A Study on the Flexural Behaviour of Geopolymer Lightweight Eco-Friendly Concrete Using Coconut Shell as Coarse Aggregate

This paper presents the flexural behaviour of concrete containing ground granulated blast furnace slag (GGBS) as a binder, manufactured sand (M-sand) as a fine aggregate, and coconut shell (CS) and crushed stone aggregate (CSA) as coarse aggregates. Alkaline activator sodium hydroxide with 10 molarity and sodium silicate were used in a weighing proportion of 1 : 2.5 to produce structural grade concrete. Out of 12 beams cast, 6 were used to study geopolymer coconut shell concrete (GPCSC) beam behaviour and 6 were used to study geopolymer conventional concrete (GPCC) beam behaviour. Data presented include cracking behaviour, ultimate moment capacitates, deflection behaviour, ductility ratio, and end rotation of the beam. Laboratory investigations show encouraging results, and it can be summarized that coconut shell has good potential as a coarse aggregate for the production of structural grade geopolymer lightweight coconut shell concrete.

Characterization and impact of curing duration on the compressive strength of coconut shell coarse aggregate in concrete

Partial replacement with coconut shell coarse aggregates was studied as a means to produce lightweight coconut shell concrete (CSC). Coconut shell concrete is a structural grade lightweight concrete that has a lower self-load compared to the normal weight concrete (NWC), which allowed the production of larger precast units. An experimental study and analysis were conducted using different volume percentages of 0%, 10%, 30%, 50%, and 70% of coconut shell as coarse aggregates, to produce M30 (30 MPa) grade concrete. The compressive strength of the NWC and CSC were obtained on the 7th and 28th day. The optimum results obtained for M30 grade concrete at 7th and 28th day of CSC were 34.2 and 38.6 MPa, respectively. In addition, the workability and weight-reduction were analyzed and compared with NWC. Scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS/EDX) and Fourier transform infrared spectroscopy (FTIR) were also used to investigate the structural morphology, chemical composition, and infrared functional groups of the concrete.

Prediction of Maritime Pine Boards Modulus of Elasticity by Means of Sonic Testing on Green Timber

Timber buildings are experiencing a rapid diffusion due to their good performance and their sustainability; however, some steps of structural timber production process, such as drying, are energy-intensive and environmentally impactful, and many wood species are also affected by low yield. Therefore, it would be important to determine the quality of the green material, that is, in wet condition, before undergoing the most impactful and expensive production steps. This paper describes a research aimed at quantifying the variation of the dynamic modulus of elasticity MoEdyn, which is commonly used for structural timber mechanical grading, from wet to dry condition in Sardinian maritime pine boards to be used for the production of laminated timber, and to examine the relationship between wet and dry MoEdyn. The MoEdyn was determined from measurements of the velocity of sonic waves propagating through the boards. The results show that the dry MoEdyn can be estimated starting from boards sonic testing in the wet condition, so providing a basis for implementing Sardinian maritime pine pre-grading in order to obtain the reduction of manufacturing costs, the abatement of environmental impact, and the increase of structural grade yield.

Strengthning Properties of Concrete with Partial Replacement of Sand by GBFS

It is an evident fact that, the rate of depletion of natural resources like sand is moving to higher grounds every year. In order to curb the later effects, an investigation is led by replacing a portion of sand by GBFS in the entire mixture. GBFS (Granulated Blast Furnace Slag) is a waste byproduct obtained from mining and other industries, whose disposal has led to various Environmental Nuisances. In this investigation the trial mixes by replacing sand by GBFS for 0%, 25%, 50%, 75% & 100% are used. The aim of the investigation is to study the strengthening properties of concrete and various attributes involved in it. In our investigation the absolute number of 30 cubes, prisms and cylinders are prepared for deciding the compressive, flexural and split strengths separately. At 7and 28 days relieving period. In view of the test outcome it was seen that the quality properties of solid increments with expanding the level of GBFS sand The optimum replacement proportion is obtained between 50-75%. The compressive strength, flexural strength and split tensile strength is increased about 3.43%, 17.11% and 10.58% respectively when compared to conventional concrete at 28 days curing period. Even at 100% replacement level of GBFS sand also we will get a good structural grade concrete. Hence utilizing GBFS sand in the concrete is economical as well as environmental friendly option for producing a greener concrete.