Abstract: A precast concrete structural unit is provided including a concrete sub-unit and a plastic resinous sheet. The sheet is adhered to the sub-unit at the time of pouring the concrete, utilizing a polychloroprene contact adhesive. The structural unit may further include adhesive coated reinforcement. Among the concrete structural units which are provided is a burial vault including concrete wall portions and a plastic resinous liner. The liner is adhered to the wall portions, at the time of pouring the concrete, utilizing the polychloroprene contact adhesive. The vault may also include adhesive coated reinforcement. The polychloroprene contact adhesive is essentially a blended aqueous latex comprising hydrophilic chloroprene copolymer latex particles and emulsified or dispersed hydrocarbon resin tackifier particles.