A Blended Cement Containing Blast Furnace Slag and Phosphorous Slag

Blended cement containing blast furnace slag (BFS) and phosphorous slag( PS) is a new kind of cement. The total content of blended materials could increase if two additives were used. Using the same admixtures , the properties of the blended cement with 70% additives could reach the standard of 525-grade slag cement according to GB. The strength of cement with 80% additives could reach the standard of 425-grade slag cement. The tests of strength, pore structure, hydration products, inhibiting alkali-aggregate reaction, resistance to sulfate corrosion of BFS-PSC were performed.

Application of Air-cooled Blast Furnace Slag Aggregates as Replacement of Natural Aggregates in Cement-based Materials：A Study on Water Absorption Property

The influence of air-cooled blast furnace slag aggregates as replacement of natural aggregates on the water absorption of concrete and mortar was studied, and the mechanism was analyzed. The interface between aggregate and matrix in concrete was analyzed by using a micro-hardness tester, a laser confocal microscope and a scanning electron microscope with backscattered electron image mode. The pore structure of mortar matrixes under different curing conditions was investigated by mercury intrusion porosimetry. The results showed that when natural aggregates were replaced with air-cooled blast furnace slag aggregates in mortar or concrete, the content of the capillary pore in the mortar matrix was reduced and the interfacial structure between aggregate and matrix was improved, resulting in the lower water absorption of mortar or concrete. Compared to the concrete made with crushed limestone and natural river sand, the initial absorption coefficient, the secondary absorption coefficient and the water absorption capacity through the surface for 7 d of the concrete made from crushed air-cooled blast furnace slag and air-cooled blast furnace slag sand were reduced by 48.9%, 52.8%, and 46.5%, respectively.

Volumetric Variation and Rheology of Cement Based Mineral Additions （Blast Furnace Slag and Silica Fume）

The partial substitution of clinker by mineral additions offers very significant, both economical and environmental benefits. This adds value to industrial waste, and contributes also in the preservation of natural resources, like clay and limestone, as well as the reduction of greenhouse gas emissions （CO2）. This study is interested in the simultaneous effect of BFS （blast furnace slag） and SF （silica fume） on setting time and water requirement of cement paste. The volumetric variations are tested in mortars, prepared in the same mixture of pastes, and the tests indicate that the addition of slag increase the fluidity, reduce the water demand, shrinkage and expansion, compared to the mortar, containing ten percent （10%） of Silica Fume only. The images of pastes obtained by SEM （scanning electron microscopy）, are indicated an improvement of the microstructure of the paste with a large amount of slag, which leads to improve durability.

Setting and Strength Characteristics of Alkali-activated Carbonatite Cementitious Materials with Ground Slag Replacement

The effect of the ground granulated blast-furnace slag （ GGBFS ） addition, the modulus n （ mole rutio of SiO2 to Na2O ） and the concentrution of sodium silicate solution on the compressive strength of the material, i e alkuli-activated carbonatite cemeutitious material （ AACCM for short ） was investiguted. In addition, it is found that barium chloride has a sutisfiwtory retarding effect on the setting of AACCM in which more than 20% （ by mass ） ground carbonatite was replaced by GGBFS. As a result, a cementitious material, in which ground carbonatite rock served as dominative starting material, with 3-day and 28-day compressive strength greuter them 30 MPa and 60 MPa and with continuous strength gain beyond 90 days was obtained.

煤气化渣替代矿渣制备超硫酸盐水泥的可行性研究

煤气化渣(CGS)富含硅、铝元素,具备作为胶凝材料前体的潜力,但其颗粒形态粗糙,活性较低。为了解决CGS活性低、利用难等问题,利用CGS部分替代矿渣(BFS),探究CGS替代BFS制备超硫酸盐水泥(SSC)的技术可行性,并借助傅里叶红外光谱、X射线衍射仪、热重分析仪、扫描电子显微镜及能谱仪等微观测试技术对SSC水化产物的微观结构进行表征分析。结果表明,CGS作为制备SSC的原料,能提供初始水化所需要的硅、铝元素,驱动SSC发生水化反应。随着CGS掺量的增加,SSC胶砂的抗压强度呈逐渐减小趋势,而抗折强度受影响较小。CGS的最佳掺量为20%(质量分数),在此掺量下胶砂试样的28 d抗折强度最大,抗压强度也达到43.9 MPa。SSC的水化产物主要是水化硅酸钙、水化硫铝酸钙等凝胶。研究结果显示CGS部分替代BFS完全可用于制备SSC。

工业废渣在湖相软土固化改良中的应用研究

为改善湖相软土承载力小、易压缩变形、含水率大的工程特性,提出采用粒化高炉矿渣(GGBS)作为主固化材料,电石渣和Na_(2)SO_(4)作为激发剂材料对湖相软土进行复配固化改良,并与水泥固化方案进行了工程性能对比试验。结果表明:单掺GGBS、电石渣或者Na_(2)SO_(4)均能提升软土强度,分别在12%、2.5%和4%掺量时达到强度最大值,但对于强度的提升程度较小;当采用GGBS(12.18%)+电石渣(2.3%)+Na_(2)SO_(4)(5.31%)的复配方案时,强度提升较为显著,28d龄期强度可以达到1107kPa,是原状软土的24.6倍,其强度改善效果与掺入13%水泥的固化改良效果相当;采用GGBS+电石渣+Na_(2)SO_(4)进行复配固化的软土稳定性强于采用水泥固化的软土,在经历9次干湿循环后,强度仅降低7kPa,而水泥固化组则降低了86kPa,复配固化改良软土具有更优越的工程力学性能。

高炉钛渣基碱激发水泥的制备及其性能

高炉钛渣用作水泥混合材是其综合利用的有效途径之一。以高炉钛渣为原料,氢氧化钠(NaOH)和水玻璃(Na_(2)O·nSiO_(2))复配为激发剂,制备高炉钛渣基碱激发水泥,研究激发剂模数、添加量、养护温度对材料性能的影响,并采用X射线衍射仪(XRD)、傅立叶变换红外光谱仪(FTIR)和扫描电子显微镜/X射线能谱(SEM-EDS)等技术手段分析材料物相组成和微观结构。研究表明,激发剂模数、添加量和养护温度显著影响高炉钛渣基碱激发水泥的抗压强度。当激发剂模数为1.6、掺量为8%、养护温度为65℃时,材料3 d的抗压强度达26.6 MPa,材料无定型相和结晶相钙钛矿CaTiO_(3)变化量分别为6.77%、5.95%。这说明碱激发剂对高炉钛渣存在一定的侵蚀活化作用,促进了C-S-H凝胶生成和材料强度的发展。

高炉重矿渣水泥稳定基层混合料性能研究

利用包钢高炉重矿渣碎石粗集料和石灰岩细集料,设计制备了C-C-2级配水泥稳定基层混合料,进行了其强度及抗冻性能研究。结果表明,水泥(PO32.5)剂量为3%时,C-C-2重矿渣水泥稳定混合料的7 d无侧限抗压强度可以达到5.0 MPa以上。随着水泥剂量的增加,混合料的7 d无侧限抗压强度增大。水泥剂量为4%时,C-C-2重矿渣水泥稳定混合料的最大干密度最大,同时,对于提高重矿渣水泥稳定混合料的180 d抗压强度和抗冻性能效果显著。

Incorporation of a nanotechnology-based additive in cementitious products for clay stabilisation

The mechanical performances and water retention characteristics of clays,stabilised by partial substitution of cement with by-products and inclusion of a nanotechnology-based additive called RoadCem(RC),are studied in this research.The unconfined compression tests and one-dimensional oedometer swelling were performed after 7 d of curing to understand the influence of addition of 1%of RC material in the stabilised soils with the cement partially replaced by 49%,59%and 69%of ground granulated blast furnace slag(GBBS)or pulverised fuel ash(PFA).The moisture retention capacity of the stabilised clays was also explored using the soil-water retention curve(SWRC)from the measured suctions.Results confirmed an obvious effect of the use of RC with the obtained strength and swell properties of the stabilised clays suitable for road application at 50%replacement of cement.This outcome is associated with the in-depth and penetrating hydration of the cementitious materials by the RC and water which results in the production of needle-like matrix with interlocking filaments e a phenomenon referred to as the‘wrapping’effect.On the other hand,the SWRC used to describe the water holding capacity and corresponding swell mechanism of clays stabilised by a proportion of RC showed a satisfactory response.The moisture retention of the RC-modified clays was initially higher but reduced subsequently as the saturation level increased with decreasing suction.This phenomenon confirmed that clays stabilised by including the RC are water-proof in nature,thus ensuring reduced porosity and suction even at reduced water content.Overall,the stabilised clays with the combination of cement,GGBS and RC showed a better performance compared to those with the PFA included.

Effect of Content and Fineness of GGBS on Pore Structure of Cement Paste

The effect of the content and specific surface area of the ground granulated blast furnace slag (GGBS) on the pore structure of the cement paste was determined through the low-field nuclear magnetic resonance (NMR).The Pearson correlation analysis method was used to calculate the correlation coefficient between the porosity and age of cement paste,the specific surface area of GGBS and the content of GGBS.The test results exhibited that the porosity of the cement paste with different ageing durations gradually decreased on increasing the content and specific surface area of GGBS.The content and specific surface area of GGBS had a negligible effect on the 1-10 nm size gel pores in the cement paste,whereas,had a significant effect on the 10-100 nm size capillary pores.In addition,these parameters did not affect the final most probable pore size of the cement paste.The correlation between age and porosity was the largest,and the correlation between GGBS content and porosity was greater than that between GGBS specific surface area and porosity.Moreover,a modified pore structure model was successfully developed to effectively predict the pore structure of the GGBS based cement paste.

Utilization of Low-Alkalinity Cementitious Materials in Cemented Paste Backfill of Gold Mine Tailings

The purpose of this paper was to explore the possility of using low alkalinity cementitious materials as binders,in which ground blast furnace slag and fly ash acted as a partial replacement of ordinary Portland cement,and CaSO_(4),Na_(2)SO_(4),and CaO were used as a sulfate activator and alkali activated additives,to solidify gold mine tail-ings for preparation of a green,inexpensive cemented paste backill(CPB).For this target,the effects of cement/tailings ratio,superplasticizer dosage,solid content,tailings fineness on the mechanical properties of the CPB were inves tigated.Additionally,the hydration mechanism of the CPB was analyzed based on X-ray diffraction and scanning electron microscopy results.The results showed that the fuidity of the CPB slurry could be improved by adding polycarboxylic acid superplasticizer.The unconfined compressive strength(UCS)of the CPB specimens was increased with the increase of cement/tailings ratio and solid content.Under the same experi-mental conditions,the 28 d UCS of the CPB specimens was 3.8-4.9 times higher than that of ordinary Portland cement.The softening coefficient of the CPB specimens was increased with the increasing cement/tailings ratio,ranging from 0.83 to 0.92.The shrinkage rate of the CPB specimens was decreased from 0.70%to 0.54%with the increase of cement/tailings ratio from 1:12 to 1:4 The UCS of the full tailings CPB was the highest,followed by the fine tailings CPB specimens,and the UCS of the coarse tailings CPB specimens was the lowest.The low alka-linity binder was proved to be a promising material to improve the engineering performances of the CPB.The optimal mixing ratio is 1:6 cement/tailings ratio,0.15 wt% superplastizer dosage,and 70 wt%solid content.Pre-pared by this mixing ratio,the UCS values of the CPB after 3,7,and 28 d curing ages reached 1.85,5.87,and 9.16 MPa,respectively,which were suitable as CPB for the Zhaoyuan gold mine in terms of strength requirements.

钢渣-矿渣复合水泥基材料3D打印性能

为了提高固体废弃物的资源化利用,探究利用钢渣制备3D打印水泥基材料的可行性,研究了钢渣、矿渣的质量比对复合水泥基材料流变特性、可打印性和力学性能的影响规律。结果表明,随着钢渣质量的增加,浆体的流动度和静态屈服应力增大,塑性粘度减小,可挤出性增强,变形率降低,同时抗压强度显著降低。通过Zeta电位测试发现,随着钢渣掺量的增加,Zeta电位绝对值变小,胶体颗粒间引力增大,导致静态屈服应力增大。而随着矿渣掺量的增加,浆体固含量增多,固体颗粒间摩擦加剧,产生了更多絮凝结构和网状结构,提高了浆体的塑性粘度。

大掺量磷石膏矿渣水泥的水化历程与长期强度研究

采用大掺量磷石膏、粒化高炉矿渣和熟石灰制备石膏矿渣水泥,通过水化热、化学收缩、孔溶液pH值和抗压强度试验,并结合XRD和SEM-EDS测试,探究磷石膏掺量对石膏矿渣水泥的水化历程与长期强度的影响规律。结果表明,当磷石膏的掺量从40%增大到70%(质量分数,下同)时,水泥浆体的第三放热峰峰值逐渐减小,14 d化学收缩从0.066 mL·g^(-1)增大到0.193 mL·g^(-1),早期(0~1 d)化学收缩速率明显增大,孔溶液pH值在28 d龄期内趋于稳定,且与28 d龄期相比,90 d龄期试件的抗压强度提高了12.3%~27.8%。XRD和SEM-EDS分析表明,水泥浆体中主要包含二水石膏、石英、钙矾石和C-S-H凝胶等物质。28 d龄期时,随着磷石膏掺量的增大,钙矾石的生成量从7.48%减小到2.84%,C-S-H凝胶的钙硅比(摩尔比)从1.08增大到2.24。

安徽某地铜尾矿资源的综合利用研究

介绍了我国铜尾矿的排放和利用现状,并利用安徽某地铜尾矿分别制备45μm孔筛筛余小于30%的普通铜尾矿粉、中位粒径小于10μm的超细铜尾矿粉及超细铜尾矿粉-超细矿渣粉复合超细粉,研究其粒度分布、活性指数和流动度比以及作为水泥混合材在水泥中应用性能。结果表明:将铜尾矿粉超细粉磨后活性指数和在水泥中应用性能显著提升;超细铜尾矿粉与超细矿渣粉按照5:5复配后可接近S95级矿渣粉技术指标,用于替代矿渣粉作水泥混合材,可降低水泥生产成本。

提钛炉渣-铁基全尾砂-水泥胶结充填体配比实验研究

为研究提钛炉渣替换水泥全尾砂胶结充填体的最佳配比及力学性能,以提钛炉渣(TBS)、铁基全尾砂(IFT)和水泥(P.O 42.5R)为实验材料,在分析该提钛炉渣的粒径级配组成、成分等物理化学特性的基础上,制备灰砂比1∶4、1∶6、1∶8和提钛炉渣掺入替换比为40%、50%、60%、70%、80%的充填体试样,测定了养护龄期分别为7 d、14 d和28 d时的充填体单轴抗压强度。实验结果表明:充填体的抗压强度与养护期龄正相关;相同养护时间下,充填体的单轴抗压强度随着灰砂比的增大而增大;随提钛炉渣替换比增大,充填体28 d强度先增大后减小;当提钛炉渣替换比为50%时,灰砂比1∶8、1∶6、1∶4的充填体28 d抗压强度分别为1.8 MPa、2.5 MPa、4.0 MPa,均超过未添加提钛炉渣的试块强度,表明掺入提钛炉渣对充填体的28 d强度具有明显的提升作用。研究结果表明,提钛炉渣可开发为矿山充填胶凝材料,从而降低矿山充填成本。

矿物掺合料对硅酸盐水泥净浆氯离子结合能力的影响

以掺粉煤灰(FA)和粒化高炉矿渣粉(GGBS)的硅酸盐水泥净浆为研究对象,开展其在不同浓度NaCl溶液中的浸泡试验.通过硝酸银滴定、X射线衍射(XRD)和热力学模拟,分析了溶液中氯离子浓度和水泥净浆中各物相含量的变化特点.结果表明:GGBS和FA的掺入可降低溶液中氯离子浓度,提高水泥净浆的氯离子结合能力;且GGBS可提高水泥净浆中水化铝酸钙(AFm)相含量及其对氯离子的化学吸附能力;FA可提高水泥净浆中水化硅(铝)酸钙C-(A)-S-H凝胶的物理吸附能力,当FA掺量为40%时,其物理吸附能力达到最大.

不同类型持载混凝土碳化性能研究

为探讨外加荷载对不同环境湿度、不同类型混凝土碳化性能的影响,本文提出了自然条件下服役钢筋混凝土构件碳化深度预测模型。基于100 mm混凝土立方体试块和持载钢筋混凝土梁的加速碳化试验结果,分别采用硅酸盐水泥、硅酸水泥掺30%粉煤灰和硅酸水泥掺50%磨细高炉矿渣浇筑混凝土试块和梁试件。结果表明:对不同类型混凝土的服役钢筋混凝土构件,在50 a和100 a的设计使用年限内,其碳化深度预测值随相对湿度的增加先增大后减小,最大碳化深度预测值均在50%~70%的相对湿度范围内。对持载钢筋混凝土构件,仅硅酸盐水泥混凝土和掺50%磨细高炉矿渣的较小水胶比混凝土满足要求。水胶比较大的掺粉煤灰和掺粒状高炉矿渣的持载混凝土,不能满足不同暴露环境在50%~70%相对湿度范围内的耐久性要求。本文对不同类型持载钢筋混凝土构件的抗碳化耐久性设计有一定的参考价值。

首钢水钢固废基胶凝材料的生产及应用实践

使用高炉水渣;转炉钢渣和脱硫石膏混合粉磨生产的全固废基胶凝材料可替代硅酸盐水泥应用于混凝土道路。不仅为水钢冶金渣固废的消纳提供有效的途径,而且契合国家双碳政策的发展目标,为全固废基胶凝材料的应用拓展奠定了良好的生产基础。生产实践表明:高炉水渣60%;转炉钢渣30%;脱磷石膏10%,全固废凝胶材料的28d抗压强度最高达到37.3 MPa;制备C20级全固废基胶材混凝土,水胶比为0.42,28d强度达到20.2 MPa;全固废基胶材混凝土应用在厂区道路改善方面取得良好的实践成效。

钢渣矿渣掺合料对水泥性能的影响

研究了钢渣的掺入量对水泥浆体性能的影响,以及钢渣单掺和钢渣与矿渣复掺对水泥胶砂强度的影响。结果表明:钢渣的掺入可以改善水泥浆体的流动性,凝结时间随钢渣掺量增加而延长。单掺钢渣时,水泥胶砂强度下降明显。钢渣与矿渣复掺会相互激发、相互促进水化,水泥胶砂强度变化不大,且钢渣在复合粉中的比例为20%,替代水泥量为50%时,28 d强度已超过基准样。