稻壳灰混凝土的力学性能和耐久性研究

将稻壳灰等量部分替代水泥加入到混凝土中制备稻壳灰混凝土,并对稻壳灰混凝土进行7d和28d龄期的力学性能、抗冻性能、抗氯离子渗透性能和抗酸侵蚀性能的测试。结果表明,稻壳灰的加入能够显著地改善混凝土的内部结构,使其更加密实,从而增强了稻壳灰混凝土的力学性能、抗冻性能、抗氯离子渗透性能和抗酸侵蚀性能。当稻壳灰的掺量为20%时,混凝土的性能最佳,此时稻壳灰对混凝土的增强效果最好。     

普通烧制稻壳灰对水泥胶砂强度的影响

通过等量替代法,研究了普通烧制稻壳灰等量替代水泥后对水泥胶砂强度的影响.结果表明,普通烧制稻壳灰替代率为2％时,试件28 d抗折强度和抗压强度均高于空白胶砂试件,表明掺入少量的稻壳灰有一定的增强作用;稻壳灰替代率为4％时,对胶砂试件的强度影响不明显;稻壳灰替代率＞8％时,胶砂强度降低幅度较大.将普通烧制稻壳灰以低替代率应用于水泥混凝土中是可行的.     

稻壳灰及掺稻壳灰混凝土应用研究进展述评

由于其独特的多孔状结构和高纯度的无定形非晶质硅含量,稻壳焚烧所形成的稻壳灰能够替代部分水泥作为胶凝材料,从而使稻壳灰在混凝土与砂浆中的应用成为可能。作为一种新的再生资源,稻壳灰在混凝土与砂浆中的应用研究日益受到广泛关注。对稻壳灰的性质及其在混凝土与砂浆中应用研究进行了回顾,在讨论稻壳灰的制备、物理化学特性、稻壳灰的火山灰特性以及颗粒特征基础之上,对掺稻壳灰混凝土的工作性能、力学性能及耐久性能研究进展进行了述评,指出了稻壳灰在混凝土应用研究中值得进一步研究的方向。     

稻壳灰混凝土性能研究

研究了稻壳灰作为一种添加剂,0～30%的等量取代水泥后,对混凝土性能的影响.混凝土的配合比为1:2:4:0.6(水泥:砂:碎石:水胶比).测试了稻壳灰混凝土试件性质、抗压强度、劈裂抗拉强度、抗折强度等.结果表明.随着稻壳灰用量的增加,混凝土凝结的时间延长,而抗压强度、劈裂抗拉强度、抗折强度相应的降低.     

稻壳灰水泥和混凝土的研究

作者研究了一种适合农村应用的烧制高活性稻壳灰的技术。对烧制的稻壳灰,进行了物理特性和活性检验。并研究了石灰稻壳灰水泥、石灾稻壳灰混凝土和掺稻壳灰混凝土的物理力学性能。     

稻壳灰对混凝土性能的影响

该文所述试验以充分利用稻谷壳为目的,对稻谷壳进行煅烧粉磨后作为矿物掺合料掺入水泥和混凝土中,研究其对水泥标准稠度用水量、凝结时间、水泥胶砂强度和混凝土抗压强度的影响。结果表明:稻壳灰会增加水泥的标准稠度用水量,以及凝结时间,随稻壳灰掺量的增加,水泥标准稠度用水量逐渐升高,凝结时间逐渐增长。稻壳灰掺量在10%~20%内对混凝土的抗压强度有利,特别是混凝土的后期抗压强度。     

稻壳灰煤矸石增强混凝土抗冻性能研究

试验研究了稻壳灰、煤矸石对混凝土力学性能和抗冻性能的影响。分别以稻壳灰1.0%、2.0%、3.0%和煤矸石20.0%、25.0%等量取代水泥,标准养护28 d后进行强度测试。试验发现,当稻壳灰以2%～3%等量取代时,可以显著提高混凝土的强度和抗冻性能,从经济的角度考虑其最优掺量为2%。煤矸石具有一定的火山灰活性,但增强效果不明显。     

纳米SiO2低温稻壳灰用于混凝土的研究

采用SEM/TEM技术,发现了稻壳灰(RHA)中含有纳米SiO2粒子,并揭示了低温稻壳灰(L-RHA)的显微结构。稻壳灰由纳米SiO2(～50nm)粒子疏松地粘聚而成。稻壳灰结构中除了以往报道的微米尺度的蜂窝孔(～10μm)外,还含有大量由SiO2粒子非紧密粘聚而形成的纳米尺度孔隙(<50nm)。纳米尺度的SiO2粒子及大量孔隙使稻壳灰对混凝土具有较强的增强改性作用。当低温稻壳灰替代10%～20%水泥时,可提高高强混凝土抗压强度10MPa以上。     

美国《国际混凝土设计与施工》杂志部分论文摘要

1.评述粉煤灰、矿渣、硅灰和稻壳灰在混凝土中的应用(P.23～28) 硅酸盐水泥是一种高耗能材料,为了节能,一直努力寻求能代替部分水泥用的掺合料,其中最有前途的掺合料有高钙或低钙粉煤灰,铁质或非铁矿渣,硅灰和稻壳灰。本文介绍这些废料在混凝土中的应用情况。 2.硅灰混凝土在桥梁工程中的应用(P.29～33) 本文评述硅灰混凝土桥梁工程中的应     

污泥灰掺量和泡沫用量对泡沫混凝土性能的影响研究

选用普通硅酸盐水泥、污泥灰(SSA)、Mighty-150减水剂、表面活性发泡剂等材料,在低水胶比(0.35)条件下,采用混合料固定体积法进行泡沫混凝土配合比设计,研究探讨了大掺量污泥灰(0~65%)和泡沫用量对污泥灰-水泥泡沫混凝土干密度、28 d抗压强度、吸水率、导热系数以及孔隙结构等性能的影响。结果表明:污泥灰-水泥泡沫混凝土的干密度主要取决于泡沫用量而非污泥灰取代率;污泥灰取代率高达50%时,泡沫混凝土的28 d抗压强度虽降低,但仍符合JC/T 1062—2007规定的相应密度等级的抗压强度要求,且此时泡沫混凝土的导热系数和吸水率不会显著增大。因此,大掺量污泥灰-水泥泡沫混凝土是一种潜在的良好的保温材料。     

Effect of rice husk ash on the strength and durability characteristics of concrete

This work investigates the effects of adding residual rice husk ash (RHA) from South Vietnam, generated when burning rice husk pellets in the boiler, to cement. To improve pozzolanic reactivity, RHA was ground for 1 h. The non-ground RHA and ground RHA were used to test strength activity index according to ASTM C311. The properties of the concrete were investigated, including compressive strength, concrete electrical resistivity, and ultrasonic pulse velocity. Results show that the non-ground RHA can be applied as a pozzolanic material. Decreasing the non-ground RHA average particle size provides a positive effect on the compressive strength of mortar. Compressive strength of cylindrical concrete in the 47–66 MPa range was obtained in this study. The results also indicate that up to 20% of ground RHA could be advantageously blended with cement without adversely affecting the strength and durability properties of concrete.     

稻壳灰替代硅灰对超高性能混凝土性能影响的试验研究

通过对单/双掺活性稻壳灰(RHA)与硅灰(SF)以及RHA的粒径对超高性能混凝土(UHPC)的抗压强度和孔结构影响的研究,得出活性RHA粒径是取代SF的关键.研究结果表明,平均粒径为5.9 μm的R HA能够部分取代SF并应用于UHPC中；在相同总掺量的情况下,复掺RHA与SF的UHPC抗压强度要高于单掺RHA或单掺SF的,并且最佳取代水泥的复掺量为10％RHA与10％SF；在UHPC中掺入RHA能够减少孔体积以及平均孔径,优化孔结构,从而提高UHPC的抗压强度.     

High-strength rice husk ash concrete incorporating quarry dust as a partial substitute for sand

Quarry dust is a by-product from the granite crushing process in quarrying activities. This paper presents the findings from experimental work undertaken to evaluate the suitability of quarry dust as a partial substitute for sand in high-strength concrete (HSC) containing rice husk ash (RHA). Two grades of HSC mixes, to achieve 60 MPa and 70 MPa at 28 days, were designed with and without the incorporation of RHA. Quarry dust was then used in the mixes containing RHA as a partial substitute for sand, in quantities ranging from 10% to 40%. The slump of the fresh concrete and the compressive strength development were monitored up to 28 days. Based on the results obtained, the mixes containing 20% quarry dust were chosen as the optimum mix design for both grades of concrete, which would then undergo further evaluation of their strength and mechanical properties up to one year. The results obtained in the next stage suggest that even though the use of quarry dust as a partial substitute for sand results in some minor negative effects in the compressive strength and other mechanical properties of concrete, these outcomes can easily be compensated by a good mix design and by the incorporation of RHA. The findings of the research assert that quarry dust can be used as a viable replacement material to sand to produce high-strength RHA concrete.     

泡沫混凝土的特性和应用及未来发展趋势

分析了泡沫混凝土的组成材料,并对泡沫混凝土的特性和应用进行了叙述,提出了目前研究中存在的问题,并对其未来发展趋势进行了展望,可为泡沫混凝土的发展和应用提供参考。     

泡沫混凝土在公路路基塌方事故处理中的应用

介绍了我国泡沫混凝土的发展现状,分析了其应用于路基塌方处理的可行性及施工要点,说明了泡沫混凝土存在的固有缺陷,以及需要进一步研究解决的问题,说明了泡沫混凝土将深刻影响我们的生活,具有广阔的发展及应用前景。     

稳泡剂对碱矿渣泡沫混凝土性能影响的研究

用纤维素醚和糯米浆作为稳泡剂对碱矿渣泡沫混凝土进行改性,用孔结构和比强度等指标探讨其改性的效果。结果表明:分别掺入0.3%纤维素醚和0.4%糯米浆时,其最可几孔径均为0.5 mm,明显小于对照样,且孔径分布均匀,圆度提高;掺纤维素醚的泡沫混凝土,其抗压强度和比强度较对照样最高分别提高25%和20%;掺糯米浆的泡沫混凝土,其抗压强度和比强度较对照样最高分别提高43%和46%。所制备的泡沫混凝土符合预期设计的密度等级为A06、强度等级为FC5的要求。     

Concrete incorporating rice-husk ash without processing

The rice-husk is a residue with low nutritional properties for animals. When it is incinerated rice-husk generates a great quantity of ashes (RHA). The use of RHA as a supplementary cementing material is of great interest to many developing countries where rice production is in abundance. A highly reactive pozzolan is obtained when RHA is burnt under controlled conditions. In other conditions a “residual RHA” is produced with a lower quality, but it can be improved by grinding. In this paper the residual RHA was used “as nature”, without any previous grinding. Mixing RHA together with the coarse aggregates during a convenient period of time, before incorporating the other component materials, an adequate RHA particle size can be obtained. The fresh and mechanical properties and the water permeability were analysed in concretes replacing cement by residual RHA. The incorporation of natural RHA in structural concrete represents a good alternative for the disposal of this residue, even without the previous optimization through a grinding process.     

Production of rice husk ash for use in concrete as a supplementary cementitious material

Rice husk ash (RHA), rich in silica content, can be produced from rice husk using appropriate combustion technique for use in concrete as a supplementary cementitious material. This paper discusses production process of RHA from rice husk and the quality of RHA produced using rudimentary furnace of the National University of Malaysia (UKM). Three combustion methods and two grinding methods were used to investigate physical characteristics and chemical aspects of RHA produced. Combustion temperature distribution of the furnace, ash particle size, silica crystallization phase and chemical content of the produced RHA were studied using X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). From the investigation, it was found that combustion period, chilling duration, and grinding process and duration are important in obtaining RHA of standard fineness and quality. In addition, air ducts in the furnace are very useful in order to supply air for proper burning of rice husk.     

The study of using rice husk ash to produce ultra high performance concrete

The limited available resource and the high cost of silica fume (SF) in producing ultra high performance concrete (UHPC) give the motivation for searching for the substitution by other materials with similar functions, especially in developing countries. Rice husk ash (RHA), an agricultural waste, is classified as “a highly active pozzolan” because it possesses a very high amount of amorphous SiO₂ and a large surface area. The possibility of using RHA to produce UHPC was investigated in this study. The result shows that the compressive strength of UHPC incorporating RHA, with the mean size between 3.6 μm and 9 μm, can be achieved in excess of 150 MPa with normal curing regime. The interesting point is that the effect of RHA on the development of compressive strength of UHPC is larger than that of SF. Besides, the sample incorporating the ternary blend of cement with 10% RHA and 10% SF showed better compressive strength than that of the control sample without RHA or SF. This blend proved to be the optimum combination for achieving maximum synergic effect.     

Properties of EPS RHA lightweight concrete bricks under different curing conditions

The depletion of non-renewable resources has become an alarming issue nowadays. Many environmentalists and researchers have been investigating the use of waste materials as a renewable resource for use especially as raw materials in construction. This paper reports on the potential use of waste rice husk ash (RHA) and expanded polystyrene (EPS) beads in producing lightweight concrete bricks. The RHA was used as a cementitious material since it is a lightweight reactive pozzolanic material. RHA was used as partial cement replacement, while the EPS was used as partial aggregate replacement in the mixes. Bricks of 215 mm × 102.5 mm × 65 mm in size were prepared in this study. The engineering properties of the bricks were investigated. Among the properties studied were hardened concrete density, compressive strength and water absorption of the EPS RHA concrete bricks. Scanning electron microscopy (SEM) analysis was also performed on the brick samples. Four types of curing conditions were employed in this study. These include full water curing, air dry curing, 3-day curing and 7-day curing. It was found that the properties of the bricks are mainly influenced by the content of EPS and RHA in the mix and also the curing condition used.