广西地区路面水泥混凝土耐久性试验研究

文章通过室内实验,研究了双掺超细矿渣和高效减水剂对路面混凝土耐久性和抗裂性的影响,并将其与硅粉混凝土进行了对比。试验结果表明,在选定合适的配合比后,改性混凝土的力学性能和耐磨性较普通混凝土有所提高,抗塑性开裂能力有明显改善。此外改性混凝土虽然强度和耐磨性较硅粉混凝土低,但抗裂性能更为优越。     

粉煤灰和硅灰对高强度纤维水泥基材料力学性能影响研究

基于纤维水泥基复合材料的发展和工程应用实际,探讨不同粉煤灰和硅灰掺量对高强度纤维水泥基材料抗压强度、抗折强度以及韧性的影响。研究结果表明:粉煤灰和硅灰的掺加会显著影响高强度纤维水泥基材料的力学性能,具体优化掺量为50%的粉煤灰和15%的硅灰可以使高强度纤维水泥基材料抗折强度增强到19.5 MPa,抗压强度提高至75.2 MPa,折压比达到0.26左右,比普通纤维混凝土在抗折和抗压强度上分别提高了35%和40%,折压比也提高了6%左右,说明该优化配合比能明显增强高强度纤维水泥基材料的抗压强度、抗折强度和韧性,可为该材料的工程应用提供参考。     

新型地面自流平水泥基材料的研究

采用正交设计，利用硅灰、普通硅酸盐水泥、减水剂、砂和抗裂防水剂配制高流动度的地面自流平材料。试验结果表明：28 d抗折强度和抗压强度可达15.6 MPa、84.3 MPa，满足水泥基自流平砂浆的要求；28 d膨胀率为＋0.033%,属于微膨胀，可避免因收缩引起的表面裂纹。     

疏水-亲水型硅胶固定化葡萄糖氧化酶的研究

目的　评价疏水 亲水型硅胶作为载体固定化葡萄糖氧化酶的性能 ,以期制备出能用于临床体液中葡萄糖浓度测定的生物传感器。方法　以甲基三甲氧基硅 (MTMOS)和γ 氨丙基三甲氧基硅烷 (APTMOS)为原料 ,利用溶胶 凝胶技术制成了一种疏水 亲水型硅胶 ,以 1 乙基 3 (3 二甲基氨丙基 ) 碳二亚胺·盐酸 (EDC)和N 羟基琥珀酰亚胺(NHS)为催化剂 ,利用葡萄糖氧化酶 (GOD)分子中的羧基基团与硅胶中氨基基团间的碳二亚胺偶联反应 ,实现了GOD在硅胶上的固定化 ,考察了固定化GOD的基本性质。结果　固定化GOD活力最优时的条件如下 :APTMOS的体积分数为 70 %、给酶量为 16 80 0U、最适温度和最适pH值分别为 35℃和 5 .5 ,固定化GOD具有很好的操作稳定性和贮存稳定性 ,其米氏常数Km为 9.1mmol·L-1。结论　疏水 亲水型硅胶是一种新型的酶固定化载体 ,可用于多种酶的固定化。     

掺硅粉混凝土在路面工程中的应用研究

在分析硅粉对混凝土作用机理的基础上,从抗折强度和经济性两方面研究了路面混凝土的硅粉最优掺量,并从强度、疲劳特性、脆性、耐磨性和抗冻性等路用性能方面进行了研究.结果表明,与不掺硅粉路面混凝土相比,路面混凝土中按最佳掺量15~20 kg/m3掺入硅粉,能显著提高路面混凝土的路用性能和降低工程造价.最后对掺硅粉路面混凝土施工工艺和技术经济性进行了分析,表明掺硅粉混凝土在路面工程中的应用是可行的.     

矿物掺合料对ASR抑制效能的试验研究

大量研究表明,矿物掺合材是预防ASR最实用、最经济和有效的途径。现行铁路客运专线标准中纳入了《矿物掺合料及外加剂抑制碱-骨料反应有效性试验方法》,从而使得部分砂浆棒膨胀率在0.2%~0.3%的碱-硅酸反应活性骨料的应用成为可行。本试验中采用该方法对比研究了粉煤灰掺量和掺合料种类对活性骨料ASR膨胀的抑制效果。试验结果表明,矿物掺合料对ASR膨胀的抑制效果显著,可以用此方法优选矿物掺合料的品种和掺量。     

Changes in dissolved silicate loads to the Baltic Sea — The effects of lakes and reservoirs

We tested the hypothesis that dissolved silicate (DSi) yields [kg km^− 2 yr^− 1] of 82 major watersheds of the Baltic Sea can be expressed as a function of the hydraulic load (HL) as a measure of water residence time and the total organic carbon (TOC) concentration, both variables potentially increasing the DSi yield. Most boreal rivers fitted a linear regression model using HL as an independent variable to explain the DSi yield. Rivers with high HL, i.e., shortest residence times, showed highest DSi yields up to 2300 kg km^− 2 yr^− 1. This is most likely caused by an excess supply of DSi, i.e., the geochemical sources prevail over biological sinks in these boreal watersheds. The DSi yield for regulated and unregulated larger rivers of the boreal watersheds constituting about 40% of the total water discharge and of the total DSi load to the Baltic Sea, respectively, can be expressed as: DSi yield = 190 + 49.5 HL[m yr^− 1] + 0.346 TOC [µM] (R² = 0.80). Since both HL and TOC concentrations have decreased after damming, the DSi yields have decreased significantly in the regulated boreal watersheds, for the River Luleälven we estimated more than 30%. The larger eutrophic watersheds draining cultivated landscape of the southern catchment of the Baltic Sea and representing about 50% of the annual water discharge to the Baltic Sea, deviated from this pattern and showed lower DSi yields between 60–580 kg km^− 2 yr^− 1. DSi yields showed saturation curve like relationship to HL and it appears that DSi is retained in the watersheds efficiently through biogenic silica (BSi) production and subsequent sedimentation along the entire river network. The relationship between HL and DSi yields for all larger cultivated watersheds was best fitted by a Freundlich isotherm (DSi = 115.7HL¹⁰⁹; R² = 0.73), because once lake and reservoir area exceeds 10% of the watershed area, minimum DSi yields were reached. To estimate an uperturbed DSi yield for the larger eutrophic southeastern watersheds is still difficult, since no unperturbed watersheds for comparison were available. However, a rough estimate indicate that the DSi flux from the cultivated watersheds to the Baltic Sea is nowadays only half the uperturbed flux. Overall, the riverine DSi loads to the Baltic Sea might have dropped with 30–40% during the last century.     

Present-day biosiliceous sedimentation in the northwestern Ross Sea, Antarctica

Sedimentological and oceanographic inferences have been obtained for the NW Ross Sea using sedimentary ²¹⁰Pb as a tracer together with determinations of biogenic silica and organic carbon. ²¹⁰Pb chronologies give apparent accumulation rates ranging between 14 and 80 mg cm⁻² yr⁻¹ (0.02–0.12 cm yr⁻¹) in the shelf basins. Even if a profile of ²¹⁰Pb is present in sediments from the top of the banks, here sediment accumulation rate is practically null, and physical mixing is responsible for the downward transport of fine particles and associated ²¹⁰Pb. The accuracy of ²¹⁰Pb-derived accumulation rates is discussed with respect to ¹⁴C dates. The annual rate of biogenic accumulation from ²¹⁰Pb appears to be ca. 8 times higher than the value derived using radiocarbon. Bioturbation is probably responsible for the discrepancy but also temporal and spatial variations in opal accumulation play a key-role. Contrasting measured and expected inventories of ²¹⁰Pb, a residence time of about 50 years has been tentatively estimated for the water in the NW Ross Sea. Furthermore, the data suggest that the pattern of present-day biosiliceous sediment accumulation in the Ross Sea is mainly driven by biogenic silica production in the water column, the SW area being the most productive part of the Ross Sea, by high sediment accumulation rate which enhances the seabed preservation, and by hydrodynamics, which is so effective to resuspend fine biogenic particles from the topographic highs. Resuspended particles are then deposited onto the flanks. The material which accumulates in the central part of the basins derives basically from primary production and settling through the water column.     

硅灰对高石粉含量机制砂制备混凝土的影响

针对天然砂日渐匮乏,而机制砂中石粉含量偏高所制备的混凝土工作性、泵送性差等问题,研究硅灰对机制砂混凝土的工作性、力学和体积稳定性的影响,并分析硅灰的作用机理。结果表明:适量硅灰可以增加混凝土工作性和稳定性,解决机制砂高石粉含量引起的混凝土黏度大和泌水问题,改善浆体微观形貌,提高混凝土力学和耐久性能,且28 d干燥收缩率400×10-6。机制砂中石粉含量为10%左右时,硅灰掺量6%~9%,制备的C50机制砂混凝土匀质性好,浆体旋转黏度约2.5 Pa·s,泌水率为0,工程应用效果良好。