0.2% TEA·HCl display the more significantly increaseed rate of hydration heat liberation in the acceleration period as well as the more total hydration heat liberation at 72 h, as comparing with the cement pastes with same content of TEA. Besides, TG result indicates that these hardened pastes with TEA·HCl form the more CH at 3 d, whereas these hardened pastes with less than 0.06% TEA have the more CH at 28 d. These hardened pastes with 1%, 0.2% and 0.5% TEA·HCl have the relatively less pore voume as compared with the pastes with same contents of TEA at 28 d. The result of the scanning electron microscope (SEM) image shows that in the presence of same content of TEA and TEA·HCl, TEA·HCl is more liable to alter AFt and CH morphology. These discriminative results in the chemical shrinkage, pore sizes distribution, hydration heat release, TG and SEM provide an envience for the differences between their influences of TEA and TEA·HCl on the properties of cement paste. These results will provide a reference for the selective use of TEA and TEA·HCl as an accelerator. [ABSTRACT FROM AUTHOR]

Naphthalene sulfonate-formaldehyde condensatation (NSF) is the main component of the naphthalene based water reducers for cement based materials, as well as an organic substance with potential toxicity. However it is still uncertain whether it can leak from the cement based materials. In this work, the leakage ratio and adsorption behavior of NSF from various cement based materials such as the different water/cement (w/c) ratio, NSF content, types of cementitious materials as well as at different hydration time were evaluated. The product components of the cement based materials cured for different times were also quantified to explore the mechanisms which are responsible for the leakage and adsorption behaviors. The results indicate that more NSF, lower w/c ratio and less mineral admixture decrease the NSF leakage ratio. The leakage ratio of NSF from cement paste mixed 0.3% NSF is up to 50.8% at 0.5 h, and it decreases to 31.0% at 28 d. The leakage ratio of NSF from cement paste decreases as the hydration time prolongs. The lower leakage ratio corresponds to the higher adsorption capacity. Less adsorption capacity and thinner adsorption film imply that lower temperature and mineral admixture decrease the NSF adsorption behavior. When 0.3% NSF is added into the cement paste, the adsorption amount and NSF layer thickness are 5.53 mg/g and 0.98 nm, 5.87 mg/g and 4.7 nm at 0.5 h and 28 d respectively. The result demonstrates that the adsorption behavior of NSF in cement significantly increases at the initial several hours and gradually stabilizes after the first day. The X-ray powder diffractometer (XRD) results show that the contents of tricalcium silicate (C 3 S) and dicalcium silicate (C 2 S) continuously decline and the amorphous phases and ettringite (AFt) increase rapidly in the early stage. NSF adsorption and leakage behaviors are closely related to the hydration process of cement. These results indicate that NSF can definitely leak from the cement based materials and thus the NSF potential environmental pollution cannot be ignored. At least, it should be restricted or cautious to produce the water tower and pipe concrete structure with it. These results will sever as a theoretically reference for the pollution control as well as better application of NSF in cement-based materials. • More NSF, lower w/c ratio and less admixture decrease the NSF leakage ratio. • NSF leakage ratio is up to 50.8% at 0.5 h, and it decreases to 31.0% at 28 d • Adsorption amount and thickness are 5.53 mg/g and 0.98 nm at 0.5 h respectively. • Adsorption amount and thickness are 5.87 mg/g and 4.7 nm at 28 d • NSF leakage behavior is closely related to hydration time and products. [ABSTRACT FROM AUTHOR]

Highlights • Moderate TEA·HCl decreases the water requirement. • It also shortens the setting times and alters strengths. • It delays the end time of the induction period. • Excessive TEA·HCl accelerates AFt conversion to AFm. Abstract Triethanolamine (C 6 H 15 NO 3 , TEA) is one of the known organic amine accelerators for the cement-based materials. Triethanolamine hydrochloride (C 6 H 15 NO 3 ·HCl, TEA·HCl), part of whose molecular structure is the same as TEA, can also be regarded as chloride. Thus the water requirement for the normal consistency, setting time, strength, hydration heat liberation, calcium hydroxide (CH) and ettringite (AFt) contents in the hardened paste with TEA·HCl were analyzed and the effect of TEA·HCl on the performance of cement paste was studied to assess the feasibility of TEA·HCl used as an identical accelerator. The results indicate that moderate TEA·HCl decreases the water requirement for the normal consistency and this decline is related to the formation of the absorbed film on the cement particle. Zeta electric potential result also proves the appearance of the absorbed film. It also shortens the setting times and alters strengths. But the alterations of setting times and strengths depend on the TEA·HCl content. Heat liberation result implies that it delays the end time of the induction period and also postpones tricalcium silicate (3CaO·SiO 2 , C 3 S) hydration at early age, however moderate TEA·HCl increases the rate of C 3 S hydration in accelerated phase. Excessive TEA·HCl accelerates the AFt conversion to monosulfoaluminate (AFm) after several hours. The conversion product is the AFm with 14 H 2 O. TEA·HCl changes the total heat liberation, and these pastes with more TEA·HCl liberate more heat before about 12 h, but this case is reverse after about 12 h. X-ray powder diffraction (XRD) and differential thermal analysis (DTA) results conformably confirm that excessive TEA·HCl delays C 3 S hydration and decreases CH content in the hardened paste, but it increases the AFt content in the hardened paste. Hardened pastes with TEA·HCl provide the higher content of AFt than the control even at 28d. Heat liberation, CH and AFt contents are closely responsible for the results of the setting times and strengths. These results will provide a reference for the TEA·HCl application as an accelerator in the practice. [ABSTRACT FROM AUTHOR]

The small solid particles and surfactants inclusion have the potential to furnish abundant nucleation sites, yet the concurrent operation mechanisms in cement remain unclear. Thus, calcium-silicate-hydrate-polycarboxylate ether (C–S–H-PCE) nanoparticles and calcium stearate (CaSt 2) all were introduced as composites nucleation agents in this work, and then the properties of fresh cement paste, hydration process and microstructure of hardened pastes were especially investigated. Experimental results demonstrated that C–S–H-PCE and CaSt 2 enhanced cement hydration by utilizing their ability to provide nucleation sites, but they were less compatible. Therefore, the combination showed the antagonistic effects: a decrease in fluidity and compressive strength. The decrease in fluidity was mainly attributed to the lowered particle dispersion. The decrease in compressive strength was associated with a lower overall density and increased cumulative porosity of the C–S–H gels. This work establish the theoretical foundation for selecting components of green composite nucleation agents. [ABSTRACT FROM AUTHOR]

• The mechanical properties are efficiently enhanced with the addition of EVA, TEA and C-S-Hs-PCE. • It significantly improves the workability of fresh cement paste. • The deepening of hydration degree is the vital reason for the increase of early-age performances. • This study is of great importance to the application of admixtures in cement based materials. This work investigates the synergistic utilization of EVA, TEA and C-S-Hs-PCE as admixtures in Portland cement. The alteration of hydration process is measured by isothermal calorimetry (ICC) and the effects of admixtures on mechanical properties are evaluated by the development of strengths and apparent density. The mechanism of admixtures acting in cement is revealed via XRD, FT-IR and TGA techniques. Results show that the fluidity of fresh cement paste is significantly improved with the addition of EVA, TEA and C-S-Hs-PCE, and consequently to the increasing in workability. The admixtures accelerate the hydration process and increase the cumulative heat release, deepening the hydration degree of cement paste. Both the improvement of fluidity and promotion of hydration are the important reasons for the enhancement of mechanical properties. Results of XRD, FT-IR and TGA indicate that the CH contents increase evidently with the content of admixtures, which further proves that the deepening of hydration process. This study could provide an experimental reference, which is of great significance to the valuable application of admixtures in cement based materials. [ABSTRACT FROM AUTHOR]

Both polyacrylamide (PAM) and sodium polyacrylate (PANA) are polypropylene based polymer, however it is still uncertain whether there are some differences between their roles on the property of fresh cement paste. Thus this work aimed to compare the property of fresh cement pastes with them, such as shear viscosity, fluidity, bleeding and water evaporation loss ratio. Meanwhile, the ultraviolet visible spectra, infrared spectroscopy and thermogravimetry were carried out to explore the mechanisms that are responsible for these differences. The experimental results indicate that as compared with PANA, PAM increases the shear viscosity and reduces the fluidity of cement paste more significantly. However, PANA more significantly reduces bleeding and water evaporation loss ratio. These differences are in conjunction with their different behaviors in the fresh cement paste, such as promotion in the cement hydration at early age and reaction with cement hydration product. [ABSTRACT FROM AUTHOR]