Influence of iron oxide pigments on the properties of concrete interlocking blocks

Concrete interlocking blocks (CIBs) are utilized in a variety of commercial, municipal, and industrial applications. Superior engineering properties, low maintenance, ease of placement and removal, reuse of original blocks, aesthetic appeal, and immediate availability are the primary reasons for choosing concrete block pavement over other paving surfaces. It is a common practice to pigment building materials, such as mortar, concrete pavers, concrete roof tiles, and prefabricated concrete products; CIBs are colored using iron oxide pigments. This article presents experimental results detailing the properties of CIBs dyed with pigments. The results of these experiments are as follows: Because the particles of iron oxide pigments are finer than those of brown iron oxide, interlocking blocks mixed with the former acquired higher color strength than with the latter. Additional analysis determined a definite relationship between the flexural strength and the absorption ratio of pigment-dyed blocks; the correlation coefficient (R²) of interlocking blocks at 91 days was .90. It is suggested that if iron oxide pigments are to be used to color CIBs, the pigment-to-cement ratio should be below 4%.     

不同混合材掺量对低碱水泥适应性的试验研究

对不同种类及掺量的混合材对低碱水泥流动洼能进行试验研究，结果为：低碱硅酸盐水泥中掺入矿渣粉、粉煤灰、石灰石等混合材有利于改善浆体流动性能，目双掺效果较单掺好；外加剂掺入量对流动性能的改善随着掺量的增加而增加，但掺入量应适宜、经济；石灰石为非活洼混合材，本试验研究结果表明它能显著增大水泥流动性且保持较小的经时损失，但其掺量不宜过大。     

Effect of shrinkage-reducing admixtures on the properties of alkali-activated slag mortars and pastes

The effect of a shrinkage-reducing admixture (SRA) based on polypropylenglycol on the dimensional stability of waterglass-activated slag mortars was studied. The analysis also showed the effect of the admixture on pore structure of the mortars as well as on the mineralogical composition and microstructure of the alkali-activated slag pastes.The SRA reduced the shrinkage by up to 85 and 50% when the alkali-activated slag mortar specimens were cured at relative humidities of 99 and 50%, respectively. The mechanism primarily involved in shrinkage reduction is the decrease in the surface tension of pore water prompted by the admixture. The SRA also modified the pore structure - under both curing conditions - increasing the percentage of pores with diameters ranging from 1.0 to 0.1 μm. Capillary stress is much lower in these pores than in the smaller capillaries prevailing in mortars prepared without admixtures.Microstructurally, the SRA occasioned a slight increase in the proportion of Si units Q² in the CSH gel and a decrease in the percentage of Al replacing the Si in the gel structure. The admixture did not, however, modify the mineralogical composition of the pastes.Finally, the SRA admixture retarded the alkaline activation of the slag, more intensely at higher admixture dosages. While the admixture did not significantly alter the degree of reaction in pastes cured for 7 days at RH = 99%, the value of this parameter dropped by 7% in the presence of the admixture in pastes cured at 50% relative humidity.     

水泥与混凝土外加剂适应性地解决

结合XM水泥厂具体情况,在对影响其水泥与混凝土外加剂适应性因素进行分析,提出改善熟料冷却速度,降低出厂水泥中温度,更换原燃材料,使用助磨剂等建议与措施。在实施部分措施后,XM水泥与外加剂的适应性差的问题得到较好解决。     

Antifungal effects of cement mortars with two types of organic antifungal agents

This study is concerned with investigating the antifungal effects of cement mortar with an organic antifungal agent on the Aspergilus niger which might be easily discovered in the interiors and exteriors of buildings. Two types of organic antifungal agents: isothiazoline/cabamate and nitrofuran, were used in this study for the purpose of investigating the antifungal effect of cement mortar with antifungal agent on the A. niger of various fungus which can be easily discovered in the interiors and exteriors of building. In addition to the investigation of the antifungal effect, the experiment of basic physical properties, such as compressive and flexural strengths, and flow test was carried out. Cement mortar with the antifungal agent of isothiazoline/cabamate exhibited the outstanding antifungal effects but the antifungal agent of nitrofuran did not give the antifungal effects to cement mortar. Although there is a very slight decrease in the strength, it is almost equal to that of cement mortar without antifungal agents.     

Influence of inorganic pigments on the fluidity of cement mortars

Among the admixtures used for cement composites, an inorganic pigment, which contributes color to the final product, enhances the esthetic value of a building. It can be reasonably assumed that the use of inorganic pigments will increase, given the recent trend to make cities more beautiful with color. The aim of this study was to investigate the effects of inorganic pigments on the fluidity of cement mortar. For this purpose, a flow test was carried out on cement mortar mixed with inorganic pigments by changing the proportion of cement mortar, water-cement ratio, and ratio of pigment. When red and yellow pigment mortars were used, the fluidity rapidly decreased with increasing ratio of pigment. To secure an acceptable workability, the amount of mixing water had to be increased or a superplasticizer employed. When a green pigment mortar was used, however, the fluidity of the mortar recorded −2.4-6.9%, indicating almost no change in flow. When a black pigment mortar was used, the pigment had no effect on fluidity.     

Engineering properties of amorphous silica as a new natural pozzolan for use in concrete

Nowadays, in order to produce the high strength concrete in the civil engineering applications, the use of different types of admixtures is well-known. In general, these materials are either chemical or mineral products. In this paper, the formations of amorphous silica of Isparta Region are defined in a technical manner and their use in the concrete manufacturing as a natural pozzolan is evaluated. The effectiveness of amorphous silica in making high strength concrete material is analysed experimentally, and the research findings are discussed.     

The optimization of a gypsum-based composite material

Contemporary requirements for gypsum-based composite materials (GBCM) for rendering or plastering include controlled setting time, good workability, sag resistance, high compressive and flexural strength, perfect bond to concrete or brick, water resistance, and improved heat and noise insulation. The application of a number of chemical admixtures and mineral additives was found to be necessary to provide the required performance for gypsum-based materials. Among the necessary chemical admixtures are the following: a retarding admixture, a water-soluble polymer (MC), an air-entraining admixture (AE), and a superplasticizer (SP). This paper describes the effect of the different admixtures on the consistency, setting time, and the compressive strength of GBCM. It also discusses the application of the stepwise optimization (SWO) method for the evaluation of the GBCM composition.     

EPS保温砂浆干燥收缩性能研究

本文主要研究了聚合物、外加剂和纤维对EPS保温砂浆干燥收缩性能的影响,以改善其收缩性能,使之能够减少因收缩而出现的开裂情况。     

Colloidal graphite as an admixture in cement and as a coating on cement for electromagnetic interference shielding

A water-based colloid of submicron graphite particles is an effective admixture for enhancing the EMI shielding effectiveness of cement paste, though it is ineffective for lowering the electrical resistivity. As an admixture, it is more effective for shielding than 15-μm-diameter discontinuous carbon fibers, though it is less effective than 0.1-μm-diameter discontinuous carbon filaments. A shielding effectiveness of 22 dB at 1 GHz is reached by cement paste at a solid graphite content of 0.92 vol.%, compared to a value of 11 dB for a coating made from the graphite colloid and a value of 14 dB for graphite-colloid-coated cement paste (without admixture).