【正文】 se mineral admixtures are represented inTable 1. . Mixes production The fluidity of the paste is evaluated according to the type of the cement, the superplasticizer and its dosage, the mineral admixture and its replacement rate as well as the W/C 2includes two sets of paste based on cements C1and C2 containing 10% of limestone powder and 15% of natural pozzolan respectively and are considered as control. The fluidity of the paste was assessed for higher replacement rate of these mineral admixtures ranging from 15%, 20% and 25% for limestone powder with cement C1 and 20% and 25% of natural pozzolan with cement C2. The replacement rate of mineral admixture is calculated taking into account the quantity of the mineral admixture in the origin cement (C1 and C2). The binder was mixed with water for various W/C ratio。 it suggests that this superplasticizer begins to disperse the cement particles. When new superplasticizers are developed, an interaction problem must be anticipated, cement and superplasticizer will be able to cause sharp variation in fluidity and produce stiffness, depending upon the bination of cement and superplasticizerSwamy et al. works concluded that it is possible to reduce the content of superplasticizer by incorporating slag in the cement。 irregularity of slump and rapid workability loss. The principal approach provided to bat against this difficulty is to select the most efficient couple cement–superplasticizer, enabling to obtain a maximum water reduction, a better workability and an acceptable rheology during the placement and the finishing concrete. The incorporation of some mineral admixtures such as blast furnace slag, fly ash, silica fume or natural pozzolan can make the interaction between the cementitious materials and superplasticizers more plex, and therefore the selection of the patible couple requires further consideration. The adsorption of superplasticizer molecules on hydrated phases creates an electrostatically charged germ which participates to the electrostatic repulsion and avoids flocculation. Also, the cement paste characterized by the long needle of ettringite formed at early age usually decreases the paste fluidity . There exists an optimum soluble alkali content with respect to the fluidity and fluidity loss, which was found to be –% Na2O equivalent. At this optimum alkali content, the initial fluidity is maximum and fluidity loss is minimum. Neubauer et al.[4]noted that superplasticizer causes the zeta potential of the cement pastes to bee increasingly negative。 and SP2 based on resins melamines(PRM). In order to examine the contribution of these mineral admixtures to the fluidity of cement grouts and their patibility with these superplasticizers, two types of minerals admixtures were used。31:153–62. [4] Neubauer C, Yang M, Jennings HM. Interparticle potential and sedimentation behavior of cement suspensions: effects of admixtures. Adv Cem Based Mater 1998。 des coulis de ciment avec adjuvants et additions min233。 1989. p. 171–88. [13] Rollet M, Levy C, Cavailles R. Evaluation of patible superplasticizer for the production of highstrength concrete. In: Proceeding of the 9th international congress on the chemistry of cement, vol. 5. New Delhi。32(August–September):479–85. [16] Aitcin P, Jolicoeur C, MacGregor JG. Superplasticizers – how do they work and why they sometimes don’t. Concr Int 1994。SP1 基于萘系高效減水劑 (PNS)。能使提高混凝土的穩(wěn)定性和可加工性。 紐鮑爾等人指出，強(qiáng)塑劑能使水泥的流動(dòng)性變?nèi)酰@表明強(qiáng)塑劑會(huì)使水泥粒子分離。 強(qiáng)塑劑 (CSP)的親和性可以用來測量流漿時(shí)間。如果沒有發(fā)現(xiàn)這些現(xiàn)象 ,水泥和強(qiáng)塑劑可以標(biāo)記為不相容的。用石灰粉和天然火山灰為原材料制造這兩個(gè)水泥。幾個(gè)每個(gè)強(qiáng)塑劑的劑量范圍中使用了 %,%,%,%, 測試步驟 低速混合 2 分鐘后 ,增加了 1/3 的一部分水和強(qiáng)塑劑 ,再高速混合 2 分鐘。流動(dòng)時(shí)間以 5 和 60 分鐘后與水接觸。 如圖 2 所示 ,C1 水泥用灰?guī)r粉顯示出了流體混合物與強(qiáng)塑劑混合后的現(xiàn)象，其中 W / C 比值為 。再拿 C2 水泥 做相同的比較，其 流動(dòng)性損失減少 ，而 SP2 用量增加 ,但仍高于 SP1。同時(shí) ,水泥漿中的鈣礬石的形成降低了流動(dòng)性。為此，采用該測試可測量流動(dòng)時(shí)間并研究水泥漿的流變特性。 低速混合 2 分鐘后 ,增加了 1/3 的一部分水和強(qiáng)塑劑 ,再高速混合 2 分鐘。強(qiáng)塑劑 SP1 與包含高含量 C3A 或高堿含量 C2 的水泥混合時(shí) 表現(xiàn)出 的 親和力較低 。這種流動(dòng)性強(qiáng)塑劑的分散性能 取決于其吸附量比例。需要指出 ,C1 水泥有更好的流動(dòng)性和低飽和性，大約為 %,遠(yuǎn)低于 1%的 C2 水泥。SP1 基于萘系高效減水劑 (PNS)。這次的時(shí)間越長 ,水泥漿粘性越高 ,若 時(shí)間越短 ,水泥漿越趨近于液體。在相同的背景下 ,這種強(qiáng)塑劑的流動(dòng)性損失相當(dāng)大的證明其不兼容 ,特別是 C2 水泥。 由此可以 得出結(jié)論 ,強(qiáng)塑劑的飽和劑量 會(huì) 根據(jù)水灰比降低。這證明了 圖 1. 馬什錐用于測量水泥漿的流動(dòng) 性 . 強(qiáng)塑劑 劑量 % 圖 2. 各種水泥漿的流動(dòng)時(shí)間變化在 5 分鐘根據(jù)強(qiáng)塑劑用量 (W/C = ). 圖 流動(dòng)性 5 至 60 分鐘 (W/C = ). 水泥的類型有很大的 影響。 水泥種類的 影響 通過使用兩個(gè)水泥 C1 和 C2，改變 W / C 和強(qiáng)塑劑 SP1 和 SP2 的劑量 ,流動(dòng)結(jié)果在 5分鐘時(shí)間內(nèi)的流動(dòng)損失如圖所示。測試在測量后需要將水泥漿通過一個(gè)直徑 5 毫米的開口容器。如表 2 表 1 材料特征 . 特征 C1 水泥 C2 水泥 石 灰石水泥 火山灰水泥 SiO2 Al2O3 Fe2O3 CaO SO3 MgO K2O Na2O Free CaO Residue Loss on ignition C3S C2S C3A C 4AF Finesses (cm2/g) 3700 3300 3400 3200 Characteristics SP1 SP2 強(qiáng)塑劑 比例 % 40 40 Form Liquid Liquid Color Dark chestnut Opaque pH 7–8 7 – 8 Density Chemical origin Polynaphthalene sulfonate (PNS) Resins melamine ( PRM ) 表 2 混合比例 . Binder Replacement rate (%) of mineral admixture E/C ratio Superplasticizer dosage ( Sp/binder ) % Cement (C1) +limestone 10, 15, 20,25 , , SP1: , , , , , , SP2: , , , , , Cement (C2)+pozzolan 15, 20, 25 , , SP1: , , , , , , SP2: , , , , , 包含 10%的石灰粉 包含 15%的天然火 山灰 C2. 和 C2 包含 10%的石灰粉和 15%的天然火山灰分別和被認(rèn)為是控制。使用兩個(gè)強(qiáng)塑劑在不同劑量上能改善漿液流動(dòng)性 。流動(dòng)性降低的兩個(gè)相關(guān)曲線在 5 和 60 分 鐘 。這表明，粉煤灰的摻入使混凝土減少強(qiáng)塑劑的需要，與混凝土相比只作為水泥的 一種 粘結(jié)劑。 強(qiáng)塑劑分子在水化階段有較高的吸附性，因?yàn)槠渲忻恳粋€(gè)靜電帶電細(xì)菌都帶有靜電排斥力和高凝聚性。強(qiáng) 塑劑 SP1 與包含高含量 C3A 或高堿含量 C2 的水泥混合時(shí) 表現(xiàn)出 的 親和力較低 。31:245–55. [20] Nehdi M, Mindess S, A PC. Rheological of high performance concrete: effect of ultra fine particles. Cem Concr Res 1998。 air entra238。 16–17 Avril, 2020. 10p. [11] De Larrard F, Puch C. Formulation des BHP: La m233。28(4):533–47.