含泥量對摻聚羧酸減水劑混凝土性能的影響
發(fā)布時間：2019-03-23 17:57
【摘要】：聚羧酸減水劑是制備高性能混凝土不可或缺的組分,也是混凝土外加劑的主要發(fā)展方向和研究熱點。砂中含泥量會對摻聚羧酸減水劑混凝土的性能產(chǎn)生不良影響�，F(xiàn)關(guān)于含泥量對摻聚羧酸減水劑混凝土性能影響的研究已有不少,但大多集中在新拌混凝土的工作性及力學(xué)性能,而且含泥量對摻聚羧酸減水劑配制的不同強度等級混凝土性能影響的對比研究尚不多見。本文研究了不同含泥量對摻聚羧酸減水劑的低、中、高三種強度等級混凝土性能的影響,并探究其影響機理,旨在為改善和解決含泥量對摻聚羧酸減水劑混凝土的不良影響提供理論依據(jù)和技術(shù)支撐。采用甲基烯基聚氧乙烯醚(TPEG)為大單體,丙烯酸(AA)、甲基丙烯磺酸鈉(SMAS)為小單體,在引發(fā)劑過硫酸銨(APS)和側(cè)鏈轉(zhuǎn)移劑巰基丙酸(MPA)的作用下,制備出分散性及保坍性良好的聚醚類聚羧酸減水劑。使用自制聚醚類聚羧酸減水劑配制不同含泥量的C25、C40及C70三種強度等級的混凝土,系統(tǒng)地研究了含泥量對混凝土工作性、抗壓強度、收縮性能、耐久性的影響,研究結(jié)果如下:(1)工作性:含泥量對低強C25和中強C40混凝土的工作性影響較大,對高強C70混凝土的工作性影響較小,這與不同強度等級混凝土聚羧酸減水劑的用量有關(guān);從含泥量對不同濃度聚羧酸減水劑的吸附量角度闡釋了含泥量對不同強度等級混凝土工作性影響程度差異的原因。(2)抗壓強度:C25、C40及C70混凝土分別在含泥量大于7%、3%及1%時不滿足其強度等級的要求。高強C70和中強C40混凝土抗壓強度對含泥量的敏感程度遠大于低強C25混凝土。(3)收縮性能:含泥量對C25、C40和C70混凝土收縮性能影響的趨勢基本相同,即對混凝土1d的收縮率基本沒有影響,可以減少混凝土3d和7d的收縮率,但混凝土14d后的收縮率變大。混凝土早期收縮率變小的原因是由于泥粉吸附的水分揮發(fā),提高混凝土內(nèi)部濕度,從而降低混凝土收縮率;后期收縮率增大主要與混凝土的自收縮及孔隙率有關(guān)。(4)耐久性:含泥量對混凝土氯離子擴散系數(shù)及碳化深度的影響規(guī)律與其強度等級成一定的負相關(guān)性,含泥量對低強C25、中強C40混凝土抗氯離子滲透性和抗碳化性能的影響明顯大于其對高強C70混凝土的影響。含泥量對不同強度等級耐久影響的差異性主要與混凝土結(jié)構(gòu)的密實度、孔隙率及堿度等有關(guān)。
[Abstract]:Polycarboxylic acid water reducer is an indispensable component in the preparation of high performance concrete, and it is also the main development direction and research hotspot of concrete admixture. The mud content in sand will have an adverse effect on the performance of concrete mixed with polycarboxylic acid water reducing agent. There have been a lot of researches on the effect of mud content on the performance of concrete with polycarboxylic acid water reducer, but most of them focus on the workability and mechanical properties of fresh concrete. Moreover, the influence of mud content on the performance of concrete with different strength grades mixed with polycarboxylic acid water reducing agent is rare. In this paper, the effects of different mud content on the properties of low, middle and high strength grade concrete mixed with polycarboxylic acid water reducer were studied, and the influence mechanism was explored. The purpose of this paper is to provide theoretical basis and technical support for improving and solving the adverse effects of mud content on polycarboxylic acid superplasticizer concrete. In the presence of ammonium persulfate (APS) and side chain transfer agent (MPA), methyl vinyl ether (TPEG) was used as macromonomer, acrylic acid (AA),) was used as small monomer, and sodium methacrylic sulfonate (SMAS) was used as small monomer. Polyether polycarboxylic acid water reducer with good dispersibility and slump-proof property was prepared. The effects of mud content on workability, compressive strength, shrinkage and durability of concrete with different strength grades of C25, C40 and C70 were systematically studied by using self-made polyether polycarboxylic acid water reducer. The results are as follows: (1) workability: the influence of mud content on workability of low strength C25 and medium strength C40 concrete is greater than that of high strength C70 concrete, which is related to the amount of polycarboxylic acid water reducer in concrete of different strength grades; The influence of mud content on the workability of concrete with different strength grades was explained from the point of adsorption capacity of different concentration of polycarboxylic acid water reducer. (2) compressive strength: C25, C40 and C70 concrete with mud content greater than 7%, respectively. 3% and 1% do not meet the strength grade requirements. The compressive strength of high strength C70 and medium strength C40 concrete is much more sensitive to mud content than that of low strength C25 concrete. (3) shrinkage performance: the effect of mud content on the shrinkage performance of C25, C40 and C70 concrete is the same as that of low strength C25 concrete. It can reduce the shrinkage of concrete for 3 days and 7 days, but the shrinkage rate of concrete increases after 14 days. The reason why the early shrinkage rate of concrete becomes smaller is due to the volatilization of moisture absorbed by mud powder, which improves the internal humidity of concrete, and thus reduces the shrinkage rate of concrete. The increase of shrinkage is mainly related to self-shrinkage and porosity of concrete. (4) durability: the influence of mud content on chloride diffusion coefficient and carbonation depth of concrete is negatively correlated with its strength grade. The influence of mud content on chloride ion permeability and carbonation resistance of low-strength and medium-strength C40 concrete is greater than that of high-strength C70 concrete. The difference of the influence of mud content on the durability of different strength grades is mainly related to the compactness, porosity and alkalinity of concrete structures.
【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU528
本文編號：2446099
[Abstract]:Polycarboxylic acid water reducer is an indispensable component in the preparation of high performance concrete, and it is also the main development direction and research hotspot of concrete admixture. The mud content in sand will have an adverse effect on the performance of concrete mixed with polycarboxylic acid water reducing agent. There have been a lot of researches on the effect of mud content on the performance of concrete with polycarboxylic acid water reducer, but most of them focus on the workability and mechanical properties of fresh concrete. Moreover, the influence of mud content on the performance of concrete with different strength grades mixed with polycarboxylic acid water reducing agent is rare. In this paper, the effects of different mud content on the properties of low, middle and high strength grade concrete mixed with polycarboxylic acid water reducer were studied, and the influence mechanism was explored. The purpose of this paper is to provide theoretical basis and technical support for improving and solving the adverse effects of mud content on polycarboxylic acid superplasticizer concrete. In the presence of ammonium persulfate (APS) and side chain transfer agent (MPA), methyl vinyl ether (TPEG) was used as macromonomer, acrylic acid (AA),) was used as small monomer, and sodium methacrylic sulfonate (SMAS) was used as small monomer. Polyether polycarboxylic acid water reducer with good dispersibility and slump-proof property was prepared. The effects of mud content on workability, compressive strength, shrinkage and durability of concrete with different strength grades of C25, C40 and C70 were systematically studied by using self-made polyether polycarboxylic acid water reducer. The results are as follows: (1) workability: the influence of mud content on workability of low strength C25 and medium strength C40 concrete is greater than that of high strength C70 concrete, which is related to the amount of polycarboxylic acid water reducer in concrete of different strength grades; The influence of mud content on the workability of concrete with different strength grades was explained from the point of adsorption capacity of different concentration of polycarboxylic acid water reducer. (2) compressive strength: C25, C40 and C70 concrete with mud content greater than 7%, respectively. 3% and 1% do not meet the strength grade requirements. The compressive strength of high strength C70 and medium strength C40 concrete is much more sensitive to mud content than that of low strength C25 concrete. (3) shrinkage performance: the effect of mud content on the shrinkage performance of C25, C40 and C70 concrete is the same as that of low strength C25 concrete. It can reduce the shrinkage of concrete for 3 days and 7 days, but the shrinkage rate of concrete increases after 14 days. The reason why the early shrinkage rate of concrete becomes smaller is due to the volatilization of moisture absorbed by mud powder, which improves the internal humidity of concrete, and thus reduces the shrinkage rate of concrete. The increase of shrinkage is mainly related to self-shrinkage and porosity of concrete. (4) durability: the influence of mud content on chloride diffusion coefficient and carbonation depth of concrete is negatively correlated with its strength grade. The influence of mud content on chloride ion permeability and carbonation resistance of low-strength and medium-strength C40 concrete is greater than that of high-strength C70 concrete. The difference of the influence of mud content on the durability of different strength grades is mainly related to the compactness, porosity and alkalinity of concrete structures.
【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU528
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