Papers by Keyword: Supplementary Cementitious Material

Abstract: The present research studies the compressive strength of cement mortar cubes prepared from different proportions of supplementary cementitious materials (Fly Ash and Slag) in blended cement. This research aims to find the tentative optimum composition of supplementary cementitious material that shows better performance under tannery wastewater condition, such as that in effluent treatment plants. Synthetic tannery wastewater was simulated in laboratory after collecting wastewater sample from local tannery industry. Eight types of cement compositions (varying supplementary materials proportions) have been chosen. Compressive strength test has been conducted on mortar cubes over a period of three months. Test results revealed that slag addition had shown significantly stronger effects than that of fly ash addition. Also, the combined effect of fly ash and slag and their order of variation on strength were studied. The observations made from this research will be helpful for selection of blended cement proportions in future structures exposed to similar severe conditions.

Abstract: The growing need for building material resources, and the requirements to preserve the environment, in a vision of sustainable development, has become necessary to study reinforcement techniques, using composite materials. Using local organic or inorganic materials in construction fields and public works is particularly important. Polymer mortar composites (PMC) are usually employed in the building industry as finishing materials, tile adhesive (mortar-adhesive) or façade coating. In repair applications, the addition of soluble polymer (latex) allows improving the adhesion properties of the materials used as coating. The use of mineral additives as partial substitutes for cement, in construction sites as well as in ready-to-use mortars, is an unknown practice in our country. For this reason, we thought it is crucial to study and assess the influence of these additions on the properties of cured composite. Supplementary cementitious materials (SCM) used in this study are silica fume and natural pozzolan, which necessarily need to be valorized.The present research work aims to use a specific experimental methodology that is able to identify the relationship between the degree of substitution by the mineral additives, the polymer and the modifications to the properties of fresh and hardened cement mixtures. Therefore, five PMC combinations were formulated from different percentages of additions, i.e. natural pozzolan (NP: 25%^w), silica fume (Sf: 5%^w) and polymer latex (P: 0, 5, 7.5, 10, 12.5 and 15%^w). Their durability factors, such as the porosity accessible to water and capillary absorption rate (sorptivity), were characterized, at different maturities. An attempt was also made to determine the thermal coefficients. The results obtained were compared with those of the reference mortars, made with Portland cement (CEMI). They showed that the decrease in porosity, sorptivity and thermal conductivity depends on the pair “SCMs/polymer”. But overall, the addition of polymer latex and pozzolanic additions have a beneficial effect on the durability and thermal properties of the composite materials.

Abstract: Metakaolin, a supplementary cementitious material, together or separately with silica fume and fly ash, has been widely used as a replacement material for cement. This research is to determine the effect of metakaolin replacement of cement (0%, 7%, 9% and 12 %) to the 3, 7, 14 and 28-day compressive strengths of wet cured concrete at water/cement ratio of 0.4 and design strength of 40 MPa. The workability of the fresh concrete was measured through slump and compacting factor tests. Results show that the workability of the fresh concrete decreased up to 80% at metakaolin replacement of 12%. Replacing metakaolin by 12 %, on the other hand, had resulted in the highest compressive strength, which is 48.5 MPa at 28 days compared to control and other percentages of replacement. The porosity measured on the broken samples taken from the compressive strength test shows that the pore diameter size of metakaolin concrete is almost 93% finer than the controlled concrete, which had contributed to the increased in the strength. The use of metakaolin as supplementary cementitiuos material is hoped to be able to replace or stand tall as others similar to it in the market either due to its strength or cost.

Abstract: The paper presents some preliminary results on using a new supplementary Cementitious material based on industrial by-products most of them unrecyclable until recently. The opportunity for using such industrial unrecyclable wastes in construction industry has recently been recognized by researchers as having net benefits for the environment. This strategy has the potential to reduce costs, conserve energy and minimize waste. The concept very much fits into the era of sustainable development. In view of this fact, the effect of curing conditions on the self weight and strength characteristics of an eco-mortar is studied and preliminary encouraging results are presented. The eco-cement, in the form of anhydrous calcium sulphate, is set to replace the ordinary Portland cement in the mix proportion. It is made from industrial wastes and can be entirely recycled after its expiration date. The curing conditions consisted in air curing for 28 days or various time intervals for curing in water until the day of testing. The strength properties at the age of 28 days are investigated in terms of bending tensile strength and compressive strength. The obtained results show that the curing conditions play an important role both on the self weight and on the strength characteristics.

Abstract: The present study aims to investigate the opportunity to largely substitute low heat Portland cement of mass concrete with supplementary cementitious materials. The pozzolanic reaction of two types of supplementary cementitious materials, phosphorous slag powder and fly ash , were determined by X-ray diffraction, differential thermal analysis–thermogravimetry and scanning electron microscopy from 28 to 90 days. The properties of mortar and mass concrete containing 30% of supplementary cementitious materials were also investigated. Results showed that supplementary cementitious materials could decrease the amount of calcium hydroxide, fill the capillary pores, thus making the mortar and mass concrete more compact and durable. Long-term strength of mass concrete containing 30% of supplementary cementitious materials were comparable (or even better) than the control concrete (without supplementary cementitious materials) at constant workability, while the Young’s modulus was lower than the control concrete.