Global concerns about climate change have led to the development of building materials that use plant biomass with the added benefit of sequestering carbon from the atmosphere. Lightweight concrete made with hemp, is a material with huge potential in terms of its ability to achieve hygro-thermal performances close to those of polystyrene. This ecological material, referred to in the literature as hemp concrete, is made of some components that, depending on the chosen combination, can generate different results of the physic-mechanical properties. The method is based on a series of experiments that are generated using a program called Design of Experiments (DoE). This program uses statistical analysis of a series of experiments performed by varying one of the input parameters, like the amount of hydrated lime or cement. Following this analysis, it is possible to identify those elements used in the composition, which produced a significant influence on the physical-mechanical properties of hemp concrete. Moreover, this method also allows a quantification of the influences so that the parameters can be ranked, with a minimum number of experiments. The method is, in the same time, a modern and an economical technique used for experimental planning. The aim of the research is to quantify numerically the influence of each component element of the mixture that determines variations of the physical-mechanical properties in hemp concrete. This study will contribute in the future to the optimization of compositions, which will be differentiated on the basis of mechanical performance or thermal insulation criteria.

The meaning of technological progress is to produce economic development and to increase the level of personal comfort. Sustainability can only be achieved if, at the microsystem level as well as at the macrosystem level, the secondary effects of the activities undertaken by people on the environment are in a state of neutrality compared to the impact they can produce on natural conditions. This neutrality can be intrinsic or can be achieved through coercive and compensatory measures. If we take into account the production of carbon dioxide that accompanies a product from the stages of conceptualisation, design, procurement of materials, execution, operation, maintenance, decommissioning and recycling the waste produced at the end of use, then nothing can be sustainable in pure form. Nevertheless, there are products whose production, both as a raw material and as a technological process, can be neutral in terms of carbon emissions. Moreover, they can even become carbon negative over time. This is also the case with eco-sustainable hemp concrete, whose capacity to absorb carbon dioxide starts from the growth phase of the plant from which the raw material is obtained and continues throughout the existence of the constructed buildings. Not only does it absorb carbon dioxide, but it also stores it for a period of at least 50 years as long as the construction is guaranteed, being at the same time completely recyclable. However, in order to obtain an optimal mixture from the point of view of raw material consumption, represented by industrial hemp wood chips and the binder based on lime and cement, multiple experiments are necessary. The study presented in this work is based on the use of an advanced method of experimental planning (design of experiments method), which makes possible the correlation between the values obtained experimentally and the algorithm that generated the matrix arrangement of the quantities of materials used in the recipes. This approach helps to create the necessary framework for parametric optimisation with a small number of trials. Thus, it is possible to obtain the mathematical law valid within the minimum and maximum limits of the studied domain that defines the characteristics of the material and allows the achievement of optimisation. The material is thus designed to satisfy the maximum thermal insulation requirements that it can achieve depending on a certain minimum admissible compressive strength.

Food, energy and construction are the three main domains in which different uses of industrial hemp confirm the role and importance that agriculture has in human life. In the current context with an increased need for energy efficiency and environmental protection, the attention of scientists is directed towards the identification of ecological construction materials, and a sustainable way of life, where the circular economy must become part of people’s living habits. The objective of the research was to analyze the thermo-mechanical properties of hempcrete. The goal is to determine a point of reference for future studies that will aim to adapt the agreed compositions to the particularities of the raw material obtained locally. Measurements were determined through laboratory tests, performed on specimens obtained using, for the base material, the woody part of industrial hemp, and for the binder, a mixture consisting of hydrated lime and Portland cement. The results place the construction materials made from hemp vegetable waste in the group of heat-insulating products characterized by low specific weight and thermal transfer coefficients, according with conventional insulating materials, with values between those of polyurethane foam and autoclaved cellular concrete.

The objectives of the research were to analyse how the treatment with sodium hydroxide solution of hemp stems influences the mechanical and thermal behaviours of concrete when hemp stems are used in the composition of concrete. Tests were performed on hemp concrete samples to evaluate the density and measure the heat transfer coefficient, compressive strength and modulus of elasticity. The activities carried out aimed to identify the influence of the sodium hydroxide solution concentration on the variations of the measured parameters and expressing some conclusions regarding the need to treat the hemp stems before their use in concrete. The need for research is given by the nowadays demand for obtaining eco-sustainable construction materials, in which the possibility of using a material that is considered plant waste becomes an economic resource in a circular economy.