Experimental Study of the Physical and Mechanical Behaviour of Mortar Formulations with Fine Sands of Recycled Glass

This work is part of an experimental contribution approach to the study of the incorporation of glass sand from the grinding of recycled glass waste in cement mortars and its influence on the physical and mechanical behavior of semi-rich mortars without adjuvants. For this purpose, after a physical characterization of the sands, eight (08) formulations of mortars based on cement CEM II B/L 32.5R and fine sands (0/2) of glass at mass contents of 0%, 10%, 20%, 30%, 40%, 50%, 75% and 100% of the silty sand (0/2) were made respectively to three (03) types of fine glass sand (white, brown, green) with water dosages on cement (W/C) of 0.50, 0.45, 0.40. The results obtained show that the fine sands of recycled glass have a higher water absorption than the silty sand and the physical properties of the mortars prepared are affected by the increase in the glass content. The mechanical performances are obtained for the ratio W/C = 0.50 and the formulation of glass mortars for an optimal compressive strength superior to glass-free mortar requires a substitution of 10% for fine white glass sand, 20% for sand fine green glass and 75% for fine brown glass sand. The comparative study between these different compositions of fine glass sand mortars shows that the mechanical performances of fine brown glass sand are better than other glass sands but generally remain inferior to the control mortar based on natural silty sand.

Filler effect of fine particle sand on the compressive strength of mortar

The river sand, which is a non-pozzolanic material, was ground into 3 different particle sizes. Portland cement type I was replaced by the ground river sands at 10wt%？40wt% of binder to cast mortar. Compressive strengths of mortar were investigated and the filler effect of different fine particles of sand on the compressive strength of mortar was evaluated. The results show that the compressive strength of mortar contributed from the filler effect of smaller particles is higher than that of the coarser ones. The difference in compressive strength of mortar tends to be greater as the difference in ground river sand fineness increases. The results also suggest that ASTM C618 specification is not practically suitable for specifying pozzolan in concrete since the strength activity index of mortar containing ground river sand （high crystalline phase） with 33.8wt% of particles retained on a 45-μm sieve can pass the strength requirement.

Optimization of Blended Mortars Using Steel Slag Sand

A new kind of mortar made of ground granulated blast-furnace slag （GGBFS）, gypsum, clinker and steel slag sand （〈4.75 mm） was developed. The ratio of steel slag sand to GGBFS was 1 ： 1 and the amount of gypsum was 4% by weight while the dosage of clinker ranged from 0% to 24%. The optimization formulation of such mortar was studied. The content of steel slag sand should be less than 50% according to the volume stability of blended mortar, and the dosage of clinker is about 10% based on the strength development. Besides strength, the hydration heat, pore structure and micro pattern of blended mortar were also determined. The experimental results show the application of steel slag sand may reduce the dosage of cement clinker and increase the content of industrial waste product such as GGBFS, and the clinker is also a better admixture for blended mortar using steel slag sand.

Optimization of the Traction Resistance of Hydraulic Mortars Based on Togo Sands

The purpose of this study is to analyze the behavior of mortars from the sands of Togo in order to optimize their traction resistance. 3660 4 cm × 4 cm × 16 cm test tubes of mortars are prepared from the sands of 20 extraction sites in Togo with variations in water and cement while keeping the water-cement ratio constant (E/C = 0.5). It emerges a quadratically increasing evolution of resistance in flexural at 28 days of age (σf) for cement-sand (C/S) and water-sand (E/S) ratios varying respectively by the interval [0.0370, 0.3580] to [0.1977, 0.5120] and [0.0185, 0.1792] to [0.0988, 0.2605]. The resistances become stationary beyond these values (σf ≈ 3.4750 MPa to 7.9010 MPa). For structures whose resistance in traction is desired, three formulas of sand mortars from Togo are therefore defined: rich mortars (C/S > 0.5120 and E/S > 0.2605), lean (C/S < 0.0370 and E/S < 0.0185) and normal (0.0370 < C/S < 0.5120 and 0.0185 < E/S < 0.2605).

Study of Durability of Siliceous Sand Based Mortars in Togo, and of Binder of Plastic Bags of the Kind “Voltic”: Hydrocarbons’ Effect

The present study aims at environmental protection through the use of plastic wastes in the production of mortar. The behavior of siliceous sand-based mortars from Togo and binders of plastic bags of the kind “voltic” is analyzed. Mortar samples from a mixture of siliceous sand and binder of plastic bags are prepared and subjected to physical and mechanical tests after immersion in the hydrocarbon from 0 hour to 504 hours. The result demonstrates that hydrocarbons have no influence on mechanical properties of mortars for an immersion time below 3 hours. Between 3 hours and 24 hours the presence of hydrocarbon increases their physical and mechanical properties. After 24 hours mortars generally lose the mechanical properties of around 8% to 24% due to the loss of viscosity and cohesiveness of the binder caused by the fuel. The behavior in the face of hydrocarbons shows that the material can be used in the surface of roads by carefully avoiding that hydrocarbons remain on the roads for a period of time beyond 24 hours.

Effect of Sand Content on Strength and Pore Structure of Cement Mortar

The effects of four sand contents on the compressive, flexural and splitting-tensile strength of cement mortars were evaluated. Moreover, we experimentally investigated the pore structure of cement mortar brought about by changing the sand content and water/cement ratio. The changes in the pore structure were quantified by measuring the porosity and pore size distribution obtained by using mercury intrusion porosimetry（MIP） technique. The test results show that the strengths of cement mortar increase with increasing sand content. It is also suggested that the traditional water/cement ratio law can be applied to cement mortar with different sand contents, provided that a slight modification is introduced. Sand content is an important parameter influencing the pore structure of cement mortar. Moreover, there is a good relationship between the pore structure and strength of cement mortar.

Density and Strength of Mortar Made with the Mixture of Wood Ash, Crushed Gneiss and River Sand as Fine Aggregate

The main purpose of this paper is to study the feasibility of using wood bottom ash to partially replace natural fine aggregate or crushed gneiss sand in the manufacturing of mortars. The experiment uses wood ash as fine aggregates, which passes through 5 mm sieve, in proportions of 5%, 10%, 15%, 20% and 25% by weight to replace partially river sand and crushed gneiss, and the both sand of the same size as the aggregate respectively. Experimental results show that density of mortar and the compressive strength of mortar decrease globally with the increase in wood ash content. At 56 days, and for all replacements with wood ash, compressive strengths values of mortar obtained with the mixture of wood ash and river sand is greater than 20 MPa, which is not the case for mortar made with crushed gneiss and wood ash. Moreover, for 5% of replacement with wood ash, compressive strengths of mortar obtained with the mixture of wood ash and river sand and the mixture of wood ash and crushed gneiss are respectively 37 MPa and 32 MPa at 56 days. These values satisfied the strength requirements. Hence, 5% replacement of crushed gneiss with wood ash is suggested and could be benefit for mortar. In addition, the replacement of sand by wood ash is preferable with river sand which contains fewer fines than crushed gneiss. The compressive strength of mortar with 25% wood ash + river sand could be suitable.

Importance of Sand Grading on the Compressive Strength and Stiffness of Lime Mortar in Small Scale Model Studies

Mortars provide the continuity required for the stability and exclusion of weather elements in masonry assemblies. But because of the heterogeneity of the mortar, its mechanism of behaviour under different load effects is dependent on the properties of the constituents of the mortar. The aim of paper is to determine the effect sand grading for various cement-sand-lime mortar designations (BS) and strength classes (EC) on the compressive strength and stiffness of mortar. Two silica sands;HST 95 and HST60 were used to make mortars in three strength classes: M2, M4 and M6, corresponding to mortar designations iv, iii and ii respectively. The results show that mortar made with the HST60 sand (coarser grading) usually resulted in mortar with a higher compressive strength and stiffness. The One Way ANOVA analysis of both compressive strength and stiffness at a significance level of 5% on the effect of sand grading on the two parameters also shows that they are both significant. There is also strong evidence of a linear correlation between the stiffness and compressive strength. The results indicate that in order to replicate full scale behaviour of masonry at model scales, the grading of fine aggregate in the models should be similar so as to properly model full scale behavior.

Interaction of the Mining Environment on the Properties of Hydraulic Mortars in Silty Sands in Togo

The objective of this study is to determine the influence of the surrounding soils on the granular properties of the silty sands of Togo and on the resistance of the mortars. Sand compositions are made by substituting silty sands with clay soil, vegetal soil, lateritic soil or fine elements (<0.08 mm) which are the surrounding land polluting the sands in Togo. After identification tests, the mixtures were used to prepare test specimens of mortar which are subjected to bending and compression. It appears that additions of clay and plastic soils (ES = 0, VBM > 0.53 and IP > 19) from 10% to 35% cause drops in resistance of mortars from 7% to 96%;this loss is 8% to 70% for the rates of addition of less clayey soil (ES = 33, VBM = 0.40 and IP = 0) at rates of 10% to 100%. As for fine powdery soils (ES = 56.53 and VBM = 0.25), they have virtually no influence on resistance (loss of less than 3% for rates of 100%). Construction stakeholders thus have a decision-making tool for the choice of silty sand extraction zones according to the surrounding land and the quality of the desired concrete.

双壳层结构氯离子结合陶砂对海砂砂浆性能的影响

为控制混凝土内源型氯离子的危害,对核壳结构氯离子结合陶砂进行了研究,采用掺纳米二氧化硅(NS)水泥浆对核壳结构陶砂进行包裹,形成双壳层结构氯离子结合陶砂,并对其控制陶砂中结合的氯离子向外迁移的作用进行了研究。首先制备了以Fe_(2)O_(3)、Ca(OH)_(2)和Al_(2)O_(3)为芯料,赤泥、粉煤灰、黏土、石英为壳料,通过1200℃、1 h烧制而成的陶砂(简称CAF陶砂),当Fe_(2)O_(3)等摩尔取代1%Al_(2)O_(3)的CAF陶砂(简称CAF1陶砂)在氯盐溶液中浸泡56 d时,氯离子结合量达到172.75 mg/g。将1%NS取代率的水泥浆包裹CAF1陶砂表面形成双壳层陶砂,按20%掺入到未洗海砂砂浆中,28 d时,抗渗强度为0.3 MPa。砂浆中氯离子含量随离陶砂颗粒距离增大而减少,证明海砂中的氯离子前期被陶砂结合,并较为稳定地固定于陶砂中。

钢纤维-海泡石纤维优化铁尾矿砂-石英砂混合砂浆性能试验研究

为了在保证经济性的同时改善铁尾矿砂-石英砂混合砂浆的性能,选用钢纤维、海泡石纤维优化混合砂浆,研究了钢纤维、海泡石纤维单掺和以不同比例混掺对混合砂浆工作性能、力学性能和自然干燥收缩率的影响。结果表明,在单掺情况下,海泡石纤维对流动性的负面影响高于钢纤维,两种纤维分别以合适掺量掺入混合砂浆中,钢纤维对抗折强度和28 d自然干燥收缩率的改善效果优于海泡石纤维,而海泡石纤维对抗压强度的改善效果更佳;钢纤维-海泡石纤维以0.50%-1.0%和0.75%-1.0%组合混掺对矿浆力学性能和干燥收缩改善效果最佳。从性能改善效果和经济性角度综合考虑,确定了最优纤维掺量组合,即钢纤维、海泡石纤维掺量分别为0.50%、1.0%。在此掺量组合下,混合砂浆3 d、7 d和28 d抗折强度分别提升了15.8%、13.0%和12.5%,混合砂浆3 d、7 d和28 d抗压强度分别提升了16.2%、14.7%和13.9%,28 d自然干燥收缩率降低了32.8%,且经济性良好,每吨混合砂浆仅增加28.8元左右的成本。

不同恒温时间下疏浚砂砂浆力学及微观性能

为了对不同恒温时间下不同疏浚砂掺量砂浆的特性进行研究,选取恒温时间(4、8、12、16 h)、疏浚砂掺量(0%、15%、50%)为试验变量,利用长江下游疏浚砂替代机制砂制备了15组试件进行试验,根据试验结果分析了不同恒温时间对不同疏浚砂掺量砂浆抗压性能及微观结构的作用机理。结果表明:当疏浚砂掺量为0%和50%时,随着恒温时间增加,后期抗压强度先增大后减小,恒温时间为8 h时最大;当疏浚砂掺量为15%时,随着恒温时间增加,后期抗压强度逐渐减小,恒温时间为4 h时最大;恒温时间越长,蒸养损伤越大,不利于后期强度发展,不同疏浚砂掺量下变化规律不同;随着疏浚砂掺量增加,后期抗压强度先增大后减小,疏浚砂掺量为15%时最大;掺入疏浚砂对砂浆抗压强度有一定的优化作用,粒径极小的疏浚砂颗粒能有效填充砂浆中的孔隙缺陷,特别是经过蒸养损伤过后的砂浆,蒸养条件下疏浚砂的优化作用被放大,疏浚砂砂浆的抗压强度得到了进一步提升,疏浚砂对蒸养砂浆抗压强度的提升远大于标养砂浆,且恒温时间越长,抗压强度提升越明显;在恒温时间为4~8 h、疏浚砂掺量为15%的情况下,能制备出性能不低于纯机制砂砂浆的蒸养疏浚砂砂浆。

静停时间对长江下游蒸养疏浚砂浆特性的影响

长江下游航道疏浚产生大量疏浚砂,疏浚砂的资源化利用受到重视。利用疏浚砂部分取代机制砂制备砂浆,研究不同静停时间对疏浚砂砂浆特性的影响,测试不同龄期的抗压强度,通过X射线衍射、扫描电镜、压汞技术,分析不同静停时间、不同疏浚砂取代率砂浆的微观特性。结果表明:随着静停时间的增加,90 d抗压强度逐渐增加,抗渗性能得到明显改善;掺入疏浚砂使得砂浆的抗压强度有所提高,且随疏浚砂取代率的增加先增大后减小;疏浚砂砂浆的抗压强度与疏浚砂取代率有较大关系,其影响程度与静停时间有关,疏浚砂对低静停时间有较突出的增强效果;疏浚砂有效改善了由蒸养造成的孔结构粗化和孔隙增大等问题,适宜的疏浚砂取代率对蒸养砂浆性能的改善效果明显。

凝灰岩机制砂吸水特征对砂浆早期收缩性能的影响研究

机制砂颗粒的吸水特性是影响砂浆性能的重要因素。通过研究凝灰岩机制砂饱和面干吸水率这一吸水特征参数对砂浆综合性能的影响,获得了凝灰岩机制砂饱和面干吸水率与砂浆早期收缩以及孔结构的关系。研究表明:凝灰岩机制砂饱和面干吸水率与砂浆早期总收缩以及孔隙分布密切相关。随着凝灰岩机制砂饱和面干吸水率的增大,砂浆早期总收缩增大,最可几孔径变小。

海砂的淡化及其对水泥砂浆性能的影响

本文采用淡水冲洗法处理海砂,探究淡水冲洗次数以及阻锈剂用量对海砂水泥砂浆试样性能的影响。结果表明,淡化海砂水泥砂浆试样性能随着水洗次数及阻锈剂用量的增加呈现先增加后下降的趋势,当水洗次数为5次时,试样对氯离子的抗渗透性能最佳,具有较好的耐久性和抗腐蚀性能。水洗次数为3次时试样的抗压强度最佳为11.373MPa,达到M10等级,抗折强度最佳为4.844 MPa。当阻锈剂用量为1%时,水泥砂浆试样对氯离子的抗渗透性、抗压性能和抗折性能最佳,其中抗氯离子渗透性和抗折强度相较于未加阻锈剂的试样得到了较为显著的增强。

机制砂复配的非线性效应研究

为了探究复配对机制砂关键技术指标及应用性能的影响,考察了复配机制砂与原料机制砂的关键技术指标、所配制水泥砂浆的流动性及试块强度之间的关系。结果表明:复配机制砂的颗粒级配、石粉含量、MB值、表观密度和片状颗粒含量与原料砂的相应指标呈线性关系,而松散堆积密度与原料砂呈非线性关系;相同流动度的复配砂水泥砂浆用水量小于原料砂水泥砂浆用水量的线性相加值;复配砂水泥砂浆试块孔隙率小于原料砂水泥砂浆试块孔隙率的线性相加值,其强度大于原料砂水泥砂浆试块强度的线性相加值。

玻璃砂对防腐砂浆耐腐蚀性能的影响

本文以废弃玻璃砂代替天然砂细骨料,采用硫铝酸盐水泥--硅酸盐水泥复配的技术手段配制的防腐砂浆的力学性能和抗氯离子渗透性能进行了系统研究,同时探讨了碱-硅酸(ASR)反应对防腐砂浆的影响。研究发现:当玻璃砂的替代率分别是10%、20%、30%、40%、50%,相比于对照组(100%天然砂)的强度下降分别为5.6%、9.8%、15.8%、15.9%和25.1%;玻璃砂可以提升砂浆的抗氯离子渗透性能,当玻璃砂替代率20%时,相比对照组6h小时的氯离子电通量下降了20.3%,其抗氯离子渗透性能最好;并且玻璃砂会导致掺入了玻璃砂的砂浆会发生ASR反应,其膨胀率在0.1%~0.2%。

聚合物改性海水海砂砂浆的粘结机理与耐久性研究

研究了SBR分散体、SAE分散体和SAE粉末3种聚合物对海水海砂砂浆粘性、结构、强度的影响,同时探究了在不同侵蚀环境下的耐久性,并利用SEM分析了砂浆的粘结机理。研究结果显示,聚合物能显著提高海水海砂砂浆的粘合结构性能和耐久性;SAE粉末对粘合结构性能和耐久性能的改善效果最好;不同聚合物形成的聚合物膜致密程度存在差异,导致其对修复系统粘合结构性能和耐久性的影响不同,聚合物形成的膜越致密,砂浆的粘性和耐久性能越好;通过SEM分析知,SAE粉末在修复界面形成的聚合物膜较致密,SAE分散体形成的膜较松散,而SBR分散体形成的膜介于两者之间。

巴基斯坦废弃粉细砂抹灰砂浆的耐久性能研究

为了解决巴基斯坦废弃粉细砂抹灰砂浆易开裂、空鼓、脱落等问题,研究了纤维掺量(0、0.3、0.6、0.9、1.2、1.5 kg/m^(3))和膨胀剂掺量(0、4%、8%、12%、16%)对砂浆干燥收缩和弹性模量的影响。结果表明:随着纤维掺量的增加,砂浆的干燥收缩先降低后增加,弹性模量先增加后降低,纤维的最佳掺量为0.9 kg/m^(3);随着膨胀剂掺量的增加,砂浆的干燥收缩和弹性模量均降低;掺入适量的纤维和膨胀剂可以提高砂浆的耐久性能。

矿物掺合料对海水海砂水泥砂浆性能影响的分析及优化

【目的】研究矿物掺合料对海水海砂水泥砂浆抗压性能与游离氯离子固化性能的影响。【方法】通过四水平三因素正交试验,研究水胶比、粉煤灰相对掺量、矿粉相对掺量对海水海砂砂浆立方体抗压强度、游离氯离子固化率的影响。通过方差分析研究3因素对立方体抗压强度、游离氯离子固化率的显著程度,通过极差分析得到3因素的影响规律。【结果】相较于基准砂浆,FAGGBS/海水海砂砂浆立方体的抗压强度最大提升幅度为14.4%。通过客观赋权法获得最佳配合比方案为SSM5试验组。【结论】合理掺入矿物掺合料能优化海水海砂水泥砂浆的性能。