Sustainable Thermal Insulation Biocomposites from Locally Available Hemp and Lime

The key focus of the presented research is on sustainable thermal insulation biocomposites which can be made from locally available hemp and lime. The main gains of the use of such material are given, with emphasis on CO2 reduction. In the first stage samples of an artificial hydraulic lime using three different limes and three hydraulic additives are created and tested, the one with the highest compressive strength (DL60 lime with 40% metakaolin addition) are chosen for further research. In the second stage three different density mixes with the chosen binder are created, optimal hemp/binder ratio is determined, as well as compressive strength and thermal conductivity. Results indicate that created mixtures have good potential as self-bearing thermal insulation material used in low-rise buildings

PRODUCTION OF MAGNESIUM BINDER COMPOSITES USING LOCAL RAW MATERIALS AND TECHNOGENIC PRODUCTS

Building sector is known as one of the biggest polluters, causing environmental pollution and carbon dioxide emissions, most of which are generated during the production process of building materials. Therefore, researchers and manufacturers have become increasingly interested in environmentally friendly materials with low energy consumption. Magnesium based cements are being studied as an alternative to a widespread material as Portland cement, thus reducing the temperature required for calcination. During this research, magnesium binder-based composites using two types of magnesium (local dolomite waste material and caustic magnesia) were produced. Within the framework of this study, several regimes of thermal treatment were used to produce low carbon dioxide and environmentally friendly magnesium binder composites. Physical, mechanical and thermal properties of obtained specimens were tested.

Experimental justification for sapropel and hemp shives use as thermal insulations in Latvia

Fossil energy resources in Latvia are imported from other countries, but at the same time, our country is rich in renewable energy resources and other raw materials, which are used very little. In the study it is proposed to create a thermal insulation material from hemp shives grown in Latvia as a filler material and lake sediment - sapropel as a binding agent. Both of the following materials are organic, renewable and locally available. Laboratory experiments show that ecological and complying with modern requirements thermal insulation material can be obtained from local, renewable raw materials: sapropel and hemp shives

EXPERIENCE OF APPLICATION HIGH PERFORMANCE CEMENT COMPOSITES FOR CREATING DURABLE SCULPTURAL ELEMENTS

Traditionally, sculptural and decorative elements of building facades are created from mortar mixes based on lime, gypsum or Portland cement. Generally these materials have porous and permeable structure, which determines their accelerated degradation, especially in the aggressive environment of modern cities. High performance cement composites (HPCC) have been considered for production and restoration of sculptural elements in historical buildings. For this purpose, fine-graded, multi-component and highly workable mixes were elaborated. Mix compositions were modified with micro-fillers, plasticizing and stabilizing admixtures, as well as fibers to improve material ductility and control shrinkage cracking. Basic mechanical properties and durability (such as water absorption, frost resistance) were determined and two types of HPCC were compared (>50 MPa: HPCC and >120 MPa: UHPCC). It has been confirmed that cement composite mixes are characterized by self-consolidating effect, high compressive strength, extremely high resistance versus freezing and thawing cycles and low water absorption. Surface quality was evaluated and initial water absorption (tube tests) were performed for laboratory samples and real sculptural elements after 5 years of exploitation. The results confirmed good potential for using HPCC for creating more attractive and durable architectural shapes and façade elements compared to elements made using traditional cement and lime mortar

COMPARATIVE STUDIES OF THE STRENGTH CHARACTERISTICS OF CONCRETE BLOCKS WITH TITANIUM AND IRON RODS (BARS)

The relevance of the topic of the work was shown by the accident of a multi-storey residential building in Miami, which was caused by corrosion of steel reinforcement in reinforced concrete.There is a need to maintain the bearing capacity of structures for a long time in a humid climate, aggressive environmental influences and temperature fluctuations with a lower consumption of materials used.The use of titanium will allow changing some parameters of titanium concrete structures in comparison with reinforced concrete structures. The protective layer of concrete, which serves to protect the reinforcement from the effects of the external environment, will be significantly reduced. This will help to reduce the mass of concrete structures while maintaining strength properties and will allow you to create lighter structures that can withstand heavy loads.Strength tests were carried out on concrete blocks reinforced with smooth iron or titanium rods Ø10 mm, which showed the prospects of replacing steel reinforcement with titanium reinforcement in reinforced concrete

THERMAL CONDUCTIVITY AND FROST RESISTANCE OF FOAMED CONCRETE WITH POROUS AGGREGATE

The paper reports a study, which was carried out to examine thermal and frost resistance properties of foamed concrete (FC) with porous aggregate (expanded glass (EG) granules and cenospheres). By adding lightweight and porous aggregate to the FC mixture, it is possible to improve important physical, mechanical, and thermal properties of the prepared FC specimens. In the framework of this study the coefficient of thermal conductivity and frost resistance of hardened FC samples were determined. The structure of FC matrix and used aggregates were characterised by using a method of optical microscopy

RESEARCH ON PROPERTIES OF COMPOSITES BASED ON MAGNESIUM BINDERS

The research is devoted to composites based on magnesium binders, which is very perspective building material in the modern construction industry. Magnesium based binders have better compatibility with organic fillers comparing to traditionally lime binder cement [1]. In this investigation two magnesium-based binders are used, such as magnesium chloride and magnesium sulphate. The aim of this study is to investigate the physical, mechanical and durability properties of composites based on magnesium binders, such as density, compressive strength, thermal conductivity and capillary water absorption, and to obtain magnesium binder that could be used to produce foamed concrete. This can be done by improving the composition of the mixture. In this framework properties of magnesium binders are analysed and how these binders can affect to the properties of magnesium based composites

Artificial hydraulic lime binder and its impact on properties of hemp-lime compositions

The rising global temperature is partly associated with the increase of anthropogenic carbon dioxide (CO2) emissions. Major part of this CO2 comes from building material industry and from energy consumed to maintain buildings. To solve this problem a building material that both has low thermal conductivity and emits low amount of CO2 is needed. Hemp and hydraulic lime building materials are one of these materials, but they are not widely used partly due to insufficient research of their possible properties. The aim of this research was to find optimal composition of artificial hydraulic lime binder and to elaborate appropriate compositions of hemp-lime insulating material. The binder itself was also to be tested as multiple air limes were supplemented with different additives and the most appropriate for use in hemp-lime material was to be chosen – a dolomitic lime DL60 with 40% metakaolin additive. The ratio of hemp/binder 0.38 gave the best results – compressive strength of 0.221 MPa at 10% deformation and thermal conductivity of 0.0757 W/m2k, which is considered a good result and shows a possibility for this material to be used as self-bearing thermal insulation building material

Sand Partial and Full Replacement in Concrete Composite with Rubber Crumbs

The objective of the research on rubberized concrete that substitutes sand fillers with rubber crumbs by volume or weight is to identify ways to utilize discarded rubber tires and improve the building industry’s sustainability. The research indicates that substituting sand fillers with rubber crumbs can have a substantial effect on the concrete’s physical and mechanical qualities. Significant decreases in flexural strength and compressive strength are observed when 100 % of the sand is replaced with rubber crumbs, showing that the attributes of rubber concrete are weaker than those of conventional concrete. Note that the precise mix design and proportion of rubber crumb replacement will alter the qualities of rubber concrete. Therefore, it is essential to conduct proper laboratory testing and trial mixing in order to optimize the mix design and determine the replacement % that would deliver the needed qualities and match the standards. The flexural strength of the reference sample was 2.7 MPa and its compressive strength was 57.7 MPa, compared to the compressive strength of the sample in which 100 % of the sand was replaced with rubber crumbs. The flexural strength of sr100 was 0.39 MPa and its compressive strength was 4.4 MPa. It is also important to note that rubberized concrete may still have some advantages over ordinary concrete, such as enhanced sound insulation, thermal insulation, and chloride ion penetration resistance. These characteristics may make it useful for applications including sound barriers, underground constructions, and marine structures

Investigation of influence of nano-reinforcement on the mechanical properties of composite materials

The present work studies the possibility to decrease the formation of micro and nano cracks around short fibres in fibre-reinforced concrete (FRC) composite with the help of nano-reinforcement, which is carbon nanotubes, or micro reinforcement, which is carbon short fibres and nano-fillers. Tensile and bending strength of FRC depends on the spatial distribution of fibres inside a material, type of fibre and cement matrix, as well as an effective micromechanical work of each fibre while pulling out of the concrete matrix. Shrinkage stresses, acting in the matrix in the vicinity of a fibre, lead to the formation of micro-cracks. Such micro-cracks were observed experimentally and were investigated numerically performing broad modelling based on the finite element method (FEM). The investigation was focused on the micromechanical behaviour of a single steel fibre in a cement matrix. Numerical modelling results demonstrated a high level of shrinkage overstresses around steel fibres in concrete. The role of nano and micro admixtures, nanotubes, short carbon fibres as well as the role of water/cement ratio in a high performance concrete matrix, changing (increasing or decreasing) the friction force between the matrix and the steel fibre, were investigated experimentally by way of per­forming a single fibre pull-out tests. The high scatters of experimental results were obtained in performed pull-out tests. At the same time, for the same series of samples, a positive role of micro and nano admixtures and carbon nanotubes in the increase of pull-out force was recognised