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Highlights • It explored a new way to reuse fine recycled concrete aggregate (FRCA) in mortar. • Different size ranges of river sand (RS) were replaced by corresponding FRCA. • Fractions of aggregate with size >0.6 mm replaced with FRCA was acceptable. • Replacement of RS with FRCA and crushed fine stone was compared. Abstract This study explored an alternative way to reuse fine recycled concrete aggregate (FRCA) in cement mortars by using a new designed method to replace natural aggregates. The river sand (RS) in different particle size ranges with varied lower limits (i.e., 4.75–2.36 mm, 4.75–1.18 mm, 4.75–0.6 mm, 4.75–0.3 mm and 4.75–0.075 mm) were replaced gradually by the corresponding FRCA. As a comparison, same particle size ranges of fine crushed stone (FCS) were also used as replacement of RS. All types of mortars were controlled by a similar consistency. The results showed that the decrease in the lower limit of the replaced particle size range of FRCA (R L (FRCA)) tended to cause reductions in the compressive and flexural strength and increases in the drying shrinkage of the mortars. Using different particle size ranges of FRCA to replace RS in mortars resulted in more adverse effects on the strength and drying shrinkage than incorporating the corresponding FCS. The results of this study could provide a guidance on which particle size ranges of FRCA could be used as the replacement of RS in cement mortars for specific performance requirement. [ABSTRACT FROM AUTHOR]

Highlights • Nanoalumina (NA) accelerated the hydration of both silicate and aluminate phases in OPC. • The CH and W n contents of NA modified OPC pastes increased at early age, but were almost unchanged at later age. • Adding NA particles increased the micropores and reduced the macropores in OPC pastes. • Al-enriched outer C-S-H products were found in NA modified OPC pastes. • NA had little impact on the compositions of the inner C-S-H products. Abstract Many studies have focused on the feasibility of using nanoparticles including nanoalumina (NA), in cement composites and reported some positive effects on the properties of concrete. However, there are still uncertainties about the effects of NA addition on cement hydration. In this study, γ-NA particles with a size of about 30 nm was incorporated into Portland cement pastes and the physicochemical and microstructural properties of the NA-modified cement pastes were analyzed. Conduction calorimetry results showed that NA accelerated the silicate and aluminate phases reactions in OPC. Compared to the plain cement paste, the NA-modified cement pastes exhibited improved compressive strength at all ages due to the reduced macropores and the accelerating effect on cement hydration induced by NA, but the strength enhancement at 28 days was less obvious. Moreover, back scattering electron imaging and energy-dispersive spectroscopy (BSE-EDS) analysis indicated that the Al-enriched outer C-S-H formed in the NA modified paste; and it was mainly due to the NA particles acting as seeding for the growth of the outer C-S-H at the early age, rather than the Al released by the aluminate phases. This also provided a possible explanation for the substantial increase in CH and chemical bounded water contents in the NA-modified pastes at 12 h, but almost no change at 28 days of hydration. [ABSTRACT FROM AUTHOR]

Abstract A coupled CO 2 -water curing regime was employed on Ordinary Portland cement (OPC) paste samples immediately after casting, which allowed carbonation and hydration of OPC to proceed simultaneously. The strength development and microstructural evolution was evaluated by using multiple-techniques. The results indicated that, compared to the normal hydrated counterpart, a lower porosity, higher amorphous phase content and overall reaction degree can be achieved in the coupled CO 2 -water cured OPC sample. By combining with the morphological observations, a new mechanism was proposed for the rapid hardening of OPC. It is shown that the carbonation reactions led to the formation of calcite particles, which provided more nucleating sites for C S H gel growth; and thus, an increase in the overall reaction degree of the cement paste can be achieved within the first 24 h compared to the conventional water curing process. Graphical abstract Image 1 Highlights • Chemically bond water in coupled CO 2- water cured paste was less than that in normally hydrated paste. • Strength gain from subsequent water curing varied inversely with the initial CO 2 uptake. • Apparent porosities of the pastes were similar after 28 days of curing, regardless of any curing regime. • Different morphologies of C S H were observed under different curing regimes. • A new mechanism was proposed for the rapid hardening of OPC under coupled CO 2 -water curing. [ABSTRACT FROM AUTHOR]

Strengthening the attached old cement mortar of recycled concrete aggregate (RCA) is a common approach to enhance the RCA properties. Accelerated CO 2 curing has been regarded as an alternative way to enhance the properties of RA. However, the improvement of the properties of RCA was limited by the shortage of reactive components in the old cement mortar available for the carbonation reactions. In this study, a CO 2 curing process associated with a limewater saturation method was performed cyclically on cement mortar samples, aiming to enhance the properties of cement mortars via artificially introducing additional calcium into the pores of the cement mortars. The results indicated that the adopted treatment method promoted the level of carbonation which was demonstrated by higher CO 2 uptake by the limewater saturated cement mortar when compared to that without limewater treatment. After 3-cycles of limewater-CO 2 treatment, the density of the cement mortar slightly increased by 5.7%, while the water absorption decreased by over a half. For mechanical properties, the compressive and flexural strength were increased by 22.8% and 42.4%, respectively. Compared to the untreated cement mortar samples, the total porosity of cement mortar was reduced by approximately 33% and the densified microstructure therefore resulted in a higher microhardness. [ABSTRACT FROM AUTHOR]

This study designed a novel cement-based architectural tile prepared with more than 70% waste glass content (by weight). The waste glass was employed not only as decorative aggregates but also as a supplementary cementitious material in the architectural mortar. In terms of shrinkage, the incorporation of glass powder (GP) could significantly reduce the drying shrinkage of the glass mortars regardless of its fineness. When the glass mortars were subjected to high temperature (800 °C), the inclusion of GP into the mortars was more able to mitigate the flexural and compressive strengths losses as compared to the control glass mortar prepared without the use of GP. Furthermore, using the GP and glass aggregates simultaneously could effectively improve the resistance of the glass mortars to sulfuric acid attack and the positive effect was more pronounced when finer GP was incorporated. In particular, an encouraging result shows that the replacement of 20% cement by fine GP successfully suppressed the deteriorative alkali-silica-reaction (ASR) expansion caused by the glass aggregates. Also, the glass mortars incorporated with fine GP exhibited comparable or even superior durability properties than that of the fly ash blended glass mortar. [ABSTRACT FROM AUTHOR]

An experimental study was carried out to evaluate the mechanical and durability properties of architectural mortar prepared with 100% glass aggregates and using supplementary cementitious materials (SCMs) to replace cement. The mechanical properties were assessed in terms of compressive and flexural strength, whilst the durability characteristics were investigated in terms of drying shrinkage, resistance to high temperature exposure, alkali-silica-reaction (ASR) and acid dissolution. Experimental results suggested that strengths of glass-based architectural mortar incorporating SCMs (fly ash, ground granulated blast-furnace slag, metakaolin and waste glass powder) were comparable or even superior to that of the pure cement mortar when the cement replacement levels was up to 20%. In particular, waste glass powder (GP) as a pozzolanic material performed better than the other SCMs for flexural strength development of the glass-based mortar. The durability results also indicated that the addition of the SCMs could significantly reduce the drying shrinkage of the glass-based architectural mortar. All the recycled glass architectural mortars prepared with SCMs showed favorable resistance to expansion due to the ASR and less strength loss after heating to 800 °C. GP and ground granulated blast-furnace slag (BS) blended mortars gave better performance below 600 °C as compared to fly ash (FA) and metakaolin (MK) blended mortar. Also, the glass-based mortar containing GP exhibited the best performance of resistance to acid attack. Therefore, there is a potential to produce high performance architectural mortars with excellent mechanical and durability properties by reutilizing recycled glass to fully replace natural aggregates and partially replace cement. [ABSTRACT FROM AUTHOR]

In this study, a CO 2 curing process was adopted in order to promote rapid strength development of concrete blocks containing recycled aggregates. The influence of several factors associated with the curing conditions on the curing degree and compressive strength of the concrete blocks were investigated, including curing time, temperature, relative humidity, pressure and post-water curing after the pressurized CO 2 curing (PCC) process. In addition a flow-through CO 2 curing (FCC) method at ambient pressure was also used. The results of the PCC experiments showed that, considerable curing degree and compressive strength were attained during the first 2 h of CO 2 curing, and a prolonged curing time yielded slower gains. The variations of temperature from 20 °C to 80 °C and relative humidity from 50% to 80% had limited impacts on PCC; but the effects of CO 2 gas pressure on the curing degree and compressive strength were more pronounced. The post-water curing after pressurized CO 2 curing allowed the concrete blocks to attain further strength gain but its effectiveness was inversely proportional to the CO 2 curing degree already attained. The FCC experimental results indicated that although a lower curing degree and slower strength development at the early age were observed, after 24 h of curing duration, they were comparable to those obtained by the PCC method. To assess the thermal stability of the concrete blocks, the optimum CO 2 curing regime was adopted for preparing the concrete blocks with recycled aggregates, and the CO 2 cured specimens exhibited better fire resistance than the water-cured ones at 800 °C. [ABSTRACT FROM AUTHOR]

In order to enhance the CO 2 curing efficiency of concrete block prepared with recycled aggregates, several material characteristics of the concrete block including moisture content, bulk density, aggregate to cement ratio, recycled aggregate content and types of binders, were studied experimentally to assess their effects on the CO 2 curing process. The results indicated that, during 2 h of CO 2 curing period, the moisture content and aggregate to cement ratio of the prepared blocks had significant effects on the CO 2 curing degree and the compressive strength. Appropriate pre-drying of the block specimens before CO 2 curing enabled the maximum curing degree, and the compressive strength attained was comparable or superior to that of the 6 h steam cured blocks. The bulk density and recycled aggregate content of the prepared blocks would also influence the CO 2 curing degree, but their effects on compressive strength were more complex. It was confirmed that the presence of recycled aggregate in the concrete blocks can promote the CO 2 curing efficiency. [ABSTRACT FROM AUTHOR]

With an increasing interest in recycling and reusing waste, there is a need to carry out research on exploring ways to transform industrial wastes into construction materials. This paper attempts to explore the feasibility of reutilizing textile effluent sludge (TES) for producing concrete blocks with a pretreatment step. The lime-based pretreatment process was adopted to remove ammonia in TES which had been found to lead to bad odor and strength loss of the concrete blocks. The concrete blocks were prepared with an aggregate to cement ratio of 12, 10 and 6. The pretreated TES was adopted to replace the fine aggregate at a mass ratio ranging from 0% to 30%. The compressive strength and drying shrinkage values were determined to evaluate the performance of concrete blocks containing TES. The results indicated that the lime-based pretreatment process can lower the ammonia concentration in TES significantly. The concrete blocks with a lower TES content and lower ammonia concentration had higher compressive strength and better volume stability. When the TES content in the concrete blocks was about 10%, the concrete blocks with an aggregate to cement ratio of 10 can satisfy the minimum strength requirement for non-load bearing applications. Meanwhile, the result of leaching test indicated that the toxic trace metals present in textile effluent sludge could be stabilized/solidified and metal leaching from the concrete blocks is not a concern. [ABSTRACT FROM AUTHOR]

Abstract: The paper presents the results of an experimental study on properties of concrete prepared with recycled mortar aggregate (RMA) that has been modified by a CO2 curing method. The experimental investigation was conducted in two parts. Firstly, the properties such as density, 10% fine value, and water absorption of CO2 improved RMA were determined. Secondly, the fresh, hardened and durability properties including slump, compressive and tensile splitting strength, drying shrinkage and chloride penetrability of the concretes prepared with RMA and CO2 cured aggregates (CI-RMA) were determined. It was found that the density, and 10% fine value of the CI-RMA was higher, and the water absorption of the CI-RMA was lower when compared to the untreated RMA. For the concrete, not only was there an improvement in the mechanical properties and resistance to chloride ion penetration for the concrete prepared with CI-RMA, but also the drying shrinkage was decreased. [Copyright &y& Elsevier]

Abstract: The research was conducted to explore the feasible use of fresh concrete waste (FCW) for the manufacturing of partition wall blocks. The FCW sourced from a ready mix concrete plant was crushed into the size of fine aggregate (<5mm), and used to replace natural sand at the proportions of 0%, 25%, 50%, 75% and 100% by weight with an aggregate/cement ratio of 12, for producing partition blocks. The properties of the blocks, such as density, water absorption, compressive and transverse strengths, and drying shrinkage as well as the loss of strength, mass and ultrasonic pulse velocity after exposure to elevated temperatures (300°C, 500°C and 800°C) were determined. The results indicate that as FCW content increased in the blocks, the water absorption increased and density decreased due to the high porosity of FCW. But the incorporation of FCW aggregates improved the mechanical properties (compressive strength and transverse strength) of the partition blocks. However it weakened the fire endurance of the blocks. The results of the study have demonstrated that it is feasible to utilize the FCW in the production of non load-bearing concrete products, such as partition blocks. [Copyright &y& Elsevier]

Abstract: In Hong Kong, a large amount of fresh concrete waste (FCW) is generated from ready mix concrete plants every day. Up to now, these wastes are usually delivered to landfills for disposal. The landfill areas in Hong Kong will be saturated in 6–8years, as a result there is a need to develop a new technique for utilizing the FCW. In this study, FCW was crushed into coarse aggregate, and then it was used to replace natural coarse granite at percentages of 0%, 15%, 30% and 50%, in producing new concrete mixes. The concrete were produced with water/cement ratios of 0.35 and 0.50. The effect of using the normal mixing approach and the two-stage mixing approach on the properties of concrete was also compared. The results indicated that the density, strength and static modulus of elasticity of new concrete were decreased with an increase in FCW content. Due to the lower density and higher water absorption of FCW, the water absorption, chloride ion permeability and dry shrinkage of the new concrete was increased with the increase in FCW content. Moreover, the two-stage mixing approach (TSMA) only improved the strength of the FCW concrete when the concrete was prepared with a lower water-to-cement of 0.35. The results demonstrated that the FCW can be used to replace natural aggregates for the production of non-structural concrete. [Copyright &y& Elsevier]

• Hydration behavior of CFBFA was investigated in a CFBFA-lime system. • The hydration products of CFBFA vary in their strength performance. • The main hydration products of CFBFA were C-S-H, AFm, AFt and C-A-S-H. • Binder differing in lime content varied in micro-morphology. In this study, the hydration behavior of circulating fluidized bed fly ash (CFBFA) as a cementitious binder was investigated in a CFBFA-lime system. Binary mixtures of CFBFA and lime were prepared with different weight ratios, and a series of experiments were performed to evaluate the hydration behavior of the mixtures. When the mixing weight ratio of CFBFA and lime was 5:1, the prepared mixtures could reach 17 MPa at 28 days. Hydration heat curves revealed that the release heat peak related to the hydration of CFBFA appeared earlier as the content of lime increased. This likely stemmed from the release of heat by the hydration of lime. Analysis of Ca(OH) 2 consumption and chemically bound water revealed that the hydration reaction of mixtures can continue for a long time after Ca(OH) 2 was depleted. In addition, the main hydration products of the CFBFA-lime system were C-S-H, C-A-S-H, AFm and AFt. The micro-morphology of the hydration products changed from needles to mesh-like and then to foil-like as the lime content in mixtures increased. [ABSTRACT FROM AUTHOR]

• Hydration behavior of CFBFA was investigated in a CFBFA-lime system. • The hydration products of CFBFA vary in their strength performance. • The main hydration products of CFBFA were C-S-H, AFm, AFt and C-A-S-H. • Binder differing in lime content varied in micro-morphology. In this study, the hydration behavior of circulating fluidized bed fly ash (CFBFA) as a cementitious binder was investigated in a CFBFA-lime system. Binary mixtures of CFBFA and lime were prepared with different weight ratios, and a series of experiments were performed to evaluate the hydration behavior of the mixtures. When the mixing weight ratio of CFBFA and lime was 5:1, the prepared mixtures could reach 17 MPa at 28 days. Hydration heat curves revealed that the release heat peak related to the hydration of CFBFA appeared earlier as the content of lime increased. This likely stemmed from the release of heat by the hydration of lime. Analysis of Ca(OH) 2 consumption and chemically bound water revealed that the hydration reaction of mixtures can continue for a long time after Ca(OH) 2 was depleted. In addition, the main hydration products of the CFBFA-lime system were C-S-H, C-A-S-H, AFm and AFt. The micro-morphology of the hydration products changed from needles to mesh-like and then to foil-like as the lime content in mixtures increased. [ABSTRACT FROM AUTHOR]

Carbonation treatment is a promising option to enhance recycled concrete aggregate (RCA) quality and eventually improve concrete performance. This study investigated the multi-scale mechanical properties of calcium silicate hydrates (C-S-H) in a mature alite paste subjected to accelerated carbonation treatment by testing macro compressive strength, microhardness and nanoindentation. The results show that, carbonation treatment resulted in a heterogeneous distribution of carbonation products in the alite sample. Reinforcement of C-S-H by the randomly precipitated calcite and vaterite crystals prevailed over the nano-structural and compositional alteration of C-S-H induced by carbonation, leading to an increase of nano-indentation modulus at the edge of the sample. Also, the microhardness at the edge zone was markedly higher than that at the core of the carbonated sample. The carbonated peripheral zone with improved nano-scale modulus and microhardness was likely serving as a "hard shell", contributing to the improved macro compressive strength. The new insights into the multi-scale mechanical properties of carbonated C-S-H contribute to further understanding of the enhanced properties of RCA after carbonation treatment. [ABSTRACT FROM AUTHOR]

Treatment by accelerated carbonation has been widely studied to enhance the quality of recycled concrete aggregates (RCA) and hence the performance of new concrete produced with the RCA. This is often ascribed to the densification of RCA. This study investigated the influence of carbonation treatment of modeled RCA on the interface between the carbonated RCA and new cement mortar/paste using frictional (shear) and tensile bond tests, microhardness, X-ray diffraction (XRD), thermal analysis (TGA), and scanning electron microscope (SEM). It was found that carbonation treatment resulted in massive calcite precipitating on the surface of RCA, which further reacted with the aluminate species of the new cement to form the monocarbonate (Mc), and served as nucleation sites for the grow of C-S-H on the surface of RCA. These led to local densification around the surface of the carbonated RCA, resulting in a slight reduction of the porosity at the innermost part of ITZ and improved microhardness of ITZ. Moreover, the chemical bonds provided a superior adhesion of the carbonated RCA with the new cement pastes. This improved the bond strengths between the carbonated RCA and the new cement mortar. [ABSTRACT FROM AUTHOR]

Red mud (RM) is a hazardous waste material generated during the alkaline leaching of bauxite in the Bayer process. The feasibility of using RM as a viscosity-modifying agent (VMA) for self-compacting concrete (SCC) was proposed in this study. In addition, RM paste, cement paste, RM-blended paste, SCC that containing RM as VMA were prepared, and those fresh properties were investigated with emphasis. The results show that compared to cement paste, the RM paste exhibited excellent water retention. In the RM-blended cement paste with equivalent fluidity, an increase in RM dosage led to a notable decrease in bleeding rate, accompanied by an increase in yield stress and plastic viscosity. Similarly, in the SCC (containing RM as VMA) with equivalent slump-flow, the segregation rate decreased significantly (17.12 % of segregation for SCC that without RM, and 6.88 % of segregation for SCC that with 12 wt% RM), while yield stress and plastic viscosity increased with higher RM dosages, demonstrating a linear relationship. These findings highlight the feasibility of achieving SCC with high slump-flow and non-segregation by using RM as VMA, and the fresh properties of prepared SCC can be effectively controlled. Meanwhile, the findings of this study offer a novel approach to utilize RM and provide valuable guidance for the application of RM used as VMA. • Red mud is an environmental contaminant generated in alumina extraction. • Red mud is used as a viscosity-modifying agent for self-compacting concrete. • Red mud particles have better water retention than the cement particles. • The SCC with High slump-flow and non-segregation can be achieved using RM and PCE together. • The fresh properties of SCC with red mud could be well controlled. [ABSTRACT FROM AUTHOR]

• Interactions between cement and effluent sludge was investigated. • Effects of effluent sludge on cement hydration were studied. • Causes of deterioration of mechanical properties of sludge mortar were revealed. • Poor interfacial bonding was found between sludge particles and hydrated cement. • The leaching behavior of sludge mortar was studied. The textile industry produces a large amount of textile effluent sludge (TES). Many studies have explored the potential use of TES in cement-based materials. However, the physicochemical interactions between the TES and ordinary Portland cement (OPC) have rarely been studied. In this study, the effects of increasing dosage (0–20% by OPC) of TES on the performance of OPC-TES blends were investigated in terms of hydration progress, mechanical strength, microstructure evolution and metal leachability. The results showed that TES markedly delayed the OPC hydration at the early age, and increasing dosages of TES decreased the portlandite content at 7 and 28 days' age. Compared to the reference, the OPC-TES mortar exhibited seriously degraded mechanical strength; when using 20% TES, the decrease in compressive and flexural strength reached up to 71% and 42% respectively at the age of 28 days. Scanning electron microcopy and mercury intrusion porosimetry found the inclusion of TES introduced more weak interfaces in the cement mortar, thus increased the total porosity especially the macropores. But leachability tests revealed all the toxic metals in the TES were stabilized after the incorporation of OPC and exhibited very low metal mobility in the OPC-TES mortar, which posed no environmental risk. [ABSTRACT FROM AUTHOR]

Mixed solids (precursors) containing equal portions of ground granulated blast-furnace slag (GGBS) and sewage sludge ash (SSA) by weight were activated by mixed alkaline solutions that was comprised of sodium hydroxide and sodium silicate in prescribed proportions to prepare geopolymer pastes in a dry-mixed form. Tests were carried out to provide data on compressive strength and microstructural properties of the geopolymer pastes synthesized from different mass ratios of alkali to the mixed solids, i.e., Na 2 O content, and different molar ratios of SiO 2 to Na 2 O in the mixed alkaline solution (i.e. different moduli). The results showed that the maximum compressive strength of 32.8 MPa at 28 days could be achieved at the optimal Na 2 O content of 4.0% and a modulus of 0.95. Analyses of the microstructures of the geopolymer pastes by XRD, QXRD, FTIR, SEM and EDX revealed that SSA participated in the geopolymerization process and the quartz and hematite crystals in it were largely dissolved in the reaction. The microanalyses also revealed that the main reaction product of the optimal geopolymer mixture was a C-(N)-A-S-H type gel with Fe substitutions. The drying shrinkage of all specimens were less than 0.06% at the age of 14 days. Testing for metal(loid)s showed that SSA could be used with GGBS as precursor materials for geopolymerization with no leaching problems. This work provides a potential option to recycle SSA and builds up a theoretical basis for proportioning design in utilizing GGBS and SSA in dry-mixed geopolymers. [ABSTRACT FROM AUTHOR]

• Natural sepiolite samples were treated with hydrochloric and acetic acid solutions. • Acid treatment led to a slight decrease in amorphous phase content of natural sepiolite. • The reactivity of natural sepiolite most likely stemmed from the activation of Si phase. • Acid-treated sepiolite can modify the hydration of cement during the early curing period. • Strong acid-treated sepiolite specimens have higher compressive strength than weak acid-treated ones. In this study, natural sepiolite samples were treated with hydrochloric and acetic acid solutions at three different concentrations (0.1 M, 0.5 M, and 1.0 M). The effect of acid treatment on the reactivity of natural sepiolite and the change in cement hydration following the addition of natural sepiolite were studied using X-ray diffraction, particle size distribution analysis, inductively coupled spectrometry, thermogravimetric analysis, and isothermal calorimetry. Although acid treatment leads to a slight decrease in the amorphous phase content in natural sepiolite, the reactivity of sepiolite increased. The results indicate that the increase in sepiolite reactivity most likely stemmed from the activation of the Si phase. In addition, acid-treated sepiolite can modify the hydration of cement during the early curing period and hinder the hydration of cement during the later curing period. The compressive strength of specimens with strong acid-treated sepiolite was higher compared with specimens with weak acid-treated sepiolite. [ABSTRACT FROM AUTHOR]

• Calcinated low-grade natural sepiolite was used as a supplementary cementitious material. • The highest pozzolanic activity was exhibited by sepiolite calcinated at 800 °C. • The addition of sepiolite negatively affected the rheological behaviors of fresh pastes. • During early curing stage, the addition of sepiolite can accelerate the hydration of cement. • The highest compressive strength appearing in the pastes blended with sepiolite calcinated at 800 °C. In this study, the pozzolanic activity of low-grade natural sepiolite was enhanced by calcination for further utilizing as a supplementary cementitious material. Sampled sepiolite was calcinated at 400, 600, 700, 800, 900, and 1000 °C, and the calcinated sepiolite were characterized and respectively blending with pastes for examining their rheological and hydration behaviors. It was found the pozzolanic activity of sepiolite was maybe mainly determined by the active Si phase content, and 800-SP showed the highest pozzolanic activity. The rheological behaviors of fresh paste blended with sepiolite calcinated at different temperatures shows obviously different. In early curing stage, the addition of sepiolite obviously accelerated the cement hydration. But in later curing stage, comparing with U-SP, the calcinated sepiolite showed hindering effect on cement hydration, and this effect was obviously regular with the increasing calcinated temperature. Additionally, by comparing with all pastes blended with sepiolite, which blended with 800-SP showed the highest compressive strength values. [ABSTRACT FROM AUTHOR]