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Mass timber (MT), a group of large engineered structural wooden panels, is becoming increasingly popular due to sustainable construction. Despite the numerous benefits of MT-based buildings, such as low-carbon emission, short construction time, and cost-effectiveness, the concerns regarding the durability of MT may limit their market acceptance. These concerns prompted studies on minimizing the degradation risk of MT structures, which was the focus of this paper. MT products fabricated from dimensional lumber with low natural durability increases their susceptibility to biological degradation. Durability issues, including degradation under weathering and biological attack, have been reported for cross-laminated timber (CLT) and glue-laminated timber (Glulam) subjected to outdoor conditions. Several protocols have been implemented for wood protection, which could be explored for MT-based structures. Therefore, this review paper explores the application of the established wood protection protocols to MT structures. We reviewed the current knowledge in wood protection, the need for large dimension building elements such as MT, and the possible implementation of the already established wood protection protocols for MT structures.

This paper presents the effects of various nano-CaCO3 (NC) contents on 28 days compressive strength and microstructure of high volume slag (HVS) pastes and high volume slag-fly ash (HVSFA) blended pastes. The results show that addition of 1–4% NC improved the compressive strengths of HVS pastes containing 70%, 80% and 90% slag, respectively by 8–24%, 1–16% and 2–20% compared to their reference pastes. The compressive strength of HVSFA paste containing combined slag and fly ash content of 70% is also increased significantly by 16–24% than the reference control paste due to the addition of 1–4% NC and maintained higher compressive strength than OPC paste after 28 days of curing. The addition of NC reduced the large capillary pores and cumulative pore volume of HVS pastes and HVSFA paste. Significant reduction of calcium hydroxide (CH) in HVSFA paste containing combined slag and fly ash content of 70% is found due to the addition of NC by thermogravimetric analysis (TGA) and a slight increase of CH is noticed in all HVS paste. A denser microstructure with fewer internal micro-cracks and more hydrated products are revealed in scanning electron microscopic (SEM) images and EDS trace analysis in all HVS and HVSFA pastes due to the addition of NC. HVS and HVSFA paste with significantly lower carbon footprint and higher compressive strength than control cement paste can be achieved with the inclusion of 1% NC.

Punching shear capacity assessment of column footings in current design codes is mainly based on experiments performed on reinforced concrete flat slabs. Experimental investigations of footings were quite rare and they were mostly performed in laboratories, where the soil was simulated in a variety of ways. For that reason, in this study an experimental investigation of footing punching was conducted in situ with a test frame buried in the subgrade soil with predesigned and controlled characteristics. Thus the answer was given to the question of how the individual characteristics of the footings and of the soil affect the punching shear capacity and how accurately the punching shear capacity of tested column footings can be predicted according to Eurocode 2 and ACI 318–19. A special attention in this paper is paid to the effects of soil reactive pressures and stiffness of the footing–subsoil system on the punching shear capacity of footings, based on which a modification of the expressions for punching shear capacity according to ACI 318–19 and Eurocode 2 is proposed. In most cases, a significantly better agreement with the results of experiments (both our own and those of other researchers) is achieved by the proposed modification compared to the considered design codes.